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Research ArticlePolychlorinated Biphenyls in the CentralizedWastewater Treatment Plant in a Chemical Industry ZoneSource Distribution and Removal
Min Yao12 Zhongjian Li1 Xingwang Zhang1 and Lecheng Lei1
1 Key Laboratory of Biomass Chemical Engineering of Ministry of Education Zhejiang University Hangzhou 310027 China2 Faculty of Architectural Civil Engineering and Environment College Ningbo University Ningbo 315211 China
Correspondence should be addressed to Lecheng Lei lcleizjueducn
Received 13 March 2014 Revised 8 June 2014 Accepted 10 July 2014 Published 5 August 2014
Academic Editor Davide Vione
Copyright copy 2014 Min Yao et alThis is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
Polychlorinated biphenyls (PCBs) could be dissolved in wastewater or adsorbed on particulate The fate of PCBs in wastewateris essential to evaluate the feasibility of wastewater treatment processes and the environmental risk Here dissolved and adsorbedconcentrations of twenty concerned PCB congeners and total PCBs have been measured in the centralized wastewater treatmentplant of a chemical industry zone in Zhejiang China It was found that the dyeing chemical processes were the main source ofPCBs which contributed more than 136 The most abundant PCB was PCB-11 in the liquid and solid phase of each treatmentstage accounting for more than 60 of the total 209 PCBs Partitioning behavior of PCBs between the dissolved and adsorbedphases suggested that Di-CBs were the dominant isomers (gt70) and more than 898 of them was adsorbed on the particles andsludge The total removal efficiency of sum209 PCBs was only 232 throughout the whole treatment process A weak correlationwas obtained between the individual PCB concentration and their log119870ow in primary sedimentation anaerobic hydrolysis aerobicbioprocess stage and the whole treatment process
1 Introduction
Polychlorinated biphenyls (PCBs) are a class of significantpersistent organic pollutants (POPs) that consist of 209congeners being of increasing global concern because oftheir high toxicity resistance to biodegradation biologicalaccumulation and long-range transport [1] Although PCBsproduction in most countries has been banned since the1970s and 1980s PCBs contaminations remain ubiquitousand coexist in most environmental matrices including watersediment soil and air all over the world [2ndash4] Exposureto PCBs can cause neurological disorder reproductive tox-icity endocrine disruption cancer and deformity even atextremely low concentrations [5] Thus it is important andnecessary to study the source distribution and removal ofPCBs in the environment
There are various sources of existing PCBs in the envi-ronment most of which were accumulated during the period1950 to 1983 due to their worldwide use as lubricants
heat transfer agents paint additives and insulating mediain capacitors and voltage regulations Also PCBs can begenerated and introduced into the environment as byprod-ucts from waste incineration and various chemical industrialprocesses [6] Therefore tracing the source of PCBs is veryimportant to study their transport and fate in the environ-ment [7] Recently it is reported that the wastewater treat-ment plants (WWTPs) are another potential source of PCBsto the ambient environment [6 8ndash11] Therefore increasingattention has been paid to the fate of PCBs in WWTPsKatsoyiannis and Samara [12] found that more than 50 ofthe total seven indicator PCB congeners (PCB-28 52 101 118138 153 and 180) were absorbed in sludge and the concen-tration of the PCBs in wastewater was decreased from 1000to 250 ngL after treatment (samples were from a WWTPin Thessaloniki northern Greece) However Bergqvist etal [10] found that the concentrations of sumPCBs (sevenindicator PCBs and PCB-47 105 156) increased from 03 to1 ngL in Umea (Sweden) and from 9 to 34 ngL in Siauliai
Hindawi Publishing CorporationJournal of ChemistryVolume 2014 Article ID 352675 10 pageshttpdxdoiorg1011552014352675
2 Journal of Chemistry
Aerobic bioprocessAnaerobic hydrolysis
Waste activated sludge
Retu
rned
Activ
ated
slud
ge
SSE
Lift pump
PSS
ASHCS
HCE
Sludge thickener
Outgoing wastewater
Mixing regulation
Incoming sewer
High-density clarifier
RWPSE AHE
Belt filter
Disposal
FS
Primary sedimentation
Secondary sedimentation
Figure 1 Flow chart of the centralized WWTP in Zhejiang China (f location of samplings) RW raw wastewater PSE primarysedimentation effluent AHE anaerobic hydrolysis effluent SSE secondary sedimentation effluent HCE high-density clarifier effluent PSSprimary sedimentation sludge AS activated sludge HCS high-density clarifier sludge and FS final sludge
(Lithuania) WWTP during the treatment process Based onthe above-mentioned two papers it is very likely that differentwastewater components and wastewater treatment processeshave significant effect on the PCBs fate In China owingto the rapid development in manufacturing industries thepollutants in wastewater are increasing dramatically whichincreased the variety and complexity of PCBs in wastewaterin WWTPs However few detail data are available for thefate and removal of PCBs in the WWTPs in China takingboth PCBs distribution inwater and absorption in sludge intoaccount
The aim of our study was to thoroughly investigatethe fate of PCBs in the conventional wastewater treatmentprocesses Here a WWTP treating dyeing chemicals anddomestic wastewater in Zhejiang province China was cho-sen in this project Firstly we investigated the PCBs in theWWTP contributed by the dyeing chemical industry Thenthe indicator PCBs dioxin-like PCB congeners and threelightly chlorinated biphenyls (PCB-11 15 19) and total PCBs(from Mono-CBs to Deca-CBs) were quantitatively analyzedboth in wastewater and sludge at each treatment stage in theWWTP The distribution of PCBs between the dissolved andadsorbed phases in the influent and effluent of each treatmentstage was investigated as well Furthermore PCBs removalefficiencies at each treatment stage and the key removalmechanismwere also studied Ourworkwill provide a deeperunderstanding of the PCBs fate in WWTP and a theoreticalbasis for the source control
2 Materials and Methods
21 Plant Description and Sampling
211 Plant Description The centralized wastewater treat-ment plant (WWTP) is located in a chemical industry zone
in Zhejiang province ChinaTheWWTP is located outdoorsand processes 90000ndash120000m3 of raw wastewater per dayAbout 70 of the total flow is contributed by industrialactivities especially by dyeing chemical industries in thezone as well as a small amount of domestic sewage Theinfluents of wastewater through pipelines first pass screeningand grit and grease chambers and then are fully mixed inthe mixing regulation tank to be the raw wastewater (iemixed influent) The wastewater treatment processes includeprimary sedimentation using chemical flocculants (polyalu-minumchloride PAC) anaerobicaerobic (AO) biochemicaltreatment (including anaerobic hydrolysis process by anaer-obic biofilter and aerobic bioprocess by activated sludge)secondary sedimentation for the settlement of activatedsludge and high-density clarifier by ferrate oxidation Theflow chart of the plant is shown in Figure 1
212 Sampling Sites The wastewater suspended particulatematter (SPM) and sludge samples were taken from theoutlet of each processing stage during late October and earlyNovember 2010 (October 26 and November 6) Duplicatesamples of wastewater were collected along the treatmentsystem to study the sampling reproducibility namely themixed influent of raw wastewater in the mixing regulationtank (RW) the effluents of primary sedimentation anaerobichydrolysis aerobic bioprocess secondary sedimentation andhigh-density clarifier tanks (PSE AHE SSE and HCEresp) Grab samples of sludge were collected from theprimary sedimentation tank (PS) the recirculation stream(activated sludge AS) high-density clarifier tank (HCS) andsludge thickener tank (final sludge FS) concurrently withthe wastewater samples All sampling containers were insequence washed with water acetone dichloromethane andthe wastewater samples before use
Journal of Chemistry 3
Furthermore in order to estimate the industrial sourcesof PCBs two wastewater samples were collected from thelargest dyeing chemical group in this zone whichmainly pro-duced disperse reactive acid vat dyestuff or pigments andintermediates One sample was the mother liquor producedduring the pigment synthesis process and the other was thetreated effluent of the mother liquor entering the WWTPThe amounts of wastewater discharged into the WWTP wereabout 8000m3 per day
22 Chemicals and Reagents All solvents including acetonen-hexane methanol and dichloromethane were of HPLCgrade and purchased from Tedia Co USA Water waspurified with an ultrapure water system (Purelab UHQ ElgaLabWater UK) Silica gel (100ndash200 mesh reagent gradeQingdao Ocean Chemical Reagent Co China) anhydroussodium sulfate (analytical grade Chongqing Kelong Chem-ical Reagent Co China) and glass fiber filters (045 120583meffective pore sizes ShanghaiMosu Scientific Equipment CoChina) were baked in a furnace oven at 450∘C for 4 h prior touse
PCB calibration standard solutions 13C-labeled surrogatestandards (13C-PCB-14 65 and 166) and injection standards(13C-PCB-9 52 101 138 and 194) complying with US EPAmethod 1668A for PCBs analysis were purchased fromCambridge Isotope Laboratories in USA Here the mainlyconcerned PCBs were 20 individual PCB congeners and totalPCBs (from Mono-CBs to Deca-CBs) The individual con-geners included six indicator congeners (PCB-28 52 101 118138 153 and 180) ten dioxin-like PCB (PCB-77 81 105 114123 126 156 167 169 and 189) and three lightly chlorinatedbiphenyls (PCB-11 15 and 19) respectively The workingstandard solutions were prepared by diluting appropriatevolumes of the standard PCB mixture with HPLC-grade n-hexane
23 Sample Extraction and Purification 1 L of wastewatersamples was filtered using glass fiber filter and spiked with200 ng of 13C-labeled surrogate standards and then extractedthree times under ultrasonic conditions using liquid-liquidextraction method The total extracted volume was 180mLof dichloromethanehexane (1 1 vv) and the extracts wereconcentrated to 2mL and subjected to a solvent exchange tohexane by a rotary evaporator (RE-52AA Yarong ShanghaiChina) The concentrated extracts were sequentially subjectto multilayer silica gel basic alumina and florisil chromatog-raphy columns for further cleanup following the publishedprocedures [9 13ndash15] The multilayered silica gel column wasself-made column which was packed from bottom to topwith 1 g of activated silica 4 g of basic silica (12 ww)1 g of activated silica 8 g of acid silica (30 ww) 2 g ofactivated silica and 4 g of anhydrous sodium sulfate Thecolumns were preserved in dichloromethanehexane (1 1vv) before loading the extracts Elution of the samples wascarried out at a rate of 1mLmin under vacuum with 5dichloromethanehexane (vv)Then the eluent was collectedand evaporated to near dryness with rotary evaporatorHexane solvent was introduced as a replacement and then
concentrated to 20120583L with gentle stream of nitrogen Then13C-labeled internal standards were added prior to the GCinjection for quantitative analysis All samples were analyzedin duplicate and the average concentrations (means plusmn SD119899 = 2) were reported
The SPM in the wastewater was separated by glass fiberfilters and the sludge was dehydrated by centrifugationThe filters and sludge were freeze dried until constantweights were maintained Solid samples were accuratelyweighted and spiked with 1 ng of 13C-labeled surrogatestandards and then Soxhlet-extracted for 24 h with 400mLof dichloromethaneacetone (1 1 vv)The extracts were con-centrated to about 5mL and subjected to a solvent exchangeto hexane The concentrated extracts were subsequentlypurified and fractionated following the above mentionedmethod under identical conditions [16]
24 GCMS Analysis and Quality Control PCBs were ana-lyzed by isotope dilution method and the analysis procedurewas similar to the method described by Yang et al [15]The quantification of PCBs extracts in the wastewater SPMand sludge samples was performed on an Agilent 6890Agas chromatograph (GC) coupled with 5795C inert massspectrometer (MS) detector (Agilent Technologies USA)with an electron impact (EI) ion sourceTheMSwas operatedin selective ion monitoring (SIM) mode Helium was used ascarrier gaswith flow rate of 12mLmin Exactly 1120583Lof extractsolution was injected with 16-sample autoinjector in splitlessmode into a DB-5MS capillary column (60m times 025mm idtimes 025 120583m film thickness JampW Scientific USA) The injectortemperature and source temperature were 280 and 250∘Crespectively The oven temperature program was as follows110∘C held for 3min 110ndash150∘C at 10∘Cmin 150ndash270∘C at25∘Cmin held for 5min and 270ndash320∘C at 25∘Cmin heldfor 10min
The blank blank spike and parallel samples were intro-duced for quality assurance and quality control The back-ground concentrations were negligible due to their signifi-cantly lower levels compared to actual samples (lt3) Recov-eries of added 13C-labeled PCB-14 PCB-65 and PCB-166surrogate standards to wastewater samples prior to extractionaveraged 84 plusmn 6 88 plusmn 6 and 94 plusmn 4 respectivelyRecoveries of added 13C-PCB-14 PCB-65 and PCB-166 toSPM and sludge samples prior to extraction averaged 68 plusmn15 72 plusmn 15 and 88 plusmn 10 respectively The recoveriesmeet the requirements of US EPA method 1668A [14]
3 Results and Discussion
31 Source Analysis of PCBs from Dyeing Chemical IndustryEntering the WWTP PCBs entering the centralized WWTPcan be mainly associated with direct discharges from indus-trial emissions in the investigated zone In order to identifythe main industrial emissions as PCB source to the WWTPwe investigated the profiles of the factories or companies inthe investigated zoneThis zone is a professional developmentzone featuring as fine chemical industry focusing on pro-ducing of pharmaceuticals and the intermediates pigments
4 Journal of Chemistry
and dyes textile dyeing and finishing biochemical inorganicchemicals and other specialty chemicals The wastewaterproduced during the chemical processes was discharged intothe WWTP after simple treatment In this zone the wastew-ater discharged by pigment and dyeing chemical industriesaccounts for about 70 of the total industrial wastewaterData provided by US EPA and other workers indicate thatPCBs have been found in various color dyestuff and pigments[3 17ndash19] Rodenburg and colleagues knewPCB-11 was linkedto the manufacture of diarylide yellow pigments [3] Hu andHornbuckle detected more than 50 PCB congeners in azoand phthalocyanine pigments [18] Litten et al also foundhigh levels of PCBs in wastewater in New York harbor andtraced them to effluent from a pigment manufacturing plant[17] Thus we mainly detected the PCBs in dyeing chemicalwastewater discharged by the largest chemical industrialgroup and identified the contribution of PCBs to theWWTPby the group
The PCB species and concentrations in wastewaterdepend on the raw materials and the process of dyestuffor pigments production It is investigated that the dyeingchemical industrial groupmainly produces disperse reactivevat pigments and some intermediates which are mainly azopigments with polycyclic ketone structures and producedthrough a reaction sequence of diazotization (coupling toafford the azo group ndashN=Nndash) condensation close-loopchlorination oxidation and reduction and so forth [20]During the synthesis of these productions there are variousderivatives of polycyclic hydrocarbons used as the precursorssuch as alkylbenzenes naphthol anthrone anthraquinoneacenaphthene and quinone [21] Therefore with high tem-perature and humidity in the dye synthesis processes it is easyto generate PCBs and other POPs byproducts Based on theconcentrations and water quantity the average contributionof each PCB congener was calculated and listed in Table 1 It isshown that lightly chlorinated biphenyls were the main PCBspecies and PCB-11 77 28 and 15 were the most abundantcongeners produced during the dyemanufacturing processesThe contribution of sum209 PCBs produced by this dyeingchemical industrial group to theWWTPwas 136The threegreatest contributors wereDi-CBs Hexa-CBs andNona-CBswith the contribution percent of 154 152 and 116respectively
32 PCBConcentrations inWastewater Samples of theWWTPThe results of PCB concentrations in wastewater samplesin the influent and effluent of each WWTP treatment stageare presented in Table 2 As shown the concerned 20 PCBcongeners and PCB isomers were detectable in the RWsamples The most abundant PCB entering the WWTP inRW was PCB-11 with mean concentration of 103216 pgLaccounting for 661 of the total 209 PCBsThe less abundantPCBs were still the lightly chlorinated biphenyls includingPCB-15 two indicator PCB congeners (PCB-52 and PCB-28) and one dioxin-like PCB congener (PCB-77) with meanconcentrations of 2416 2491 1735 and 1144 pgL respec-tivelyThe concentrations of total 209 PCBs were two or threeorders of magnitude lower than the ones observed in the
previous studies [12 22 23] which indicated the risk causedby dissolved PCBs was relatively low around the WWTPCompared with the data in the literature of Vogelsang et al[24] the concentration of indicator PCBs was three times asours
In PSE AHE SSE and HCE samples the presence ofmost PCB congeners was in general similar to that in RWsamples with PCB-11 being the most abundant compoundand PCB-15 PCB-28 PCB-52 and PCB-77 being the lessabundant compounds PCB-126 PCB-169 and PCB-189 werenot detected in the effluent samples of each treatment stagealthough found in RW PCB-81 and PCB-180 were notdetected in HCE samples Interestingly sum209 PCBs meanconcentration in AHE samples was higher than that in PSEsamples In detail the concentration of PCB-28 PCB-52 andPCB-77 in AHE samples suddenly increased by 270 357and 523 respectively In anaerobic hydrolysis stage theanaerobic microbes or anaerobic sludge always stay in theanaerobic fluidized bed without replacementThus the PCBsresults may be associated with the role of anaerobic microbesand the release of PCBs from solid to liquid phase
33 PCB Concentrations in SPM and Sludge Samples of theWWTP Table 3 summarizes the mean concentrations (nggdry weight) of the 20 PCB congeners and PCB isomers inthe SPM and sludge samples Here five PCB congeners werenot detected in the SPM of raw wastewater that is PCB-15PCB-19 and three dioxin-like PCBs (PCB-126 PCB-156 andPCB-169) All the 20 PCBs were detectable in the solid-phasesamples taken from following stage As seen in Tables 2 and3 the levels of PCB congeners in the solid phase were closelyrelated to the liquid concentrations in the influentThe higherconcentrations of PCBs in the influent the higher levels inSPM and sludge samples from effluent For example PCB-11was themost abundant PCBs both in liquid and in solid phasewith a high proportion of more than 60
In primary sedimentation stage the concentrations oftotal PCBs were nearly 2 times that in SPMof rawwastewaterdue to adsorption and sedimentation by PAC flocculantsHigh levels of PCBs were detected in anaerobic SPM andaerobic activated sludge indicating that the microbial sludgehad a strong biosorption and bioaccumulation for PCBswhichmade the contribution of biotransformation biodegra-dation and volatilization obscure Therefore sorption ofPCBs onto sludge was the most likely removal mechanismin the primary and biochemical treatment stages In high-density clarifier stage PCBs concentrations in effluent andsludge samples decreased more significantly than the ones inthe aerobic bioprocess stage owing to the oxidation (althoughno evidence is available in the literature of ferrate reactionwith PCBs) or the coagulation by ferrate because ferrateat pH lt 7 generates Fe(III) ions with excellent flocculationcapability and Fe(OH)
3that is a good adsorbent [25]
The mean concentrations of PCBs in the final sludgeof the centralized WWTP were also within the range ofreported values in Table 3 sum209 PCBs mean concentration(64323 ngg dw) was one or two orders of magnitude higherthan the values observed in previous studies reported by
Journal of Chemistry 5
Table 1 The concentrations (means plusmn SD) and contribution of PCBs discharged by the largest dyeing chemical industrial group entering theWWTP
Blanchard et al Guo et al and Katsoyiannis and Samara[12 16 22] According to the Chinese regulated law (GB18918-2002) PCB levels should be less than 200 ngg dw foragricultural use [26]Therefore the PCB levels in theWWTPsludge hereweremuchhigher than themaximumpermissibleconcentration andwere not suitable for agricultural purposes
34 Phase Distribution of PCBs in Wastewater and Sludgeof the WWTP The distribution of single compounds variedamong different systems whichmight be attributed to severalfactors such as the solute concentration the amount of
solids available for sorption and the competition betweenpollutants for sorption sites of the particles [7 27] Seenfrom Figure 2 Di-CBs (783ndash931) were the predominantisomers in wastewater samples followed by Tri-CBs (29ndash79) and Tetra-CBs (22ndash59) The proportion of otherhighly chlorinated biphenyls (Hexa-CBs to Deca-CBs) wasless than 5 in each stage effluent Similar to the profilesof PCB isomers in wastewater Di-CBs (704ndash840) werethe dominant isomers in sludge followed by Mono-CBs(79ndash152) and Tri-CBs (54ndash168) with less than 3 ofcontribution of other PCBs isomers
6 Journal of Chemistry
Table 2 The concentrations (means plusmn SD) of PCBs in wastewater of each treatment stage at the WWTP
PCBs (pgL) RW PSE AHE SSE HCEIndicator PCB congener
The partitioning behaviors of organic chemicals areessential to their fate in the WWTP as dissolved andadsorbed phases are differently available to different fateprocesses [11] Based on the PCBs concentrations in liquid-solid phase water quantity and SPM yield the relativedistribution of PCB isomers between the dissolved andadsorbed phases was obtained in the present study Figure 3presents the proportions of adsorbed PCB isomers in theinfluent and effluents of each treatment stage It is clearthat the adsorbed fraction of sum209 PCBs was found torange from 898 to 974 in the influent and effluent ofeach treatment stage much higher than the findings of
Katsoyiannis and Samara [28] with less than 60 of adsorbedsumPCBs in the influent ofWWTP inThessaloniki GreeceTheadsorbed PCB isomers in secondary sedimentation effluentwere absolutely predominant varying between 873 forOcta-CBs and 998 for Mono-CBs Likewise significantadsorbed fractions of PCB isomers were also found in the rawwastewater primary sedimentation effluent and anaerobichydrolysis effluent varying between 534 for Nona-CBs and991 for Tri-CBs 540 for Nona-CBs and 994 for Tri-CBs and 459 for Nona-CBs and 983 for Mono-CBsrespectively Differently in high-density clarifier effluentNona-CBs and Deca-CBs were more ldquodissolvedrdquo among
Journal of Chemistry 7
Table 3 The concentrations (means plusmn SD) of PCBs in SPM and sludge of each treatment stage at the WWTP
SPM suspended particulate matter RW mixing influent (raw wastewater) PSS primary sedimentation sludge AHE anaerobic hydrolysis effluent ASactivated sludge HCS high-density clarifier sludge FS final sludge ND not detected sum Ind sum indicator PCBs and sum DL sun DL-PCBs
the PCB isomers with only 300 and 392 in the solidphase although the adsorbed fractions of other PCB isomerswere all above 65 in this stage Generally better removalcan be obtained for higher MW congeners by sorption ontoparticles or microbes owing to their high hydrophobicity [11]But what was reason about this unusual result As seen fromTables 2 and 3 the mean concentrations of dissolved Nano-CBs and Deca-CBs were 318 and 82 pgL in HCE and the
average levels of adsorbed Nano-CBs and Deca-CBs were0226 and 0082 ngg respectively On the one hand maybedue to the very low concentrations of them in dissolved(possible) oxidation by ferrate or flocculationadsorption byFe(OH)
3cannot occur accompanied with the competitive
effect among various pollutants On the other hand thefraction remaining in the treated wastewater unexpectedlyhigh for hydrophobic compounds could be explained by
8 Journal of Chemistry
Deca-CBsNona-CBsOcta-CBsHepta-CBsHexa-CBs
Penta-CBsTetra-CBsTri-CBsDi-CBsMono-CBs
RW PSE AHE SSE HCE PSS AS HCS FS0
20
40
60
80
100
Con
cent
ratio
n (
)
Wastewater and sludge samples
Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP
0
20
40
60
80
100
Sorb
ed P
CBs (
)
RW PSE AHE SSE HCE
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs
Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage
possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]
35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation
119877 () =(119862in minus 119862out)
119862intimes 100 (1)
where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic
0
20
40
60
80
100
Prim
ary
sedi
men
tatio
n
Ana
erob
ichy
drol
ysis
Aero
bic b
io-
proc
ess
Hig
h-de
nsity
clarifi
er
Who
le tr
eatm
ent
proc
ess
Rem
oval
()
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBs
minus20
ΣPCBs
minus528
minus150
minus118
minus587
minus182
minus322
Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage
sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents
Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes
Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal
Journal of Chemistry 9
50 55 60 65 70 750
20
40
60
80
100
120
Primary sedimentation
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
Figure 1 Flow chart of the centralized WWTP in Zhejiang China (f location of samplings) RW raw wastewater PSE primarysedimentation effluent AHE anaerobic hydrolysis effluent SSE secondary sedimentation effluent HCE high-density clarifier effluent PSSprimary sedimentation sludge AS activated sludge HCS high-density clarifier sludge and FS final sludge
(Lithuania) WWTP during the treatment process Based onthe above-mentioned two papers it is very likely that differentwastewater components and wastewater treatment processeshave significant effect on the PCBs fate In China owingto the rapid development in manufacturing industries thepollutants in wastewater are increasing dramatically whichincreased the variety and complexity of PCBs in wastewaterin WWTPs However few detail data are available for thefate and removal of PCBs in the WWTPs in China takingboth PCBs distribution inwater and absorption in sludge intoaccount
The aim of our study was to thoroughly investigatethe fate of PCBs in the conventional wastewater treatmentprocesses Here a WWTP treating dyeing chemicals anddomestic wastewater in Zhejiang province China was cho-sen in this project Firstly we investigated the PCBs in theWWTP contributed by the dyeing chemical industry Thenthe indicator PCBs dioxin-like PCB congeners and threelightly chlorinated biphenyls (PCB-11 15 19) and total PCBs(from Mono-CBs to Deca-CBs) were quantitatively analyzedboth in wastewater and sludge at each treatment stage in theWWTP The distribution of PCBs between the dissolved andadsorbed phases in the influent and effluent of each treatmentstage was investigated as well Furthermore PCBs removalefficiencies at each treatment stage and the key removalmechanismwere also studied Ourworkwill provide a deeperunderstanding of the PCBs fate in WWTP and a theoreticalbasis for the source control
2 Materials and Methods
21 Plant Description and Sampling
211 Plant Description The centralized wastewater treat-ment plant (WWTP) is located in a chemical industry zone
in Zhejiang province ChinaTheWWTP is located outdoorsand processes 90000ndash120000m3 of raw wastewater per dayAbout 70 of the total flow is contributed by industrialactivities especially by dyeing chemical industries in thezone as well as a small amount of domestic sewage Theinfluents of wastewater through pipelines first pass screeningand grit and grease chambers and then are fully mixed inthe mixing regulation tank to be the raw wastewater (iemixed influent) The wastewater treatment processes includeprimary sedimentation using chemical flocculants (polyalu-minumchloride PAC) anaerobicaerobic (AO) biochemicaltreatment (including anaerobic hydrolysis process by anaer-obic biofilter and aerobic bioprocess by activated sludge)secondary sedimentation for the settlement of activatedsludge and high-density clarifier by ferrate oxidation Theflow chart of the plant is shown in Figure 1
212 Sampling Sites The wastewater suspended particulatematter (SPM) and sludge samples were taken from theoutlet of each processing stage during late October and earlyNovember 2010 (October 26 and November 6) Duplicatesamples of wastewater were collected along the treatmentsystem to study the sampling reproducibility namely themixed influent of raw wastewater in the mixing regulationtank (RW) the effluents of primary sedimentation anaerobichydrolysis aerobic bioprocess secondary sedimentation andhigh-density clarifier tanks (PSE AHE SSE and HCEresp) Grab samples of sludge were collected from theprimary sedimentation tank (PS) the recirculation stream(activated sludge AS) high-density clarifier tank (HCS) andsludge thickener tank (final sludge FS) concurrently withthe wastewater samples All sampling containers were insequence washed with water acetone dichloromethane andthe wastewater samples before use
Journal of Chemistry 3
Furthermore in order to estimate the industrial sourcesof PCBs two wastewater samples were collected from thelargest dyeing chemical group in this zone whichmainly pro-duced disperse reactive acid vat dyestuff or pigments andintermediates One sample was the mother liquor producedduring the pigment synthesis process and the other was thetreated effluent of the mother liquor entering the WWTPThe amounts of wastewater discharged into the WWTP wereabout 8000m3 per day
22 Chemicals and Reagents All solvents including acetonen-hexane methanol and dichloromethane were of HPLCgrade and purchased from Tedia Co USA Water waspurified with an ultrapure water system (Purelab UHQ ElgaLabWater UK) Silica gel (100ndash200 mesh reagent gradeQingdao Ocean Chemical Reagent Co China) anhydroussodium sulfate (analytical grade Chongqing Kelong Chem-ical Reagent Co China) and glass fiber filters (045 120583meffective pore sizes ShanghaiMosu Scientific Equipment CoChina) were baked in a furnace oven at 450∘C for 4 h prior touse
PCB calibration standard solutions 13C-labeled surrogatestandards (13C-PCB-14 65 and 166) and injection standards(13C-PCB-9 52 101 138 and 194) complying with US EPAmethod 1668A for PCBs analysis were purchased fromCambridge Isotope Laboratories in USA Here the mainlyconcerned PCBs were 20 individual PCB congeners and totalPCBs (from Mono-CBs to Deca-CBs) The individual con-geners included six indicator congeners (PCB-28 52 101 118138 153 and 180) ten dioxin-like PCB (PCB-77 81 105 114123 126 156 167 169 and 189) and three lightly chlorinatedbiphenyls (PCB-11 15 and 19) respectively The workingstandard solutions were prepared by diluting appropriatevolumes of the standard PCB mixture with HPLC-grade n-hexane
23 Sample Extraction and Purification 1 L of wastewatersamples was filtered using glass fiber filter and spiked with200 ng of 13C-labeled surrogate standards and then extractedthree times under ultrasonic conditions using liquid-liquidextraction method The total extracted volume was 180mLof dichloromethanehexane (1 1 vv) and the extracts wereconcentrated to 2mL and subjected to a solvent exchange tohexane by a rotary evaporator (RE-52AA Yarong ShanghaiChina) The concentrated extracts were sequentially subjectto multilayer silica gel basic alumina and florisil chromatog-raphy columns for further cleanup following the publishedprocedures [9 13ndash15] The multilayered silica gel column wasself-made column which was packed from bottom to topwith 1 g of activated silica 4 g of basic silica (12 ww)1 g of activated silica 8 g of acid silica (30 ww) 2 g ofactivated silica and 4 g of anhydrous sodium sulfate Thecolumns were preserved in dichloromethanehexane (1 1vv) before loading the extracts Elution of the samples wascarried out at a rate of 1mLmin under vacuum with 5dichloromethanehexane (vv)Then the eluent was collectedand evaporated to near dryness with rotary evaporatorHexane solvent was introduced as a replacement and then
concentrated to 20120583L with gentle stream of nitrogen Then13C-labeled internal standards were added prior to the GCinjection for quantitative analysis All samples were analyzedin duplicate and the average concentrations (means plusmn SD119899 = 2) were reported
The SPM in the wastewater was separated by glass fiberfilters and the sludge was dehydrated by centrifugationThe filters and sludge were freeze dried until constantweights were maintained Solid samples were accuratelyweighted and spiked with 1 ng of 13C-labeled surrogatestandards and then Soxhlet-extracted for 24 h with 400mLof dichloromethaneacetone (1 1 vv)The extracts were con-centrated to about 5mL and subjected to a solvent exchangeto hexane The concentrated extracts were subsequentlypurified and fractionated following the above mentionedmethod under identical conditions [16]
24 GCMS Analysis and Quality Control PCBs were ana-lyzed by isotope dilution method and the analysis procedurewas similar to the method described by Yang et al [15]The quantification of PCBs extracts in the wastewater SPMand sludge samples was performed on an Agilent 6890Agas chromatograph (GC) coupled with 5795C inert massspectrometer (MS) detector (Agilent Technologies USA)with an electron impact (EI) ion sourceTheMSwas operatedin selective ion monitoring (SIM) mode Helium was used ascarrier gaswith flow rate of 12mLmin Exactly 1120583Lof extractsolution was injected with 16-sample autoinjector in splitlessmode into a DB-5MS capillary column (60m times 025mm idtimes 025 120583m film thickness JampW Scientific USA) The injectortemperature and source temperature were 280 and 250∘Crespectively The oven temperature program was as follows110∘C held for 3min 110ndash150∘C at 10∘Cmin 150ndash270∘C at25∘Cmin held for 5min and 270ndash320∘C at 25∘Cmin heldfor 10min
The blank blank spike and parallel samples were intro-duced for quality assurance and quality control The back-ground concentrations were negligible due to their signifi-cantly lower levels compared to actual samples (lt3) Recov-eries of added 13C-labeled PCB-14 PCB-65 and PCB-166surrogate standards to wastewater samples prior to extractionaveraged 84 plusmn 6 88 plusmn 6 and 94 plusmn 4 respectivelyRecoveries of added 13C-PCB-14 PCB-65 and PCB-166 toSPM and sludge samples prior to extraction averaged 68 plusmn15 72 plusmn 15 and 88 plusmn 10 respectively The recoveriesmeet the requirements of US EPA method 1668A [14]
3 Results and Discussion
31 Source Analysis of PCBs from Dyeing Chemical IndustryEntering the WWTP PCBs entering the centralized WWTPcan be mainly associated with direct discharges from indus-trial emissions in the investigated zone In order to identifythe main industrial emissions as PCB source to the WWTPwe investigated the profiles of the factories or companies inthe investigated zoneThis zone is a professional developmentzone featuring as fine chemical industry focusing on pro-ducing of pharmaceuticals and the intermediates pigments
4 Journal of Chemistry
and dyes textile dyeing and finishing biochemical inorganicchemicals and other specialty chemicals The wastewaterproduced during the chemical processes was discharged intothe WWTP after simple treatment In this zone the wastew-ater discharged by pigment and dyeing chemical industriesaccounts for about 70 of the total industrial wastewaterData provided by US EPA and other workers indicate thatPCBs have been found in various color dyestuff and pigments[3 17ndash19] Rodenburg and colleagues knewPCB-11 was linkedto the manufacture of diarylide yellow pigments [3] Hu andHornbuckle detected more than 50 PCB congeners in azoand phthalocyanine pigments [18] Litten et al also foundhigh levels of PCBs in wastewater in New York harbor andtraced them to effluent from a pigment manufacturing plant[17] Thus we mainly detected the PCBs in dyeing chemicalwastewater discharged by the largest chemical industrialgroup and identified the contribution of PCBs to theWWTPby the group
The PCB species and concentrations in wastewaterdepend on the raw materials and the process of dyestuffor pigments production It is investigated that the dyeingchemical industrial groupmainly produces disperse reactivevat pigments and some intermediates which are mainly azopigments with polycyclic ketone structures and producedthrough a reaction sequence of diazotization (coupling toafford the azo group ndashN=Nndash) condensation close-loopchlorination oxidation and reduction and so forth [20]During the synthesis of these productions there are variousderivatives of polycyclic hydrocarbons used as the precursorssuch as alkylbenzenes naphthol anthrone anthraquinoneacenaphthene and quinone [21] Therefore with high tem-perature and humidity in the dye synthesis processes it is easyto generate PCBs and other POPs byproducts Based on theconcentrations and water quantity the average contributionof each PCB congener was calculated and listed in Table 1 It isshown that lightly chlorinated biphenyls were the main PCBspecies and PCB-11 77 28 and 15 were the most abundantcongeners produced during the dyemanufacturing processesThe contribution of sum209 PCBs produced by this dyeingchemical industrial group to theWWTPwas 136The threegreatest contributors wereDi-CBs Hexa-CBs andNona-CBswith the contribution percent of 154 152 and 116respectively
32 PCBConcentrations inWastewater Samples of theWWTPThe results of PCB concentrations in wastewater samplesin the influent and effluent of each WWTP treatment stageare presented in Table 2 As shown the concerned 20 PCBcongeners and PCB isomers were detectable in the RWsamples The most abundant PCB entering the WWTP inRW was PCB-11 with mean concentration of 103216 pgLaccounting for 661 of the total 209 PCBsThe less abundantPCBs were still the lightly chlorinated biphenyls includingPCB-15 two indicator PCB congeners (PCB-52 and PCB-28) and one dioxin-like PCB congener (PCB-77) with meanconcentrations of 2416 2491 1735 and 1144 pgL respec-tivelyThe concentrations of total 209 PCBs were two or threeorders of magnitude lower than the ones observed in the
previous studies [12 22 23] which indicated the risk causedby dissolved PCBs was relatively low around the WWTPCompared with the data in the literature of Vogelsang et al[24] the concentration of indicator PCBs was three times asours
In PSE AHE SSE and HCE samples the presence ofmost PCB congeners was in general similar to that in RWsamples with PCB-11 being the most abundant compoundand PCB-15 PCB-28 PCB-52 and PCB-77 being the lessabundant compounds PCB-126 PCB-169 and PCB-189 werenot detected in the effluent samples of each treatment stagealthough found in RW PCB-81 and PCB-180 were notdetected in HCE samples Interestingly sum209 PCBs meanconcentration in AHE samples was higher than that in PSEsamples In detail the concentration of PCB-28 PCB-52 andPCB-77 in AHE samples suddenly increased by 270 357and 523 respectively In anaerobic hydrolysis stage theanaerobic microbes or anaerobic sludge always stay in theanaerobic fluidized bed without replacementThus the PCBsresults may be associated with the role of anaerobic microbesand the release of PCBs from solid to liquid phase
33 PCB Concentrations in SPM and Sludge Samples of theWWTP Table 3 summarizes the mean concentrations (nggdry weight) of the 20 PCB congeners and PCB isomers inthe SPM and sludge samples Here five PCB congeners werenot detected in the SPM of raw wastewater that is PCB-15PCB-19 and three dioxin-like PCBs (PCB-126 PCB-156 andPCB-169) All the 20 PCBs were detectable in the solid-phasesamples taken from following stage As seen in Tables 2 and3 the levels of PCB congeners in the solid phase were closelyrelated to the liquid concentrations in the influentThe higherconcentrations of PCBs in the influent the higher levels inSPM and sludge samples from effluent For example PCB-11was themost abundant PCBs both in liquid and in solid phasewith a high proportion of more than 60
In primary sedimentation stage the concentrations oftotal PCBs were nearly 2 times that in SPMof rawwastewaterdue to adsorption and sedimentation by PAC flocculantsHigh levels of PCBs were detected in anaerobic SPM andaerobic activated sludge indicating that the microbial sludgehad a strong biosorption and bioaccumulation for PCBswhichmade the contribution of biotransformation biodegra-dation and volatilization obscure Therefore sorption ofPCBs onto sludge was the most likely removal mechanismin the primary and biochemical treatment stages In high-density clarifier stage PCBs concentrations in effluent andsludge samples decreased more significantly than the ones inthe aerobic bioprocess stage owing to the oxidation (althoughno evidence is available in the literature of ferrate reactionwith PCBs) or the coagulation by ferrate because ferrateat pH lt 7 generates Fe(III) ions with excellent flocculationcapability and Fe(OH)
3that is a good adsorbent [25]
The mean concentrations of PCBs in the final sludgeof the centralized WWTP were also within the range ofreported values in Table 3 sum209 PCBs mean concentration(64323 ngg dw) was one or two orders of magnitude higherthan the values observed in previous studies reported by
Journal of Chemistry 5
Table 1 The concentrations (means plusmn SD) and contribution of PCBs discharged by the largest dyeing chemical industrial group entering theWWTP
Blanchard et al Guo et al and Katsoyiannis and Samara[12 16 22] According to the Chinese regulated law (GB18918-2002) PCB levels should be less than 200 ngg dw foragricultural use [26]Therefore the PCB levels in theWWTPsludge hereweremuchhigher than themaximumpermissibleconcentration andwere not suitable for agricultural purposes
34 Phase Distribution of PCBs in Wastewater and Sludgeof the WWTP The distribution of single compounds variedamong different systems whichmight be attributed to severalfactors such as the solute concentration the amount of
solids available for sorption and the competition betweenpollutants for sorption sites of the particles [7 27] Seenfrom Figure 2 Di-CBs (783ndash931) were the predominantisomers in wastewater samples followed by Tri-CBs (29ndash79) and Tetra-CBs (22ndash59) The proportion of otherhighly chlorinated biphenyls (Hexa-CBs to Deca-CBs) wasless than 5 in each stage effluent Similar to the profilesof PCB isomers in wastewater Di-CBs (704ndash840) werethe dominant isomers in sludge followed by Mono-CBs(79ndash152) and Tri-CBs (54ndash168) with less than 3 ofcontribution of other PCBs isomers
6 Journal of Chemistry
Table 2 The concentrations (means plusmn SD) of PCBs in wastewater of each treatment stage at the WWTP
PCBs (pgL) RW PSE AHE SSE HCEIndicator PCB congener
The partitioning behaviors of organic chemicals areessential to their fate in the WWTP as dissolved andadsorbed phases are differently available to different fateprocesses [11] Based on the PCBs concentrations in liquid-solid phase water quantity and SPM yield the relativedistribution of PCB isomers between the dissolved andadsorbed phases was obtained in the present study Figure 3presents the proportions of adsorbed PCB isomers in theinfluent and effluents of each treatment stage It is clearthat the adsorbed fraction of sum209 PCBs was found torange from 898 to 974 in the influent and effluent ofeach treatment stage much higher than the findings of
Katsoyiannis and Samara [28] with less than 60 of adsorbedsumPCBs in the influent ofWWTP inThessaloniki GreeceTheadsorbed PCB isomers in secondary sedimentation effluentwere absolutely predominant varying between 873 forOcta-CBs and 998 for Mono-CBs Likewise significantadsorbed fractions of PCB isomers were also found in the rawwastewater primary sedimentation effluent and anaerobichydrolysis effluent varying between 534 for Nona-CBs and991 for Tri-CBs 540 for Nona-CBs and 994 for Tri-CBs and 459 for Nona-CBs and 983 for Mono-CBsrespectively Differently in high-density clarifier effluentNona-CBs and Deca-CBs were more ldquodissolvedrdquo among
Journal of Chemistry 7
Table 3 The concentrations (means plusmn SD) of PCBs in SPM and sludge of each treatment stage at the WWTP
SPM suspended particulate matter RW mixing influent (raw wastewater) PSS primary sedimentation sludge AHE anaerobic hydrolysis effluent ASactivated sludge HCS high-density clarifier sludge FS final sludge ND not detected sum Ind sum indicator PCBs and sum DL sun DL-PCBs
the PCB isomers with only 300 and 392 in the solidphase although the adsorbed fractions of other PCB isomerswere all above 65 in this stage Generally better removalcan be obtained for higher MW congeners by sorption ontoparticles or microbes owing to their high hydrophobicity [11]But what was reason about this unusual result As seen fromTables 2 and 3 the mean concentrations of dissolved Nano-CBs and Deca-CBs were 318 and 82 pgL in HCE and the
average levels of adsorbed Nano-CBs and Deca-CBs were0226 and 0082 ngg respectively On the one hand maybedue to the very low concentrations of them in dissolved(possible) oxidation by ferrate or flocculationadsorption byFe(OH)
3cannot occur accompanied with the competitive
effect among various pollutants On the other hand thefraction remaining in the treated wastewater unexpectedlyhigh for hydrophobic compounds could be explained by
8 Journal of Chemistry
Deca-CBsNona-CBsOcta-CBsHepta-CBsHexa-CBs
Penta-CBsTetra-CBsTri-CBsDi-CBsMono-CBs
RW PSE AHE SSE HCE PSS AS HCS FS0
20
40
60
80
100
Con
cent
ratio
n (
)
Wastewater and sludge samples
Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP
0
20
40
60
80
100
Sorb
ed P
CBs (
)
RW PSE AHE SSE HCE
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs
Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage
possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]
35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation
119877 () =(119862in minus 119862out)
119862intimes 100 (1)
where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic
0
20
40
60
80
100
Prim
ary
sedi
men
tatio
n
Ana
erob
ichy
drol
ysis
Aero
bic b
io-
proc
ess
Hig
h-de
nsity
clarifi
er
Who
le tr
eatm
ent
proc
ess
Rem
oval
()
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBs
minus20
ΣPCBs
minus528
minus150
minus118
minus587
minus182
minus322
Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage
sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents
Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes
Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal
Journal of Chemistry 9
50 55 60 65 70 750
20
40
60
80
100
120
Primary sedimentation
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
Furthermore in order to estimate the industrial sourcesof PCBs two wastewater samples were collected from thelargest dyeing chemical group in this zone whichmainly pro-duced disperse reactive acid vat dyestuff or pigments andintermediates One sample was the mother liquor producedduring the pigment synthesis process and the other was thetreated effluent of the mother liquor entering the WWTPThe amounts of wastewater discharged into the WWTP wereabout 8000m3 per day
22 Chemicals and Reagents All solvents including acetonen-hexane methanol and dichloromethane were of HPLCgrade and purchased from Tedia Co USA Water waspurified with an ultrapure water system (Purelab UHQ ElgaLabWater UK) Silica gel (100ndash200 mesh reagent gradeQingdao Ocean Chemical Reagent Co China) anhydroussodium sulfate (analytical grade Chongqing Kelong Chem-ical Reagent Co China) and glass fiber filters (045 120583meffective pore sizes ShanghaiMosu Scientific Equipment CoChina) were baked in a furnace oven at 450∘C for 4 h prior touse
PCB calibration standard solutions 13C-labeled surrogatestandards (13C-PCB-14 65 and 166) and injection standards(13C-PCB-9 52 101 138 and 194) complying with US EPAmethod 1668A for PCBs analysis were purchased fromCambridge Isotope Laboratories in USA Here the mainlyconcerned PCBs were 20 individual PCB congeners and totalPCBs (from Mono-CBs to Deca-CBs) The individual con-geners included six indicator congeners (PCB-28 52 101 118138 153 and 180) ten dioxin-like PCB (PCB-77 81 105 114123 126 156 167 169 and 189) and three lightly chlorinatedbiphenyls (PCB-11 15 and 19) respectively The workingstandard solutions were prepared by diluting appropriatevolumes of the standard PCB mixture with HPLC-grade n-hexane
23 Sample Extraction and Purification 1 L of wastewatersamples was filtered using glass fiber filter and spiked with200 ng of 13C-labeled surrogate standards and then extractedthree times under ultrasonic conditions using liquid-liquidextraction method The total extracted volume was 180mLof dichloromethanehexane (1 1 vv) and the extracts wereconcentrated to 2mL and subjected to a solvent exchange tohexane by a rotary evaporator (RE-52AA Yarong ShanghaiChina) The concentrated extracts were sequentially subjectto multilayer silica gel basic alumina and florisil chromatog-raphy columns for further cleanup following the publishedprocedures [9 13ndash15] The multilayered silica gel column wasself-made column which was packed from bottom to topwith 1 g of activated silica 4 g of basic silica (12 ww)1 g of activated silica 8 g of acid silica (30 ww) 2 g ofactivated silica and 4 g of anhydrous sodium sulfate Thecolumns were preserved in dichloromethanehexane (1 1vv) before loading the extracts Elution of the samples wascarried out at a rate of 1mLmin under vacuum with 5dichloromethanehexane (vv)Then the eluent was collectedand evaporated to near dryness with rotary evaporatorHexane solvent was introduced as a replacement and then
concentrated to 20120583L with gentle stream of nitrogen Then13C-labeled internal standards were added prior to the GCinjection for quantitative analysis All samples were analyzedin duplicate and the average concentrations (means plusmn SD119899 = 2) were reported
The SPM in the wastewater was separated by glass fiberfilters and the sludge was dehydrated by centrifugationThe filters and sludge were freeze dried until constantweights were maintained Solid samples were accuratelyweighted and spiked with 1 ng of 13C-labeled surrogatestandards and then Soxhlet-extracted for 24 h with 400mLof dichloromethaneacetone (1 1 vv)The extracts were con-centrated to about 5mL and subjected to a solvent exchangeto hexane The concentrated extracts were subsequentlypurified and fractionated following the above mentionedmethod under identical conditions [16]
24 GCMS Analysis and Quality Control PCBs were ana-lyzed by isotope dilution method and the analysis procedurewas similar to the method described by Yang et al [15]The quantification of PCBs extracts in the wastewater SPMand sludge samples was performed on an Agilent 6890Agas chromatograph (GC) coupled with 5795C inert massspectrometer (MS) detector (Agilent Technologies USA)with an electron impact (EI) ion sourceTheMSwas operatedin selective ion monitoring (SIM) mode Helium was used ascarrier gaswith flow rate of 12mLmin Exactly 1120583Lof extractsolution was injected with 16-sample autoinjector in splitlessmode into a DB-5MS capillary column (60m times 025mm idtimes 025 120583m film thickness JampW Scientific USA) The injectortemperature and source temperature were 280 and 250∘Crespectively The oven temperature program was as follows110∘C held for 3min 110ndash150∘C at 10∘Cmin 150ndash270∘C at25∘Cmin held for 5min and 270ndash320∘C at 25∘Cmin heldfor 10min
The blank blank spike and parallel samples were intro-duced for quality assurance and quality control The back-ground concentrations were negligible due to their signifi-cantly lower levels compared to actual samples (lt3) Recov-eries of added 13C-labeled PCB-14 PCB-65 and PCB-166surrogate standards to wastewater samples prior to extractionaveraged 84 plusmn 6 88 plusmn 6 and 94 plusmn 4 respectivelyRecoveries of added 13C-PCB-14 PCB-65 and PCB-166 toSPM and sludge samples prior to extraction averaged 68 plusmn15 72 plusmn 15 and 88 plusmn 10 respectively The recoveriesmeet the requirements of US EPA method 1668A [14]
3 Results and Discussion
31 Source Analysis of PCBs from Dyeing Chemical IndustryEntering the WWTP PCBs entering the centralized WWTPcan be mainly associated with direct discharges from indus-trial emissions in the investigated zone In order to identifythe main industrial emissions as PCB source to the WWTPwe investigated the profiles of the factories or companies inthe investigated zoneThis zone is a professional developmentzone featuring as fine chemical industry focusing on pro-ducing of pharmaceuticals and the intermediates pigments
4 Journal of Chemistry
and dyes textile dyeing and finishing biochemical inorganicchemicals and other specialty chemicals The wastewaterproduced during the chemical processes was discharged intothe WWTP after simple treatment In this zone the wastew-ater discharged by pigment and dyeing chemical industriesaccounts for about 70 of the total industrial wastewaterData provided by US EPA and other workers indicate thatPCBs have been found in various color dyestuff and pigments[3 17ndash19] Rodenburg and colleagues knewPCB-11 was linkedto the manufacture of diarylide yellow pigments [3] Hu andHornbuckle detected more than 50 PCB congeners in azoand phthalocyanine pigments [18] Litten et al also foundhigh levels of PCBs in wastewater in New York harbor andtraced them to effluent from a pigment manufacturing plant[17] Thus we mainly detected the PCBs in dyeing chemicalwastewater discharged by the largest chemical industrialgroup and identified the contribution of PCBs to theWWTPby the group
The PCB species and concentrations in wastewaterdepend on the raw materials and the process of dyestuffor pigments production It is investigated that the dyeingchemical industrial groupmainly produces disperse reactivevat pigments and some intermediates which are mainly azopigments with polycyclic ketone structures and producedthrough a reaction sequence of diazotization (coupling toafford the azo group ndashN=Nndash) condensation close-loopchlorination oxidation and reduction and so forth [20]During the synthesis of these productions there are variousderivatives of polycyclic hydrocarbons used as the precursorssuch as alkylbenzenes naphthol anthrone anthraquinoneacenaphthene and quinone [21] Therefore with high tem-perature and humidity in the dye synthesis processes it is easyto generate PCBs and other POPs byproducts Based on theconcentrations and water quantity the average contributionof each PCB congener was calculated and listed in Table 1 It isshown that lightly chlorinated biphenyls were the main PCBspecies and PCB-11 77 28 and 15 were the most abundantcongeners produced during the dyemanufacturing processesThe contribution of sum209 PCBs produced by this dyeingchemical industrial group to theWWTPwas 136The threegreatest contributors wereDi-CBs Hexa-CBs andNona-CBswith the contribution percent of 154 152 and 116respectively
32 PCBConcentrations inWastewater Samples of theWWTPThe results of PCB concentrations in wastewater samplesin the influent and effluent of each WWTP treatment stageare presented in Table 2 As shown the concerned 20 PCBcongeners and PCB isomers were detectable in the RWsamples The most abundant PCB entering the WWTP inRW was PCB-11 with mean concentration of 103216 pgLaccounting for 661 of the total 209 PCBsThe less abundantPCBs were still the lightly chlorinated biphenyls includingPCB-15 two indicator PCB congeners (PCB-52 and PCB-28) and one dioxin-like PCB congener (PCB-77) with meanconcentrations of 2416 2491 1735 and 1144 pgL respec-tivelyThe concentrations of total 209 PCBs were two or threeorders of magnitude lower than the ones observed in the
previous studies [12 22 23] which indicated the risk causedby dissolved PCBs was relatively low around the WWTPCompared with the data in the literature of Vogelsang et al[24] the concentration of indicator PCBs was three times asours
In PSE AHE SSE and HCE samples the presence ofmost PCB congeners was in general similar to that in RWsamples with PCB-11 being the most abundant compoundand PCB-15 PCB-28 PCB-52 and PCB-77 being the lessabundant compounds PCB-126 PCB-169 and PCB-189 werenot detected in the effluent samples of each treatment stagealthough found in RW PCB-81 and PCB-180 were notdetected in HCE samples Interestingly sum209 PCBs meanconcentration in AHE samples was higher than that in PSEsamples In detail the concentration of PCB-28 PCB-52 andPCB-77 in AHE samples suddenly increased by 270 357and 523 respectively In anaerobic hydrolysis stage theanaerobic microbes or anaerobic sludge always stay in theanaerobic fluidized bed without replacementThus the PCBsresults may be associated with the role of anaerobic microbesand the release of PCBs from solid to liquid phase
33 PCB Concentrations in SPM and Sludge Samples of theWWTP Table 3 summarizes the mean concentrations (nggdry weight) of the 20 PCB congeners and PCB isomers inthe SPM and sludge samples Here five PCB congeners werenot detected in the SPM of raw wastewater that is PCB-15PCB-19 and three dioxin-like PCBs (PCB-126 PCB-156 andPCB-169) All the 20 PCBs were detectable in the solid-phasesamples taken from following stage As seen in Tables 2 and3 the levels of PCB congeners in the solid phase were closelyrelated to the liquid concentrations in the influentThe higherconcentrations of PCBs in the influent the higher levels inSPM and sludge samples from effluent For example PCB-11was themost abundant PCBs both in liquid and in solid phasewith a high proportion of more than 60
In primary sedimentation stage the concentrations oftotal PCBs were nearly 2 times that in SPMof rawwastewaterdue to adsorption and sedimentation by PAC flocculantsHigh levels of PCBs were detected in anaerobic SPM andaerobic activated sludge indicating that the microbial sludgehad a strong biosorption and bioaccumulation for PCBswhichmade the contribution of biotransformation biodegra-dation and volatilization obscure Therefore sorption ofPCBs onto sludge was the most likely removal mechanismin the primary and biochemical treatment stages In high-density clarifier stage PCBs concentrations in effluent andsludge samples decreased more significantly than the ones inthe aerobic bioprocess stage owing to the oxidation (althoughno evidence is available in the literature of ferrate reactionwith PCBs) or the coagulation by ferrate because ferrateat pH lt 7 generates Fe(III) ions with excellent flocculationcapability and Fe(OH)
3that is a good adsorbent [25]
The mean concentrations of PCBs in the final sludgeof the centralized WWTP were also within the range ofreported values in Table 3 sum209 PCBs mean concentration(64323 ngg dw) was one or two orders of magnitude higherthan the values observed in previous studies reported by
Journal of Chemistry 5
Table 1 The concentrations (means plusmn SD) and contribution of PCBs discharged by the largest dyeing chemical industrial group entering theWWTP
Blanchard et al Guo et al and Katsoyiannis and Samara[12 16 22] According to the Chinese regulated law (GB18918-2002) PCB levels should be less than 200 ngg dw foragricultural use [26]Therefore the PCB levels in theWWTPsludge hereweremuchhigher than themaximumpermissibleconcentration andwere not suitable for agricultural purposes
34 Phase Distribution of PCBs in Wastewater and Sludgeof the WWTP The distribution of single compounds variedamong different systems whichmight be attributed to severalfactors such as the solute concentration the amount of
solids available for sorption and the competition betweenpollutants for sorption sites of the particles [7 27] Seenfrom Figure 2 Di-CBs (783ndash931) were the predominantisomers in wastewater samples followed by Tri-CBs (29ndash79) and Tetra-CBs (22ndash59) The proportion of otherhighly chlorinated biphenyls (Hexa-CBs to Deca-CBs) wasless than 5 in each stage effluent Similar to the profilesof PCB isomers in wastewater Di-CBs (704ndash840) werethe dominant isomers in sludge followed by Mono-CBs(79ndash152) and Tri-CBs (54ndash168) with less than 3 ofcontribution of other PCBs isomers
6 Journal of Chemistry
Table 2 The concentrations (means plusmn SD) of PCBs in wastewater of each treatment stage at the WWTP
PCBs (pgL) RW PSE AHE SSE HCEIndicator PCB congener
The partitioning behaviors of organic chemicals areessential to their fate in the WWTP as dissolved andadsorbed phases are differently available to different fateprocesses [11] Based on the PCBs concentrations in liquid-solid phase water quantity and SPM yield the relativedistribution of PCB isomers between the dissolved andadsorbed phases was obtained in the present study Figure 3presents the proportions of adsorbed PCB isomers in theinfluent and effluents of each treatment stage It is clearthat the adsorbed fraction of sum209 PCBs was found torange from 898 to 974 in the influent and effluent ofeach treatment stage much higher than the findings of
Katsoyiannis and Samara [28] with less than 60 of adsorbedsumPCBs in the influent ofWWTP inThessaloniki GreeceTheadsorbed PCB isomers in secondary sedimentation effluentwere absolutely predominant varying between 873 forOcta-CBs and 998 for Mono-CBs Likewise significantadsorbed fractions of PCB isomers were also found in the rawwastewater primary sedimentation effluent and anaerobichydrolysis effluent varying between 534 for Nona-CBs and991 for Tri-CBs 540 for Nona-CBs and 994 for Tri-CBs and 459 for Nona-CBs and 983 for Mono-CBsrespectively Differently in high-density clarifier effluentNona-CBs and Deca-CBs were more ldquodissolvedrdquo among
Journal of Chemistry 7
Table 3 The concentrations (means plusmn SD) of PCBs in SPM and sludge of each treatment stage at the WWTP
SPM suspended particulate matter RW mixing influent (raw wastewater) PSS primary sedimentation sludge AHE anaerobic hydrolysis effluent ASactivated sludge HCS high-density clarifier sludge FS final sludge ND not detected sum Ind sum indicator PCBs and sum DL sun DL-PCBs
the PCB isomers with only 300 and 392 in the solidphase although the adsorbed fractions of other PCB isomerswere all above 65 in this stage Generally better removalcan be obtained for higher MW congeners by sorption ontoparticles or microbes owing to their high hydrophobicity [11]But what was reason about this unusual result As seen fromTables 2 and 3 the mean concentrations of dissolved Nano-CBs and Deca-CBs were 318 and 82 pgL in HCE and the
average levels of adsorbed Nano-CBs and Deca-CBs were0226 and 0082 ngg respectively On the one hand maybedue to the very low concentrations of them in dissolved(possible) oxidation by ferrate or flocculationadsorption byFe(OH)
3cannot occur accompanied with the competitive
effect among various pollutants On the other hand thefraction remaining in the treated wastewater unexpectedlyhigh for hydrophobic compounds could be explained by
8 Journal of Chemistry
Deca-CBsNona-CBsOcta-CBsHepta-CBsHexa-CBs
Penta-CBsTetra-CBsTri-CBsDi-CBsMono-CBs
RW PSE AHE SSE HCE PSS AS HCS FS0
20
40
60
80
100
Con
cent
ratio
n (
)
Wastewater and sludge samples
Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP
0
20
40
60
80
100
Sorb
ed P
CBs (
)
RW PSE AHE SSE HCE
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs
Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage
possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]
35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation
119877 () =(119862in minus 119862out)
119862intimes 100 (1)
where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic
0
20
40
60
80
100
Prim
ary
sedi
men
tatio
n
Ana
erob
ichy
drol
ysis
Aero
bic b
io-
proc
ess
Hig
h-de
nsity
clarifi
er
Who
le tr
eatm
ent
proc
ess
Rem
oval
()
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBs
minus20
ΣPCBs
minus528
minus150
minus118
minus587
minus182
minus322
Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage
sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents
Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes
Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal
Journal of Chemistry 9
50 55 60 65 70 750
20
40
60
80
100
120
Primary sedimentation
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
and dyes textile dyeing and finishing biochemical inorganicchemicals and other specialty chemicals The wastewaterproduced during the chemical processes was discharged intothe WWTP after simple treatment In this zone the wastew-ater discharged by pigment and dyeing chemical industriesaccounts for about 70 of the total industrial wastewaterData provided by US EPA and other workers indicate thatPCBs have been found in various color dyestuff and pigments[3 17ndash19] Rodenburg and colleagues knewPCB-11 was linkedto the manufacture of diarylide yellow pigments [3] Hu andHornbuckle detected more than 50 PCB congeners in azoand phthalocyanine pigments [18] Litten et al also foundhigh levels of PCBs in wastewater in New York harbor andtraced them to effluent from a pigment manufacturing plant[17] Thus we mainly detected the PCBs in dyeing chemicalwastewater discharged by the largest chemical industrialgroup and identified the contribution of PCBs to theWWTPby the group
The PCB species and concentrations in wastewaterdepend on the raw materials and the process of dyestuffor pigments production It is investigated that the dyeingchemical industrial groupmainly produces disperse reactivevat pigments and some intermediates which are mainly azopigments with polycyclic ketone structures and producedthrough a reaction sequence of diazotization (coupling toafford the azo group ndashN=Nndash) condensation close-loopchlorination oxidation and reduction and so forth [20]During the synthesis of these productions there are variousderivatives of polycyclic hydrocarbons used as the precursorssuch as alkylbenzenes naphthol anthrone anthraquinoneacenaphthene and quinone [21] Therefore with high tem-perature and humidity in the dye synthesis processes it is easyto generate PCBs and other POPs byproducts Based on theconcentrations and water quantity the average contributionof each PCB congener was calculated and listed in Table 1 It isshown that lightly chlorinated biphenyls were the main PCBspecies and PCB-11 77 28 and 15 were the most abundantcongeners produced during the dyemanufacturing processesThe contribution of sum209 PCBs produced by this dyeingchemical industrial group to theWWTPwas 136The threegreatest contributors wereDi-CBs Hexa-CBs andNona-CBswith the contribution percent of 154 152 and 116respectively
32 PCBConcentrations inWastewater Samples of theWWTPThe results of PCB concentrations in wastewater samplesin the influent and effluent of each WWTP treatment stageare presented in Table 2 As shown the concerned 20 PCBcongeners and PCB isomers were detectable in the RWsamples The most abundant PCB entering the WWTP inRW was PCB-11 with mean concentration of 103216 pgLaccounting for 661 of the total 209 PCBsThe less abundantPCBs were still the lightly chlorinated biphenyls includingPCB-15 two indicator PCB congeners (PCB-52 and PCB-28) and one dioxin-like PCB congener (PCB-77) with meanconcentrations of 2416 2491 1735 and 1144 pgL respec-tivelyThe concentrations of total 209 PCBs were two or threeorders of magnitude lower than the ones observed in the
previous studies [12 22 23] which indicated the risk causedby dissolved PCBs was relatively low around the WWTPCompared with the data in the literature of Vogelsang et al[24] the concentration of indicator PCBs was three times asours
In PSE AHE SSE and HCE samples the presence ofmost PCB congeners was in general similar to that in RWsamples with PCB-11 being the most abundant compoundand PCB-15 PCB-28 PCB-52 and PCB-77 being the lessabundant compounds PCB-126 PCB-169 and PCB-189 werenot detected in the effluent samples of each treatment stagealthough found in RW PCB-81 and PCB-180 were notdetected in HCE samples Interestingly sum209 PCBs meanconcentration in AHE samples was higher than that in PSEsamples In detail the concentration of PCB-28 PCB-52 andPCB-77 in AHE samples suddenly increased by 270 357and 523 respectively In anaerobic hydrolysis stage theanaerobic microbes or anaerobic sludge always stay in theanaerobic fluidized bed without replacementThus the PCBsresults may be associated with the role of anaerobic microbesand the release of PCBs from solid to liquid phase
33 PCB Concentrations in SPM and Sludge Samples of theWWTP Table 3 summarizes the mean concentrations (nggdry weight) of the 20 PCB congeners and PCB isomers inthe SPM and sludge samples Here five PCB congeners werenot detected in the SPM of raw wastewater that is PCB-15PCB-19 and three dioxin-like PCBs (PCB-126 PCB-156 andPCB-169) All the 20 PCBs were detectable in the solid-phasesamples taken from following stage As seen in Tables 2 and3 the levels of PCB congeners in the solid phase were closelyrelated to the liquid concentrations in the influentThe higherconcentrations of PCBs in the influent the higher levels inSPM and sludge samples from effluent For example PCB-11was themost abundant PCBs both in liquid and in solid phasewith a high proportion of more than 60
In primary sedimentation stage the concentrations oftotal PCBs were nearly 2 times that in SPMof rawwastewaterdue to adsorption and sedimentation by PAC flocculantsHigh levels of PCBs were detected in anaerobic SPM andaerobic activated sludge indicating that the microbial sludgehad a strong biosorption and bioaccumulation for PCBswhichmade the contribution of biotransformation biodegra-dation and volatilization obscure Therefore sorption ofPCBs onto sludge was the most likely removal mechanismin the primary and biochemical treatment stages In high-density clarifier stage PCBs concentrations in effluent andsludge samples decreased more significantly than the ones inthe aerobic bioprocess stage owing to the oxidation (althoughno evidence is available in the literature of ferrate reactionwith PCBs) or the coagulation by ferrate because ferrateat pH lt 7 generates Fe(III) ions with excellent flocculationcapability and Fe(OH)
3that is a good adsorbent [25]
The mean concentrations of PCBs in the final sludgeof the centralized WWTP were also within the range ofreported values in Table 3 sum209 PCBs mean concentration(64323 ngg dw) was one or two orders of magnitude higherthan the values observed in previous studies reported by
Journal of Chemistry 5
Table 1 The concentrations (means plusmn SD) and contribution of PCBs discharged by the largest dyeing chemical industrial group entering theWWTP
Blanchard et al Guo et al and Katsoyiannis and Samara[12 16 22] According to the Chinese regulated law (GB18918-2002) PCB levels should be less than 200 ngg dw foragricultural use [26]Therefore the PCB levels in theWWTPsludge hereweremuchhigher than themaximumpermissibleconcentration andwere not suitable for agricultural purposes
34 Phase Distribution of PCBs in Wastewater and Sludgeof the WWTP The distribution of single compounds variedamong different systems whichmight be attributed to severalfactors such as the solute concentration the amount of
solids available for sorption and the competition betweenpollutants for sorption sites of the particles [7 27] Seenfrom Figure 2 Di-CBs (783ndash931) were the predominantisomers in wastewater samples followed by Tri-CBs (29ndash79) and Tetra-CBs (22ndash59) The proportion of otherhighly chlorinated biphenyls (Hexa-CBs to Deca-CBs) wasless than 5 in each stage effluent Similar to the profilesof PCB isomers in wastewater Di-CBs (704ndash840) werethe dominant isomers in sludge followed by Mono-CBs(79ndash152) and Tri-CBs (54ndash168) with less than 3 ofcontribution of other PCBs isomers
6 Journal of Chemistry
Table 2 The concentrations (means plusmn SD) of PCBs in wastewater of each treatment stage at the WWTP
PCBs (pgL) RW PSE AHE SSE HCEIndicator PCB congener
The partitioning behaviors of organic chemicals areessential to their fate in the WWTP as dissolved andadsorbed phases are differently available to different fateprocesses [11] Based on the PCBs concentrations in liquid-solid phase water quantity and SPM yield the relativedistribution of PCB isomers between the dissolved andadsorbed phases was obtained in the present study Figure 3presents the proportions of adsorbed PCB isomers in theinfluent and effluents of each treatment stage It is clearthat the adsorbed fraction of sum209 PCBs was found torange from 898 to 974 in the influent and effluent ofeach treatment stage much higher than the findings of
Katsoyiannis and Samara [28] with less than 60 of adsorbedsumPCBs in the influent ofWWTP inThessaloniki GreeceTheadsorbed PCB isomers in secondary sedimentation effluentwere absolutely predominant varying between 873 forOcta-CBs and 998 for Mono-CBs Likewise significantadsorbed fractions of PCB isomers were also found in the rawwastewater primary sedimentation effluent and anaerobichydrolysis effluent varying between 534 for Nona-CBs and991 for Tri-CBs 540 for Nona-CBs and 994 for Tri-CBs and 459 for Nona-CBs and 983 for Mono-CBsrespectively Differently in high-density clarifier effluentNona-CBs and Deca-CBs were more ldquodissolvedrdquo among
Journal of Chemistry 7
Table 3 The concentrations (means plusmn SD) of PCBs in SPM and sludge of each treatment stage at the WWTP
SPM suspended particulate matter RW mixing influent (raw wastewater) PSS primary sedimentation sludge AHE anaerobic hydrolysis effluent ASactivated sludge HCS high-density clarifier sludge FS final sludge ND not detected sum Ind sum indicator PCBs and sum DL sun DL-PCBs
the PCB isomers with only 300 and 392 in the solidphase although the adsorbed fractions of other PCB isomerswere all above 65 in this stage Generally better removalcan be obtained for higher MW congeners by sorption ontoparticles or microbes owing to their high hydrophobicity [11]But what was reason about this unusual result As seen fromTables 2 and 3 the mean concentrations of dissolved Nano-CBs and Deca-CBs were 318 and 82 pgL in HCE and the
average levels of adsorbed Nano-CBs and Deca-CBs were0226 and 0082 ngg respectively On the one hand maybedue to the very low concentrations of them in dissolved(possible) oxidation by ferrate or flocculationadsorption byFe(OH)
3cannot occur accompanied with the competitive
effect among various pollutants On the other hand thefraction remaining in the treated wastewater unexpectedlyhigh for hydrophobic compounds could be explained by
8 Journal of Chemistry
Deca-CBsNona-CBsOcta-CBsHepta-CBsHexa-CBs
Penta-CBsTetra-CBsTri-CBsDi-CBsMono-CBs
RW PSE AHE SSE HCE PSS AS HCS FS0
20
40
60
80
100
Con
cent
ratio
n (
)
Wastewater and sludge samples
Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP
0
20
40
60
80
100
Sorb
ed P
CBs (
)
RW PSE AHE SSE HCE
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs
Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage
possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]
35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation
119877 () =(119862in minus 119862out)
119862intimes 100 (1)
where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic
0
20
40
60
80
100
Prim
ary
sedi
men
tatio
n
Ana
erob
ichy
drol
ysis
Aero
bic b
io-
proc
ess
Hig
h-de
nsity
clarifi
er
Who
le tr
eatm
ent
proc
ess
Rem
oval
()
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBs
minus20
ΣPCBs
minus528
minus150
minus118
minus587
minus182
minus322
Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage
sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents
Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes
Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal
Journal of Chemistry 9
50 55 60 65 70 750
20
40
60
80
100
120
Primary sedimentation
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
Blanchard et al Guo et al and Katsoyiannis and Samara[12 16 22] According to the Chinese regulated law (GB18918-2002) PCB levels should be less than 200 ngg dw foragricultural use [26]Therefore the PCB levels in theWWTPsludge hereweremuchhigher than themaximumpermissibleconcentration andwere not suitable for agricultural purposes
34 Phase Distribution of PCBs in Wastewater and Sludgeof the WWTP The distribution of single compounds variedamong different systems whichmight be attributed to severalfactors such as the solute concentration the amount of
solids available for sorption and the competition betweenpollutants for sorption sites of the particles [7 27] Seenfrom Figure 2 Di-CBs (783ndash931) were the predominantisomers in wastewater samples followed by Tri-CBs (29ndash79) and Tetra-CBs (22ndash59) The proportion of otherhighly chlorinated biphenyls (Hexa-CBs to Deca-CBs) wasless than 5 in each stage effluent Similar to the profilesof PCB isomers in wastewater Di-CBs (704ndash840) werethe dominant isomers in sludge followed by Mono-CBs(79ndash152) and Tri-CBs (54ndash168) with less than 3 ofcontribution of other PCBs isomers
6 Journal of Chemistry
Table 2 The concentrations (means plusmn SD) of PCBs in wastewater of each treatment stage at the WWTP
PCBs (pgL) RW PSE AHE SSE HCEIndicator PCB congener
The partitioning behaviors of organic chemicals areessential to their fate in the WWTP as dissolved andadsorbed phases are differently available to different fateprocesses [11] Based on the PCBs concentrations in liquid-solid phase water quantity and SPM yield the relativedistribution of PCB isomers between the dissolved andadsorbed phases was obtained in the present study Figure 3presents the proportions of adsorbed PCB isomers in theinfluent and effluents of each treatment stage It is clearthat the adsorbed fraction of sum209 PCBs was found torange from 898 to 974 in the influent and effluent ofeach treatment stage much higher than the findings of
Katsoyiannis and Samara [28] with less than 60 of adsorbedsumPCBs in the influent ofWWTP inThessaloniki GreeceTheadsorbed PCB isomers in secondary sedimentation effluentwere absolutely predominant varying between 873 forOcta-CBs and 998 for Mono-CBs Likewise significantadsorbed fractions of PCB isomers were also found in the rawwastewater primary sedimentation effluent and anaerobichydrolysis effluent varying between 534 for Nona-CBs and991 for Tri-CBs 540 for Nona-CBs and 994 for Tri-CBs and 459 for Nona-CBs and 983 for Mono-CBsrespectively Differently in high-density clarifier effluentNona-CBs and Deca-CBs were more ldquodissolvedrdquo among
Journal of Chemistry 7
Table 3 The concentrations (means plusmn SD) of PCBs in SPM and sludge of each treatment stage at the WWTP
SPM suspended particulate matter RW mixing influent (raw wastewater) PSS primary sedimentation sludge AHE anaerobic hydrolysis effluent ASactivated sludge HCS high-density clarifier sludge FS final sludge ND not detected sum Ind sum indicator PCBs and sum DL sun DL-PCBs
the PCB isomers with only 300 and 392 in the solidphase although the adsorbed fractions of other PCB isomerswere all above 65 in this stage Generally better removalcan be obtained for higher MW congeners by sorption ontoparticles or microbes owing to their high hydrophobicity [11]But what was reason about this unusual result As seen fromTables 2 and 3 the mean concentrations of dissolved Nano-CBs and Deca-CBs were 318 and 82 pgL in HCE and the
average levels of adsorbed Nano-CBs and Deca-CBs were0226 and 0082 ngg respectively On the one hand maybedue to the very low concentrations of them in dissolved(possible) oxidation by ferrate or flocculationadsorption byFe(OH)
3cannot occur accompanied with the competitive
effect among various pollutants On the other hand thefraction remaining in the treated wastewater unexpectedlyhigh for hydrophobic compounds could be explained by
8 Journal of Chemistry
Deca-CBsNona-CBsOcta-CBsHepta-CBsHexa-CBs
Penta-CBsTetra-CBsTri-CBsDi-CBsMono-CBs
RW PSE AHE SSE HCE PSS AS HCS FS0
20
40
60
80
100
Con
cent
ratio
n (
)
Wastewater and sludge samples
Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP
0
20
40
60
80
100
Sorb
ed P
CBs (
)
RW PSE AHE SSE HCE
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs
Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage
possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]
35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation
119877 () =(119862in minus 119862out)
119862intimes 100 (1)
where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic
0
20
40
60
80
100
Prim
ary
sedi
men
tatio
n
Ana
erob
ichy
drol
ysis
Aero
bic b
io-
proc
ess
Hig
h-de
nsity
clarifi
er
Who
le tr
eatm
ent
proc
ess
Rem
oval
()
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBs
minus20
ΣPCBs
minus528
minus150
minus118
minus587
minus182
minus322
Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage
sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents
Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes
Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal
Journal of Chemistry 9
50 55 60 65 70 750
20
40
60
80
100
120
Primary sedimentation
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
The partitioning behaviors of organic chemicals areessential to their fate in the WWTP as dissolved andadsorbed phases are differently available to different fateprocesses [11] Based on the PCBs concentrations in liquid-solid phase water quantity and SPM yield the relativedistribution of PCB isomers between the dissolved andadsorbed phases was obtained in the present study Figure 3presents the proportions of adsorbed PCB isomers in theinfluent and effluents of each treatment stage It is clearthat the adsorbed fraction of sum209 PCBs was found torange from 898 to 974 in the influent and effluent ofeach treatment stage much higher than the findings of
Katsoyiannis and Samara [28] with less than 60 of adsorbedsumPCBs in the influent ofWWTP inThessaloniki GreeceTheadsorbed PCB isomers in secondary sedimentation effluentwere absolutely predominant varying between 873 forOcta-CBs and 998 for Mono-CBs Likewise significantadsorbed fractions of PCB isomers were also found in the rawwastewater primary sedimentation effluent and anaerobichydrolysis effluent varying between 534 for Nona-CBs and991 for Tri-CBs 540 for Nona-CBs and 994 for Tri-CBs and 459 for Nona-CBs and 983 for Mono-CBsrespectively Differently in high-density clarifier effluentNona-CBs and Deca-CBs were more ldquodissolvedrdquo among
Journal of Chemistry 7
Table 3 The concentrations (means plusmn SD) of PCBs in SPM and sludge of each treatment stage at the WWTP
SPM suspended particulate matter RW mixing influent (raw wastewater) PSS primary sedimentation sludge AHE anaerobic hydrolysis effluent ASactivated sludge HCS high-density clarifier sludge FS final sludge ND not detected sum Ind sum indicator PCBs and sum DL sun DL-PCBs
the PCB isomers with only 300 and 392 in the solidphase although the adsorbed fractions of other PCB isomerswere all above 65 in this stage Generally better removalcan be obtained for higher MW congeners by sorption ontoparticles or microbes owing to their high hydrophobicity [11]But what was reason about this unusual result As seen fromTables 2 and 3 the mean concentrations of dissolved Nano-CBs and Deca-CBs were 318 and 82 pgL in HCE and the
average levels of adsorbed Nano-CBs and Deca-CBs were0226 and 0082 ngg respectively On the one hand maybedue to the very low concentrations of them in dissolved(possible) oxidation by ferrate or flocculationadsorption byFe(OH)
3cannot occur accompanied with the competitive
effect among various pollutants On the other hand thefraction remaining in the treated wastewater unexpectedlyhigh for hydrophobic compounds could be explained by
8 Journal of Chemistry
Deca-CBsNona-CBsOcta-CBsHepta-CBsHexa-CBs
Penta-CBsTetra-CBsTri-CBsDi-CBsMono-CBs
RW PSE AHE SSE HCE PSS AS HCS FS0
20
40
60
80
100
Con
cent
ratio
n (
)
Wastewater and sludge samples
Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP
0
20
40
60
80
100
Sorb
ed P
CBs (
)
RW PSE AHE SSE HCE
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs
Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage
possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]
35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation
119877 () =(119862in minus 119862out)
119862intimes 100 (1)
where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic
0
20
40
60
80
100
Prim
ary
sedi
men
tatio
n
Ana
erob
ichy
drol
ysis
Aero
bic b
io-
proc
ess
Hig
h-de
nsity
clarifi
er
Who
le tr
eatm
ent
proc
ess
Rem
oval
()
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBs
minus20
ΣPCBs
minus528
minus150
minus118
minus587
minus182
minus322
Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage
sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents
Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes
Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal
Journal of Chemistry 9
50 55 60 65 70 750
20
40
60
80
100
120
Primary sedimentation
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
SPM suspended particulate matter RW mixing influent (raw wastewater) PSS primary sedimentation sludge AHE anaerobic hydrolysis effluent ASactivated sludge HCS high-density clarifier sludge FS final sludge ND not detected sum Ind sum indicator PCBs and sum DL sun DL-PCBs
the PCB isomers with only 300 and 392 in the solidphase although the adsorbed fractions of other PCB isomerswere all above 65 in this stage Generally better removalcan be obtained for higher MW congeners by sorption ontoparticles or microbes owing to their high hydrophobicity [11]But what was reason about this unusual result As seen fromTables 2 and 3 the mean concentrations of dissolved Nano-CBs and Deca-CBs were 318 and 82 pgL in HCE and the
average levels of adsorbed Nano-CBs and Deca-CBs were0226 and 0082 ngg respectively On the one hand maybedue to the very low concentrations of them in dissolved(possible) oxidation by ferrate or flocculationadsorption byFe(OH)
3cannot occur accompanied with the competitive
effect among various pollutants On the other hand thefraction remaining in the treated wastewater unexpectedlyhigh for hydrophobic compounds could be explained by
8 Journal of Chemistry
Deca-CBsNona-CBsOcta-CBsHepta-CBsHexa-CBs
Penta-CBsTetra-CBsTri-CBsDi-CBsMono-CBs
RW PSE AHE SSE HCE PSS AS HCS FS0
20
40
60
80
100
Con
cent
ratio
n (
)
Wastewater and sludge samples
Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP
0
20
40
60
80
100
Sorb
ed P
CBs (
)
RW PSE AHE SSE HCE
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs
Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage
possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]
35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation
119877 () =(119862in minus 119862out)
119862intimes 100 (1)
where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic
0
20
40
60
80
100
Prim
ary
sedi
men
tatio
n
Ana
erob
ichy
drol
ysis
Aero
bic b
io-
proc
ess
Hig
h-de
nsity
clarifi
er
Who
le tr
eatm
ent
proc
ess
Rem
oval
()
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBs
minus20
ΣPCBs
minus528
minus150
minus118
minus587
minus182
minus322
Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage
sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents
Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes
Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal
Journal of Chemistry 9
50 55 60 65 70 750
20
40
60
80
100
120
Primary sedimentation
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
Figure 2 PCB isomer profiles in wastewater and sludge samples ofthe WWTP
0
20
40
60
80
100
Sorb
ed P
CBs (
)
RW PSE AHE SSE HCE
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBsΣPCBs
Figure 3 Distribution of PCBs in the adsorbed phase of the influentand effluent of each treatment stage
possible adsorption of PCBs onto nonsettleable solids whichremain in the wastewater stream due to the lack of chemicalcoagulation [28]
35 Removal of PCBs throughout the Treatment Processes inthe WWTP Based on the mean concentrations of dissolvedPCB isomers in each treatment stage the mean removals canbe calculated using the general equation
119877 () =(119862in minus 119862out)
119862intimes 100 (1)
where 119862in and 119862out are the daily amounts of PCBs enteringand exiting each treatment stage respectively The results areshown in Figure 4 Poor removal efficiencies were obtained inprimary sedimentation and anaerobic hydrolysis stage whichmay be due to the competitive adsorption between pollutantsand the selective adsorption of PACflocculants and anaerobic
0
20
40
60
80
100
Prim
ary
sedi
men
tatio
n
Ana
erob
ichy
drol
ysis
Aero
bic b
io-
proc
ess
Hig
h-de
nsity
clarifi
er
Who
le tr
eatm
ent
proc
ess
Rem
oval
()
Mono-CBsDi-CBsTri-CBsTetra-CBsPenta-CBsHexa-CBs
Hepta-CBsOcta-CBsNona-CBsDeca-CBs
minus20
ΣPCBs
minus528
minus150
minus118
minus587
minus182
minus322
Figure 4 Mean removal percentages of dissolved PCB isomersduring each treatment stage
sludge In the following treatment stages removal efficienciesfor most PCB isomers were around or above 40 exceptfor Di- Nona- and Deca-CBs in aerobic bioprocess and Di-and Tetra-CBs in high-density clarifier stage Furthermoreinterestingly removal efficiencies of several PCB isomers(Octa-CBs andNona-CBs in primary sedimentation Tri-CBsand Tetra-CBs in anaerobic hydrolysis etc) were negative(below zero) as shown which resulted from the surge of thePCBs in the effluents
Throughout the whole treatment process the totalremoval efficiency of sum209 PCBs was 232 In detail theremoval efficiencies of Di-CBs and Nona-CBs were thelowest among all the isomers (88 for Di-CBs and 207for Nona-CBs) The removals of other PCB isomers werehigher than those Especially for Mono-CBs and Hexa-CBsthe removal efficiencies were higher than 90 and highefficiencies of over 80 were achieved for Penta-CBs andHepta-CBs In comparison the removals of PCBs were 20ndash91 in 26 WPCPs in New York and average removal were773 described by Durell and Lizotte [23] Higher removalwas found in the WWTPs in Norway with more than 90removal [24] This was because PCB concentrations werevery low with pgL grade in the WWTP tested and theconcentrations in other WWTPs were with ngL grade Thelower the concentration of PCBs is the more difficult theirremoval becomes
Based on the results above and other published papersthe removals of hydrophobic chemicals in wastewater treat-ment system are strongly dependent on their sorptive behav-iors [8 12] The adsorption of the hydrophobic organicpollutants is generally affected by their octanol-water par-tition coefficients (119870ow) In order to verify whether thesefindings are applicable to the WWTPs in China the removal
Journal of Chemistry 9
50 55 60 65 70 750
20
40
60
80
100
120
Primary sedimentation
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
Anaerobic hydrolysisAerobic bioprocessHigh-density clarifierWhole treatment process
Rem
oval
()
logKow
R2
Primary = 034
R2
Aerobic = 027
R2
whole = 056
R2
Anaerobic = 031
R2
High-density = 019
Figure 5 Percent removal of individual PCBs versus log119870ow in eachtreatment stage
efficiency of each PCB congener is plotted against the log119870ow[29 30] which is shown in Figure 5 There was a weaklinear correlation (1198772 = 056) between the removal of PCBcongeners and their log119870ow values in the whole treatmentprocess However a relatively poor linear relationship (1198772019ndash034) was observed in primary sedimentation anaerobichydrolysis aerobic bioprocess and high-density clarifierstage which indicated that except for adsorption on sludgeparticles or microorganisms other mechanisms such asadvection volatilization biotransformation or (possible)oxidation and coagulation by ferrate might also be importantfor the less hydrophobic compounds of this class (log119870ow52ndash72) [12 31]
4 Conclusions
Dissolved and adsorbed concentrations of twenty PCB con-geners and total PCBs (from Mono-CBs to Deca-CBs) weredetected in each treatment stage in a centralized WWTPlocated in a chemical industry zone in Zhejiang China It wasinvestigated that the industrial activities especially the dyeingchemical processes were the main sources of PCBs enteringthe WWTP The contribution of sum209 PCBs discharged bythe largest dyeing chemical group to the WWTP was about136
PCBs entering the WWTP could be dissolved in thewastewater or adsorbed onto the particulates The mostabundant PCB was PCB-11 in the liquid and solid phaseof each treatment stage accounting for more than 60of the total 209 PCBs Meanwhile the PCB levels in theWWTP sludge were much higher than the limit set byChinese regulated laws Thus the sludge was not suitable foragricultural purposes Partitioning behavior of PCBs betweenthe dissolved and adsorbed phases suggested that Di-CBswere the most dominant isomers in the WWTP accountingfor over 70 of sum209 PCBs 898ndash974 of Di-CBs were
mainly adsorbed on the particles and sludge in the influentand effluent of each treatment stage The total removalefficiency of sumPCBs (209) was only 232 throughout thewhole treatment process although more than 80 of Mono-CBs Penta-CBsHexa-CBs andHepta-CBswere removed Ineach treatment stage poor removal efficiencies were foundin primary sedimentation and anaerobic hydrolysis whichwas due to the difficult settlement and biodegradation ofPCB-11 Furthermore a weak linear correlation between theremoval of PCB congeners and their log119870ow valueswas foundthroughout the whole treatment process which indicatedthat except for adsorption on sludge particles or microor-ganisms othermechanisms such as advection volatilizationbiotransformation or oxidation and coagulation by ferratemight also be important for the less hydrophobic compoundsof this class
Conflict of Interests
The authors declare that there is no conflict of interestsregarding this paper
Acknowledgments
The authors would appreciate the financial support tothis study provided by MOST Project of China (no2008BAC32B06) and NSFC of China (nos 2107618820836008 20976158 20990221 and 21076189) and the KeyInnovation Team for Science and Technology of ZhejiangProvince of China (2009R50047) They are sincerely gratefulto Professor Jiang Guibin and Zhang Qinghua in ResearchCenter for Eco-Environmental Sciences ChineseAcademy ofSciences Beijing for providing us with sample pretreatmentand analytical method
References
[1] K C Jones and P de Voogt ldquoPersistent organic pollutants(POPs) state of the sciencerdquo Environmental Pollution vol 100no 1ndash3 pp 209ndash221 1999
[2] K Breivik A Sweetman J M Pacyna and K C JonesldquoTowards a global historical emission inventory for selectedPCB congenersmdashamass balance approach 1 Global productionand consumptionrdquo Science of the Total Environment vol 290no 1ndash3 pp 181ndash198 2002
[3] L A Rodenburg J Guo S Du and G J Cavallo ldquoEvidencefor unique and ubiquitous environmental sources of 331015840-dichlorobiphenyl (PCB 11)rdquo Environmental Science and Technol-ogy vol 44 no 8 pp 2816ndash2821 2010
[4] B Fraser ldquoResearchers find little-known PCB lsquopretty mucheverywherersquordquo Environmental Science and Technology vol 44 no8 pp 2753ndash2754 2010
[5] M Pandelova R Piccinelli S Kasham B Henkelmann CLeclercq and K W Schramm ldquoAssessment of dietary exposureto PCDDF and dioxin-like PCB in infant formulae available onthe EUmarketrdquo Chemosphere vol 81 no 8 pp 1018ndash1021 2010
[6] F Samara CW Tsai andD S Aga ldquoDetermination of potentialsources of PCBs and PBDEs in sediments of the Niagara RiverrdquoEnvironmental Pollution vol 139 no 3 pp 489ndash497 2006
10 Journal of Chemistry
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984
[7] AMartinez KWang and K C Hornbuckle ldquoFate of PCB con-geners in an industrial harbor of lakeMichiganrdquo EnvironmentalScience amp Technology vol 44 no 8 pp 2803ndash2808 2010
[8] T Pham and S Proulx ldquoPCBs and PAHs in the Montreal urbancommunity (Quebec Canada) wastewater treatment plant andin the effluent plume in the St Lawrence riverrdquoWater Researchvol 31 no 8 pp 1887ndash1896 1997
[9] Y W Wang X M Li A Li et al ldquoEffect of municipal sewagetreatment plant effluent on bioaccumulation of polychlorinatedbiphenyls and polybrominated diphenyl ethers in the recipientwaterrdquo Environmental Science amp Technology vol 41 no 17 pp6026ndash6032 2007
[10] P-A Bergqvist L Augulyte and V Jurjoniene ldquoPAH and PCBremoval efficiencies in Umea (Sweden) and Siauliai (Lithuania)municipal wastewater treatment plantsrdquo Water Air and SoilPollution vol 175 no 1ndash4 pp 291ndash303 2006
[11] G Byrns ldquoThe fate of xenobiotic organic compounds inwastewater treatment plantsrdquoWater Research vol 35 no 10 pp2523ndash2533 2001
[12] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the sewage treatment plant ofThessaloniki NorthernGreece occurrence and removalrdquoWater Research vol 38 no 11pp 2685ndash2698 2004
[13] H Liu Q Zhang Z Cai A Li Y Wang and G Jiang ldquoSep-aration of polybrominated diphenyl ethers polychlorinatedbiphenyls polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisilfractionation chromatographyrdquo Analytica Chimica Acta vol557 no 1-2 pp 314ndash320 2006
[14] US EPA ldquoMethod 1668 Revision A Chlorinated biphenylcongeners inwater soil sediment and tissue byHRGCHRMSrdquoWashington DC USA EPA No EPA-821-R-00-002 1999
[15] R Yang Y Wang A Li et al ldquoOrganochlorine pesticidesand PCBs in fish from lakes of the Tibetan Plateau and theimplicationsrdquo Environmental Pollution vol 158 no 6 pp 2310ndash2316 2010
[16] L Guo B Zhang K Xiao Q H Zheng andMH Zheng ldquoLev-els and distributions of polychlorinated biphenyls in sewagesludge of urban wastewater treatment plantsrdquo Journal of Envi-ronmental Sciences vol 21 no 4 pp 468ndash473 2009
[17] S Litten B Fowler and D Luszniak ldquoIdentification of a novelPCB source through analysis of 209 PCB congeners by US EPAmodified method 1668rdquo Chemosphere vol 46 no 9-10 pp1457ndash1459 2002
[18] D Hu and K C Hornbuckle ldquoInadvertent polychlorinatedbiphenyls in commercial paint pigmentsrdquo Environmental Sci-ence and Technology vol 44 no 8 pp 2822ndash2827 2010
[19] F Rajaei A Esmaili-Sari N Bahramifar M Ghasempouri andM Savabieasfahani ldquoAvian liver organochlorine and PCB fromSouth coast of the Caspian Sea Iranrdquo Ecotoxicology vol 19 no2 pp 329ndash337 2010
[20] W Herbst and K Hunger Industrial Organic Pigments Wiley-VCH Weinheim Germany 3rd edition 2004
[21] H L He Fine Chemicals Daquan Dyes (Chinese Version)Zhejiang Science and Technology Press Hangzhou China2000
[22] M Blanchard M J Teil D Ollivon L Legenti and MChevreuil ldquoPolycyclic aromatic hydrocarbons and polychloro-biphenyls inwastewaters and sewage sludges from the Paris area(France)rdquo Environmental Research vol 95 no 2 pp 184ndash1972004
[23] G SDurell andRD Lizotte Jr ldquoPCB levels at 26NewYorkCityand New Jersey WPCPs that discharge to the New YorkNewJersey Harbor Estuaryrdquo Environmental Science amp Technologyvol 32 no 8 pp 1022ndash1031 1998
[24] C Vogelsang M Grung T G Jantsch K E Tollefsen and HLiltved ldquoOccurrence and removal of selected organic microp-ollutants at mechanical chemical and advanced wastewatertreatment plants in NorwayrdquoWater Research vol 40 no 19 pp3559ndash3570 2006
[25] S J de Luca M Cantelli and M A de Luca ldquoFerrate vstraditional coagulants in the treatment of combined industrialwastesrdquo Water Science and Technology vol 26 no 9ndash11 pp2077ndash2080 1992
[26] Ministry of Environmental Protection of the Peoplersquos Republicof China ldquoDischarge standard of pollutants for municipalwastewater treatment plant (GB 18918-2002)rdquo
[27] S Morris and J N Lester ldquoBehaviour and fate of polychlori-nated biphenyls in a pilot wastewater treatment plantrdquo WaterResearch vol 28 no 7 pp 1553ndash1561 1994
[28] A Katsoyiannis and C Samara ldquoPersistent organic pollutants(POPs) in the conventional activated sludge treatment processfate and mass balancerdquo Environmental Research vol 97 no 3pp 245ndash257 2005
[29] D W Hawker and D W Connell ldquoOctanol-water partitioncoefficients of polychlorinated biphenyl congenersrdquo Environ-mental Science and Technology vol 22 no 4 pp 382ndash387 1988
[30] M F Yeh and C S Hong ldquoOctanol-water partition coefficientsof non-ortho- and mono-ortho-substituted polychlorinatedbiphenylsrdquo Journal of Chemical amp Engineering Data vol 47 no2 pp 209ndash215 2002
[31] T D Waite and K A Gray ldquoOxidation and coagulationof wastewater effluent utilizing ferrate (VI) ionrdquo Studies inEnvironmental Science vol 23 pp 407ndash420 1984