Marie Skłodowska-Curie actions TreatRec - Interdisciplinary concepts for municipal wastewater treatment and resource recovery. Tackling future challenges MARIE SKŁODOWSKA-CURIE ACTIONS Innovative Training Networks (ITN) Modality: EID – European Industrial Doctorate Call: H2020-MSCA-ITN-2014 AOPs for wastewater treatment (reuse and disinfection) Dr. Pilar Fernández Ibáñez; Plataforma Solar de Almería-CIEMAT
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Marie Skłodowska-Curie actions
TreatRec - Interdisciplinary concepts for municipal wastewater treatment and
resource recovery. Tackling future challenges
MARIE SKŁODOWSKA-CURIE ACTIONS Innovative Training Networks (ITN) Modality: EID – European Industrial Doctorate Call: H2020-MSCA-ITN-2014
AOPs for wastewater treatment (reuse and disinfection)
Dr. Pilar Fernández Ibáñez; Plataforma Solar de Almería-CIEMAT
Sustainable and Integrated Urban Water System Management
Contents
• Solar radiation and CPC photoreactors • Solar AOPs coupled to Bio-treament • Emerging contaminants removal • Solar reactors for water disinfection • Solar treated MWW reuse: case study • Concluding remarks
Sustainable and Integrated Urban Water System Management
• PSA is an European Large Scientific Installation, being the largest and most
complete R+D center in the World devoted to solar thermal concentrating
systems. PSA is also a Singular Science and Technology Infrastructure (ICTS) of
Spain.
• Goal: R+D in potential industrial applications of concentrated solar thermal
energy and solar photochemistry.
• Location: Distributed over 103 hectares in the Tabernas desert (Almería, South-
Sustainable and Integrated Urban Water System Management
25
Solar heterogeneous photocatalysis (TiO2)
Linearly dependent on the energy flux but only ~5% of the whole solar
spectrum is available for TiO2 band-gap.
Solar collector efficiency of 75% and 1% for the catalyst means 0.04%
original solar photons are efficiently used. This is a rather inefficient process.
Pure TiO2 can utilize only UV and new catalysts able to work with the visible
component of the solar spectrum are needed.
Sustainable and Integrated Urban Water System Management
26
Photo-Fenton has good potential for wastewater treatment applications.
Several aspects may also contribute to market introduction:
Catalysts based on immobilized iron.
Additives which enhance the process performance, either regarding kinetics
or pH operation range.
Optimization of treatment taking into account the wastewater specific
requirements.
Ways to minimize hydrogen peroxide consumption, which is the main factor
regarding operation costs.
Photo-Fenton
Sustainable and Integrated Urban Water System Management
AOP-BIO and BIO-AOP
Sustainable and Integrated Urban Water System Management
WW characterization: TOC, COD, BOD, main inorganics, contaminants (LC-MS/GC-MS)
Non-toxic or partially
toxic (<50%)
TOXICITY
Toxic (>50%)
EVALUATION OF
BIODEGRADABILITY
2: Biodegradable. COD>Guideline
AOP EVALUATION OF
BIODEGRADABILITY DURING AOP
1: Partially or not biodegradable
BIOLOGICAL
TREATMENT
COD and
toxicity<Guideline
DISCHARGE
TOC<500 mg/L TOC>500 mg/L
DILUTION AND EVALUATION OF
BIODEGRADABILITY
AOP EVALUATION OF
BIODEGRADABILITY
DURING AOP BIOLOGICAL
TREATMENT
AOP
Biorecalcitrant
compounds COD and toxicity<Guideline
DISCHARGE
BIOLOGICAL
TREATMENT
AOP EVALUATION OF
BIODEGRADABILITY
DURING AOP
1
1 2
2
2
2
1
1 1 2
AOP-BIO and BIO-AOP
Science of the Total Environment, 409, 4141–4166, 2011.
Sustainable and Integrated Urban Water System Management
29
Photocatalytic processes only make sense for hazardous non-biodegradable
pollutants.
The use of photocatalysis as a pre-treatment makes sense when the
intermediates are biodegradable.
Toxicity tests of the treated wastewater are needed when incomplete
degradation is planned.
However, if we consider that toxicity is a biological response, the values
obtained by a single toxicity assay can be insufficient. Consequently, a
battery of assays is recommended.
Toxicity results are reliable when two or more different bioassays point in the
same direction.
AOP treatment coupled to BIO (AOP-BIO)
Sustainable and Integrated Urban Water System Management
Combined photo-Fenton and biotreatment
Biological
treatment (IBR) Solar Photo-Fenton
Industrial
wastewater
DOC0: 480
mg/L
Non-biodegradable
pesticides
Biodegradable
compounds
Decontaminated
water
DOC: 75 mg/L • 20 mg/L Fe / pH: 2.8
• 44 % mineralization
• DOCf: 270 mg/L
• 21 mM H2O2 consumed
• DOC0: 300 mg/L
• 1.5 days of biotreatment
• 75 % mineralization
• DOCresidual: 75 mg/L
0 4 8 12 16 20 24 280
20
40
60
80
100%
BIO
DE
G.
Time (days)
S1 (DOC0: 490 mg/L) S5 (DOC
0: 345 mg/L)
S2 (DOC0: 460 mg/L) S6 (DOC
0: 255 mg/L)
S3 (DOC0: 440 mg/L) S7 (DOC
0: 170 mg/L)
S4 (DOC0: 400 mg/L) S8 (DOC
0: 145 mg/L)
Biodegradability limit
0 1 2 3 20 400
250
500
750
1000
1250
0.0
0.2
0.4
0.6
0.8
1.0
IBR
Illumination time (hours)
DOC
COD
H2O
2 consumed
C (
mg/L
)
Treatment time (hours)
Photo-Fenton
AOS
AO
S
AOP-BIO
Sustainable and Integrated Urban Water System Management
31
Pesticides identification and quantification by LC-TOF-MS in real
wastewater
1. SPE extraction
Oasis® HLB
1 2 3 4
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Pesticides identified in real wastewater
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Imidacloprid
Dimethoate
Pyrimethanil
Thiacloprid
Carbofuran
Metalaxyl
Spinosyn a
Bupirimate
Fenamiphos
Azoxystrobin
Malathion
Tebufenozide
Mezcua et al., Anal. Chem. 81, 2009.
2. LC-TOF-MS 3. Automatic screening using a pesticide accurate
mass-database (ca 300 compounds in 20 minutes)
Sustainable and Integrated Urban Water System Management
Compound % Reduction
combined system
Final conc
(g/L)
Imidacloprid 96.4 25
Dimethoate 99.4 5
Pyrimethanil 81 161
Thiacloprid 84.2 88
Azoxystrobin 99.4 3
Malathion 100 < 0.1
Carbofuran 100 < 0.1
Metalaxyl 100 < 0.1
Spinosyn a 100 < 0.1
Bupirimate 100 < 0.1
Fenamiphos 100 < 0.1
Tebufenozide 100 < 0.1
Concentration of all pesticides decreased gradually throughout
the process (mainly during the photo-Fenton process).
After the combined system: totally removed, except
pyrimethanil and thiacloprid, found in range of g/L
1. SPE extraction
Oasis® HLB
1 2 3 4
2. LC-TOF-MS
AOP-BIO
Chemical Engineering Journal, 160, 447–456, 2010.
Sustainable and Integrated Urban Water System Management
Parameter Amount
pH 3.98
Conductivity 7 mS.cm-1
TOC 775 mg.L-1
COD 3420 mg.L-1
Nalidixic acid 45 mg.L-1
TSS 0.407 g.L-1
Cl- 2.8 g.L-1
PO43- 0.01 g.L-1
SO42- 0.16 g.L-1
Na+ 2 g.L-1
Ca2+ 0.02 g.L-1
Real WW
N N
O
OH
O
BIO-AOP
Sustainable and Integrated Urban Water System Management
0 50 100 150 200 250 3000
150
300
450
600
750
900
TOC
H2O
2 consumed
t30W
(min)
TO
C (
mg
/L)
0
10
20
30
40
50
60
70
H2O
2 c
on
su
med
(m
M)
0 50 100 150 200 250 300
0
10
20
30
40
50
Na
lid
ixic
acid
(m
g/L
)
t30W
(min)
0 50 100 150 200 250 3000
150
300
450
600
750
900
TOC
H2O
2 consumed
t30W
(min)
TO
C (
mg
/L)
0
10
20
30
40
50
60
70
H2O
2 c
on
su
med
(m
M)
0 50 100 150 200 250 300
0
10
20
30
40
50
Na
lid
ixic
acid
(m
g/L
)
t30W
(min)
INITIAL CONDITIONS (photo-Fenton)
• Nalidixic acid: 39 mg/L
• Initial TOC: 822 mg/L
• [NaCl] : 6.5 g/L
• Total degradation of the nalidixic acid
at 350 minutes (illumination time)
(65 mM H2O2)
• 28% of the initial TOC was removed
• Nalidixic acid: 38 mg/L
• Initial TOC: 725 mg/L
• [NaCl] : 4.3 g/L
INITIAL CONDITIONS (Biotreatment)
• NH4+ : <0.1 mg/L
• NO3- : <0.1 mg/L
• pH: 6.6
• 96% of the initial TOC was removed
• Nalidixic acid persists after biological treatment (~15 mg/L)
0 1 2 3 40
100
200
300
400
500
600
700
800
TOC
Nalidixic acid
Time (days)
TO
C (
mg
/L)
0
10
20
30
40
50
Na
lid
ixic
acid
(m
g/L
)
BIO-AOP
photo-Fenton
Sustainable and Integrated Urban Water System Management
AOP-BIO versus BIO-AOP
0
20
40
60
80
100
% T
OC r
educ
tion
AO
P
BIO
Biotr.
time =
4 days Biotr.
time =
4 days
BIO
A
OP
t30w = 350
min; H2O2
= 65 mM (elim.NXA)
t30w = 21 min (elim. NXA) !!!
H2O2 = 12 mM (elim. NXA) !!!
Wat. Res., 45, 1736-1744, 2011.
Sustainable and Integrated Urban Water System Management
LC-TOF-MS chromatograms
10 20 30 40 50
Initial wastewater
IBR
IBR + photo-Fenton
Time (min)Retention time (min)
N N
O
O
OH
O
O
P34
N N
OH
OO
OH
P2
N N
OH
OO
NXA
N N
O
O
O
OH
OH
P3
N ON
O
O OH
P4
N N
OH
OO
P5
N N
OH
OO
OH
P9
N NH
OH
OO
P6
N N
OH
OH
P14
N N
OH
OHP1
N N
OH
O
O
O
HO
P11
N NH
O
O
OH
OH
P12
N NH
OH
O
P15
N NH
O
P13
N N
OH
O
O
P7
N N
HO
OO
OH
ClP17
N N
OH
O
H
O
OHP22
N N
OH
O
OH
O
P27
No DPs
BIO-AOP
Sustainable and Integrated Urban Water System Management
37
Solar reactors for water disinfection (PSA)
Sustainable and Integrated Urban Water System Management
38
Design of solar reactor for water disinfection
(i) maximizing the collection of solar energy dose
(ii) enhancing the disinfecting efficacy especially against resistant pathogens
(iii) increasing the output of treated water in given solar exposure time
(iv) reducing the treatment time
(v) reducing the user dependence of the process
(vi) finding cheap and robust disinfection systems, which may also be
constructed with local materials without sophisticated technological needs
(this is especially important for developing countries)
(vii)optimizing photoreactor design taking into account the disinfection
mechanisms and previous knowledge based on practical experiences on
disinfection of real contaminated waters and wastewaters.
Sustainable and Integrated Urban Water System Management
39
Damage of solar radiation on cells
39
Malato et al. Catalysis
Today. 147 (2009) 1-59.
Sustainable and Integrated Urban Water System Management
40
The challenge: to improve SODIS
What is SODIS?
Transparent containers are filled with contaminated water and placed in
direct sunlight for at least 6 hours, after which time it is safe to drink.
55 countries where, in 2009, SODIS was in daily use by more
than 4.5 million people (Meierhofer and Landolt, 2009).
Sustainable and Integrated Urban Water System Management
SODIS for drinking water disinfection
The positives: • Low cost, since usually only the poorest communities tend to be affected. • Easy to use. Compliance will suffer if the protocol is overly complicated. • Sustainable. The technique must not require consumables that are difficult or too expensive to obtain. The negatives: • Undesirable bacterial re-growth may occur. • Some water pathogens are very resistant. • Small water outputs and large treatment times. • Strongly dependantg on weather conditions.
Sustainable and Integrated Urban Water System Management
42
The challenge: to improve SODIS
Water being treated by SODIS at a primary school in Southern Uganda. Students fill their bottles at home
and expose them to the sun while they are in class (McGuigan et al., 2012).
Sustainable and Integrated Urban Water System Management
43
CPC enhancement for SODIS
Navntoft et al., J. Photochem. Photobiol. B: Biology, 93, 155-161, 2008.
Cloudy days
11:00 12:00 13:00 14:00 15:0010
0
101
102
103
104
105
106
107
0
10
20
30
40
50
60
Ba
cte
ria
Co
nc.
(CF
U/m
l)
Local time(hh:mm)
Old CPC
Controls
DL
UV IrradianceNo CPC
UV
Irr
ad
ian
ce
(W
/m2)
New CPC
Clear days
11:00 12:00 13:00 14:00 15:00 10
0
10 1
10 2
10 3
10 4
10 5
10 6
10 7
0
10
20
30
40
50
60
Ba
cte
ria
Co
nc. (C
FU
/ml)
Local time(hh:mm)
Tube+CPC
DL
Controls
UV Irradiance
Dark
Bottle U
V I
rra
dia
nce
(W
/m
2 )
Tube
Sustainable and Integrated Urban Water System Management
44
Solar energy distribution in the CPC reactor
1. Solar radiation is
applied for
inactivation of
microorganisms
2. Ray tracing
model in a
CPC+tube system
0I
IT
)(log10 TlCA l
lll
E. coli absorption
E. coli extinction
Sustainable and Integrated Urban Water System Management
45
Local volumetric adsorption energy (LVAE, W m-2) in the CPC photo-reactor • UVAave.= 30 w/m2. Incidence angle = 45º.
• Isotropic dispersion of E. coli Glass transmission = 90 %
• Loses (surface, shape, etc.) = 10%.
De tube LVAE efficiency (%)
20 cm 0.62 0.32 0.04
5 cm 0.51 0.11 0.01
108 CFU mL-1 107 CFU mL-1 106 CFU mL-1
Solar energy distribution in the CPC reactor
Sustainable and Integrated Urban Water System Management
46
11:00 12:00 13:00 14:00 15:0010
0
101
102
103
104
105
106
107
0
10
20
30
40
50
60
0 l/min
UV
irr
ad
ian
ce
(W
/m2)
10 l/min
2 l/min
Ba
cte
ria
Co
nc.
(CF
U/m
l)Local time (hh:mm)
DL
Controls
How is the solar energy delivered?
Increasing flow rate has a negative effect on inactivation of bacteria, irrespective of the
long exposure time of 5 hours.
At a given time point there needs to be maximum exposure of bacteria to UV to ensure
inactivation as compared with having bacteria exposed to sub-lethal doses over a long
period of time.
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
0 10 20 30 40 50 60 70 80 90 100
Time (min)
Bacte
ria
l surv
ival (C
FU
/ml)
30 minutes of
continuous irradiation
30 minutes of interrumped
illumination
Sustainable and Integrated Urban Water System Management
47
Bactericidal (lethal) solar dose
It was observed that bacterial inactivation depends on UVA dose instead of UVA
irradiance (for 14 - 40 W·m-2). There is a minimum and uninterrupted UVA dose
needed for a complete inactivation of bacteria; this dose was defined as the
“uninterrupted lethal UVA dose".
10 15 20 25 30 35 60 70
100
101
102
103
104
105
106
107
100
101
102
103
104
105
106
107
Final bacteria concentration
Ba
cte
ria
Co
nce
ntr
atio
n (
CF
U/m
l)
UV Energy (Wh/m2) (0,295-0,385 um)
Detection Limit:
4 CFU/ml
Average C0
Exposure to different uninterrupted UV dose
Sustainable and Integrated Urban Water System Management
48 25l CPC-SODIS batch reactor
Static batch reactors
CPC reflector
Glass tube
CPC tube – 2.5 l
1.5l PET-bottles
Sustainable and Integrated Urban Water System Management
49
Sequential batch reactor
C=1.89
Aperture=29.70cm
19
.37
cm
- decreasing the treatment time required
- increasing the total volume of water treated per day
- reducing user dependency.
Sustainable and Integrated Urban Water System Management
50
Electronic dosimetric
control system CPC reflector
Borosilicate tube
Storage tank with
treated water
Platform titled 37ºC
Sequential batch reactor
Sustainable and Integrated Urban Water System Management
51 Fontán-Sainz et al., Am. J. Trop. Med. Hyg. 2012, 86 (2) 223-228
• Mineral water for positive (with spiked E. coli) and negative controls.
Sustainable and Integrated Urban Water System Management
Watering of lettuce crops
with solar treated water
Sustainable and Integrated Urban Water System Management
www.seward.co.uk
E. coli presence/absence method
Sustainable and Integrated Urban Water System Management
E. coli detection on Chromocult plates
RE
(untreated)
EC1E6
(Control +) PW
(Control -)
b1-b2
(SODIS)
What does a “+” mean?
≥ 1 CFU/ 0.3 g lettuce
ie. ≥ 100 CFU/ 30 g lettuce
(one serving)
Sustainable and Integrated Urban Water System Management
Recovery of E. coli bacteria after blending treatment
1,0E+00
1,0E+01
1,0E+02
1,0E+03
1,0E+04
1,0E+05
1,0E+06
1,0E+07
1,0E+00 1,0E+02 1,0E+04 1,0E+06
Conc. inicial (cfu/ml)
Co
nc
. d
es
pu
és
de
ba
tir
4*1
5s
eg
sin lechuga
con lechuga
C0 (CFU mL-1)
C a
fter
ble
nd
ing (
CF
U m
L-1
)
○ With lettuce
■ Without lettuce
Sustainable and Integrated Urban Water System Management
E. coli presence/absence method • Lettuce leaves sample collection 24h after irrigation.
• 3 x ~0.1-g sample of lettuce leaves (duplicate).
• 24-hr incubation at 37ºC in 15 ml LB.
• 10-fold diluted in PBS: spreading in Chromocult-agar plates.
Sustainable and Integrated Urban Water System Management
40
Sustainable and Integrated Urban Water System Management
0 100 200 300 400 500 600 700
100
101
102
103
104
105
106
107
Time (h)E
. c
oli (
CF
U m
L-1)
DoseUV
(kJ m-2)
Distilled water
Well water
Simulated WWTPE
Real WWTPE
DL
0 1 2 3 4 5
100
101
102
103
104
105
106
107
Solar disinfection in solar CPC reactors
34-
40°C 39-
47°C
33-
34°C
35-
41°C
Total volume: 20L
Bichai et al., Wat. Res. 40 (2012) 6040-50.
Sustainable and Integrated Urban Water System Management
0 100 200 300 400 500 600 700
100
101
102
103
104
105
106
107
E. c
oli (
CF
U m
L-1)
DoseUV
(kJ m-2)
Distiled water
Well water
Simulated WWTPE
Real WWTPE
5 mg/L-1 H
2O
2(open symbols)
10 mg/L-1 H
2O
2(solid symbols)
DL
0 1 2 3 4 5
100
101
102
103
104
105
106
107
Time (h)
H2O2/sunlight disinfection in solar CPC reactors
49°C
48°C
39-
41°C
46°C
Total volume: 20L
Bichai et al., Wat. Res. 40 (2012) 6040-50.
Sustainable and Integrated Urban Water System Management
Solar disinfection of real WWTPE in PET bottles
0 100 200 300 400 500 600 700 800
100
101
102
103
104 Solar light/H
2O
2
10 mgL-1
5 mgL-1
SODIS
Time (h)
E. c
oli (
CF
U m
L-1)
DoseUV
(kJ m-2)
DL
0 1 2 3 4 5
100
101
102
103
104
Max. T in SODIS bottles 40.2 - 43.4°C Total volume: 1.5L
Bichai et al., Wat. Res. 40 (2012) 6040-50.
Sustainable and Integrated Urban Water System Management
Irrigation results (presence/absence of E. coli)
Before treatment Initial conc. of E. coli (CFU
mL-1) of 4 real WWTPE 2.4 x 103 1.3 x 104 3.8 x 103 3.1 x 103
Untreated real
WWTPE
+ + + + + + + +
‒ + + + + ‒ + +
After solar treatment SODIS H2O2-solar
SODIS1 SODIS2 10mg L-1 5mg L-1
CPC experiment-R1 ‒ ‒ + ‒ ‒ ‒ ‒ ‒
CPC experiment-R2 ‒ ‒ ‒ ‒ ‒ ‒ ‒ ‒
Bottle test-b1 ‒ ‒ ‒ ‒ ‒ ‒ ‒ ‒
Bottle test-b2 ‒ ‒ ‒ ‒ ‒ ‒ ‒ +
Controls Mineral water
(negative control) ‒ ‒ ‒ ‒ ‒ ‒ ‒ ‒
Mineral water + E. coli K-12
(positive control; 106 CFUmL-1) + + + + + + + +
+/- indicate the presence/absence of E. coli in ~0.3 g of lettuce leaves samples.
For each water, 2 crops (2 leaves samples) were evaluated.
What does a “+” mean?
≥ 1 CFU/ 0.3 g lettuce
ie. ≥ 100 CFU/ 30 g lettuce
(one serving)
Sustainable and Integrated Urban Water System Management
Summary – solar treated WW reuse
• Characterizing 20-L batch SODIS reactors.
• Using real wastewater effluents and describing E. coli inactivation in
solar and solar-H2O2 disinfection assays.
• Using SODIS simple PET-bottle technique for improving the microbial
safety of wastewater irrigation in developing communities.
• ‘Closing the loop’ by measuring E. coli contamination on crops
(lettuce) irrigated with the solar-disinfected or untreated wastewater.
• More detailed and large scale
research on WW reuse for irrigation
and its Implications for health risk
analysis is still needed.
Sustainable and Integrated Urban Water System Management
79
Sunlight/H2O
2 treated wastewater reused for
lettuce irrigation: micropollutants and antibiotic
resistant bacteria contamination
To assess chemical and microbial cross contamination on crops irrigated
with real urban wastewater treatment plant (UWTP) effluents after a H2O
2
(20 mg L-1
)/sunlight treatment at pilot-scale by a solar compound
parabolic collector (CPC) system, in terms of:
transfer of multi-drug resistant (MDR) bacteria to both lettuce
leaves and top soil;
uptake of CECs by lettuce leaves and top soil.
Ferro, et al., Env. Sci. Technol. 2015, DOI: 10.1021/acs.est.5b02613.
Sustainable and Integrated Urban Water System Management
H2O2
(20 mg L-1)
Experimental design
MDR E. coli
MDR E. faecalis
(105 CFU mL-1)
Carbamazepine
Flumequine
Thiabendazole
(100 g L-1)
MDR E. coli ?
MDR E. faecalis ?
Crop irrigation
CECs?
Sustainable and Integrated Urban Water System Management
Disinfection/oxidation experiments
Solar CPC photo-reactor (V=8.5 L)
Flow rate: 16 L min-1
Real autoclaved wastewater spiked with MDR E. coli and MDR E. faecalis
(ca 105 CFU mL
-1) and carbamazepine (CBZ), flumequine (FLU) and
thiabendazole (TBZ) (ca 100 g L-1
)
Two treatment time for irrigation tests: 300 min (R1) and 90 min (R2).
Sustainable and Integrated Urban Water System Management
Irrigation experiments
Lettuce leaves.
5 weeks irrigation experiments.
Drip irrigation and sprinkling irrigation (50 mL) were simulated.
Plated counting method was used for MDR bacteria enumeration.
CECs were extracted by application of QuEChERS method.
Sustainable and Integrated Urban Water System Management
Inactivation of MDR E. coli and MDR E. faecalis strains by
H2O2/sunlight disinfection in solar CPC reactor
Sustainable and Integrated Urban Water System Management
Degradation of CECs by H2O2/sunlight disinfection in solar CPC
reactor
Sustainable and Integrated Urban Water System Management
Transfer of MDR bacteria to lettuce leaves and top soil
All negative controls samples were detected as negative;
During the first two weeks of drip irrigation, positive control samples
were detected as positive just for top soil samples;
During the sprinkling irrigation weeks, all positive control samples were
detected as positive;
Through all irrigation experiments using wastewater treated with
H2O
2/sunlight process for 300 min, all samples (both lettuce leaves and top
soil) were detected as negative for the presence of both MDR bacteria
strains;
In the 5th
sampling week, MDR E. faecalis was detected on one lettuce
leaves sample (6.4x103 CFU 100 mL
-1) and MDR E. coli was detected on one
top soil sample (2.5x101 CFU 100 g
d
-1), when wastewater treated with
H2O
2/sunlight process for 90 min was used.
Sustainable and Integrated Urban Water System Management
CECs uptake by lettuce leaves
R1 refers to UWTP effluent treated within 5 h of H2O
2/sunlight and then used as irrigation
water; R2 refers to UWTP effluent treated within 90 min of H2O
2/sunlight and then used as
irrigation water.
0
20
40
60
80
100
120
I week III week V week
EC
s c
oncentr
atio
n [
ng g
-1]
CBZ (R1)
TBZ (R1)
CBZ (R2)
TBZ (R2)
Sustainable and Integrated Urban Water System Management
CECs uptake by top soil
R1 refers to UWTP effluent treated within 5 h of H2O
2/sunlight and then used as irrigation
water; R2 refers to UWTP effluent treated within 90 min of H2O
2/sunlight and then used as
irrigation water.
0
50
100
150
200
250
300
350
400
450
500
550
I week II week III week IV week V week
EC
s c
on
ce
ntr
atio
n [
ng
g-1
]
CBZ (R1)
TBZ (R1)
CBZ (R2)
TBZ (R2)
Sustainable and Integrated Urban Water System Management
Conclusions (treated WW reuse)
When the effluents are treated and the final MDR bacterial concentration is below the detection limit (for both E. coli and E. faecalis), non-cross contamination of pathogens in lettuce leaves and top soil was observed.
When MDR bacterial load was as high as 102 CFU mL-1 in the treated effluent, the complete absence of cross contamination in crops was not achieved.
For the first time, a new developed analytical methodology, adapted from QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method, permitted to extract, detect and quantify CECs at nano-range in solid samples like lettuce leaves and soil.
Partial removal of selected CECs leads to chemical contamination in both lettuce and soil.
H2O2/sunlight process should be properly operated to effectively inactivate MDR bacteria as well as to minimize CECs residual concentration in order to reduce their subsequent uptake in crops irrigated with the treated wastewater.
Sustainable and Integrated Urban Water System Management
89
Concluding remarks - CPC photoreactors have been demonstrated at pilot and full scale to be
effective for solar treatment of water for removing hazardous chemical
compounds and disinfect contaminated water.
- The removing of emerging contaminants from real wastewater has also
been demonstrated.
- New photocatalysts able to work with the visible component of the solar
spectrum are needed.
- Improvements in reactor design utilising immobilized photocatalyst are
required to increase efficiencies.
- More work is needed to assess photocatalyst longevity and fouling under
real working conditions.
-Cost-benefit and life cycle analysis are required before these technologies