ORIGINAL PAPER Comparison of the treatment for isopropyl alcohol wastewater from silicon solar cell industry using SBR and SBBR Y. Xiao • H.-Y. Xu • H.-M. Xie • Z.-H. Yang • G.-M. Zeng Received: 26 August 2013 / Revised: 26 March 2014 / Accepted: 3 June 2014 / Published online: 17 June 2014 Ó Islamic Azad University (IAU) 2014 Abstract In the present study, isopropyl alcohol con- taining wastewater generated from silicon solar cell man- ufacture was sequentially treated with sequencing batch biofilm reactor and sequencing batch reactor. Sequencing batch biofilm reactor could remove 90 % of isopropyl alcohol from wastewater efficiently as the chemical oxy- gen demand lower than 1,200 mg L -1 . However, 1,600 mg L -1 of chemical oxygen demand damaged the biofilm. The operation mode was changed to sequencing batch reactor on day 30, and sequencing batch reactor showed a greater ability to remove isopropyl alcohol. When the influent chemical oxygen demand was 1,600 mg L -1 , the reactors achieved stable removal effi- ciencies of [ 95 % for chemical oxygen demand, and the effluent chemical oxygen demand was lower than 100 mg L -1 . Denaturing gradient gel electrophoresis ana- lysis showed an increase in bacteria diversity as the oper- ation mode was switched from sequencing batch biofilm reactor to sequencing batch reactor, which might increase the stability of flocs in sequencing batch reactor. Though 13 bands were sequenced from the denaturing gradient gel electrophoresis and a phylogenetic analysis was conducted based on these sequences, it is difficult to analyze the function of these predominant strains in the reactors. Two models were constructed for interpreting the structure of biofilm in sequencing batch biofilm reactor and flocs in sequencing batch reactor, respectively. Higher efficient transfer rate of dissolved oxygen in flocs was proposed as the main reason for the higher isopropyl alcohol removal ability in sequencing batch reactor. Keywords Dissolved oxygen Sequencing batch biofilm reactor Denaturing gradient gel electrophoresis Industrial wastewater treatment Solar energy Introduction The volume of isopropyl alcohol (IPA) wastewater that is yielded from the wafer cleaning process in the silicon solar cell (SSC) manufacturing industry has continuously increased due to the increase demand on solar cell to obtain clean electric power. IPA and its metabolite, acetone, act as central nervous system depressants (Burkhart and Kulig 1990). Besides, the IPA wastewater contains many other refractory and complex organic compounds, e.g., fluoride and suspended solids, which not only introduce direct or indirect contamination to environment but also are harmful to human health (Lin and Kiang 2003). However, few studies have been conducted aiming to solve this problem in the industry, and the wastewater has consequently brought the industry in China a bigger and bigger trouble since Chinese factories produced more than one-half of solar cells in the world since the year of 2010. Though methanol and ethanol are usually used as carbon source in wastewater treatment and bio-treatment of wastewater has been successfully applied as a low-cost treatment method in many other industrial applications, the use of bio-treat- ment for IPA wastewater has not been reported as suc- cessful as that in other industry. Sequencing batch reactor (SBR) technology, a periodic discontinuous process with activated sludge, has been Y. Xiao (&) Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China e-mail: [email protected]Y. Xiao H.-Y. Xu H.-M. Xie Z.-H. Yang G.-M. Zeng College of Environmental Science and Engineering, Hunan University, Changsha 410082, China 123 Int. J. Environ. Sci. Technol. (2015) 12:2381–2388 DOI 10.1007/s13762-014-0634-8
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ORIGINAL PAPER
Comparison of the treatment for isopropyl alcohol wastewaterfrom silicon solar cell industry using SBR and SBBR
Y. Xiao • H.-Y. Xu • H.-M. Xie • Z.-H. Yang •
G.-M. Zeng
Received: 26 August 2013 / Revised: 26 March 2014 / Accepted: 3 June 2014 / Published online: 17 June 2014
� Islamic Azad University (IAU) 2014
Abstract In the present study, isopropyl alcohol con-
taining wastewater generated from silicon solar cell man-
ufacture was sequentially treated with sequencing batch
biofilm reactor and sequencing batch reactor. Sequencing
batch biofilm reactor could remove 90 % of isopropyl
alcohol from wastewater efficiently as the chemical oxy-
gen demand lower than 1,200 mg L-1. However,
1,600 mg L-1 of chemical oxygen demand damaged the
biofilm. The operation mode was changed to sequencing
batch reactor on day 30, and sequencing batch reactor
showed a greater ability to remove isopropyl alcohol.
When the influent chemical oxygen demand was
1,600 mg L-1, the reactors achieved stable removal effi-
ciencies of[95 % for chemical oxygen demand, and the
effluent chemical oxygen demand was lower than
100 mg L-1. Denaturing gradient gel electrophoresis ana-
lysis showed an increase in bacteria diversity as the oper-
ation mode was switched from sequencing batch biofilm
reactor to sequencing batch reactor, which might increase
the stability of flocs in sequencing batch reactor. Though
13 bands were sequenced from the denaturing gradient gel
electrophoresis and a phylogenetic analysis was conducted
based on these sequences, it is difficult to analyze the
function of these predominant strains in the reactors. Two
models were constructed for interpreting the structure of
biofilm in sequencing batch biofilm reactor and flocs in
et al. 2009). A universal consensus sequence was used as
the reverse primer (517R: 50-ATTACCGCGGCTGCTGG-30) (Muyzer et al. 1993; Murray et al. 1996). Each 50 lLPCR mixture contained about 150 ng of genomic DNA,
5 pmol each primer (Sangon, Shanghai, China), 25 lL of
2 9 PCR mix (BioTek, Beijing, China), 10 lg bovine
serum albumin (BSA) V (Sangon), and about 22 lL of
sterilized Milli-Q water. PCRs were performed using a
MyCycler (Bio-Rad, Hercules, USA). PCR mixtures were
pre-incubated at 95 �C for 4 min. Denaturing, annealing,
and extension were carried out at 94, 55, and 72 �C,respectively, and the duration was 30 s in all the steps. This
cycle was repeated 30 times and then incubated at 72 �Cfor 7 min for the final elongation.
Denaturing gradient gel electrophoresis
The DGGE was carried out by using a DCodeTM Universal
Detection System instrument and gradient former model
475 (Bio-Rad) according to the manufacturer’s instruc-
tions. The denaturant solution was prepared as Muyzer
et al. (1998) reported, and in this study, the optimal
acrylamide concentration in the gel was 8 % and the
optimal denaturing gradient was 35–55 %. Gels were run
in 1 9 TAE buffer at 60 �C for 8 h at 120 V. Gels were
stained with 1 9 SYBRTM Green I and visualized in UV
light with the Gel Doc XR System (Bio-Rad). Bands were
recognized both by the program QuantityOne V4.63 (Bio-
Rad) and manual identify; therefore, some weak bands on
the DGGE pattern also were sequenced.
16S rDNA cloning, sequencing, and phylogenetic
analysis
Each manually recognized band was excised from DGGE
gel under UV light, and the DNA was extracted from the
gel by bathing the gels in water at 4 �C. The extracted
DNA was amplified with primer pair GC341F/517R. The
PCR products were cloned, re-DGGE affirmed, and
sequenced as our previous study reported (Xiao et al.
2011a, b).
Phylogenetic identity was determined by comparing the
partial 16S rDNA sequences of the clones with sequences
which were found in GenBank using the BLAST (http://
blast.ncbi.nlm.nih.gov/Blast.cgi), and a phylogenetic tree
was constructed using the program MEGA5 as that in our
previous study (Tamura et al. 2011).
Nucleotide sequence accession numbers
The retrieved thirteen sequences of the 16S rRNA gene
clones have been deposited orderly in the GenBank data-
base under Accession No. JX872406-JX872418.
Results and discussion
Reactors performance
Figure 1 shows the average COD concentration (plus
standard deviation) in influent and effluent in reactors A
and B. The COD removal efficiencies in both reactors were
also shown in this figure. Figure 2 shows the daily removed
COD of each reactor.
Int. J. Environ. Sci. Technol. (2015) 12:2381–2388 2383