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Evaluations of conventional, ozone and Uv/H2O2 for removal of emerging contaminants and THM-FPS

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Although potential risk of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds (EDCs) and trihalomethanes to humans is small or unconfirmed, it is advisable to remove these wastewater-related contaminants to increase public confidence and acceptance as a precautionary principle and consequently their elimination or reduction during drinking water treatment is warranted. Experiments were conducted using the dual train pilot-scale conventional treatment plant with ozone and ultraviolet/hydrogen peroxide (UV/H2O2) with three different raw water sources. Reductions of trihalomethanes-formation potentials (THM-FPs) were 8–52%. Ozone was found to decrease THM-FPs while UV/H2O2 was found to increase THM-FPs in most of the experiments under experimental conditions. Conventional treatment poorly removed the selected PPCPs and EDCs while ozone þ conventional treatment provided excellent removal. ConventionalþUV/H2O2 treatment also demonstrated effective removal. However, removal of PPCPs and EDCs by conventionalþUV/H2O2 treatment provided lower efficacy for Sites B and C, likely due to the presence of scavengers such as organics, bicarbonates, carbonates and particles.
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Evaluation and Comparison of Conventional and
Advanced Oxidation Processes for the Removal of
PPCPs and EDCs and Their Effect on THM-Formation
Potentials
Devendra Borikarab, Madjid Mohsenib & Saad Jasimc
a Walkerton Clean Water Center, Walkerton, Ontario N0G 2V0, Canada
b Department of Chemical and Biological Engineering, University of British Columbia,
Vancouver, British Columbia V6T 1Z3, Canada
c SJ Environmental Consultants, Inc., Windsor, Ontario N9G 2S9, Canada
Accepted author version posted online: 28 Jul 2014.
To cite this article: Devendra Borikar, Madjid Mohseni & Saad Jasim (2015) Evaluation and Comparison of Conventional
and Advanced Oxidation Processes for the Removal of PPCPs and EDCs and Their Effect on THM-Formation
Potentials, Ozone: Science & Engineering: The Journal of the International Ozone Association, 37:2, 154-169, DOI:
10.1080/01919512.2014.940028
To link to this article: http://dx.doi.org/10.1080/01919512.2014.940028
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Ozone: Science & Engineering, 37: 154–169
Copyright © 2015 International Ozone Association
ISSN: 0191-9512 print / 1547-6545 online
DOI: 10.1080/01919512.2014.940028
Evaluation and Comparison of Conventional and Advanced
Oxidation Processes for the Removal of PPCPs and EDCs
and Their Effect on THM-Formation Potentials
Devendra Borikar,1,2Madjid Mohseni,2and Saad Jasim3
1Walkerton Clean Water Center, Walkerton, Ontario N0G 2V0, Canada
2Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia V6T 1Z3,
Canada
3SJ Environmental Consultants, Inc., Windsor, Ontario N9G 2S9, Canada
Pharmaceuticals and personal care products (PPCPs),
endocrine disrupting compounds (EDCs) and disinfection
by-products are suspected to have potential adverse impact
on humans and hence their elimination during drinking water
treatment is often desired or regulated. Based on pilot-plant
experiments with three raw water sources, conventional treat-
ment poorly removed the selected PPCPs and EDCs, while
ozone/H2O2and UV/H2O2(both) with conventional treat-
ment effectively removed PPCPs and EDCs. In most of the
experiments, ozone/H2O2+conventional treatment addition-
ally removed THM formation potentials (THM-FPs) com-
pared to those of conventional treatment. However, UV/H2O2
treatment was found to increase THM-FPs compared to con-
ventionally treated water.
Keywords Ozone, Advanced Oxidation Processes, Endocrine-
Disrupting Compounds, Pharmaceuticals and Personal
Care Products, Trihalomethanes, Ultraviolet-Hydrogen
Peroxide
INTRODUCTION
Many pharmaceuticals and personal care products (PPCPs)
and endocrine disrupting compounds (EDCs) were detected
in the untreated drinking water sources (Facazio et al. 2008;
Kolpin et al. 2002; Vieno et al. 2007). PPCPs and EDCs are
suspected to have effects on human health (Richthoff et al.
2003; Shaw and McCully 2002). Although potential risk to
humans is low at the concentration found in treated water, it
Received 5/8/2014; Accepted 6/2/2014
Address correspondence to Devendra Borikar, Walkerton Clean
Water Center, 20 Ontario Road, Walkerton, ON N0G 2V0, Canada.
E-mail: dborikar@wcwc.ca
Color versions of one or more of the figures in the article can be
found online at www.tandfonline.com/bose.
is advisable to remove these wastewater related contaminants
to increase public confidence and acceptance as a precaution-
ary principle (Zwiener 2007). Removal of PPCPs and EDCs
through conventional treatment is very limited (Stackelberg
et al. 2004).
The issue concerning PPCPs and EDCs is very recent.
Disinfection by-products (DBPs) have long been an issue as a
result of water disinfection using chlorine. In North America
and most of the world, chlorine is the disinfectant agent to
inactivate most of the pathogens in water. However, chlorine
reacts with natural organic matter (NOM) forming poten-
tially harmful DBPs such as THMs resulting in regulation
of trihalomethanes (THMs) (Health Canada 2006a; Ontario
Ministry of the Environment [OMOE] 2006a,b). DOC is a
known precursor of disinfection by-products (Roccaro and
Vagliasindi 2009). Ozone could partially mineralize dissolved
organic carbon (DOC) and have a potential to reduce THMs
(Yan et al. 2010). As UV/H2O2reduces THM precursors,
some researchers reported a decrease in THMs (Knight et al.
2012).
There is increasing public concern over the presence of
emerging contaminants along with the increasingly strin-
gent regulations on different DBPs, which necessitate the
need for alternative treatment strategies. Advanced oxida-
tion process (AOPs) such as ozone/H2O2and UV/H2O2
are potential alternatives that are reported very effective in
degrading PPCPs and EDCs (Huber et al. 2003; Pereira et al.
2007a). Although these reports seem promising, there is lim-
ited data available on the extent of effectiveness using a pilot
plant or large-scale setup. Most studies were conducted on
bench-scale experiments and using deionized water (Jiang
and Adams 2006;Wuetal.2012). There has been little
research done on comparing the performance of ozone/H2O2
154 D. Borikar et al. March–April 2015
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and UV/H2O2, in conjunction with conventional (chemical
assisted coagulation +filtration) treatments. Hence, there
remain some important research questions with regards to the
efficacies of each process and the comparison in a treatment
train involving conventional treatments. There is no study
that aims to remove PPCPs and EDCs and reduce THMs at
the same time using ozone/H2O2and UV/H2O2in the same
experiment.
This study evaluated and compared conventional drinking
water treatment with treatment processes that include AOPs
consisting of ozone/H2O2and UV/H2O2for the degrada-
tion of selected PPCPs and EDCs. The effects of ozone/H2O2
and UV/H2O2treatment on DBP- formation potentials (DBP-
FPs) were also examined. The impact of water quality
parameters such as organics, bicarbonates and carbonate, and
particles on the removal of selected PPCPs and EDCs and
THM-formation potentials (THM-FPs) (used as a surrogate
of DBP-FPs) was evaluated.
Results of this study will be directly applicable to large
and small water treatment plants in Canada. Water of Site A
is from one of the Great Lakes and assuming similar quality
for all Great Lakes, Site A water is considered to be represen-
tative water for the Great Lakes, which supports 8.5 million
Canadians and 24.5 million in the United States (Environment
Canada 2012). The outcome provides insight on the effects
of ozone dose, UV dose, hydrogen peroxide dose, and the
impact of organics, particles, bicarbonates and carbonates on
the removal of PPCPs and EDCs and their effects on THM-
FPs. Many water treatment plants will find this study useful as
it covers a wide range of parameters including DOC, alkalinity
and turbidity. This study will also be useful to compare and
upgrade potential advanced water technologies in addition
to conventional treatment to meet regulatory requirements or
pro-active initiatives and to enhance acceptability of treated
water.
MATERIALS AND METHODS
Experimental Work
In total, three source waters were selected in the study.
Two sources are surface water: Site A, Lake Huron; and
Site B, a smaller lake serving a community of approxi-
mately 7000 people. The third water source is a groundwater
source (Site C), a poor quality GUDI (groundwater under
direct influence of surface water) to add a different perspec-
tive. After transporting water, via tanker truck, from each
of the sources to the Technology Demonstration Facility,
Walkerton Clean Water Center (WCWC), Ontario, the water
was stored in three ground level tanks. Any water treatment
plant in Ontario, Canada using either surface water or GUDI
water as a source requires minimum treatment of chemically
assisted coagulation (rapid mixing, flocculation, and sedimen-
tation) followed by filtration which is also referred to as
“conventional treatment” followed by chlorination (OMOE
2006a).
Experimental Setup
Dual Train Pilot Plant
A completely automatic, gravity flow system that consists
of two process trains (Trains 1 and 2); each rated to treat
up to 18.9 L/min. Each train consists of rapid mixing with
provisions to inject two chemicals, mechanical flocculation
with three flocculation cells (30 min detention time), plate
settlers with 75 min detention time (25.62 LPM/m2aver-
age), and two filter columns (15 cm diameter). For each train,
the filter columns contain sand (30 cm) and anthracite media
(45 cm). Turbidity was measured using Hach 1720E Low
Range Turbidity meter (manufactured by Hach Company,
Loveland, CO, USA).
Ozone/H2O2System
The ozone/H2O2system with a capacity of 8 L/min was
incorporated into Train 2 of the pilot plant. The ozone treat-
ment was incorporated in the pilot plant to allow ozonation
either prior to coagulation or post-sedimentation. Water was
pumped to the ozone system at the top inlet port of the
first glass column (15 cm diameter) and then flowed by
gravity through the system. It passed through baffles and
exited at the top of the second column (15 cm diame-
ter). To create the proper mixing and higher residual ozone,
the ozone gas produced by an ozone generator (Model
SGC11, Pacific Ozone Technology, Benicia, CA, USA) was
injected through a Mazzei injector at the top of the first
column followed by a flash reactor and half-inch glass
tube. The ozone level leaving the generator was measured
using an IN-USA Ozone Analyzer Model Mini-Hicon (IN
USA Incorporated, Needham, MA, USA). Hydrogen peroxide
(H2O2) was injected after ozonation using a master-flex pump
(drive: 7523-70, pump head: 77250-62).
The second column in the ozone system was equipped with
14 baffles and five sampling ports along the side of the col-
umn. Off gas from the system was collected at the top of
each column and directed to an ozone destruct unit (Model
0212, Pacific Ozone Technology, Benicia, CA, USA) prior
to being released to the air outside the building. The resid-
ual dissolved ozone, at the inlet (Port 1) and outlet (Port
5) were continuously monitored using a three way solenoid
valve and an ATI Dissolved Ozone Monitor Model Q45H-2-
2 (ATI Analytical Technology, Inc., Collegeville, PA, USA).
A calcium thiosulphate-ozone quenching system (ProMinent,
Guelph, Ontario, Canada) was operated depending on the
residual ozone observed in the ozone system effluent.
UV/H2O2System
The UV/H2O2system includes a Trojan UVSwiftSC
(model A02, Trojan Technologies, London, Ontario), a pilot
plant backwash and treated water reservoir, a pump, flow con-
trol valves, flow meters, a hydrogen peroxide injection port, a
tank, a Masterflex dosing pump (drive: 7524-50, pump head:
77250-62) and a sampling port.
Oxidation Processes for Removal of PPCPs and EDCs March–April 2015 155
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Process Flow Chart and Sampling Points
Figure 1 presents a process flow chart of the conventional
dual train pilot plant, ozone/H2O2system and UV/H2O2
treatment and sample ports. Spiked raw water was divided
into two equal parts and flowed by gravity into Trains
1 and 2. Samples of spiked raw water were collected
when water moved from the splitter box to Train 1 (rapid
mixer). Samples of conventionally treated water were col-
lected after the filters. Effluent of Train 1 filters was collected
in the backwash tank that served as feed water tank for
the UV/H2O2system. On Train 2, during pre-coagulation
ozonation (Experiments 1–3), spiked raw water flowed
through the ozone/H2O2system and thereafter through
conventional treatment. In post-sedimentation ozone/H2O2
experiments (Experiments 4–6), spiked raw water first flowed
through rapid mixing, flocculation and sedimentation and then
was pumped into the ozone/H2O2system. The effluent of the
ozone/H2O2system was taken to the pilot plant and a sam-
ple of ozone/H2O2followed by conventional treatment was
collected.
Pilot-Plant Experiments
Details of experimental conditions are shown in Table 1.
Experiments 1 and 2, Experiments 3 and 4, and Experiments
5 and 6 were conducted for Sites A, B, and C, respectively.
Once raw water was received in the tank, experiments were
conducted approximately after 2–3 h. The flow rate to each
train was 6.2 L/min that provided an approximate filtration
rate of 10 m/h. The total length of each experiment was
approximately 20 h. The coagulant chemicals used were the
same as those used by the source site water treatment plant. Jar
tests (model Phipps and Bird 900, Richmond, Virginia, USA)
were conducted before each experiment to optimize coagulant
dose to reduce turbidity by coagulation, flocculation, and
settling processes.
During Experiments 1 to 6, each experiment incorpo-
rated an ozone gas dose (0.80–4.4 mg/L) and a ratio of
H2O2/ozone was kept approximately at 0.10 (mass-based).
The ratio was decided based on the results of Irabelli et al.
(2008) that reported the lowest THMs formation when the
ratio of H2O2/ozone was 0.1. For UV/H2O2treatment,
5mg/LofH
2O2were used with three different UV dosages.
Required UV dose was controlled by flow through the reac-
tor. UV fluence was calculated using the equation [(UV dose
in mJ/cm2)=Intensity (W/m2)×retention time (seconds)],
provided by Trojan Technologies, London (as per the manual
of Trojan UVSwiftSC).
Selection criteria used for the PPCPs and EDCs were: a)
compounds that are found or likely to be present in Great
Lakes water; b) compounds which belong to different struc-
tural and chemical groups such as antibiotics, pesticides, plas-
ticizers; and c) compounds with feasible analysis techniques.
Rahman et al. (2010) reported that average concentrations
FIGURE 1. Process flow chart and sample ports.
156 D. Borikar et al. March–April 2015
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TABLE 1. Details of Experiments
Source water Experiment
Coagulant dosage-
(mg/L)
Coagulant aid
dosage (mg/L)
Average ozone
added (mg/L)
Average H2O2
added (mg/L)
UVdoseinmJ/cm2
(approx.) for Set 1,
2 and 3 respectively with
5mg/LH
2O2. Remarks
Site A 1 Clar+Ion A5 -10 Magnafloc
LT27AG-0.05
0.80 0.25 1000, 1000, and 2000 Pre-coagulation ozone
2Clar+Ion A5 -10 Magnafloc
LT27AG-0.05
3.3 0.08 2000, 2000, and 1000 Pre-coagulation ozone
Site B 3 Alum-15 Liquipam-0.032 4.4 0.13 680,1000, and 2000 Pre-coagulation ozone
4 Alum-15 Liquipam-0.032 4.0 0.13 2000, 1000, and 700 Post-sedimentation ozone
Site C (GUDI) 5 PACl WW8320 - 15 NIL 4.0 0.07 500, 1000, and 1000 Post-sedimentation ozone
6 PACl WW8320- 15 NIL 3.9 0.02 1000, 1000, and 500 Post-sedimentation ozone
WW8320 =polyaluminum chloride, polyhydroxosulphatoaluminum chloride made by Jutzi chemicals, Stratford, ON.
Note: 1) PPCPs samples and bromide/bromate samples were collected in Set 1.
2) For Uniform formation conditions (UFC)-THM tests, three sets of samples were collected during Experiments.
3) For general water quality, a total of three sets of samples were collected and analyzed for each experiment.
Oxidation Processes for Removal of PPCPs and EDCs March–April 2015 157
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of atrazine, carbamazepine, fluoxetine in Lake Huron were
57, 29, and 20 ng/L, respectively, for four out of six sam-
ples during their study. However, atorvastatin and ibuprofen
were detected only once. Based on this study (Rahman et al.
2010) and considering other criteria, the selected PPCPs and
EDCs were atrazine, bisphenol A, carbamazepine, fluoxetine,
diclofenac, ibuprofen, naproxen, gemfibrozil, atorvastatin,
and triclosan.
Stocks of Bisphenol A, diclofenac, carbamazepine,
gemfibrozil, and naproxen were obtained from Sigma-Aldrich
(Oakville, ON, Canada). Atrazine was obtained from Chem
Service (West Chester, PA, USA), fluoxetine was purchased
from Interchem (Paramus, New Jersey, USA), atorvastatin
from SynFine (Richmond Hill, ON, Canada), triclosan from
Alfa Aesar (Ward Hill, MA, USA), and ibuprofen from TCI
America (Portland, OR, USA). All selected PPCPs and EDCs
were mixed together to make 1-g/L solution. PPCPs and
EDCs requirements for each experiment (20-h duration) were
calculated and the raw water was spiked with the mixture of
all study compounds to obtain a 200-ng/L concentration in
the raw water, in addition to any background concentration,
if any.
Sampling and Analytical Methods
Pilot-plant operation was started as per experimental con-
ditions and monitored for various parameters such as flow
rate and turbidity. For all experiments, raw water, spiked raw
water and effluents of ozone/H2O2, the anthracite/sand fil-
ters (end points of conventional treatment) of both trains and
UV/H2O2treatment were sampled. Alkalinity, color (HACH
DR2400 model, Loveland, CO, USA), pH (Minilab IQ125),
turbidity (HACH portable turbidity meter model 2100 P), UV
absorbance (Real Tech Inc., Ontario), and DOC (GE Sievers
5310 C laboratory TOC analyzer, Boulder, CO, USA, by
persulfate-UV method) were analyzed on-site at the WCWC
laboratory. Samples of ozone/H2O2and UV/H2O2treated
water were collected as per experimental conditions, specified
in Table 1.
Three sets of samples from each sampling point were
shipped to the Department of Chemical and Biological
Engineering (CHBE), University of British Columbia (UBC)
for uniform formation condition (UFC)-THM tests and analy-
sis. The UFC-THM method was used for determining the level
of THM-FPs in the samples (Summers et al. 1996), and THMs
analysis was conducted using the US EPA (1995) method
(551.1).
Analysis of PPCPs and EDCs was conducted at the
University of Waterloo, ON. Solid phase extraction using
Oasis HLB cartridges followed by liquid chromatography/
tandem mass spectrometry (LC-MS/MS) (Agilent 1200 LC,
Applied Biosystems MDS Sciex 3200 Qtrap MS) using elec-
trospray ionization (ESI) in both negative and positive modes
were used to analyze target EDCs and PPCPs (Rahman et al.
2010).
Reproducibility of Experiments and Statistical
Analyses
Each experiment was replicated to confirm reproducibility
of the experiments, sampling, analysis and results. Three sets
of PPCPs and EDCs samples were collected for each sampling
point. UFC-THMs tests were conducted on three samples in
each set. For general water quality data such as turbidity,
pH, alkalinity, DOC, and UV254, three sets of samples were
collected, analyzed and the average values were reported of
these data. For each sample, DOC and turbidity analyses were
repeated three and two times, respectively. However, it should
be noted that these experiments were conducted on natural
water which, with changes in water quality parameters from
time to time, may have an impact on results.
When there was only two experimental results/data avail-
able, maximum and minimum values were shown on the
error bars in each figure. When there were three or more
experimental results available, standard deviation (SD) was
presented as an error bar. When three or more results of
experimental means are available, comparison of two treat-
ments was conducted using Student’s t-tests, and pvalue
is presented. If three results of experimental means were
available for three or more treatments, one-way analysis of
variance (ANOVA) analysis was undertaken and pvalue is
presented. The confidence level of 95% (significance level, α
=0.05) was used to report results as statistically significant.
Statistical analysis was carried out using Microsoft Excel.
Assumptions
Because of insufficient mixing and detention time until the
sampling point at the pilot plant, measured PPCPs and EDCs
concentrations of spiked raw water were different (varying)
from those expected and therefore, measured PPCPs and
EDCs concentrations were ignored. Addition of target PPCPs
and EDCs concentration (200 ng/L) and raw water PPCPs
and EDCs concentration was considered as spiked raw water
concentrations for evaluating results.
Methanol was used as a solvent to dissolve PPCPs and
EDCs. Approximately 15,000 L of raw water was used for
each pilot plant experiment. Although methanol is a hydroxyl
radical scavenger, the concentrations of methanol was negli-
gible compared to other scavengers.
RESULTS AND DISCUSSIONS
Raw Water Quality
Average DOC concentrations of Site A and B were 1.9 and
2.8 mg/L, respectively, and Site C had an average DOC
of 7.7 mg/L that was much higher than those for Sites A
and B. Average specific UV absorbance (SUVA) values for
Sites A and B were 0.89 and 1.96 L/mg-m, respectively
while Site C had the highest SUVA values of 2.70 L/mg-
m. Average alkalinity from Sites A, B, and C were 87,
250, and 210 mg/LasCaCO
3, respectively. Differences
in SUVA, DOC, alkalinity and turbidity of the three sites
158 D. Borikar et al. March–April 2015
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indicate significant variations in the quality of these raw
waters. Organics (DOC) and particles (turbidity) are likely
to create oxidation and coagulant demand, respectively, while
bicarbonate and carbonate (alkalinity) can scavenge hydroxyl
radicals. Table 2 shows the selected water quality of different
source waters.
Occurrence of PPCPs and EDCs in the Selected
Drinking Water Sources
Table 3 presents the presence of PPCPs and EDCs in the
selected water soures. During experiments of Site A, aver-
age concentrations of atrazine, fluoxetine, atorvastatin, and
carbamazepine found in Site A were 30, 15, 13, and 7 ng/L,
respectively, while diclofenac, naproxen, and gemfibrozil
were not detected. Triclosan and ibuprofen were found only
in one out of two samples and the concentrations were 42 and
3ng/L, respectively. These results are in agreement with the
literature (Jasim et al. 2006), which observed concentrations
of carbamazepine and atrazine in the range of 0–4 ng/L and
7–79 ng/L, respectively in the Detroit River. Benotti et al.
(2009) also reported the presence of all the selected PPCPs
and EDCs (except ibuprofen) in some of the 19 U.S. drinking
water sources in the range of 0.4–32.0 ng/L.
Raw water of Site B showed similar concentrations
of the selected PPCPs and EDCs except atrazine was
14 ng/L which was about 50% lower that of Site A, while
triclosan and diclofenac concentrations were found once at
112 and 27 ng/L concentration, respectively. Site C showed
an atrazine concentration of 10 ng/L, and carbamazepine,
fluoxetine, ibuprofen, and gemfibrozil were found to be
less than 10 ng/L. Overall, all sites showed some presence
of atrazine, carbamazepine, fluoxetine, and some samples
showed the presence of atorvastatin, diclofenac, ibuprofen,
naproxen, gemfibrozil and/or triclosan at low concentrations,
while bisphenol A was not detected at any site. This data indi-
cates that issue of PPCPs and EDCs is probably a current issue
rather than an emerging issue.
Reduction of DOC, UV254, and SUVA
NOM is the main precursor of DBPs and DOC is com-
monly used as a quantitative measure of NOM. Therefore,
it is important to evaluate DOC removal in each process.
Reduction of DOC would be expected to reduce DBPs
(Wang et al. 2010). UV absorbance at wavelength (λ)of
254 nm (UV254) is sometimes considered a surrogate of
NOM concentration (Crittenden et al. 2005) as it indicates
specific molecular structure (chromophores such as aromatic
compounds) which can absorb UV light. Similarly, specific
UV absorbance (SUVA) can be obtained by dividing UV254
by DOC. Higher SUVA values indicate higher hydrophobic
organic matter which can be reduced by coagulation (Edzwald
and Tobiason 1999).
Figure 2 shows reductions of DOC and UV254 and levels
of SUVA observed during all experiments.
Conventional Treatment
Reductions of DOC, UV254 and SUVA were 20.9 ±4.5%
(SD), 36.6 ±4.3% (SD), and 20.0 ±3.6% (SD), respectively,
compared to those of raw water. These results indicated that
the portion of organic matter, which absorbs light at 254 nm
was largely removed as compared to those which did not
absorb light.
For Site A, removal of DOC was 23.9% by conventional
treatment and 27.6% by ozone/H2O2+conventional treat-
ment. However, the difference between the two treatments
was not significant. DOC removal (24%) by conventional
treatment is in agreement with the literature (Edzwald and
Tobiason 1999), which indicates that for SUVA <2, 25%
DOC removal is expected. DOC reduction (24%) is likely due
to a reduction in pH because of the use of Clar+Ion A5, which
contains 5 mg/LofH
2SO4.
Higher DOC removals for Site C were likely due to the
higher DOC and higher SUVA values of the raw water. Higher
SUVA value indicates the characteristics of organics such as
high hydrophobicity and high molecular weight compounds
TABLE 2. Selected Raw Water Quality of Water Sources
Parameters Site A Site B Site C
pH 8.3 ±0.1 8.2 ±0.1 8.0 ±0.1
Turbidity (NTU) 0.65 ±0.26 0.96 ±0.17 6.59 ±1.70
DOC (mg/L) 1.86 ±0.1 2.78 ±0.14 7.70 ±0.27
UV254 (cm 1) 0.017 ±0.003 0.0548 ±0.06 0.206 ±0.02
SUVA (L/mg·m)0.89 ±0.16 1.97 ±0.29 2.70 ±0.32
Alkalinity (mg/LasCaCO
3)87±2 250 ±3 212 ±7
Hardness (mg/LasCaCO
3)N/AN/A 227 ±9
Iron (mg/L) N/AN/A0.58±0.17
Manganese (mg/L) N/AN/A2.1±2.7
Temperature (C) 14 N/A 19.5
SUVA =UV254/DOC.
±Standard deviation.
Oxidation Processes for Removal of PPCPs and EDCs March–April 2015 159
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TABLE 3. Background PPCPs and EDCs Concentrations of the Selected Water Sources
Site A (ng/L) Site B (ng/L) Site C (ng/L)
PPCPs and EDCs Exp 1 Exp 2 Exp 3 Exp 4 Exp 5 Exp 6
Atrazine 23 ±336±14 15 ±313±310±210±2
Carbamazepine 0.0 7 ±110±317±12 6 ±16±1
Fluoxetine N.A. 7 ±650±89±20.07±0
Diclofenac 0.0 0.0 27 ±30 0.0 0.0 0.0
Ibuprofen 0.0 0.0 6 ±60.0 4±21±2
Naproxen 0.0 0.0 0.0 0.0 7.7 ±1.3 0.0
Gemfibrozil 0.0 0.0 16 ±17 0.0 1 ±10
Atorvastatin 0.0 0.0 14 ±57±0 101 ±15 95 ±3
Triclosan 42 ±13 0.0 112 ±80 0.0 0.0 0.0
Bisphenol A was not observed in any raw water sample.
FIGURE 2. Reductions of DOC and UV254 and levels of SUVA.
Note: Error bars show maximum and minimum values.
that are more likely to coagulate than organics having lower
SUVA values (Edzwald and Tobiason 1999).
Ozone/H2O2Followed by Conventional (Ozone/H2O2
+Conventional) Treatment
Eliminations of DOC were 28.2 ±7.2% (SD) by
ozone/H2O2+conventional treatment and 20.9 ±4.5% (SD)
by conventional treatment, which were not significantly dif-
ferent. Reductions of UV254 and SUVA were 68.0 ±18.3%
(SD) and 53.2 ±26.7% (SD) by ozone/H2O2+conventional
treatment compared to those of raw water. However, reduc-
tions of UV254 and SUVA were not significantly different than
those of conventional treatment due to the large variance of
ozone/H2O2+conventional treatment.
Additional reductions of DOC were up to 9.1% by
ozone/H2O2+conventional treatment compared to that by
standalone conventional treatment. These results are in agree-
ment with the findings in the literature (Irabelli et al. 2008)
that reported 45% reduction of DOC using a pre-ozonation
peroxone system. These findings were much higher than the
current study and likely due to different experimental condi-
tions. As ozone partially oxidizes DOC (as in Experiment 2), a
higher ozone dose increased removal of DOC when compared
to a lower ozone dose (as in Experiment 1).
For Site A (Experiment 2), ozone/H2O2reduced only 6.6%
of raw water DOC, but reduced 37.5% of UV254. Ozone
removed aromatic structures and double bonds of NOM effec-
tively resulting in decreased UV254 (Kleiser and Frimmel
2000).
Conventional Treatment Followed by UV/H2O2
(Conventional Treatment +UV/H2O2)
Reductions of DOC and UV254 were 23.6 ±3.5% (SD) and
34.8 ±6.6% (SD), respectively by conventional +UV/H2O2
treatment relative to raw water. Removals of DOC and UV254
by conventional +UV/H2O2were not significantly differ-
ent than those by conventional treatment alone. Moreover,
160 D. Borikar et al. March–April 2015
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reduction of UV254 by conventional +UV/H2O2was not sig-
nificantly different than that by ozone/H2O2+conventional
treatment. In UV/H2O2treatment, hydroxyl radicals are the
main oxidants which work much less selectively than ozone.
Consequently, in most of the experiments, UV254 of conven-
tional +UV/H2O2treatment remained the same or slightly
lower than conventional treatment alone. On the other hand,
ozone reacts selectively and attacks the aromatic ring which
absorbs light. Likely due to a higher SUVA, reduction of
UV254 by conventional +UV/H2O2for Site C was also higher
than that for Site B.
Effects on THM-FPs
THMs are one of the DBPs that are suspected carcino-
gens and are regulated (OMOE 2006b). It is not proven
that THMs can cause cancer at the drinking water level in
humans. However, THMs are used as a surrogate of unreg-
ulated and uncharacterized chlorinated DBPs that have a
greater risk of cancer (Bull 2012). Figure 3 illustrates UFC-
THM results. In most of the experiments (e.g., Site A exper-
iments) during UFC-THM tests, THM-FPs were reduced
by conventional treatment compared to that of raw water.
During experiments of Sites B and C, levels of THM-FP
by ozone/H2O2+conventional treatment were lower than
that by conventional treatment alone. During Site A exper-
iments, the levels of THM-FP were higher by conventional
treatment +UV/H2O2than that by conventional treatment
alone.
Chloroform was the main contributor to the THM-
FPs among four THMs. Organics in water, represented by
propanone (acetone) were easily oxidized by chlorine to gen-
erate trichloro propanone and then hydrolysis of trichloro
propanone produced chloroform and brominated propanone
generated brominated THMs (Xie 2004).
Conventional Treatment
For Site A, an average reduction of THM-FPs by conven-
tional treatment was 63% as compared to that of raw water.
This trend is in agreement with the literature (Page et al.
2002) that conducted jar tests using alum as a coagulant and
observed that reduction of THM-FPs was 66.7%. Average
DOC removal by Site A was 24% which was likely the main
reason behind such THM-FPs reduction.
Conventional treatment reduced THM-FPs by the reduc-
ing aromatic components of dissolved organic matter (DOM)
(Page et al. 2002). Conventional treatment removes the
hydrophobic part of organics, which are more amenable for
the coagulation process, while the hydrophilic part remains
in conventionally treated water due to the negligible charge
density (Sharp et al. 2006). Overall, based on the THM-FP
levels in µg/L, reductions of THM-FP were 13–63% by con-
ventional treatment compared to those of raw waters of Sites
A, B, and C.
FIGURE 3. Levels of THM-FP by various treatments. Note: Error
bars show maximum and minimum values.
Ozone/H2O2+Conventional Treatment
In Experiment 1 (Site A), ozone/H2O2+conventional
treatment exhibited 46% lower THM-FPs than that by con-
ventional treatment. These results were comparable to exper-
iments conducted in the literature (Irabelli et al. 2008), which
reported that THM-FPs by ozone/H2O2+conventional treat-
ment samples were 45% to 85% lower than that by conven-
tional treatment. The amount of THM-FP reduction (Irabelli
et al. 2008) was higher than that of the current study that may
be possibly due to different experimental conditions such as
quality of raw water, ozone, H2O2, and/or chlorine dosages.
Ozone satisfies a part of chlorine demand and changes the
Oxidation Processes for Removal of PPCPs and EDCs March–April 2015 161
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structure of organics which are less reactive to chlorine or
transforms organics into electron rich moieties and conse-
quently reduces THM-FPs (Karnik et al. 2005; von Sonntag
and von Gunten 2012). Although hydroxyl radicals increase
THM-FP (Dotson et al. 2010; Kleiser and Frimmel 2000), the
concentration of hydroxyl radicals in the ozone/H2O2process
is comparatively less than those in UV/H2O2treatment.
Similarly, reductions of THM-FPs were 33–48% for Sites
B and 22–43% for Site C by ozone/H2O2+conventional
treatment (2009) compared to those by standalone conven-
tional treatment. This result is in agreement with Muttamara
et al. (1995) that observed additional 20–30% reduction of
THMs due to ozone/H2O2. This indicates that average reduc-
tions are similar to that of Site A. The likely reason behind
such reduction is ozone, which reduces centers for THMs
formation (Kleiser and Frimmel 2000) and hydroxyl radicals
have a limited role in ozone/H2O2treatment.
Conventional Treatment +UV/H2O2
For Site A, the increases of THM-FP were 73–203% by
conventional treatment +UV/H2O2compared to those by
conventional treatment. These results are similar to the litera-
ture (Dotson et al. 2010) that explains an increase in THMs
during UV/H2O2treatment. UV/H2O2treatment generates
hydroxyl radical, which increases transformation of less reac-
tive hydrophobic dissolved organic matter (DOM) into more
reactive hydrophilic DOM. Such reconfiguration (changes)
creates more chlorine demand and THMs formation (Dotson
et al. 2010). During the UV/H2O2process, DOC is partially
oxidized into smaller particles and if the UV/H2O2dose is
not very high, no mineralization would occur and forma-
tion of THMs after chlorination would increase (Sarathy and
Mohseni 2009). Furthermore, the current study results are
in agreement with Jasim et al. (2012), which concluded that
THM-FPs by conventional +UV/H2O2were 2.5-5.5 times
higher than those of ozone/H2O2+conventional treatment.
For Site B during UFC-THMs test, levels of THM-FP were
14% lower for conventional treatment +UV/H2O2compared
those for raw water. However, it demonstrated similar THM-
FP levels compared to conventional treatment alone. As Site
B has an average alkalinity level of 250 mg/LasCaCO
3;
hydroxyl radicals might have been scavenged by bicarbonate
or carbonate ions to generate carbonate radicals that are more
selective and have a lower rate constant (Parsons 2004).
Similarly, during Site C experiments, levels of THM-FP
were 4–51% higher for conventional +UV/H2O2treat-
ment compared to those for conventional treatment. One
of the explanations of such increase is given by CNOM
(chromophoric natural organic matter), which is obtained by
dividing THM-FP by UV254 and is a measure of capacity to
form THMs. For Site C, increase in CNOM was 45% during
UV/H2O2treatment which is in agreement with the literature
(Sarathy and Mohseni 2010).
Zheng et al. (1999) also reported increase in THM-FPs by
UV/H2O2treatment. Zheng et al. (1999) conducted pilot scale
experiments with medium pressure UV lamps and H2O2and
observed that THM concentrations linearly increased up to
2000 mJ/cm2. Moreover, the likely reasons of such reactivity
increase were the addition of hydroxyl radicals into aromatic
structures, substitution of all hydrogen atoms by chorine in
the α-position of keto group and formation of organic acid
catalyzed by hydroxyl radicals (Kleiser and Frimmel 2000).
In the current study, Sites A, B and C showed an increased
level of THM-FPs likely due to higher organics in the raw
water from Sites A to Site C. Nevertheless, levels of THM-
FP were found to increase during UV/H2O2treatment at the
experimental conditions in the current study or at the typi-
cal UV/H2O2dosages applied in the water treatment practice,
Sarathy and Mohseni (2010) observed that the application of
higher (2000 mJ/cm2) UV dosages with (15 mg/L) H2O2,
THM-FPs were reduced due to mineralization of organics.
Increases of the THM-FP of conventional +UV/H2O2
were lower from Site A to Site B when compared to those by
conventional treatment alone. This can be possibly explained
by reduction of efficacy of UV/H2O2treatment from Site A
to Site B and from Site B to Site C. SUVA of raw waters
increased from Site A to Site C which indicates a higher
hydrophobic character of organics (Ezwald and Tobiason
1999). Increase in hydrophobic character from Site A to Sites
B and C also resulted in higher THM-FPs from Site A to
Site C. This phenomenon is also reported by Buchanan et al.
(2006). Furthermore, UV can generate potentially hazardous
by-products and it is recommended to deploy a biologi-
cal active process after UV (Buchanan et al. 2006). On the
same ground, a biological active process should be used
after ozone/H2O2or UV/H2O2to treat biodegradable and/or
potentially hazardous by-products.
Degradation of PPCPs and EDCs
Conventional Treatment
It is necessary to evaluate conventional treatment for the
removal of selected PPCPs and EDCs in order to evaluate and
compare additional capabilities of advanced oxidation pro-
cesses such as ozone/H2O2or UV/H2O2.Figure 4 shows the
removal of PPCPs and EDCs by conventional treatment.
Overall, conventional treatment poorly removed the
selected PPCPs and EDCs. Removals of gemfibrozil, and
carbamazepine were 2% and 5%, respectively. Eliminations
of atorvastatin, bisphenol A, ibuprofen, atrazine and naproxen
were 17–26%, while removals of fluoxetine, diclofanec and
triclosan were 38–59%.
For Site A, conventional treatment was able to partially
remove few of PPCPs and EDCs such as diclofenac (57%),
fluoxetine (55%), naproxen (39%), triclosan (36%), ibuprofen
(26%), and atrazine (22%). However, carbamazepine (6%)
and gemfibrozil and atorvastatin (1%) were slightly removed.
These results are in agreement with the literature which
demonstrated that removal of less than 20% was achieved for
atrazine, carbamazepine, diclofenac, fluoxetine, gemfibrozil,
ibuprofen, naproxen, and triclosan using coagulation and
162 D. Borikar et al. March–April 2015
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FIGURE 4. Removal of PPCPs and EDCs by conventional treat-
ment.
Note:
1) Error bar shows maximum and minimum values.
2) Coagulant and polymer dosages are in mg/L.
lime-softening treatment at a full-scale plant (Snyder et al.
2007b). However, in the current study, removal of atrazine
by conventional treatment was marginally higher compared
to the literature (Snyder et al. 2007b; Jasim et al. 2006). This
higher removal might likely be due to the optimized conven-
tional treatment and lower flow rate (6.2 L/min) of each train
against the design flow of 18.9 L/min which resulted in higher
detention time. Overall, average removal of all the selected
PPCPs and EDCs were 27 ±21% (SD) for Site A.
For Site B, conventional treatment exhibited varying
removals such as 20% for ibuprofen, 25% for carbamazepine,
62% for diclofenac, and 39% for naproxen. Vieno et al. (2007)
conducted similar experiments and found that the removal
of ibuprofen, carbamazepine, diclofenac, and naproxen were
12%, 7%, 8%, and 10%, respectively. In that study (Vieno
et al. 2007), pH was lowered to 4.9–5 before coagulation
which makes the PPCPs more soluble and harder to remove.
Therefore, lower removal was observed by conventional treat-
ment as compared to the current study. Overall, current study
results are in agreement with the study by Vieno et al. (2007).
Atorvastatin (additional 16% removal, log KOW =6.36) and
gemfibrozil (additional 3% removal, log KOW =4.77) demon-
strated characteristic (tendency) for higher removal as com-
pared to Site A, which may be likely due to higher log KOW
and higher hydrophobic nature of these PPCPs (Snyder et al.
2007b). Figure 5 demonstrates removal of PPCPs and EDCs
by conventional treatment with reference to their log Kow val-
ues. Removal of target compounds by conventional treatment
was related to their log KOW, however not dependent on log
KOW.
Removals of atrazine were 22% and 23% for conventional
treatment using Sites A and B waters, respectively. These
results are in agreement with the literature (Ormad et al. 2008)
that observed removal of atrazine was 10–25% using an alum
dose of 10–40 mg/L during full-scale conventional treatment.
FIGURE 5. Removal of PPCPs and EDCs by conventional treat-
ment related to their log Kow.
Although, current study results for conventional treatment are
at higher end likely due to the use of 33% capacity of the pilot
plant and the difference between raw water qualities in terms
of turbidity and DOC because of partitioning effect (Snyder
et al. 2007b). The water quality of Site C was very different
in terms of DOC (organics) and turbidity (particles). Another
possible reason of a higher atrazine removal is the higher sur-
face area of the pilot plant per unit flow rate as compared to
full-scale plants that may have allowed atrazine to precipitate
in the pilot plant during experiments.
Upon further analysis of data from a therapeutic use/class,
atorvastatin has the highest log Kow value (6.36); conse-
quently its removals by conventional treatment were 1% and
17% for Sites A and B, respectively. Similarly, gemfibrozil
(log Kow =4.77) showed increased removal of 1% and 4% for
Sites A and B, respectively likely due to increase in organics
and particles. Personal care product (triclosan) showed 36%
and 41% removal for Sites A and B probably due to its log
KOW value of 4.76.
pKa(a dissociation constant) is also one of the factors
which may be responsible for the removal of PPCPs and
EDCs during conventional treatment by electrostatic interac-
tion. Among selected PPCPs and EDCs, fluoxetine has a pKa
value of 8.7 (Snyder et al. 2007a) and is generally present in
cationic form in natural water (Li et al. 2011) and is near
the operational guideline (6.5–8.5) of drinking water treat-
ment conditions (OMOE 2006a). Likely because pKa(8.7),
fluoxetine was removed 40–69% during conventional treat-
ment using Site A water (pH 8.3) and 43–49% for Site B (pH
8.1). Similarly, because triclosan has a pKa value of 8 and is
present in anionic form (Li et al. 2011; Snyder et al. 2008),
conventional treatment removed 30–42% of triclosan using
Site A water and 31–50% of triclosan using Site B water.
Overall, higher removals of fluoxetine and triclosan were
likely obtained due to their pKa value being within or closer
to the pH under typical water treatment conditions. Table 4
presents removal of PPCPs and EDCs by conventional treat-
ment with reference to their pKa values, which suggests that
Oxidation Processes for Removal of PPCPs and EDCs March–April 2015 163
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TABLE 4. Removal of PPCPs and EDCs by Conventional Treatment
and Their pKa Values
PPCPs and
EDCs pKa Site A Site B Reference
Atrazine 1.7 22 23 Snyder et al. 2007a
Bisphenol A 9.6, 10.2 N/A 18 Deborde et al. 2005
Carbamazepine 13.9 6 5 Snyder et al. 2008
Flouxetine 8.7 55 46 Snyder et al. 2007b
Diclofenac 4.15 57 62 Snyder et al. 2008
Ibuprofen 4.9 26 20 Snyder et al. 2008
Naproxen 4.15 39 26 Snyder et al. 2008
Gemfibrozil 4.42 1 4 Snyder et al. 2008
Atorvastatin 1 17 not available
Triclosan 8 36 41 Snyder et al. 2008
pKa is a one of the factors responsible for removing PPCPs
and EDCs. However, it is not a sole factor because other
PPCPs and EDCs were removed by conventional treatment,
even though pKa values were beyond a typical drinking water
range (pH 7–8).
Removal of the selected PPCPs and EDCs was 27% by
conventional treatment which was higher than most of the
cases reported by Snyder et al. (2007b). In the current study,
three flocculator cells having 30-min detention time in each
cell with revolutions per minute (RPM) of 15, 10, and 5 pro-
vided more opportunities and time for adsorption of PPCPs
and EDCs on organics, particles, and floc particles. Moreover,
the three flocculators have a baffling wall to prevent short-
circuiting. The pilot plant has plate settlers with a detention
time of 228 min, which is close to the higher end of typical
detention time of 90–240 min for water treatment plant con-
ditions (Crittenden et al. 2005). Enhanced flocculation and
sedimentation conditions at the pilot plant likely resulted in
the higher removal of PPCPs and EDCs at the pilot plant
compared to the literature (Snyder et al. 2007b).
Ozone/H2O2+Conventional Treatment
Ozone has two pathways to react with organics when
it is used in water treatment: as molecular ozone and as
free radicals (hydroxyl radicals). Molecular ozone selectively
reacts with amines, phenols and double bonds in aliphatic
compounds. On the contrary, hydroxyl radicals work nonse-
lectively and react to all organics at a faster rate (Snyder et al.
2007b). Ozone/H2O2+conventional treatment resulted in
excellent removal of the selected PPCPs and EDCs. Bisphenol
A, carbamazepine, fluoxetine, naproxen, gemfibrozil, and
triclosan were completely eliminated under experimental con-
ditions. Diclofenac and ibuprofen were also removed at a
rate of 97% and 98%, respectively. However, atrazine and
atorvastatin showed some resistance and they were removed
by 86% and 88%, respectively. Figure 6 shows removal of
the selected PPCPs and EDCs by ozone/H2O2+conventional
treatment.
FIGURE 6. Removal of PPCPs and EDCs by ozone/H2O2+
conv. treatment.
In Experiment 2 (Site A), eliminations of carbamazepine,
fluoxetine, diclofenac, ibuprofen, gemfibrozil, triclosan,
naproxen and atorvastatin were more than 95% by ozone
(3.3 mg/L)-H2O2(0.08 mg/L) +conventional treatment.
Snyder et al. (2007b) conducted comparable experiments for
Colorado River water (DOC: 2.5 mg/L, pH: 8.2, alkalinity:
140 mg/LasCaCO
3) using ozone/H2O2treatment. Snyder
et al. (2007b) observed removals for carbamazepine (>98%),
diclofenac (>96%), fluoxetine (>98%), ibuprofen (88%),
gemfibrozil (>99%), and naproxen (>94%). However,
removal of atrazine was only 52%. In this current study,
removal of atrazine was 82% which was due to the additional
(20%) removal by conventional treatment with ozone/H2O2.
Overall, results of this current study are in agreement with
the study conducted by Snyder et al. (2007b). Furthermore,
Zwiener and Frimmel (2000) conducted bench-scale experi-
ments for ibuprofen and diclofenac using river water having
a DOC level of 3.7 mg/L and observed 99.9% removal of
diclofenac and 99.4% removal of ibuprofen. In the current
study, diclofenac was completely removed while removal
of ibuprofen was 98%. Thus, current study results were in
agreement with the literature (Zwiener and Frimmel 2000).
In Experiment 1, due to a lower ozone dose (0.8 mg/L)
removals of PPCPs and EDCs were considerably lower
such as gemfibrozil (12%), atrazine (44%), ibuprofen (51%),
carbamazepine (79%), and fluoxetine (79%). This implies
that these PPCPs and EDCs need a higher ozone dose for
additional oxidation.
For Site C water, removal of atorvastatin was limited to
70% by ozone/H2O2+conventional treatment which might
be due to the generation and scavenging of hydroxyl rad-
icals generating condition of the absence of an oxidant.
Moreover, generation of hydroxyl radicals lowers the ozone
concentration and requires a higher ozone dose.
Eliminations of atrazine were 82%, 85%, and 90% by
ozone/H2O2+conventional treatment using Sites A, B and
C waters, respectively. Current results are in agreement with
Scheidler et al. (2011) who conducted a study on pretreated
164 D. Borikar et al. March–April 2015
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river water having a DOC level of 4 mg/L and observed 58%
removal of atrazine by ozone/H2O2treatment. The source
water used (Scheidler et al. 2011) is comparable with the Site
B water as it had a DOC level of 2.8 mg/L. For Site B water,
ozone/H2O2treatment resulted in an additional 63% atrazine
removal along with conventional treatment removal (23%).
From the point of view of therapeutic use/class, the per-
sonal care product (triclosan) and plasticizer showed complete
removal of the selected PPCPs and EDCs by ozone/H2O2
+conventional treatment, while anti-depressants, analgesics,
and lipid regulator (gemfibrozil) were removed greater
than 98%. Only herbicide and lipid regulator (atorvastatin)
removals were lower than 90% likely due to the persis-
tent characteristic and the presence of scavengers (such as
organics), respectively.
Sites B and C have higher concentrations of organics,
bicarbonate and carbonate which might have scavenged
hydroxyl radicals during ozone/H2O2treatment and resulted
in slightly less removal as compared to Site A. On the other
hand, such reduction was compensated by higher PPCPs
and EDCs removal by conventional treatment due to higher
amount of particles (turbidity) and organics (DOC) in Sites
B and C waters. Therefore, the performance of ozone/H2O2
+conventional treatment was similar with regard to site and
resulted in an excellent elimination of the selected PPCPs and
EDCs for all sites.
Atorvastatin was completely removed by ozone +conven-
tional treatment by ozone/H2O2+conventional treatment for
Sites A and B in the 2009 experiments. However, removal of
atorvastatin was limited to 69–70% for Site C by ozone/H2O2
+conventional treatment. The likely reason for this was the
generation and scavenging of hydroxyl radicals. The concen-
tration of molecular ozone could have been reduced due to
the generation of hydroxyl radicals and such hydroxyl radi-
cals were destroyed by scavengers such as organics (DOC-
7.7 mg/L) and bicarbonate/carbonate (alkalinity-212 mg/L
as CaCO3).
The use of hydroxyl radicals can be more useful for con-
trolling bromate formation. Presence of bromide in the water
source in an ozone system results in formation of bromate
which is an issue for an ozone drinking water system. In other
words, one of the methods to control bromate formation is
the addition of hydrogen peroxide in ozone drinking water
treatment which generates hydroxyl radicals and reduces the
concentration of molecular ozone. Thus, hydroxyl radicals
not only eliminate micropollutants but also reduce bromate
formation.
Conventional Treatment +UV/H2O2
UV/H2O2is the other AOP used in the experiments
to degrade PPCPs and EDCs. Removal of the selected
PPCPs and EDCs by conventional treatment +UV/H2O2
is presented in Figure 7. Overall, conventional treatment
+(high) UV/H2O2demonstrated effective removal of
the selected PPCPs and EDCs. Triclosan, bisphenol A
FIGURE 7. Removal of PPCPs and EDCs by conv. treatment +
UV/H2O2(5 mg/L).
(except Site A) and diclofenac were completely removed.
Removals of carbamazepine, fluoxetine, ibuprofen, naproxen
and atorvastatin were 86–98% while removals of atrazine and
gemfibrozil were 82–83%.
In Experiment 2 (Site A), excellent removals of
carbamazepine (96%) and ibuprofen (98%) were achieved
by conventional +UV/H2O2treatment which are in close
agreement with the literature (Vogna et al. 2004a,b), which
reported that carbamazepine was completely removed after
four minutes of treatment of UV/H2O2while diclofenac was
also removed after 90 min of UV/H2O2treatment. Removal
of atrazine was also comparatively higher (93%) as compared
to those of Sites B and C, probably due to the lower numbers
of particles (turbidity) and lower concentration of organics,
which enhance penetration of UV radiation. The effect of
the UV dose (with H2O2) was obvious because atrazine was
only removed by 75% with 1000 mJ/cm2(lower than that
reported by Snyder et al. 2007b), but it increased to 93% with
2000 mJ/cm2. Similarly, removals of ibuprofen (from 89 to
98%), gemfibrozil (from 12 to 99%), and naproxen (from
94 to 100%) also showed enhanced eliminations with increas-
ing UV dosages. Furthermore, results of the current study are
in agreement with the literature (Pereira et al. 2007a), which
demonstrated that removals of carbamazepine and naproxen
were increased from 90% to 99% when UV dosages (both
with 10 mg/LH
2O2) were approximately doubled.
During Experiment 4, removals of bisphenol A, diclofenac,
triclosan, atorvastatin, fluoxetine and atrazine were effective
by conventional +UV (2000 mJ/cm2)/H2O2(5 mg/L) treat-
ment. However, eliminations of carbamazepine, gemfibrozil,
ibuprofen, and naproxen were lower when compared to
those by ozone/H2O2+conventional treatment. Pereira
et al. (2007b) investigated the removals of carbamazepine
and naproxen using laboratory grade water. The removals
were more than 99% for carbamazepine (1706 mJ/cm2
with 10 mg/LH
2O2) and more than 99% for naproxen
(1535 mJ/cm2with 10 mg/LH
2O2). In the current study,
removals of carbamazepine and naproxen were 82% and
Oxidation Processes for Removal of PPCPs and EDCs March–April 2015 165
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95%, respectively. The relatively lower percentage of removal
obtained in this study may be likely due to the lower H2O2
dosages (as compared to literature) as well as using natural
water instead of laboratory grade water. Additionally, lower
efficacy of this current study is probably due to the scav-
enging effect of the hydroxyl radicals caused by the higher
bicarbonate and carbonate concentrations of Site B (Parsons
2004).
In Experiment 6, removals of bisphenol A, fluoxetine,
diclofenac, naproxen, and triclosan were greater than 90%
by conventional +UV (1000 mJ/cm2)/H2O2treatment, but
removals of atrazine, ibuprofen, carbamazepine, gemfibrozil,
and atorvastatin ranged from 48% to 85% which was likely
due to lower UV dose (1000 mJ/cm2) and higher level of
organics and particles.
Current experimental results are comparable to what oth-
ers have reported in the literature (Sanches et al. 2010), which
conducted experiments using surface water and a UV dose
of 1500 mJ/cm2with 40 mg/LH
2O2. Percent removal and
the reaction rate constant (hydroxyl radical) of atrazine were
72% and 7.3 ×109M1s1, respectively. In the current study,
degradations of atrazine were 93% and 82% for Sites A and
B, respectively by conventional +UV (2000 mJ/cm2)/H2O2
(with 5 mg/L). The difference between the two studies is that
current study results include some removal by conventional
treatment. However, the current study used only 5 mg/LH
2O2
as compared to 40 mg/LH
2O2used by the literature study
(Sanches et al. 2010). Furthermore, the current study results
are also comparable to Snyder et al. (2007b) that conducted
bench scale testing with 1000 mJ/cm2with 5 mg/LH
2O2
and observed moderate (58–65%) removal of atrazine using
water with DOC levels between 2.5 and 3.5 mg/L. In the
current study using a pilot plant and Site B water (DOC-
2.8–3.5 mg/L), the removal of atrazine was 82% by conven-
tional +UV (2450 mJ/cm2)/H2O2(5 mg/L) treatment. The
difference in result is likely due to the use of conventional
treatment in the current study.
The efficacy of UV/H2O2was reduced for Sites B and C as
compared to Site A due to more hydroxyl radical scavengers
in terms of organics (DOC) (irradiation filtering effect), the
presence of bicarbonate and carbonate (scavenging effect) and
amount of particles (stopping UV propagation). Results of
carbamazepine and diclofenac removal are in agreement with
the literature (Lekkerkerker et al. 2009), which conducted
pilot-plant experiments using pretreated river water and had
UV transmittance (78–80%) and DOC (5 mg/L). The removal
of carbamazepine was 70% using UV (950 mJ/cm2) with
9mg/LH
2O2. In the current study, removal of carbamazepine
was 82% and 79% for Sites B and C, respectively by conven-
tional treatment +UV (2450 and 1000 mJ/cm2, respectively)
with5mg/LH
2O2. Moreover, diclofenac was completely
removed (Lekkerkerker et al. 2009) by 950 mJ/cm2with
9mg/LH
2O2whereas in the current study, diclofenac was
also removed 100% using Site B and C waters by conven-
tional treatment +UV/H2O2at the experimental conditions
mentioned above.
Comparing efficacy of UV/H2O2treatment for Sites B
and C, DOC (organics) was a more important parameter than
alkalinity (bicarbonate and carbonate). As DOC of Site B
(2.8 mg/L) was lower than Site C (7.7 mg/L), efficacy of con-
ventional treatment +UV/H2O2for the removal of PPCPs
and EDCs was higher for Site B than that for Site C. Although
Site B had a higher alkalinity (250 mg/LasCaCO
3) than
Site C (212 mg/LasCaCO
3), it did not lower efficacy of the
UV/H2O2treatment when compared to that of Site C. This
phenomenon is in agreement with the literature (Brezonik and
Fulkerson-Brekken 1998). Furthermore, as Sites B and C had
higher alkalinity levels than that of Site A, the removal of
PPCPs and EDCs were lower than that of Site A. This phe-
nomenon is in agreement with the literature (Sarathy et al.
2011), which reported slower degradation of organics with
high alkalinity during UV/H2O2treatment.
As per therapeutic use/class, personal care product
(triclosan) and plasticizer (bisphenol A) were completely
removed by conventional treatment +UV/H2O2, while anal-
gesics and antidepressants were partially removed. The class
of lipid regulator was the most resistant (85% eliminations)
among the pharmaceuticals group; while herbicide (82%
elimination) was the most resistant compound among the
selected PPCPs and EDCs. Moreover, both groups resulted in
reduced efficacy from Sites A to C when compared to those of
other groups. Personal care product was completely removed
indicating that the two aromatic rings make it susceptible to
degradation.
As atrazine and carbamazepine have the same (hydroxyl
radical) rate constant 5.85 ×109M1s1(Pereira et al. 2007b;
Yoon et al. 2012), their results of removal were similar for
all sites. Nevertheless, it is found that hydroxyl radicals are
nonselective oxidants, rate constants do vary in a small range.
Although conventional treatment +UV/H2O2was affected
by water quality, bisphenol A, and diclofenac were completely
removed because their constants were 8–10 ×109M1s1
(Yoon et al. 2012), which is slightly higher when compared to
other selected PPCPs and EDCs.
NOM, dissolved or suspended solids, alkalinity, pH, tem-
perature, chloride and nitrates have influence on the advanced
oxidation process. Suspended solids scatter light and interfere
with photolysis (Pereira et al. 2012), and color competes with
organics and/or PPCPs and EDCs to absorb UV light. NOM
and alkalinity (bicarbonate and carbonate) are the most influ-
encing scavengers. Dissolved organics absorb UV light and
therefore effective UV fluence rate decreases, which results
in reduced elimination of the selected PPCPs and EDCs
(Canonica et al. 2008).
Bicarbonates and carbonates (main components of
alkalinity) react with hydroxyl radicals to generate carbonate
radicals with kOH, HCO3 =1.5×107M1s1and kOH,CO3 =
4.2 ×107M1s1, respectively (Parsons 2004). However,
carbonate radicals react with organics selectively, primarily
with aromatic or sulfur containing molecules (Mazellier et al.
2002) and as a result reduce the efficacy of hydroxyl radicals.
Kruithof et al. (2007) reported that quantum yield, UV path
166 D. Borikar et al. March–April 2015
Downloaded by [Dr Saad Jasim] at 05:19 17 March 2015
length and chemical structure (double bonds, H atoms) were
important parameters in UV/H2O2treatment that could have
an impact on the degradation of PPCPs and EDCs.
Either the UV dose and/or hydrogen peroxide can be
increased in the presence of higher concentrations of scav-
engers. High UV dose will increase photo degradation of
the compound with increased capital and operational costs.
However, it will not have any side effects. An increase in H2O2
will also improve degradation; however, it will increase cost
and create residual or un-reacted H2O2causing issues related
to maintaining chlorine residual.
Removal of atrazine was 86% by ozone/H2O2+conven-
tional treatment. On the contrary, the removal of atrazine was
93% for conventional +(high) UV/H2O2treatment for Site
A water because the atrazine molecule is a strong absorber
of UV light (Parsons 2004). However, when hydroxyl rad-
ical scavengers were increased using Site B and C waters,
the removals of atrazine were limited to 82% and 73%,
respectively, for conventional treatment +(high) UV/H2O2.
In ozone/H2O2treatment ozone does most of the oxidation
while hydroxyl radicals enhance or improve the oxidation per-
formance (Snyder et al. 2007b) and consequently, in spite of
presences of hydroxyl radical scavengers, ozone/H2O2treat-
ment has not appeared to be impacted by water quality. On the
contrary, in UV/H2O2treatment hydroxyl radical is the sole
oxidant in the advanced oxidation process and the scavenging
of the hydroxyl radical had a great impact on degradation of
PPCPs and EDCs.
Comparison between Different Processes
Removals of PPCPs and EDCs during various treatments
were influenced by the raw water quality, type of treatment,
and dosages of oxidant. However, it is important to gener-
alize experimental results to draw conclusions about overall
concepts. Figure 8 demonstrates the average removals of the
selected PPCPs and EDCs during all experiments.
Overall, removal of the selected PPCPs and EDCs was poor
(26 ±3% [SD], experiments for Site C were not considered)
FIGURE 8. Removal of PPCPs and EDCs during various treat-
ments.
by conventional treatment. On the contrary, removal of the
selected PPCPs and EDCs was excellent by ozone/H2O2+
conventional treatment and resulted in an average removal
of 97 ±1% (SD) (Experiment 1 was not considered due to
a much lower ozone dose). Selected PPCPs and EDCs also
demonstrated very effective removal (an average of (92 ±7%
[SD]) capability by conventional treatment +UV/H2O2.
However, the results for conventional treatment +
UV/H2O2were likely affected by raw water quality and pro-
vided 98%, 93%, and 85% removal of PPCPs and EDCs using
Sites A, B and C waters, respectively. Based on statistics, there
was no significant difference between removal of the selected
PPCPs and EDCs by ozone/H2O2+conventional treatment
and conventional treatment +UV/H2O2. However, removal
of the selected PPCPs and EDCs by ozone/H2O2+conven-
tional treatment and conventional treatment +UV/H2O2were
significantly different, (p=0.0015) using ANOVA, single
factor test) compared to conventional treatment alone.
CONCLUSIONS
Reductions of DOC, UVA254 and SUVA were 20.9 ±4.5%
(SD), 36.6 ±4.3% (SD) and 20.0 ±3.6% (SD), respec-
tively, compared to those of raw water. Although ozone/H2O2
+conventional and conventional +UV/H2O2treatments
reduced additional DOC and UV254, the results were not
significantly different than those of conventional treatment.
Reductions of THM-FP were 13–63% by conventional
treatment compared to those of raw waters of Sites A, B and
C which were likely due to reduction of DOC. Reductions
of THM-FPs were 46% for Site A (Experiment 1), 33–48%
for Sites B and 22–43% for Site C by ozone/H2O2+con-
ventional treatment compared to those by standalone conven-
tional treatment. Ozone satisfies a part of chlorine demand
and changes the structure of organics which are less reactive
to chlorine or transforms organics into electron rich moi-
eties and consequently reduces THM-FPs. Although hydroxyl
radicals increase THM-FP, the concentration of hydroxyl
radicals in the ozone/H2O2process is comparatively less
than that in UV/H2O2treatment. In most of the exper-
iments, UV/H2O2increased THM-FPs of conventionally
treated water. UV/H2O2treatment generates OH, which
increases transformation of less reactive hydrophobic dis-
solved organic matter (DOM) into more reactive hydrophilic
DOM. Such reconfiguration creates more chlorine demand
and THM formation.
Conventional treatment poorly removed (26 ±3% [SD]),
the selected PPCPs and EDCs mainly due to solubility of
the PPCPs and EDCs. However, some removal was observed
likely due to hydrophobic nature (indicated by log Kow val-
ues) and ionization at certain pH (demonstrated by pKaval-
ues). Removals of gemfibrozil, and carbamazepine were 2%
and 5%, respectively. Eliminations of atorvastatin, bisphenol
A, ibuprofen, atrazine and naproxen were 17–26%, while
removals of fluoxetine, diclofanec and triclosan were 38–59%.
Oxidation Processes for Removal of PPCPs and EDCs March–April 2015 167
Downloaded by [Dr Saad Jasim] at 05:19 17 March 2015
Ozone/H2O2+conventional treatment resulted in excel-
lent removal (97 ±1% [SD]) of the selected PPCPs
and EDCs due to oxidation capability of ozone and
hydroxyl radicals. However, involvement of hydroxyl rad-
icals in ozone/H2O2treatment was limited. Bisphenol
A, carbamazepine, fluoxetine, naproxen, gemfibrozil, and
triclosan were completely eliminated under experimental con-
ditions. Diclofenac and ibuprofen were also removed by 97%
and 98%, respectively. However, atrazine and atorvastatin
showed some resistance and they were removed by 86% and
88%, respectively.
Conventional treatment +(high) UV/H2O2also demon-
strated effective removal (92 ±7% [SD]) of the selected
PPCPs and EDCs due to oxidation capability of hydroxyl
radicals. However, oxidation capability of hydroxyl radicals
was affected by hydroxyl radical scavengers such as organics,
bicarbonate, carbonate and particles. Triclosan, bisphenol A
(except Site A), and diclofenac were completely removed.
Removals of carbamazepine, fluoxetine, ibuprofen, naproxen,
and atorvastatin were 86–98%, and removals of atrazine, and
gemfibrozil were 82–83%.
Based on statistics, there was no significant difference
between removal of the selected PPCPs and EDCs by
ozone/H2O2+conventional treatment and conventional treat-
ment +UV/H2O2. However, removal of the selected PPCPs
and EDCs by ozone/H2O2+conventional treatment and con-
ventional treatment +UV/H2O2were significantly different
(p=0.0015) compared to conventional treatment alone.
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Oxidation Processes for Removal of PPCPs and EDCs March–April 2015 169
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... The presence of CECs in the various water matrices such as groundwater, surface water, and drinking water has been reported. 45 The UV/H 2 O 2 process is studied for removal of carbamazepine, gemfibrozil, ibuprofen, naproxen, and diclofenac from the wastewater matrices 52 wherein only triclosan is completely removed. The degradation of carbamazepine by UV/Cl forms 10,11-epoxy carbamazepine and acridine substituted compounds as TPs of carbamazepine. ...
... 59 It has been reported that as compared to UV/H 2 O 2 , UV/Cl efficiently removes sulfamethoxazole, trimethoprim, 17-a ethinylestradiol, diclofenac, etc. [59][60][61] The results obtained by UV/Cl were compared with UV/H 2 O 2 and it was found that the H 2 O 2 is not totally consumed and subsequently requires another process for removal, making the cost of UV/H 2 O 2 more than that of UV/Cl. 52,53 The photo-Fenton method (Fe 21 /Fe 21 /H 2 O 2 ) eliminates some of the organic contaminants such as ciprofloxacin, oxacillin, chloramphenicol, amoxicillin, ampicillin, and trimethoprim with complete mineralization or partial mineralization, which forms TPs. 25 The chemical reactions involved in the degradation of the ciprofloxacin by the photo-Fenton method and UV/H 2 O 2 take place at the piperazinyl ring and forms a degraded product, as shown in Figure 1.5. The oxidation of the quinolone moiety results in defluorination and a hydroxyl-substitution reaction, wherein the fluorine atom is replaced by a hydroxyl group. ...
... The combinations of oxidants act more efficiently than traditional oxidation methods alone, such as Cl 2 , HClO, H 2 O 2 , KMnO 4 and ClO 2 [7]. Diclofenac, ibuprofen, carbamazepine, fluoxetine, naproxen, gemfibrozil, triclosan and sulfamethoxazole can be removed by up to 90% in wastewater treatment plants equipped with advanced oxidation processes [47]. Also, it is reported that these processes can be used for degradation of herbicides and present promising technologies in terms of detoxifying and mineralizing herbicide molecules [48]. ...
Chapter
The contamination of wastewater with micropollutants has been placed at the forefront of environmental problems in recent decades due to the adverse impacts of these chemicals on human and aquatic life. Micropollutants include a diverse range of chemicals, e.g. those labeled as hormone disrupters, pharmaceutical residues, personal care products, pesticides, heavy metals, etc. Most of these chemicals cannot be fully treated by conventional treatment processes because treatment facilities are not specifically intended for removal of micropollutants, and many of them are resistant to biodegradation. Although no specific treatment can be proposed for complete elimination of micropollutants from wastewater, membrane-based technologies provide promising alternatives due to their rejection capabilities for lower molecular weight organic compounds and ions. One or more of the removal mechanisms (size exclusion, adsorption, electrostatic exclusion, and hydrophobic interaction) may be effective in the removal of micropollutants by membranes. The elimination of micropollutants by membrane processes can be influenced by various factors such as micropollutant characteristics, membrane properties, and background matrix of wastewater. The aim of this chapter is to provide a brief overview of occurrence of micropollutants, impacts of micropollutants on ecosystem and human health, regulations and legislation used for micropollutants management, micropollutants treatment processes, removal performances of micropollutants by membrane processes, the mechanisms that affects micropollutants rejection in the membrane process, and factors influencing micropollutants removal.
... However, these types of membrane separation systems still own slightly permeable for some pollutants with relatively small size and accompany by membrane fouling (Schäfer et al., 2011). Advanced oxidation processes (AOPs), such as ozonation (O 3 ), Fenton reaction (Deng et al., 2023a;Gao et al., 2021;Hasani et al., 2020;Wang et al., 2024;Seidmohammadi et al., 2023), ultraviolet light (UV) or combination process (UV/O 3 , UV/H 2 O 2 ), also have been widely used for micropollutants removal in water (Beltrán et al., 1993;Zwiener and Frimmel, 2000;Jin et al., 2012;Shu et al., 2013) and wastewater (Audenaert et al., 2013;Borikar et al., 2015;Deng et al., 2023b). However, the pollutants with low concentration and large volumes still are less viable removal by AOPs. ...
... A study on pilot-scale experiments in a WTP was conducted by (Borikar et al., 2014). The results indicated that conventional WTPs equipped with either ozone/ H 2 O 2 or UV/H 2 O 2 greatly improved PPCP removal from 26% to 97% or 92%, respectively. ...
Book
The worldwide trend toward urbanization leads to increasing contamination of aquatic environments by thousands of synthetic and natural compounds which are known as micropollutants. Although most of these chemicals occur at low concentrations, due to persistent, bioaccumulative, and toxic features, many of them show the considerable toxicological concerns and health side effects. Because of their partial removal during conventional wastewater treatment processes and lack of international safety and environmental standards, a large number of micropollutants and their metabolites still remained there and released in the nearby aquatic environments. In recent years, there has been a growing tendency to research about micropollutants’ impacts on the receiving environment and human health. These compounds are more significantly sensitive in detecting processes than classic compounds. Therefore, using micropollutants as environmental indicators for anthropogenic activities is a common method and frequently applied today. This book on micropollutants and challenges emerging in the aquatic environments and treatment processes contains comprehensive information on the fate and removal methods of the various emerging micropollutants from water and wastewater plants and their human health threats. This book addresses the needs of both researchers and graduate students in fields of environmental health engineering, environmental engineering, civil engineering, chemistry, etc.
... Most of the reviewed studies considered the application of ozonation to effluents from conventional secondary treatment plants. However, since ozonation uses non-specific oxidation pathways to transform target compounds, the versatility of this process allows its wide application, such as for the removal of pollutants from surface groundwaters [21][22][23] as well as other types of wastewaters, e.g., industrial effluents [24,25] or reject streams from ultrafiltration and reverse osmosis units [26]. 70% of the reviewed studies were located in Europe, whereas none of them was in Africa, as depicted in Fig. 3C. ...
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In a context of increasing water scarcity, it is essential to ensure an integrated watershed management, savings in the consumption of water as a finite resource and improve the performance of wastewater treatment plants to guarantee the quality of treated effluents. Therefore, advanced technologies for tertiary wastewater treatment have been widely studied in recent decades. These treatments have been reviewed over the years mainly providing comparisons from a technical perspective. However, there is a lack of a holistic evaluation considering environmental and economic aspects together with the aforementioned technical aspects. In this review, treatment alternatives for micropollutant and pathogen abatement have been identified based on technologies implemented on a large scale (ozonation, ultraviolet treatment, adsorption on activated carbon or membrane filtration) as well as those treatments in the process of implementation, such as electrochemical, Fenton-based or photocatalytic techniques. Thus, a systematic bibliographic search was performed considering works applying pilot and full-scale equipment, leaving lab-scale results out of the analysis. The description of each process allowed the identification of the technical feasibility, operating costs and associated environmental impacts, providing a comparative assessment that will help decision-making in the development and application of the different technologies. The benchmarking results reveal that the selected treatment should be chosen based on the source and specific pollutants present in the wastewater, as there is no single solution for the treatment of micropollutants and pathogens. In addition, recommendations are presented for the publication of reliable process-related data to facilitate comparison between different technologies and treatment scenarios.
... The oxidation method exhibited a fast reaction speed and high removal efficiency [15,16]. Borikar et al. [17] investigated the pilot-scale advanced oxidation processes (AOPs) for removing various PPCPs. The results showed the superior removal rates of over 95% involving carbamazepine, fluoxetine, naproxen, gemfibrozil, and ibuprofen. ...
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Biological activated carbon (BAC) biofilter coupling ultrafiltration (UF) is a promising process for the treatment of river water contaminated by pharmaceutical and personal care products (PPCPs). However, the pilot-scale study should be conducted to reveal the long-term removal performance and the respective contributions of BAC and UF. In this study, a BAC-UF system with treatment capacity of 0.16 m3 h−1 was operated for 130 days. The water quality was analyzed in terms of CODMn, UV254, NH4+-N, and PPCPs. The results showed that both BAC and UF were related to the removal of organic matter (CODMn and UV254), achieving the removals of 56.00% and 55.25%, respectively. Similarly, BAC and UF were both relevant to the removal effects of ammonia nitrogen, nitrite, and nitrate. Moreover, the BAC-UF process was featured with a high efficiency in the removal of PPCPs, and the average removal of total PPCPs reached 47.84%, especially anhydroerythromycin, sulfachloropyridazine, sulfadiazine, trimethoprim, and caffeine. Besides, it was found that the BAC unit played a key role in PPCPs removal and the UF unit also degraded them by the biomass on UF membranes. Therefore, this study proved the removal performance of BAC-UF for treating popular pollutants from river water, and the BAC-UF process in this work can be considered as a feasible method of producing clean drinking water.
Article
Microorganic pollutants (MOPs) in aquatic environment with low levels but high toxicity are harmful to ecosystem and human health. Fe(VI) has a dual-functional role in oxidation and coagulation, and can effectively remove MOPs, heavy metal, phosphate, particulates and colloids. Moreover, Fe(VI) can combine with traditional coagulants, or use as a pretreatment for membrane treatment because of its characters to generate nanoparticles by degradation in water. Based on the relevant toxicity experiments, Fe(VI) had been proved to be safe for the efficient treatment of MOPs. For better utilization of Fe(VI), its oxidation and coagulation mechanisms are summarized, and the knowledge about the control parameters, utilization methods, and toxicity effect for Fe(VI) application are reviewed in this paper. pH, different valences of iron, environmental substances, and other parameters are summarized in this study to clarify the important factors in the treatment of MOPs with Fe(VI). In the future study, aiming at cost reduction in Fe(VI) preparation, transportation and storage, enhancement of oxidation in the intermediate state, and better understanding the mechanism between interface and Fe(VI) oxidation will help promote the application of Fe(VI) in the removal of MOPs. This study offers guidelines for the application and development of Fe(VI) for the treatment of MOPs in aquatic environment.
Chapter
The global increase in the quality of life accompanied by the demand for emerging pollutants has introduced a new threat to an already scarce natural resource for humans, which is water. These also drew considerable attention over the last decades due to the number of emerging pollutants have detected in aqueous environment compartments. Various studies also indicated that the occurrence of emerging pollutants in environmental water bodies is because of both domestic and industrial activities. Moreover, their fate and impact on the aquatic environment are not well documented or understood as such they are classified as emerging pollutants. With alarming concern about environmental pollution, increasing research has been focused on the development of methodologies for environmental analysis, monitoring, and remediation. This chapter covers a comprehensive review of the research efforts related to treatment technologies for the removal of emerging pollutants in wastewater treatment plants. These include adsorption technology, biological technology, advanced oxidation process (AOP), multiple treatment, and membrane technology, among others. The performances (in terms of types of pollutants to be removed, process conditions, and removal efficiencies) of the treatment technologies are compared.
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This research developed a differential kinetic model to predict the partial degradation of natural organic matter (NOM) during ultraviolet plus hydrogen peroxide (UV/H2O2) advanced oxidation treatment. The absorbance of 254 nm UV, representing chromophoric NOM (CNOM) was used as a surrogate to track the degradation of NOM. To obtain reaction rate constants not available in the literature, i.e., reactions between the hydroxyl radical ((OH)-O-center dot) and NOM, experiments were conducted with "synthetic" water, using isolated Suwannee River NOM, and parameter estimation was applied to obtain the unknown model parameters. The reaction rate constant for the reaction between (OH)-O-center dot and total organic carbon (TOC), k(center dot OH,TOC), was estimated at 1.14(+/- 0.10) x 10(4) Lmg(-1) s(-1), and the reaction rate constant between (OH)-O-center dot and CNOM, k(center dot OH,CNOM), was estimated at 3.04(+/- 0.33) x 10(4) Lmol(-1) s(-1). The model was evaluated on two natural waters to predict the degradation of CNOM and H2O2 during UV/H2O2 treatment. Model predictions of CNOM degradation agreed well with the experimental results for UV/H2O2 treatment of the natural waters, with errors up to 6%. For the natural water with additional alkalinity, the model also predicted well the slower degradation of CNOM during UV/H2O2 treatment, owing to scavenging of (OH)-O-center dot by carbonate species. The model, however, underpredicted the degradation of H2O2, suggesting that, when NOM is present, mechanisms besides the photolysis of H2O2 contribute appreciably to H2O2 degradation. DOI: 10.1061/(ASCE)EE.1943-7870.0000390. (C) 2011 American Society of Civil Engineers.
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The current study undertaken by the Walkerton Clean Water Centre (WCWC) is to evaluate the application of Advanced Oxidation Processes (AOPs) involving Ozone and UV with the addition of hydrogen peroxide, as one of the methods used in the process of the removal of PPCPs and EDCs, or taste and odor. The amount of hydrogen peroxide used with UV is much higher than that used with the ozone application. The concern is the impact of the hydrogen peroxide on the chlorine residual in the water that is pumped to the distribution system. One of the methods used to deal with this problem is to increase the chlorine addition to maintain the required residual. That could increase the disinfectant by-products (DBPs), namely Trihalomethanes (THMs), in addition to increase to the cost of operation. The findings of these experiments would provide useful information regarding the AOPs application using ozone vs. UV with hydrogen peroxide.
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Enhanced Coagulation is a new regulatory requirement in the United States aimed at removing TOC by coagulation thereby controlling formation of disinfection byproducts. Coagulation principles are summarized for alum coagulation of natural organic matter (NOM). Negatively charged NOM creates a coagulant demand for positively charged Al species resulting in a stoichiometric relationship between the alum dosage and the raw water DOC that is pH dependent. The paper addresses coagulation with a broader view than Enhanced Coagulation, termed multiple objective coagulation. In general the objectives include: 1) to maximize particle and turbidity removals by downstream solid-liquid separation, 2) to maximize TOC and DBP precursor removals, 3) to minimize residual coagulant, 4) to minimize sludge production, and 5) to minimize operating costs. Optimum coagulation conditions are those that maximize pathogen removals, produce low turbidities and particle counts, and minimize residual Al. It is shown, for treatment of waters of low alkalinity, that the optimum alum dosage selected to minimize UV absorbance with strict pH control produced excellent treatment for turbidity, pathogens, and NOM. Full scale plant data are used to demonstrate a dual coagulation strategy of alum and cationic polymer that reduces sludge production and overall operating costs compared to alum alone.
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Even though ozone has been applied for a long time for disinfection and oxidation in water treatment, there is lack of critical information related to transformation of organic compounds. This has become more important in recent years, because there is considerable concern about the formation of potentially harmful degradation products as well as oxidation products from the reaction with the matrix components. In recent years, a wealth of information on the products that are formed has accumulated, and substantial progress in understanding mechanistic details of ozone reactions in aqueous solution has been made. Based on the latter, this may allow us to predict the products of as yet not studied systems and assist in evaluating toxic potentials in case certain classes are known to show such effects. Keeping this in mind, Chemistry of Ozone in Water and Wastewater Treatment: From Basic Principles to Applications discusses mechanistic details of ozone reactions as much as they are known to date and applies them to the large body of studies on micropollutant degradation (such as pharmaceuticals and endocrine disruptors) that is already available. Extensively quoting the literature and updating the available compilation of ozone rate constants gives the reader a text at hand on which his research can be based. Moreover, those that are responsible for planning or operation of ozonation steps in drinking water and wastewater treatment plants will find salient information in a compact form that otherwise is quite disperse. A critical compilation of rate constants for the various classes of compounds is given in each chapter, including all the recent publications. This is a very useful source of information for researchers and practitioners who need kinetic information on emerging contaminants. Furthermore, each chapter contains a large selection of examples of reaction mechanisms for the transformation of micropollutants such as pharmaceuticals, pesticides, fuel additives, solvents, taste and odor compounds, cyanotoxins. ISBN: 9781843393139 (Print) ISBN: 9781780400839 (eBook)
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This study investigates the bactericidal efficiency of the different kind of disinfectants as well as their effects on trihalomethane (THM) formation in the reaction with humic substances in the natural water. The application of chlorine as a disinfectant has caused much awareness and concern among health authorities in Thailand because it formed THM which are carcinogenic. Analysis revealed that with the same initial dosage of chlorine, the level of THM concentration will increase with increasing level of THM precursors. Alternative chemical disinfectants such as chlorine dioxide, ozone and peroxone (ozone + hydrogen peroxide) were also investigated. Ozone and peroxone were not only found to be very effective in Coliform inactivation hut also were good agent in controlling THM formation through maximizing the total organic carbon (TOC) removal. For 99.9% Coliform inactivation, the minimum chlorine dosage required was 3 mg/L whereas the required dosage for ozone and peroxone were only 0.6 and 0.34 mg/L respectively. Peroxone application can also increase the THM removal by ozone to 20-30%.
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Results from UFC tests will enable direct comparison of DBP formation in different water sources. A new chlorination approach has been developed for assessing disinfection by‐product (DBP) formation under constant, yet representative conditions. The rationale used in the development of the uniform formation conditions (UFC) test and the results of a parametric sensitivity analysis are presented. Within the acceptable range of conditions, the DBP formation varied by less than 4 percent for the three waters examined. UFC test results will allow a direct comparison of DBP formation among different waters and allow the evaluation of how treatment changes affect DBP formation in a specific water.