UV/H2O2 Treatment an Essential Barrier in a - PWN Technologies
UV/H2O2 Treatment an Essential Barrier in a - PWN Technologies
UV/H2O2 Treatment an Essential Barrier in a - PWN Technologies
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<strong>UV</strong>/<strong>H2O2</strong> TREATMENT AN ESSENTIAL BARRIER IN A MULTI BARRIER<br />
APPROACH FOR ORGANIC CONTAMINANT CONTROL<br />
Bram J. Martijn, 1 Peer C. Kamp 1 1, 2<br />
<strong>an</strong>d Joop C. Kruithof<br />
1. <strong>PWN</strong> Water Supply Comp<strong>an</strong>y North Holl<strong>an</strong>d, PO Box 2113, 1990 AC VELSERBROEK The Netherl<strong>an</strong>ds<br />
2. Wetsus Centre for Susta<strong>in</strong>able Water Technology, PO box 1113, 8900 CC LEEUWARDEN The Netherl<strong>an</strong>ds<br />
Abstract<br />
Caused by the presence of pesticides, endocr<strong>in</strong>e disruptors <strong>an</strong>d pharmaceuticals, <strong>PWN</strong> has implemented multiple<br />
barriers <strong>in</strong> their surface water treatment pl<strong>an</strong>ts (Kamp 1997). In addition to reverse osmosis (RO), a comb<strong>in</strong>ation of<br />
<strong>UV</strong>/<strong>H2O2</strong> treatment <strong>an</strong>d gr<strong>an</strong>ular activated carbon (GAC) filtration is implemented. A research program, r<strong>an</strong>g<strong>in</strong>g<br />
from lab-scale <strong>an</strong>d pilot research to process optimization by k<strong>in</strong>etic <strong>an</strong>d CFD model<strong>in</strong>g has resulted <strong>in</strong> full-scale<br />
application of <strong>UV</strong>/<strong>H2O2</strong> technology.<br />
Dur<strong>in</strong>g the research stage, the scope broadened from degradation of pesticides to pharmaceuticals, endocr<strong>in</strong>e<br />
disrupt<strong>in</strong>g compounds, solvents <strong>an</strong>d algae tox<strong>in</strong>s. In bench scale experiments dose-response relationships were<br />
established for these org<strong>an</strong>ic micro-pollut<strong>an</strong>ts. The required degradation of 80% at process conditions 0.56 kWh/m 3<br />
<strong>an</strong>d 6 mg/L <strong>H2O2</strong> was confirmed at pilot scale.<br />
At WTP Andijk (20 MGD; 3,000 m 3 /h), <strong>UV</strong>/<strong>H2O2</strong> is <strong>in</strong>tegrated <strong>in</strong> the exist<strong>in</strong>g process tra<strong>in</strong>, preceded by<br />
conventional surface water treatment <strong>an</strong>d followed by GAC filtration, provid<strong>in</strong>g a robust barrier aga<strong>in</strong>st reaction<br />
products from both oxidation <strong>an</strong>d photolytic degradation (AOC, nitrite).<br />
The full-scale <strong>UV</strong>/<strong>H2O2</strong> <strong>in</strong>stallation is operational s<strong>in</strong>ce November 2004. Pilot results were confirmed. LC <strong>an</strong>d GC-<br />
MS broad screen<strong>in</strong>g of the f<strong>in</strong>ished water confirmed the nonselectivity of the <strong>UV</strong>/<strong>H2O2</strong>-GAC process, while no<br />
harmful byproducts have been observed <strong>in</strong> f<strong>in</strong>ished water. All targets for org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control are achieved.<br />
Key words: Ultraviolet; <strong>UV</strong>/<strong>H2O2</strong>; adv<strong>an</strong>ced oxidation; org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control.<br />
Introduction<br />
<strong>PWN</strong>’s treatment facility Andijk (20 MGD; 3,000 m 3 /h) treats IJssel Lake water orig<strong>in</strong>at<strong>in</strong>g from the river Rh<strong>in</strong>e. In<br />
the raw water, concentrations of org<strong>an</strong>ic micro-pollut<strong>an</strong>ts such as pesticides, endocr<strong>in</strong>e disruptors <strong>an</strong>d<br />
pharmaceuticals as high as 1.0 �g/L have been observed. The highest concentration observed after storage <strong>in</strong> a<br />
process bas<strong>in</strong> was 0.5 �g/L.<br />
After almost 40 years of operation the water quality of WTP Andijk still complies with the EC <strong>an</strong>d Dutch dr<strong>in</strong>k<strong>in</strong>g<br />
water st<strong>an</strong>dards. Nevertheless <strong>an</strong> upgrade of the treatment process is <strong>in</strong>troduced <strong>in</strong> view of the follow<strong>in</strong>g aspects:<br />
avoid<strong>an</strong>ce of the use of chlor<strong>in</strong>e for breakpo<strong>in</strong>t chlor<strong>in</strong>ation thereby restrict<strong>in</strong>g the byproduct (THM)<br />
formation;<br />
multiple barriers aga<strong>in</strong>st pathogenic micro-org<strong>an</strong>isms such as Giardia <strong>an</strong>d Cryptosporidium;<br />
a dis<strong>in</strong>fection credit by multi barrier approach based on a 10 -4 health risk;<br />
a nonselective barrier aga<strong>in</strong>st org<strong>an</strong>ic micro-pollut<strong>an</strong>ts such as pesticides, endocr<strong>in</strong>e disrupt<strong>in</strong>g compounds,<br />
algae tox<strong>in</strong>s <strong>an</strong>d pharmaceuticals based on EC <strong>an</strong>d Dutch st<strong>an</strong>dards <strong>an</strong>d/or a health risk approach <strong>in</strong> order<br />
to satisfy customer confidence.<br />
Initially <strong>PWN</strong> <strong>in</strong>vestigated the suitability of O3/<strong>H2O2</strong> treatment for org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control. Although the results<br />
were very promis<strong>in</strong>g the process was not pursued <strong>in</strong> view of the bromate formation (up to 20 µg/L) <strong>in</strong> bromide rich<br />
(300 – 500 µg/L) IJssel Lake water (Kruithof, 1995). Consequently <strong>PWN</strong> has pursued <strong>UV</strong>/<strong>H2O2</strong> treatment for both<br />
primary dis<strong>in</strong>fection <strong>an</strong>d org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control.<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof
Water treatment pl<strong>an</strong>t Andijk has been retrofitted twice s<strong>in</strong>ce it was built <strong>in</strong> 1968. Orig<strong>in</strong>ally, the treatment consisted<br />
of breakpo<strong>in</strong>t chlor<strong>in</strong>ation, coagulation, rapid s<strong>an</strong>d filtration <strong>an</strong>d post-chlor<strong>in</strong>ation. The first modifications, up to<br />
1978, were the <strong>in</strong>troduction of GAC filtration <strong>an</strong>d post-dis<strong>in</strong>fection with chlor<strong>in</strong>e dioxide. Only recently, adv<strong>an</strong>ced<br />
oxidation by <strong>UV</strong>/<strong>H2O2</strong> treatment has been implemented for org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control <strong>an</strong>d improved primary<br />
dis<strong>in</strong>fection. Breakpo<strong>in</strong>t chlor<strong>in</strong>ation is elim<strong>in</strong>ated from the process. The <strong>UV</strong>/<strong>H2O2</strong> treatment is located just before<br />
the exist<strong>in</strong>g GAC filters.<br />
<strong>Treatment</strong> Objectives<br />
In the Netherl<strong>an</strong>ds around 350 pesticides are used with a great variety <strong>in</strong> persistence, degradability <strong>an</strong>d toxicity.<br />
Monitor<strong>in</strong>g programs have shown the presence of m<strong>an</strong>y of these pesticides <strong>in</strong> dr<strong>in</strong>k<strong>in</strong>g water sources such as the<br />
IJssel Lake. Priority pollut<strong>an</strong>ts such as atraz<strong>in</strong>e, pyrazon, diuron, bentazone, bromacil, methabenzthiaxuon, dicamba,<br />
2,4-D, TCA <strong>an</strong>d trichlorpyr are found <strong>in</strong> concentrations up to 1 µg/l. After storage these concentrations were<br />
lowered to a maximum of 0.5 �g/L. For these compounds the st<strong>an</strong>dard of the EC <strong>an</strong>d Dutch dr<strong>in</strong>k<strong>in</strong>g water act of<br />
0.1 �g/L must be satisfied. In view of the maximum concentrations after storage, the required degradation by<br />
treatment was set at 80%.<br />
More recently monitor<strong>in</strong>g programs have been focused on the presence of endocr<strong>in</strong>e disruptors <strong>an</strong>d pharmaceuticals.<br />
In the raw water sources up to several hundred n<strong>an</strong>ograms per liter were found for bisphenol A, diethylphtalate,<br />
diclofenac, ibuprofen, phenazone, carbamazep<strong>in</strong>e <strong>an</strong>d several <strong>an</strong>tibiotics <strong>an</strong>d X-ray contrast media. Although no<br />
st<strong>an</strong>dards have been set for these compounds at this moment, <strong>PWN</strong> focused on the removal as well to satisfy<br />
customer confidence.<br />
<strong>UV</strong>/<strong>H2O2</strong> treatment, a comb<strong>in</strong>ation of <strong>UV</strong> photolysis <strong>an</strong>d hydroxyl radical reactions (Bolton, 1994) was pursued for<br />
org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control. Some literature data for the qu<strong>an</strong>tum yield Φ <strong>an</strong>d kOH of a number of herbicides are<br />
summarized <strong>in</strong> table 1 (Stef<strong>an</strong>, 2005).<br />
Table 1: Literature data for Φ <strong>an</strong> kOH of herbicides<br />
Herbicide Φ kOH (M -1 s -1 )<br />
Atraz<strong>in</strong>e 0.05 (254 nm) 2.4 – 3.0 x 10 9<br />
2,4-D 0.0262 (254 nm) 2.3 x 10 9<br />
Diuron 0.022 (254 nm) 4.6 x 10 9<br />
Isoproturon 0.045 (254 nm) 5.2 x 10 9<br />
Simaz<strong>in</strong>e 0.083 (254nm) 2.9 x 10 9<br />
TCA 0.06 x 10 9<br />
Plott<strong>in</strong>g these const<strong>an</strong>ts <strong>in</strong> a simplified k<strong>in</strong>etic model for herbicide decay showed that 80% degradation could be<br />
achieved under realistic conditions. After prelim<strong>in</strong>ary research <strong>PWN</strong> considered the perspective of <strong>UV</strong> light <strong>in</strong><br />
comb<strong>in</strong>ation with <strong>H2O2</strong> dosage for org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control very promis<strong>in</strong>g. Partly <strong>in</strong> collaboration with Troj<strong>an</strong><br />
<strong>Technologies</strong> Inc. three major objectives were pursued:<br />
model degradation by <strong>UV</strong> photolysis <strong>an</strong>d hydroxyl radical reaction for selected priority pollut<strong>an</strong>ts<br />
(pesticides, endocr<strong>in</strong>e disruptors, pharmaceuticals);<br />
predict <strong>an</strong>d determ<strong>in</strong>e the potential of a medium pressure <strong>UV</strong> reactor to degrade those priority pollut<strong>an</strong>ts;<br />
design a full scale <strong>UV</strong>/<strong>H2O2</strong> system for both dis<strong>in</strong>fection <strong>an</strong>d org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control.<br />
This paper focuses on the degradation of org<strong>an</strong>ic micro-pollut<strong>an</strong>ts, aspects of dis<strong>in</strong>fection (Kruithof, 2005) <strong>an</strong>d post<br />
treatment (Kruithof, 2006) are described elsewhere.<br />
Results <strong>an</strong>d Discussion<br />
Bench scale research <strong>UV</strong>/<strong>H2O2</strong> phase 1<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof
Review<strong>in</strong>g the research experiences with the ozone peroxide oxidation process (Kruithof, 1995), <strong>PWN</strong> decided to<br />
pursue <strong>an</strong> adv<strong>an</strong>ced oxidation process without the formation of <strong>an</strong>y bromate. <strong>UV</strong>/<strong>H2O2</strong> treatment was ideally suited<br />
for this purpose. It has been observed that bromate formation by •OH-radicals c<strong>an</strong> be avoided <strong>in</strong> presence of <strong>an</strong><br />
excess <strong>H2O2</strong> (Gunten, 1997).<br />
<strong>UV</strong>/<strong>H2O2</strong> treatment is based on the oxidation by hydroxyl-radicals produced by photolysis of <strong>H2O2</strong>, comb<strong>in</strong>ed with<br />
direct photolysis of org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>ts. Depend<strong>an</strong>t on the chemical characteristics of the pollut<strong>an</strong>t, one of the two<br />
processes plays a pre-dom<strong>in</strong><strong>an</strong>t role.<br />
Feasibility of the <strong>UV</strong>-peroxide process has been studied on bench scale. Figure 1 shows the results of orientat<strong>in</strong>g<br />
tests performed on reconstituted water, with similar characteristics as the pre-treated IJssel Lake water.<br />
atraz<strong>in</strong>e<br />
[µg/L]<br />
1,0<br />
0,5<br />
H 2O 2 25 mg/L<br />
0,0<br />
0<br />
0 1 2 3 4 5<br />
uv-dosage [kWh/m 3 ]<br />
Figure 1: Atraz<strong>in</strong>e degradation <strong>an</strong>d bromate formation by <strong>UV</strong>/<strong>H2O2</strong> treatment<br />
atraz<strong>in</strong>e<br />
bromate<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof<br />
10<br />
bromate<br />
[µg/L]<br />
Atraz<strong>in</strong>e was removed to values lower th<strong>an</strong> 0.1 �g/L at <strong>an</strong> <strong>UV</strong>-dose of 0.5 kWh/m 3 , while no bromate formation<br />
could be observed at <strong>an</strong> energy <strong>in</strong>put as high as 4 kWh/m 3 . Formation of metabolites was <strong>in</strong>signific<strong>an</strong>t. No<br />
concentrations > 0.1 �g/L were observed.<br />
In additional bench scale experiments (figure 2), dose-response relationships for atraz<strong>in</strong>e degradation were<br />
established <strong>in</strong> pre-treated IJssel Lake water. For a r<strong>an</strong>ge of comb<strong>in</strong>ations of <strong>UV</strong>-dose <strong>an</strong>d <strong>H2O2</strong> dosage, the desired<br />
80% degradation of atraz<strong>in</strong>e was achieved.<br />
5
degradation [%]<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
0 0.2 0.4 0.6 0.8 1<br />
energy <strong>in</strong>put [kWh/m 3 ]<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof<br />
4 mg/L <strong>H2O2</strong><br />
8 mg/L <strong>H2O2</strong><br />
15 mg/L <strong>H2O2</strong><br />
25 mg/L <strong>H2O2</strong><br />
Figure 2: Atraz<strong>in</strong>e degradation for several process conditions, bench scale experiments <strong>in</strong> pre-treated IJssel Lake<br />
water<br />
Depend<strong>an</strong>t on the chemical characteristics of the pollut<strong>an</strong>t, either photolysis or hydroxyl radical oxidation plays a<br />
pre-dom<strong>in</strong><strong>an</strong>t role. Figure 3 illustrates this for the degradation of NDMA, primarily due to photolysis, 1,4-diox<strong>an</strong>e,<br />
completely based on hydroxyl radical oxidation <strong>an</strong>d atraz<strong>in</strong>e degradation, based on a comb<strong>in</strong>ation of both.<br />
degradation<br />
[%]<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
<strong>UV</strong>/<strong>H2O2</strong>-oxidation <strong>UV</strong>-photolysis<br />
NDMA atraz<strong>in</strong>e 1,4-diox<strong>an</strong>e<br />
Figure 3: Ratio of degradation by oxidation <strong>an</strong>d photolysis for NDMA, atraz<strong>in</strong>e <strong>an</strong>d 1,4-diox<strong>an</strong>e<br />
Pilot scale research <strong>UV</strong>/<strong>H2O2</strong> phase 1<br />
Research was extended to pilot scale. Figure 4 presents the atraz<strong>in</strong>e degradation for several hydrogen peroxide<br />
dosages for both the bench scale <strong>an</strong>d the pilot scale <strong>in</strong>stallation. A slight decrease <strong>in</strong> efficiency c<strong>an</strong> be observed,<br />
mov<strong>in</strong>g from bench scale to pilot scale.
EE/O [kWh/m 3 ]<br />
2<br />
1,5<br />
1<br />
0,5<br />
0<br />
4 8 15 25<br />
<strong>H2O2</strong> [g/m 3 ]<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof<br />
bench scale<br />
pilot pl<strong>an</strong>t<br />
Figure 4: Required electrical energy per order for atraz<strong>in</strong>e degradation <strong>in</strong> pre-treated IJssel Lake water <strong>in</strong> bench<br />
scale experiments <strong>an</strong>d pilot scale experiments for four <strong>H2O2</strong> concentrations<br />
Based on the established dose-response relationship for reference pollut<strong>an</strong>t atraz<strong>in</strong>e <strong>in</strong> the bench scale experiments<br />
phase 1, the desired 80% degradation <strong>an</strong>d the good agreement between bench scale experiments <strong>an</strong>d pilot scale<br />
experiments, degradation of pesticides atraz<strong>in</strong>e, pyrazone, diuron, bentazone <strong>an</strong>d bromacil was determ<strong>in</strong>ed <strong>in</strong> pilot<br />
experiments at <strong>an</strong> <strong>UV</strong>-dose of 0.9 kWh/m 3 <strong>an</strong>d a <strong>H2O2</strong> dosage of 4 g/m 3 (figure 5).<br />
100<br />
80<br />
degradation [%]<br />
60<br />
40<br />
20<br />
0<br />
<strong>UV</strong> 0.9 kWh/m 3<br />
<strong>H2O2</strong> 4 g/m 3<br />
atraz<strong>in</strong>e pyrazone diuron bentazone bromacil<br />
Figure 5: Degradation of pesticides at process conditions for 80% degradation of atraz<strong>in</strong>e<br />
Figure 5 shows that at the selected process conditions, a pesticide degradation vary<strong>in</strong>g from 68% for bentazone to<br />
88% for diuron was achieved. Pilot research was extended. For a selection of ten pesticides <strong>an</strong>d one atraz<strong>in</strong>e<br />
metabolite, the degradation by <strong>UV</strong>-photolysis as a function of <strong>UV</strong>-dose has been studied <strong>in</strong> <strong>an</strong> <strong>in</strong> l<strong>in</strong>e Berson pilot.<br />
The electric energy was r<strong>an</strong>g<strong>in</strong>g from 0.25 – 2.0 kWh/m 3 . All priority pollut<strong>an</strong>ts showed a signific<strong>an</strong>t degradation by<br />
<strong>UV</strong>-photolysis. The conversion for <strong>an</strong> electric energy of 1 kWh/m 3 (~ 1000 mJ/cm2) is summarized <strong>in</strong> figure 6.
100<br />
80<br />
degradation [%]<br />
60<br />
40<br />
20<br />
0<br />
atraz<strong>in</strong>e<br />
pyrazon<br />
diuron<br />
bentazon<br />
bromacil<br />
Figure 6: Pesticide degradation by <strong>UV</strong>-photolysis with 1 kWh/m 3<br />
methabenzthiaxuon<br />
dicamba<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof<br />
electrical energy 1.0 kWh/m 3<br />
photolysis only<br />
By <strong>UV</strong>-photolysis with 1 kWh/m 3 , degradation r<strong>an</strong>ged from 18 % for trichloroacetic acid (TCA) to 70 % for<br />
atraz<strong>in</strong>e. The criterion of 80 % conversion had to be achieved by <strong>an</strong> additional <strong>H2O2</strong>-dosage to <strong>in</strong>itiate a<br />
supplementary conversion by hydroxyl radicals.<br />
The degradation of emerg<strong>in</strong>g pesticides by comb<strong>in</strong>ed <strong>UV</strong>-photolysis <strong>an</strong>d hydroxyl radical oxidation, for several<br />
peroxide-electrical energy comb<strong>in</strong>ations was studied. Examples for a compound with a high <strong>an</strong>d a low <strong>UV</strong>photolysis<br />
susceptibility are shown <strong>in</strong> figure 7 <strong>an</strong>d 8.<br />
degradation [%]<br />
100<br />
80<br />
60<br />
40<br />
2,4-D<br />
trichlorpyr<br />
0 5 10 15<br />
hydrogen peroxide [mg/L]<br />
0.33 kWh/m3<br />
0.5 kWh/m3<br />
1.0 kWh/m3<br />
1.5 kWh/m3<br />
2.2 kWh/m3<br />
Figure 7: Atraz<strong>in</strong>e degradation by comb<strong>in</strong>ed <strong>UV</strong>-photolysis <strong>an</strong>d hydroxyl radical oxidation<br />
Degradation of atraz<strong>in</strong>e by <strong>an</strong> electric energy of 1 kWh/m 3 amounted 70 %. This degradation was <strong>in</strong>creased to the<br />
required 80 % by add<strong>in</strong>g 13 g/m 3 <strong>H2O2</strong>.
degradation [%]<br />
100<br />
80<br />
60<br />
0.33 kWh/m3<br />
0.5 kWh/m3<br />
1.0 kWh/m3<br />
1.5 kWh/m3<br />
40<br />
2.2 kWh/m3<br />
0 5 10 15<br />
hydrogen peroxide [mg/L]<br />
Figure 8: Pyrazon degradation by comb<strong>in</strong>ed <strong>UV</strong>-photolysis <strong>an</strong>d hydroxyl radical oxidation<br />
Degradation of pyrazon by <strong>an</strong> electric energy of 1 kWh/m 3 amounted 54 %. This degradation was <strong>in</strong>creased to the<br />
required 80 % by add<strong>in</strong>g 8 g/m 3 <strong>H2O2</strong>.<br />
Depend<strong>in</strong>g on the <strong>UV</strong> molar absorption coefficients <strong>an</strong>d qu<strong>an</strong>tum yields on the one h<strong>an</strong>d <strong>an</strong>d the chemical structure<br />
(double bonds, aromaticity, H-atoms) on the other h<strong>an</strong>d either direct photolysis or hydroxyl radical reactions play a<br />
predom<strong>in</strong><strong>an</strong>t role.<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof
Research <strong>UV</strong>/<strong>H2O2</strong> phase 2<br />
In collaboration with <strong>UV</strong>-equipment supplier Troj<strong>an</strong> <strong>Technologies</strong> Inc., k<strong>in</strong>etic models for the dom<strong>in</strong><strong>an</strong>t oxidation<br />
processes by <strong>UV</strong>/<strong>H2O2</strong> treatment, OH-radical oxidation <strong>an</strong>d photolysis have been developed. Extensive research on<br />
bench scale provided the k<strong>in</strong>etic parameters (qu<strong>an</strong>tum yield, rate const<strong>an</strong>ts) (Stef<strong>an</strong>, 2005). Based on CFD-model<strong>in</strong>g<br />
<strong>in</strong> comb<strong>in</strong>ation with the established k<strong>in</strong>etic models, <strong>an</strong> <strong>UV</strong>-pilot reactor was designed <strong>an</strong>d optimized for org<strong>an</strong>ic<br />
contam<strong>in</strong><strong>an</strong>t control.<br />
Predicted org<strong>an</strong>ic micro-pollut<strong>an</strong>t degradation at several process conditions was confirmed <strong>an</strong>d ref<strong>in</strong>ed by<br />
experimental work with the newly designed pilot reactor (figure 9).<br />
predicted<br />
log removal<br />
1.0<br />
[-]<br />
0.8<br />
0.6<br />
0.4<br />
0.2<br />
0.0<br />
<strong>H2O2</strong> 1 - 6 mg/L<br />
energy 0.11 - 0.56 kWh/m 3<br />
NO3 4.4 - 13.5 mg/L<br />
0.0 0.2 0.4 0.6 0.8 1.0<br />
experimental log removal [-]<br />
atraz<strong>in</strong>e<br />
bromacil<br />
diuron<br />
Figure 9: Experimental log removal versus predicted log removal for diuron, atraz<strong>in</strong>e <strong>an</strong>d bromacil at several<br />
process conditions <strong>an</strong>d nitrate levels (pilot experiments <strong>in</strong> pre-treated IJssel Lake water)<br />
Figure 10 presents the dose-response relationship for atraz<strong>in</strong>e degradation by <strong>UV</strong>/<strong>H2O2</strong> treatment. In the newly<br />
designed pilot <strong>UV</strong>-reactor (20 m 3 /h), under <strong>UV</strong>/<strong>H2O2</strong> process conditions of 0.56 kWh/m 3 <strong>an</strong>d 6 mg/L <strong>H2O2</strong>, <strong>PWN</strong>’s<br />
atraz<strong>in</strong>e degradation target of 80% is achieved. Compared to results <strong>in</strong> a reactor designed for dis<strong>in</strong>fection purposes<br />
the electric energy consumption <strong>an</strong>d <strong>H2O2</strong> dose were lowered by 44 <strong>an</strong>d 54% respectively.<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof
degradation [%]<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
0 0.2 0.4 0.6<br />
energy <strong>in</strong>put [kWh/m 3 ]<br />
Figure 10: Degradation of atraz<strong>in</strong>e as a function of the <strong>UV</strong>-dose <strong>in</strong> comb<strong>in</strong>ation with 6 g/m 3 <strong>H2O2</strong> (pilot data)<br />
Research <strong>in</strong>to degradation characteristics of org<strong>an</strong>ic micro-pollut<strong>an</strong>ts, observed <strong>in</strong> IJssel Lake water, is ongo<strong>in</strong>g. For<br />
several pharmaceuticals, the degradation under st<strong>an</strong>dard process conditions was studied (figure 11). The observed<br />
degradations <strong>in</strong> bench scale experiments <strong>an</strong>d pilot pl<strong>an</strong>t experiments match well.<br />
100<br />
80<br />
degradation [%]<br />
60<br />
40<br />
20<br />
0<br />
ibuprofen diclofenac clofibric acid carbamazep<strong>in</strong>e sulphametoxalol<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof<br />
bench scale data<br />
pilot data<br />
Figure 11: Observed correspondence between degradation results for pharmaceuticals, obta<strong>in</strong>ed <strong>in</strong> both bench scale<br />
experiments <strong>an</strong>d pilot pl<strong>an</strong>t research<br />
Based on the results, a full scale <strong>UV</strong>-reactor was designed by Troj<strong>an</strong> <strong>an</strong>d a reactor configuration consist<strong>in</strong>g of three<br />
l<strong>in</strong>es of four 30 <strong>in</strong>ch SWIFT reactors, each with sixteen 12 kW MP <strong>UV</strong>-lamps was <strong>in</strong>stalled at WTP Andijk.
Full Scale <strong>UV</strong>/<strong>H2O2</strong> Installation<br />
Upon start up of the retrofitted pl<strong>an</strong>t Andijk, a site accept<strong>an</strong>ce test was performed. For operat<strong>in</strong>g purposes, the<br />
<strong>UV</strong>/<strong>H2O2</strong> <strong>in</strong>stallation is equipped with a control-unit, calculat<strong>in</strong>g the atraz<strong>in</strong>e degradation capacity under actual<br />
process conditions. Both for the ‘<strong>in</strong>stallation software’ as for the ‘k<strong>in</strong>etic model prediction’, the presented<br />
predictions were based on the actual water characteristics.<br />
For test<strong>in</strong>g purposes, one of the three full scale <strong>UV</strong>/<strong>H2O2</strong> production l<strong>in</strong>es was isolated <strong>an</strong>d spiked with atraz<strong>in</strong>e <strong>an</strong>d<br />
bromacil (~3 �g/L). Figure 12 presents the measured atraz<strong>in</strong>e degradation (experimental data) together with the<br />
predicted degradation (k<strong>in</strong>etic model prediction <strong>an</strong>d the on l<strong>in</strong>e atraz<strong>in</strong>e destruction calculation).<br />
120<br />
100<br />
degradation [%] 80<br />
60<br />
40<br />
20<br />
0<br />
0.56 0.42<br />
energy <strong>in</strong>put [kWh/m 3 ]<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof<br />
model prediction<br />
on l<strong>in</strong>e calculation<br />
experimental data<br />
Figure 12: Degradation of atraz<strong>in</strong>e for two electrical energies <strong>an</strong>d 6 mg/L <strong>H2O2</strong> (full scale data)<br />
Process parameter electrical energy was set at two levels, 0.42 kWh/m 3 <strong>an</strong>d st<strong>an</strong>dard process condition 0.56 kWh/m 3 .<br />
It was found that with<strong>in</strong> accept<strong>an</strong>ce limits the measured degradation of atraz<strong>in</strong>e was predicted by the <strong>in</strong>stallation<br />
software. Furthermore, good agreement was found between the model calculations <strong>an</strong>d the measured atraz<strong>in</strong>e<br />
degradation <strong>in</strong> the full scale <strong>in</strong>stallation.<br />
Collimated beam <strong>an</strong>d pilot work showed that atraz<strong>in</strong>e is degraded predom<strong>in</strong><strong>an</strong>tly by photolysis while bromacil is<br />
more susceptible to hydroxyl radical oxidation. These characteristics have been taken <strong>in</strong>to account <strong>in</strong> the developed<br />
k<strong>in</strong>etic models. Figure 13 presents the agreement between the predicted degradation of bromacil <strong>in</strong> the full scale<br />
<strong>UV</strong>/<strong>H2O2</strong> <strong>in</strong>stallation <strong>an</strong>d the measured degradation dur<strong>in</strong>g the site accept<strong>an</strong>ce test.
120<br />
100<br />
degradation [%] 80<br />
60<br />
40<br />
20<br />
0<br />
model prediction<br />
experimental data<br />
0.56 0.42<br />
energy <strong>in</strong>put [kWh/m 3 ]<br />
Figure 13: Degradation of bromacil for two electrical energies <strong>an</strong>d 6 mg/L <strong>H2O2</strong> (full scale data)<br />
Based upon the results of the site accept<strong>an</strong>ce test, it was concluded that the full scale <strong>UV</strong>/<strong>H2O2</strong> equipment met the<br />
design criteria.<br />
After <strong>in</strong>troduction of <strong>UV</strong>/<strong>H2O2</strong>, raw water <strong>an</strong>d f<strong>in</strong>ished water have been monitored on the presence of org<strong>an</strong>ic<br />
compounds by LC <strong>an</strong>d GC-MS broad screen<strong>in</strong>g. These methods are suited for identification of org<strong>an</strong>ic compounds<br />
but have restricted value for qu<strong>an</strong>tification.<br />
In IJssel Lake water, 25 org<strong>an</strong>ic compounds have been identified (107 observations), after storage 22 org<strong>an</strong>ic<br />
compounds were found (84 observations). In f<strong>in</strong>ished water, this number was reduced to 9 org<strong>an</strong>ic compounds (14<br />
observations).<br />
In raw water flame retard<strong>an</strong>t trichloropropylphospate was identified 5 times. Detergent Surfynol 104 <strong>an</strong>d melam<strong>in</strong>e<br />
were detected 11 <strong>an</strong>d 7 times respectively while <strong>an</strong>ti-epileptic carbamazep<strong>in</strong>e was detected 4 times. All compounds<br />
were not detected <strong>in</strong> the f<strong>in</strong>ished water.<br />
Solvent diglyme was detected 8 times <strong>in</strong> raw water <strong>an</strong>d 5 times <strong>in</strong> f<strong>in</strong>ished water. The observed degradation was<br />
approximately 50%.<br />
Figure 14 presents the EDTA content <strong>in</strong> raw <strong>an</strong>d f<strong>in</strong>ished water before <strong>an</strong>d after <strong>in</strong>troduction of <strong>UV</strong>/<strong>H2O2</strong> treatment.<br />
After the <strong>in</strong>troduction of <strong>UV</strong>/<strong>H2O2</strong> per 2005, no EDTA is detected <strong>in</strong> f<strong>in</strong>ished water even with the high EDTA levels<br />
<strong>in</strong> raw water <strong>in</strong> the first half of 2005.<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof
EDTA [ g/L]<br />
8<br />
6<br />
4<br />
2<br />
0<br />
J<strong>an</strong>-March 2004<br />
April-June 2004<br />
July-Sept 2004<br />
Oct-Dec 2004<br />
J<strong>an</strong>-March 2005<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof<br />
<<br />
April-June 2005<br />
<<br />
July-Sept 2005<br />
raw water<br />
f<strong>in</strong>ished water<br />
<<br />
Oct-Dec 2005<br />
Figure 14: EDTA <strong>in</strong> raw <strong>an</strong>d f<strong>in</strong>ished water before <strong>an</strong>d after <strong>in</strong>troduction of <strong>UV</strong>/<strong>H2O2</strong> (full scale data)<br />
Evaluation<br />
This paper describes the research <strong>an</strong>d full scale application of the <strong>UV</strong>/<strong>H2O2</strong> process as nonselective barrier for<br />
org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control at <strong>PWN</strong>’s water treatment facility Andijk (20 MGD; 3000 m 3 /h).<br />
Bench scale research on <strong>UV</strong>/<strong>H2O2</strong> proved that 80% degradation of reference pollut<strong>an</strong>t atraz<strong>in</strong>e to achieve the set<br />
st<strong>an</strong>dard of 0.1 �g/L was feasible without <strong>an</strong>y bromate formation.<br />
From additional pilot work, it was concluded that <strong>UV</strong>/<strong>H2O2</strong> treatment is a nonselective barrier for a broad selection<br />
of emerg<strong>in</strong>g org<strong>an</strong>ic micro-pollut<strong>an</strong>ts.<br />
Degradation target of selected reference pollut<strong>an</strong>t atraz<strong>in</strong>e (80% degradation) was reached <strong>in</strong> <strong>an</strong> optimized pilot <strong>UV</strong>reactor<br />
at <strong>an</strong> <strong>UV</strong>-<strong>in</strong>put of 0.56 kWh/m 3 (~540 mJ/cm 2 ) <strong>in</strong> comb<strong>in</strong>ation with 6 g/m 3 <strong>H2O2</strong>. This has resulted <strong>in</strong> a 40%<br />
reduction <strong>in</strong> energy consumption <strong>an</strong>d a 50% reduction of <strong>H2O2</strong> dosage compared to the degradation achieved <strong>in</strong> a<br />
reactor designed for dis<strong>in</strong>fection purposes only.<br />
Full scale test<strong>in</strong>g showed that the <strong>UV</strong>/<strong>H2O2</strong> <strong>in</strong>stallation meets the design criteria. Model calculations are confirmed<br />
by the perform<strong>an</strong>ce of the full scale <strong>in</strong>stallation. Collimated beam experiments with solvent diglyme resulted <strong>in</strong> 60%<br />
degradation under st<strong>an</strong>dard process conditions. In the full scale <strong>in</strong>stallation 50% degradation was observed,<br />
confirm<strong>in</strong>g the predicted perform<strong>an</strong>ce of the full scale <strong>UV</strong>/<strong>H2O2</strong> <strong>in</strong>stallation.<br />
By LC <strong>an</strong>d GC-MS screen<strong>in</strong>g of the raw water 22 org<strong>an</strong>ic compounds (84 observations) were detected. After<br />
<strong>UV</strong>/<strong>H2O2</strong> treatment, only 9 different org<strong>an</strong>ic compounds were found (14 observations). Complex<strong>in</strong>g agent EDTA,<br />
present <strong>in</strong> the raw water <strong>in</strong> relatively high concentrations (2.5 – 6.5 �g/L), was completely degraded by <strong>UV</strong>/<strong>H2O2</strong><br />
treatment.<br />
Despite the limited full scale data of WTP Andijk until now, from the observed complete degradation of compounds<br />
such as EDTA, signific<strong>an</strong>t degradation of diglyme <strong>an</strong>d the results of the LC <strong>an</strong>d GC-MS screen<strong>in</strong>g, it is concluded<br />
that photolysis <strong>an</strong>d oxidation processes are a robust nonselective barrier for org<strong>an</strong>ic contam<strong>in</strong><strong>an</strong>t control.<br />
In the near future <strong>UV</strong>/<strong>H2O2</strong> treatment will be implemented at WTP Heemskerk, <strong>PWN</strong>’s UF/RO pl<strong>an</strong>t, as well.<br />
Acknowledgements<br />
The authors th<strong>an</strong>k Troj<strong>an</strong> <strong>Technologies</strong> Inc. <strong>an</strong>d their colleagues at <strong>PWN</strong> Water Supply Comp<strong>an</strong>y North-Holl<strong>an</strong>d for<br />
their contribution <strong>in</strong> realiz<strong>in</strong>g this project.<br />
References<br />
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Surface <strong>an</strong>d Aquatic Environmental Photochemistry, Chapter 33, 467-490.<br />
Gunten, U. von, Oliveras, Y. (1997) K<strong>in</strong>etics of the reaction between peroxide <strong>an</strong>d hypobromous acid: Implication<br />
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Science&Technology, 30, 2382-2390.<br />
Stef<strong>an</strong> M., Kruithof J.C., (2005) Adv<strong>an</strong>ced oxidation treatment of herbicides: From bench scale studies to full scale<br />
<strong>in</strong>stallation, proceed<strong>in</strong>gs Third International Congress on Ultraviolet <strong>Technologies</strong>, Whistler, C<strong>an</strong>ada.<br />
© Bram J. Martijn, Peer C. Kamp, Joop C. Kruithof