Oxidative degradation of dimethyl phthalate (DMP) by UV/H(2)O(2) process.

The photochemical degradation of dimethyl phthalate (DMP) in UV/H(2)O(2) advanced oxidation process was studied and a kinetic model based on the elementary reactions involved was developed in this paper. Relatively slow DMP degradation was observed during UV radiation, while DMP was not oxidized by H(2)O(2) alone. In contrast, the combined UV/H(2)O(2) process could effectively degraded DMP, which is attributed to the strong oxidation strength of hydroxyl radical produced. Results show that DMP degradation rate was affected by H(2)O(2) concentration, intensity of UV radiation, initial DMP concentration, and solution pH. A kinetic model without the pseudo-steady state assumption was established according to the generally accepted elementary reactions in UV/H(2)O(2) advanced oxidation process. The rate constant for the reaction between DMP and hydroxyl radical was found to be 4.0 x 10(9) M(-1)s(-1) through fitting the experimental data to this model. The kinetic model could adequately describe the influence of key factors on DMP degradation rate in UV/H(2)O(2) advanced oxidation process, and could serve as a guide in designing treatment systems for DMP removal.

Formation of iodinated trihalomethanes during breakpoint chlorination of iodide-containing water.

This study investigated the formation of toxic iodinated trihalomethanes (I-THMs) during breakpoint chlorination of iodide-containing water. Impact factors including I- concentration, natural organic matter (NOM) concentration and type, pH as well as Br-/I- molar ratio were systematically investigated. Moreover, the incorporation of I- into I-THM formation was also calculated. The results showed that I-THM formation varied in different zones of the breakpoint curves. I-THMs increased with increasing chlorine dosage to breakpoint value and then dropped significantly beyond it. Iodoform (CHI3) and chlorodiiodomethane (CHClI2) were the major I-THMs in the pre-breakpoint zone, while dichloroiodomethane (CHCl2I) was the dominant one in the post-breakpoint zone. The formation of I-THMs increased remarkably with I- and dissolved organic carbon (DOC) concentrations. More bromine-containing species were formed as Br-/I- molar ratio increased from 0.5 to 5. In addition, the major I-THM compound shifted from CHCl2I to the more toxic CHClBrI. As pH increased from 6.0 to 8.0, I-THM formation kept increasing in the pre-breakpoint zone and the speciation of I-THMs changed alongside the breakpoint curves. The incorporation of I- during breakpoint chlorination was highly dependent on chlorine, I-, and NOM concentrations, NOM type, solution pH and Br-/I- molar ratio.

Degradation of acrylamide during chlorination as a precursor of haloacetonitriles and haloacetamides.

Acrylamide is a monomer of polyacrylamide, which is widely used in the water treatment process as a flocculant. The degradation kinetics and formation of disinfection by-products (DBPs) during acrylamide chlorination were investigated in this study. The reaction between chlorine and acrylamide followed a pseudo-first-order kinetics. A kinetic model regarding acrylamide chlorination was established and the rate constants of each predominant elementary reaction (i.e., the base-catalyzed reaction of acrylamide with ClO- as well as the reactions of acrylamide with HOCl and ClO-) were calculated as 7.89×107M-2h-1, 7.72×101M-1h-1, and 1.65×103M-1h-1, respectively. The presence of Br- in water led to the formation of HOBr and accelerated the rate of acrylamide degradation by chlorine. The reaction rate constant of acrylamide with HOBr was calculated as 1.33×103M-1h-1. The degradation pathways of acrylamide chlorination were proposed according to the intermediates identified using ultra-performance liquid chromatography and electrospray ionization-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Five chlorinated DBPs including chloroform (CF), dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), dichloroacetamide (DCAcAm), and trichloroacetamide (TCAcAm) were identified during acrylamide chlorination. The formation of CF, DCAN, DCAcAm, and TCAcAm kept increasing, while that of TCAN increased and then decreased with increasing reaction time. As the chlorine dosage increased from 0.75 to 4.5mM, DCAN became the dominant DBP. Large amounts of CF, DCAN, and TCAN were formed at basic pHs. The hydrolysis of DCAN and TCAN led to the formation of DCAcAm and TCAcAm, respectively. The results of this study elucidated that acrylamide can be a precursor for the formation of haloacetonitriles (HANs) and haloacetamides (HAcAms) during drinking water treatment.

Photochemical degradation of diethyl phthalate with UV/H2O2.

The decomposition of diethyl phthalate (DEP) in water using UV-H2O2 process was investigated in this paper. DEP cannot be effectively removed by UV radiation and H2O2 oxidation alone, while UV-H2O2 combination process proved to be effective and could degrade this compound completely. With initial concentration about 1.0mg/L, more than 98.6% of DEP can be removed at time of 60 min under intensity of UV radiation of 133.9 microW/cm2 and H2O2 dosage of 20mg/L. The effects of applied H2O2 dose, UV radiation intensity, water temperature and initial concentration of DEP on the degradation of DEP have been examined in this study. Degradation mechanisms of DEP with hydroxyl radicals oxidation also have been discussed. Removal rate of DEP was sensitive to the operational parameters. A simple kinetic model is proposed which confirms to pseudo-first order reaction. There is a linear relationship between rate constant k and UV intensity and H2O2 concentration.

Drinking water production by ultrafiltration of Songhuajiang River with PAC adsorption.

In recent years, membrane ultrafiltration (UF) of surface water for drinking water treatment has become a more attractive technology worldwide as a possible alternative treatment to conventional clarification. To evaluate the performance of ultrafiltration membranes for treatment of surface water in North China, a 48-m2 low pressure hollow fiber membrane ultrafiltration pilot plant was constructed. Ultrafiltration was operated in cross-flow and with powdered activated carbon (PAC) adsorption. Turbidity was almost completely removed to less than 0.2 NTU (below Chinese standard 1 NTU). It was found that PAC addition enhanced organic matter removal. The combined process of PAC/UF allowed to 41% removal of COD(Mn), 46% removal of DOC and 57% decrease in UV254 absorbance. The elimination of particles, from average 12000/ml in the raw water to approximately 15/ml in the permeated, was observed. When PAC concentration was below 30 mg/L, backwashing could recovery the membrane flux with backwash interval/backwashing duration of 1/30.

Chlor(am)ination of iopamidol: Kinetics, pathways and disinfection by-products formation.

The degradation kinetics, pathways and disinfection by-products (DBPs) formation of iopamidol by chlorine and chloramines were investigated in this paper. The chlorination kinetics can be well described by a second-order model. The apparent second-order rate constants of iopamidol chlorination significantly increased with solution pH. The rate constants of iopamidol with HOCl and OCl- were calculated as (1.66 ± 0.09) × 10-3 M-1 s-1 and (0.45± 0.02) M-1 s-1, respectively. However, the chloramination of iopamidol fitted well with third-order kinetics and the maximum of the apparent rate constant occurred at pH 7. It was inferred that the free chlorine (i.e., HOCl and OCl-) can react with iopamidol while the combined chlorine species (i.e., NH2Cl and NHCl2) were not reactive with iopamidol. The main intermediates during chlorination or chloramination of iopamidol were identified using ultra performance liquid chromatography - electrospray ionization-mass spectrometry (UPLC-ESI-MS), and the destruction pathways including stepwise deiodination, hydroxylation as well as chlorination were then proposed. The regular and iodinated DBPs formed during chlorination and chloramination of iopamidol were measured. It was found that iodine conversion from iopamidol to toxic iodinated DBPs distinctly increased during chloramination. The results also indicated that although chloramines were much less reactive than chlorine toward iopamidol, they led to the formation of much more toxic iodinated DBPs, especially CHI3.

Degradation of acrylamide by the UV/chlorine advanced oxidation process.

The degradation of acrylamide (AA) during UV/chlorine advanced oxidation process (AOP) was investigated in this study. The degradation of AA was negligible during UV irradiation alone. However, AA could be effectively degraded and mineralized during UV/chlorination due to the generation of hydroxyl radicals (OH). The degradation kinetics of AA during UV/chlorination fitted the pseudo-first order kinetics with the rate constant between AA and OH radicals being determined as 2.11 × 109 M-1 s-1. The degradation rate and mineralization of AA during UV/chlorination were significantly promoted at acidic conditions as well as increasing chlorine dosage. The volatile degradation products of AA during UV/chlorination were identified using gas chromatography-mass spectrometry and the degradation pathways were then proposed accordingly. The formation of disinfection by-products (DBPs) in Milli-Q water and tap water during UV/chlorination of AA was also investigated. The DBPs included chloroform, dichloroacetonitrile, trichloroacetonitrile, 2,2-dichloroacetamide and 2,2,2-trichloroacetamide. Furthermore, the variations of AA degradation during UV/chlorination in different real water samples were evaluated.

Effect of UV irradiation on the proportion of organic chloramines in total chlorine in subsequent chlorination.

This study investigated the changes of chlorine species and proportion of organic chloramines during the chlorination process after UV irradiation pretreatment in drinking water. It was found that the UV pretreatment could enhance the percentage of organic chloramines by increasing free chlorine consumption in the chlorination of raw waters. The percentage of organic chloramines in total chlorine increased with UV intensity and irradiation time in raw waters. However, for the humic acid synthesized water, the percentage of organic chloramines increased first and then decreased with the increase of UV irradiation time. The value of SUVA declined in both raw and humic acid synthesized waters over the UV irradiation time, which indicated that the decomposition of aromatic organic matter by UV could be a contributor to the increase of free chlorine consumption and organic chloramine proportion. The percentage of organic chloramines during chlorination of raw waters after 30-min UV irradiation pretreatment varied from 20.2% to 41.8%. Total chlorine decreased obviously with the increase of nitrate concentration, but the percentage of organic chloramines increased and was linearly correlated to nitrate concentration.

Formation of iodinated trihalomethanes during UV/chloramination with iodate as the iodine source.

Iodinated trihalomethanes (I-THMs) are a group of emerging disinfection by-products with high toxicity, and iodide (I(-)) as well as iodinated organic compounds are expected to be their iodine sources. Nevertheless, in this study, iodate (IO3(-)) was proven to be a new iodine source of I-THM formation during UV/chloramination. In the iodate-containing waters (without any other iodine sources), I-THM formation increased with the increase of UV dose, IO3(-) and NH2Cl concentrations. With the increase of Br(-)/IO3(-) molar ratio, I-THM formation (especially for the brominated species) increased. Besides, NOM species could affect I-THM formation from IO3(-) during UV/chloramination. Fulvic acid could promote IO3(-) phototransformation to I(-) but humic acid impeded the production of I(-) during UV irradiation. Under realistic drinking water treatment conditions (DOC = 5.0 mg-C/L, IO3(-) = 12.7 µg-I/L, UV dose = 50 mJ/cm(2), NH2Cl = 5 mg-Cl2/L), CHCl2I was detected as 0.17 µg/L using solid-phase microextraction method, and the production rate of I-THMs from IO3(-) was about 7% of that from I(-).

Formation of organic chloramines during chlor(am)ination and UV/chlor(am)ination of algae organic matter in drinking water.

Surface water are frequently subjected to problems of algal blooms and release of algae organic matter (AOM) from the algae cells, which cause many water quality issues. This study investigated the formation of organic chloramines and nitrogenous disinfection by-products (N-DBPs) during chlor(am)ination and UV/chlor(am)ination of AOM in drinking water. AOM caused higher organic chloramine formation than humic acid and fulvic acid during chlor(am)ination. The formation of organic chloramines increased first and then decreased with the increase of free chlorine dosage, but kept increasing with the increase of NH2Cl dosage. During AOM chlorination, the formation of organic chloramines kept decreasing as the reaction time went by, and the maximum organic chloramine proportion (79.1%) in total chlorine occurred at 8 h. However, during AOM chloramination, the formation of organic chloramines increased first, decreased in the following and then increased again as the reaction time went by, and the maximum organic chloramine proportion (22.1%) in total chlorine occurred at 24 h. UV irradiation pretreatment did not effectively influence organic chloramine formation during AOM chlor(am)ination, but accelerated the degradation of organic chloramines during chloramination. Besides, UV pretreatment enhanced the formation of N-DBPs during the subsequent chlor(am)ination of AOM, especially dichloroacetonitrile.

[Composition of NOM in raw water of Danjiangkou Reservoir of South-to-North Water Diversion Project and comparison of efficacy of enhanced coagulation].

The best enhanced coagulation conditions for the raw water of Danjiangkou Reservoir of South-to-North Water Diversion Project and the molecular weights as well as hydrophobicity composition of Natural organic matter (NOM) in the water were investigated in this study. The results showed that the NOM in the raw water of Danjiangkou Reservoir of South-to-North Water Diversion Project was mainly composed of the fraction with a molecular weight of < 1 000 and transphilic components. Dissolved organic carbon (DOC, 39.98%) and UV254 (39.10%) were the major components. And the fraction with a molecular weight of < 1 000 had the highest contents of THMFP and N-DBPFP. In the raw water of Danjiangkou Reservoir, the sum of transphilic and hydrophobic fractions was up to 80%, and the hydrophobic fraction was the minimum contributor of the NOM, but the THMFP of the hydrophobic fraction had the highest percentage. And when the raw water of Danjiangkou Reservoir was treated using polymeric ferric sulfate (PFS, 4 mg x L(-1)) and poly-acrylamide (PAM, 0.4 mg x L(-1)) , the optimal removal rates of turbidity, DOC, UV254 and THMFP were 76.33%, 25.57%, 37.78% and 23.16%, respectively. The results of this paper can provide theoretical and technological basis for upgrading of the process and operation optimization of original drinking water treatment plants in the intake area of South-to-North Water Diversion Project.

[Formation of Disinfection By-Products During Chlor(am)ination of Danjiangkou Reservoir Water and Comparison of Disinfection Processes].

This study discussed the formation of volatile carbonaceous disinfection by-products (DBPs) and nitrogenous DBPs during chlor(am) ination of Danjingkou Reservoir water which was the source of the Middle Route Project of South-to-North Water Diversion Project. The effects of disinfection methods, disinfectant dosage, reaction time, pH values and bromide ion concentration were investigated. And the disinfection parameters were optimized. Four DBPs, including chloroform (CF), bromodichloromethane (BDCM), dichloroacetonitrile(DCAN) and trichloronitromethane(TCNM), were observed during the chlorination. But only CF and TCNM were detected during the chloramination of water. The disinfection by-product (DBP) concentration from chlorination is 7. 5 times higher than that from chloramination, and the yield of DBPs from short time chlorination then chloramination is in between the first two methods. All kinds of DBPs detected increased with the dosage of increasing chlorine, but the increases slowed down when the dosage was higher than 2 mg . L -1. The formation of CF varied a little as the dosage of chloramine increasing. TCNM was detected when the chloramine dosage was greater than 2 mg . L -1. As reaction time going on, chlorine decayed much faster than chloramine, while DBP formation under chlorination was faster than that of chloramination. THM produced by chlorine increased with the increasing pH, while chloramination showed no obvious changes. As the bromide ion increasing, the species of DBPs transformed from chlorinated DBPs to brominated ones, and the total yield of DBPs increased during both chlorination and chloramination, but the former one was obviously more than that of the latter one. In order to reduce the risk of DBP formation, the chloramination is suggested in the treatment of water from Danjiangkou Reservoir. And if chlorination is applied, the disinfectant dosage should be controlled seriously.

Comparison of iodinated trihalomethanes formation during aqueous chlor(am)ination of different iodinated X-ray contrast media compounds in the presence of natural organic matter.

Iodinated trihalomethanes (I-THMs) formation during chlorination and chloramination of five iodinated X-ray contrast media (ICM) compounds (iopamidol, iopromide, iodixanol, histodenz, and diatrizoate) in the presence of natural organic matter (NOM) was evaluated and compared. Chlorination and chloramination of ICM in the absence of NOM yielded only a trace amount of I-THMs, while levels of I-THMs were enhanced substantially in raw water samples. With the presence of NOM, the order with respect to the maximum yield of I-THMs observed during chlorination was iopamidol >> histodenz > iodixanol > diatrizoate > iopromide. During chloramination, I-THM formation was enhanced for hisodenz, iodixanol, diatrizoate, and iopromide. The order with respect to the maximum yield of I-THMs observed during chloramination was iopamidol > diatrizoate > iodixanol > histodenz > iopromide. With the exception of iopamidol, I-THM formation was favored at relatively low chlorine doses (≤100 µM) during ICM chlorination, and significant suppression was observed with high chlorine doses applied (＞100 µM). However, during chloramination, increasing monochloramine dose monotonously increased the yield of I-THMs for the five ICM. During chlorination of iodixanol, histodenz, and diatrizoate, the yields of I-THMs exhibited three distinct trends as the pH increased from 5 to 9, while peak I-THM formation was found at circumneutral pH for chloramination. Increasing bromide concentration not only considerably enhanced the yield of I-THMs but also shifted the I-THMs towards bromine-containing ones and increased the formation of higher bromine-incorporated species (e.g., CHBrClI and CHBr2I), especially in chloramination. These results are of particular interest to understand I-THM formation mechanisms during chlorination and chloramination of waters containing ICM.

Degradation kinetics and chloropicrin formation during aqueous chlorination of dinoseb.

The kinetics of chlorination of dinoseb and the corresponding formation of disinfection by-products (DBPs) were studied between pH 4 and 9 at room temperature (25±1°C). The reactivity shows a minimum at pH 9, a maximum at pH 4 and a medium at neutral conditions. pH profile of the apparent second-order rate constant of the reaction of dinoseb with chlorine was modeled considering the elementary reactions of HOCl with dinoseb species and an acid-catalyzed reaction. The predominant reactions at near neutral pH were the reactions of HOCl with the two species of dinoseb. The rate constants of 2.0 (±0.8)×10(4)M(-2)s(-1), 3.3 (±0.6) and 0.5 (±0.1)M(-1)s(-1) were determined for the acid-catalyzed reaction, HOCl reacted with dinoseb and dinoseb(-), respectively. The main degradation by-products of the dinoseb formed during chlorination have been separated and identified by GC-MS with liquid-liquid extraction sample pretreatment. Six volatile and semi-volatile DBPs were identified in the chlorination products, including chloroform (CF), monochloroacetone, chloropicrin (TCNM), 1,1-dichloro-2-methy-butane, 1,2-dichloro-2-methy-butane, 1-chloro-3-methy-pentanone. A proposed degradation pathway of dinoseb during chlorination was then given. TCNM and CF formation potential during chlorination of dinoseb reached as high as 0.077 and 0.097µMµM(-1) dinoseb under the traditional condition (pH=7 and Cl2/C=2). Their yields varied with Cl2/C, pH and time. The maximum yields of TCNM appeared at molar ratio as Cl2/C=1 and pH 3, while the maximum of CF appeared at molar ratio as Cl2/C=4 and pH 7. [TCNM]/[CF] decreased with reaction time and increased solution pH.

Formation of iodinated disinfection by-products during oxidation of iodide-containing water with potassium permanganate.

This study shows that iodinated disinfection by-products (I-DBPs) including iodoform (IF), iodoacetic acid (IAA) and triiodoacetic acid (TIAA) can be produced when iodide-containing waters are in contact with potassium permanganate. IF was found as the major I-DBP species during the oxidation. Iodide was oxidized to HOI, I(2) and I(3)(-), consequently, which led to the formation of iodinated organic compounds. I-DBPs varied with reaction time, solution pH, initial concentrations of iodide and potassium permanganate. Yields of IF, IAA and TIAA increased with reaction time and considerable I-DBPs were formed within 12 h. Peak IF yields were found at circumneutral pH range. However, formation of IAA and TIAA was favored under acidic conditions. Molar ratio of iodide to potassium permanganate showed significant influence on formation of IF, IAA and TIAA. The formation of IF, IAA and TIAA also depended on the characteristics of the waters.

Degradation kinetics and N-Nitrosodimethylamine formation during monochloramination of chlortoluron.

The degradation of chlortoluron by monochloramination was investigated in the pH range of 4-9. The degradation kinetics can be well described by a second-order kinetic model, first-order in monochloramine (NH(2)Cl) and first-order in chlortoluron. NH(2)Cl was found not to be very reactive with chlortoluron, and the apparent rate constants in the studied conditions were 2.5-66.3M(-1)h(-1). The apparent rate constants were determined to be maximum at pH 6, minimum at pH 4 and medium at alkaline conditions. The main disinfection by-products (DBPs) formed after chlortoluron monochloramination were identified by ultra performance liquid chromatography-ESI-MS and GC-electron capture detector. N-Nitrosodimethylamine (NDMA) and 5 volatile chlorination DBPs including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone and trichloronitromethane were identified. The distributions of DBPs formed at different solution pH were quite distinct. Concentrations of NDMA and CF were high at pH 7-9, where NH(2)Cl was the main disinfectant in the solution. NDMA formation during chlortoluron monochloramination with the presence of nitrogenous salts increased in the order of nitrite

[Chlorination byproducts formation potentials of typical nitrogenous organic compounds in water].

Twelve typical nitrogenous organic compounds including herbicides, pesticides, amino acids, industrial products etc in polluted raw water were selected to investigate formation of typical carbonaceous and nitrogenous DBPs during chlorination and chloramination. To indentify the formation mechanism of carbonaceous and nitrogenous disinfection byproducts from nitrogenous chemicals, chlorination and chloroamination of urea herbicides, triazine herbicides, amino acid, and other compounds were investigated. As a result, the potential precursors for different DBPs were defined as well. It has been identified that widely used urea herbicides could produce as many as 9 specific DBPs. The chlorotoluron shows highest reactivity and yields chloroform (CF), monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), 1,1-dichloro-acetone (1,1-DCP), 1,1,1-trichloro-acetone (1,1,1-TCP), chloropicrin (NTCM), dichloro-acetonitrile (DCAN), dimethylnitrosamine (NDMA). The results indicated that aldicarb and dinoseb are important precursors of CF, DCAA, MCAA, NTCM as well. High concentrations of CF and DCAA were found during L-tryptophan chlorination. Furthermore, DBPs formation pathways and mechanisms were suggested during chlorination and chloramination of chlorotoluron, ametryn, dinoseb L-tryptophan.

Chlorination of chlortoluron: kinetics, pathways and chloroform formation.

Chlortoluron chlorination is studied in the pH range of 3-10 at 25 ± 1°C. The chlorination kinetics can be well described by a second-order kinetics model, first-order in chlorine and first-order in chlortoluron. The apparent rate constants were determined and found to be minimum at pH 6, maximum at pH 3 and medium at alkaline conditions. The rate constant of each predominant elementary reactions (i.e., the acid-catalyzed reaction of chlortoluron with HOCl, the reaction of chlortoluron with HOCl and the reaction of chlortoluron with OCl(-)) was calculated as 3.12 (± 0.10)×10(7)M(-2)h(-1), 3.11 (±0.39)×10(2)M(-1)h(-1) and 3.06 (±0.47)×10(3)M(-1)h(-1), respectively. The main chlortoluron chlorination by-products were identified by gas chromatography-mass spectrometry (GC-MS) with purge-and-trap pretreatment, ultra-performance liquid chromatography-electrospray ionization-MS and GC-electron capture detector. Six volatile disinfection by-products were identified including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone, dichloronitromethane and trichloronitromethane. Degradation pathways of chlortoluron chlorination were then proposed. High concentrations of CF were generated during chlortoluron chlorination, with maximum CF yield at circumneutral pH range in solution.

Measurement of dissolved organic nitrogen in a drinking water treatment plant: size fraction, fate, and relation to water quality parameters.

This paper investigates the characteristics of dissolved organic nitrogen (DON) in raw water from the Huangpu River and also in water undergoing treatment in the full-scale Yangshupu drinking water treatment plant (YDWTP) in Shanghai, China. The average DON concentration of the raw water was 0.34 mg/L, which comprised a relatively small portion (~5%) of the mass of total dissolved nitrogen (TDN). The molecular weight (MW) distribution of dissolved organic matter (DOM) was divided into five groups: >30, 10-30, 3-10, 1-3 and <1 kDa using a series of ultrafiltration membranes. Dissolved organic carbon (DOC), UV absorbance at wavelength of 254 nm (UV254) and DON of each MW fraction were analyzed. DON showed a similar fraction distribution as DOC and UV254. The <1 kDa fraction dominated the composition of DON, DOC and UV254 as well as the major N-nitrosodimethylamine formation potential (NDMAFP) in the raw water. However, this DON fraction cannot be effectively removed in the treatment line at the YDWTP including pre-ozonation, clarification and sand filtration processes. The results from linear regression analysis showed that DON is moderately correlated to DOC, UV254 and trihalomethane formation potential (FP), and strongly correlated to haloacetic acids FP and NDMAFP. Therefore, DON could serve as a surrogate parameter to evaluate the reactivity of DOM and disinfection by-products FP.

[Pilot scale study on emergent treatment for As (III) pollution in water source].

Based on the conventional water treatment processes widely used in China, a pilot scale study was performed to investigate emergent treatment for arsenite pollution in water source. The results show that As removal efficiency can only reach to 71.85% by conventional water treatment process. The removal efficiencies of dissolved arsenic and total arsenic by mixing, first flocculation, second flocculation, sedimentation, filtration units were 36.00%, 5.42%, 9.30%, 14.95%, 7.88% and 9.10%, -3.62%, 2.74%, 55.12%, 8.51% respectively, when the concentration of As(III) in raw water was 150 microg/L. The arsenic concentration in treated water can not be effectively controlled below 10 microg/L. Hence, the pre-oxidation is necessary. The pre-chlorination-enhanced coagulation process can effectively deal with the sudden As(III) pollution. But for lower chlorine dosage, both ammonia concentration and different pre-chlorination sites have significant effects on arsenic removal, which should be taken into account. Potassium permanganate pre-oxidation-enhanced coagulation process can be more effectively deal with the sudden As(III) pollution than pre-chlorination. Moreover the different pre-oxidation sites have no obvious effect on arsenic removal. As a result, potassium permanganate is recommended as an oxidant for As(III).