Occurrence of Haloacetic Acids in Drinking Water in Certain Cities of China

BIOMEDICAL AND ENVIRONMENTAL SCIENCES 17, 299-308 (2004)Occurrence of Haloacetic Acids in Drinking Waterin Certain Cities of ChinaHONG ZHOU , XIAO-JIAN ZHANG", AND ZHAN-SHENG WANG#*Institute of Civil Engineering, Guangzhou Universit, Guangzhou 510405, Guangdong, China;“Departmentof Environmental Science and Engineering, Tsinghua Universiry, Beijing 100084, Chinaare common species of chlorinated disinfection by- products(DBPs) in drinking water, and litle hasbeen known in China, it is necessary to make a survey about the kinds and levels of HAAs in drinkingwater of the nation. Method HAAs were analyzed using gas chromatography with electroncapture detector(GC/ECD) and relatively complex pretreatment process of sample was applied. Fivemain cities in different areas of China were chosen in the survey. Results Studies showed that themain species of HAAs in drinking water in China were DCAA and TCAA, ranging from 0.4 μg/L to12.85 ug/L and from 0.56 ug/L to 10.98 ug/L, respectively. MBAA and DBAA were also detected inone city, ranging from 2.20 ug/L to 4.95 ug/L and 1.10 ug/L to 2.81 ug/L, respectively. Therefore, thecontents of HAAs varied, usually no more than 25 ug/L. Based on the acquired data to date, it isknown that the concentrations of HAAs in drinking water in China we re surely under the limits ofSanitary Standard for Drinking Water Quality (China, 2001). Conclusion A wider survey ofHAAS in drinking water should be conducted throughout the nation to get adequate data andinformation, the ultimate aim of which is to control HAAs pollution and keep the balance betweenmicrobiological safety insurance and chemical risk control, minimize the formation of DBPs andensure the safety of water supply at the same time.Key words: Haloacetic acids (HAAs); Disinfection; Drinking water; Waterworks; Disinfectionby-products (DBPs)INTRODUCTIONDisinfection by chlorine or other chlorine-related reagents is common in water treatmentprocess, though it has been found that haloacetic acids (HAAs), which were firstly found asa nonvolatile and high carcinogenic risk chemical in the middle of 1980s, are a main kind ofchlorinated disinfection by-products besides trihalomethane (THMs)l-. Among them,monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA),monobromoacetic acid (MBAA) and dibromoacetic acid (DBAA) are the most commonones detected in drinking water. Usually, they are not biosynthetic and come from reactionsbetween chlorine and natural organic materials (NOM), such as fulvic acid and humic acid,or some species of fatty organicsAbbreviations: HAAS, haloacetic acids; MCAA, monochloroacetic acid; DCAA, dichlorocetic acid; TCAAtrichloroacetic acid; MBAA, monobromoacetie acid; DBAA, dibromoacetic acid; NOM, natural organic materials;Biographical note of first author: Hong ZHOU, female, born in 1971, lecturer, Doctor graduated fromEnvironmental Science and Engineering Dept, Tsinghua University. maioring in drinking water quality andmicropolluted source water treatment. Tel: 86- 10-62781779(O中国煤化工rg.cnYHCNMHG .CN 11-2816Copyright 02004 by China CDC299300ZHOU, ZHANG, AND WANGOn the other hand, DCAA is a metabolic product of many chlorides， such aschloromycetin and hydrochloroaldehyde. There are toxicological tests showing that DCAAmay increase occurrence rates of liver cancer in mice or rats. DCAA is also clinically usefulin curing some kinds of metabolic diseases or diseases of heart and blood vessel, whosepharmacological effect has been carefully studied!91.Several kinds of HAAs are genotoxic and have been identified as rodent hepatocarcinogens.It has been testified that MCAA, DCAA, TCAA, MBAA and DBAA were toxic to rat cecalmicrobiota, especially to enterococcilo. As to their possible toxicity in the body of humanbeings, a lot should be done to make decisions.In the newly printed Sanitary Standard for Drinking Water Quality (issued byMinistry of Public Health, China, 2001), for the first time, the upper limits of DCAA andTCAA are suggested to be 50 ug/L and 100 ug/L, respectively. Though they are not routineitems required at present, such problem is being paid increasing attention. Because Ministryof Public Health in China is responsible for monitoring and supervising drinking waterquality, this standard is truly applicable and practical in drinking water quality management.Researches concerning DBPs in China are mostly about THMsl12- 141 and not much hasbeen known about HAAs in drinking water except some studies in 1998. DCAA and TCAAwere detected and concentration of HAAs in finished water and distribution water weremostly below or around 10 ug/LOther countries have done much more work about HAAS and the first step of researchusually is undertaking surveys. For example, in Canadian finished water and distributionwater, the concentrations of MCAA were 0.3-9.7 ug/L, DCAA 0.2-163.3 μg/L， TCAA0.04-473.1 ug/L, MBAA<0.01-9.2 μg/L and DBAA <0.01-1.9 μg/L. MCAA, DCAA andTCAA were detected in all samples and the occurrence rate of MBAA and DBAA were31 % and 62%. Surveys in Australia showed that MCAA, DCAA and TCAA were found inboth finished water and distribution water and the concentration of MCAA varied from 10 ug/Lto 244 ug/L, DCAA 1-46 ug/L and TCAA<0.02-14 μg/LI6]. It seemed that MCAA inAustralia was much higher than DCAA and TCAA.Content ranges of HAAS in distribution system were reported to be 0.1-222 μg/L in1991 and 0.2-223 μg/L in 1992 in USA17. The latest survey of disinfection and DBPs inwater supply system of different sizes (large, medium and small) in USA provided theconcentration ranges of five main kinds of HAAs: MCAA 1.8-4.0 ug/L, DCAA 11-51 ug/L,TCAA 8-53 ug/L, MBAA 0-1.2 ug/L and DBAA 0.5-1.4 ug/L, respectively18.19). Therewere more HAAS in distribution system than in finished water in general (with someexceptions). It was clear that DCAA and TCAA were dominant species in drinking water ofUSA.Thus, initial investigations were carried out from 1999 to 2003 in China. Five maincities were chosen as sampling sites, and the kinds and distribution of HAAS in drinkingwater in different areas of China were presented here.METHODSHAAs were analyzed using gas chromatography with electron capture detector (GC/ECD)and the pretreatment was relatively complex. For the limits of eauipments and pretreatmentprocess, only a few cities were selected in the surv中国煤化工PA StandardMethod 522, a method with minor changes was usYH. CN MH Gg procedurewas altered according to actual tests and acidic me..心wuing agent thatwas safe and effective. The details were as follows.HALOACETIC ACIDS IN DRINKING WATER301Standards and ChemicalsFive single HAAs standards were used to make mixed standard solution of 100 ug/L.Thereinto, chloroacetic acid, dichloroacetic acid and trichloroacetic acid were from SigmaAldrich, USA. Bromoacetic acid and dibromoacetic acid were produced by Supelco USA.Their purity was all above 97.3%. Reagent-grade H2SO4 and Na2SO4， tert- butyl-methyllaether (METB) (for HPLC, product of Fluka, US), methanol (for GC, product ofTianjin Si You) and 1,2-dibromopropane (for GC, product of Fluka, US) were also used.Samples CollectionsWater samples were collected in glass bottles and bottles must be filled with water. Ifthere was chlorine residual in the sample, certain amount of Na2S2O3 solution should beadded in the bottle to consume it before sampling in order to stop the reaction betweenchlorine and the organic substances in water. As experiments were carried out in differentcities for about three years, specific sampling time and places would be pointed outseparately when results and discussions were given.Samples PreparationsSince HAAs were of high boiling points (187 C-210*C), pretreatment was neededbefore analysis by GC/MS. Extraction reagent was tert-butyl -methyllaether (METB) andinternal standard was 1,2-dibromopropane. After HAAs turned into methyl acetate (whoseboiling points were lower, between 129C-185 C), they could be analyzed. Fig. 1 showed theprocedure of water sample preparations clearly.Sampling water 25 mL1.5 mL HSO,2mL METB(containing intermnal standard)12g Na.SO% .Surge and extract for 3 mins(baked for 4 hours under 550C)Take 1 mL of upper METB layer2 mL methanol (H,SO, added)50"C water bath for 1h1 mL METB5mL 10% NaSO, (solution)Surge and extract for 2 minsake upper aether layer 1 mLinto 40 mL extration bottle中国煤化工GC-ECDMHCNMHGFIG. 1. Procedure of water samples preparations.ZHOU, ZHANG, AND WANGGas ChromatographyGC-ECD analysis was done with a Shimadzu GC-17A with the CLASS GC10workstation. J&W DB-1 or HP-5 capillary column (25 mx0.2 mmx0.33 um) was used indifferent labs. Maximum volume of sample injector was 5 μL and it was airtight to ensureaccuracy. Injector temperature was at 220C, detector temperature was at 300C. Oventemperature raising procedure was as follows, controlled by CLASS-GC10 Workstation.40'C- Smin + 40C .10Cmiy 135C- 20C/miy 240'G- 3min+ 240CHigh pure nitrogen ( 3 299.99) was used as carrying gas and its chapiter pressure was65.0 kPa (controlled by electronic pressure-controlling system). Velocity of N2 was 16.8 cm/s.Injection volume was 1 μL and sampling time was 0.5 min. Flow of tailing gas was 40 mL/min.Qualitative and Quantitative AnalysisQuality of five HAAs was determined by matching the retention time with standardsand quantitative analysis was realized by standard curves, which were obtained by a seriesstandard solutions (11 points, from 0 ug/L to 100 ug/L). Every kind of HAAs had its ownstandard curve and all the regressive coefficients were above 0.99. For l,2-dibromopropanewas used as internal standard, precision of this method was assured to some extent. FromFig. 2, it could be seen that there was no interference peak in actual water samples, fordrinking water was rather clean or pure and there was hardly interfering peak nearby.DaTxA12.D01Method:LYS. METCh=1Chrom:A12C01Buck chroon:RT:743 Level: 336 Aten:23FIG. 2. GC of HAAS and intermal standard in an actual sample when DB- 1 column was used.Method ValidatingWhen DB-1 column was used, 20 ug/L stan中国煤化工in 15 watersamples, and each sample was taken for double ana:YHCNMH(As were gotand are listed in Tablel. The lowest detection limithy followingformula:HALOACETIC ACIDS IN DRINKING WATERLDLs=3*Sp/SWhere S denotes absolute difference, and S is the slope of standard curve. Namely,LDLs equals to noise 3. When HP-5 column was used, 5 μg/L standard reagents was addedin 25 water samples and each sample was taken for double analysis, average recoveries andLDLs of five HAAs were calculated and results were listed also in Table 1. Recoveries wereall in the range of EPA regulations and the lowest detection limits (except MCAA) weremuch higher than possible content of HAAs in actual water. Therefore, the method waspractical in drinking water analysis for HAAs.TABLE1Average Recoveries and LDLs of Five HAAsColumnMCAAMBAADCAATCAADBAARecoveriesDB-191.0091.1596.6894.69(%)HP-5123.5797.4685.04.91.53111.97LDLsDB- 10.2410.1010.1190. 105(4g/L)0.2790.0800.0200.030RESULTSW ater samples from five cities in different area of China were collected and analyzedfrom 1999 to 2003. Kinds of source water were investigated, such as water from river orreservoir. In the waterworks, the treatment process consisted of coagulation, sedimentation,sand or anthracite filtration and chlorination. Chlorine was used in pre-oxidation process anddisinfection in water facilities was liquid chlorine or chlorine -ammonia. During chlorine-ammonia disinfection, the Cl2-to-N ratio was 3: 1-4:1. Residual chlorine in finished waterusually varied from 0.8-1.2 mg/L (total chlorine), no more than 1 .5 mg/L.City H in Southeast ChinaQ river is the main source water of city H and the other is T stream, which is a smallstream in the northwest of H and feeds to waterworks E as a water source. The other fourwaterworks are all depending on Q river. Samples from different water facilities and onedistribution system were collcted in April 2002, July 2002 and February 2003, held inportable icebox and taken to Beijing, then pretreated in the Environmental Sciences andEngineering Department of Tsinghua University.Liquid hlorine and ammonia are both added before coagulation tank together withaluminum sulfate as flocculant. Results showed DCAA and TCAA were both detected infinished water and distribution system water and their concentrations were not high.TABLE2Concentrations of HAAs in Finished Water From Five Waterworks (μg/L)SeasonsADESpring4.845.65中国煤化工5.43 .Summer3.395.14TYHCNMHG 5.16Winter3.41ZHOU, ZHANG, AND WANGFrom Table 2, it could be seen that the concentration of HAAs in drinking water herewas in the range of 3.3-6.4 ug/L. During sampling period, TOC of source water wasbetween 4-5.5 mg/L.Fig. 3 shows concentrations of HAAs (DCAA and TCAA) changing in distributionsystem of waterworks A in summer. It is clear that at the end of the net which is 3.2 km farfrom the waterworks, it reached its highest content, increased by 50%. This was becauseresidual chlorine continued to react with organic matters in the water along the pipeline andthe concentration of HAAs continuously increased.C+DCAA--TCAAHAAS .Pipelinee length (ilometre,km)FIG. 3. Concentrations of HAAs in distribution system of city H.City D and City M in the Southwes1 AreaPeople of city D is living on surface water. The area is rich in water. There are severalwater treatment facilities and drinking water from the Sixth waterworks was carefullystudied from October 1999 to November 2000. HAAs analysis system was established inWater Quality Section of Drinking Water Company in city D and then water samples couldbe prepared and analyzed as soon as they were taken. During this period, TOC was about 2mg/LChlorine was adopted as a disinfectant during the experimental period and there weretwo chlorine- adding points, namely before sedimentation and before entering clear watertank. No HAAs existed in source water and two species of HAAs were detected in finishedwater and distribution water. It proved again that DCAA and TCAA were two main kinds ofHAAs in drinking water in China. The concentration of HAAs in finished water varied from1.64 ug/L (in winter) to 12.85 ug/L (in summer).Because in winter and summer, the dose of residual chlorine did not vary much, it couldbe concluded that increasing organic matters in source water and higher temperature isummer had obvious effects on formation of HAAs.-SpringI - - Spring 2- - Summer- *-Autumn-Winter663t中国煤化工ASampling placesfYHCNMHGFIG. 4. Change of DCAA in distribution system of city D.HALOACETIC ACIDS IN DRINKING WATER0515.00一Spring 1+ Spring2 -★- -Sumner12.00→- Autunn - + - Winter9.006.003.000.00BSampling placsPIG. 5. Change of TCAA in distribution system of city D.It could be known from Figs. 3 and 4 that the contents of DCAA and TCAA indistribution system were increasing after water left the waterworks. The highest value ofDCAA occurred at place B, which was the changing point of net, 5 km away from the :facility. Similar to DCAA, the concentration of TCAA rose with the length of pipeline firstly.At the entrance of city, namely place C which is 27 km far and starting from it there is civilnet, TCAA was up to its highest value, about 1.5-2.6 times of the finished water. Then thecontent of TCAA changed a little or just the same. Similar phenomena were present insmaller distribution systems of city H, at the end of the system the highest content of HAASoccured.Because the sixth waterworks is in the suburb, far from the city zone, retention time ofclear water tank is not long. Before water left the facility, reaction between disinfectant andorganic substances were not complete. During the transferring process, the reactioncontinued. Thus, with the time passing by, DCAA and TCAA reached their highestconcentrations far from the facility. Conclusion can be drawn that finished water is notdefinitely the supervising point of HAAs, for in distribution system, reaction is continuing.There is another fact worth attention. Along the conventional water treatment processesHAAs were not removed. It appears that once HAAs are formed, it is difficult to get rid ofthem from the drinking water. Such situation warns of removing precursors of disinfctionby-products (DBPs) before DBPs coming into being.City M is more southern than city D, in another beautiful and fancy province. Watersamples from there were collected in July 2002, kept in portable icebox and brought toBeijing. In the lab of Tsinghua University, pretreatment was done as soon as samplesreached. Except 1# sample was finished water, the others were all distribution water samples.TABLE3Results of HAAs Content in Water of City M (μg/L)Sample Number245MBAA2.204.54ND2.314.95DCAAND*2.641.091.42TCAA .4.572.269614.00DBAA1.171.10中国煤化工2.81HAAS7.9410.54MHCNMHG13.18Note.' "ND=not dected.306ZHOU, ZHANG, AND WANGIt is the first time that brominated HAAs were detected since the beginning of theresearch in China. The content of MBAA was up to nearly 5 μg/L and DBAA 2.8 ug/L. Atthe same time, DCAA and TCAA were in the range of 0.4-11 ug/L.City P and City T in North ChinaSurvey in city P was conducted in 2002. Raw water was from reservior M and there wasno prechlorination. Only DCAA and TCAA were found in the finished water, the content ofHAAs ranging from 4 ug/L to 10 ug/L. Trihalomethane, another kind of DBPs was detectedalso and whose level in finished water varied from 15 ug/L to 30 ug/L, higher than HAAs.Nevertheless, as HAAS possess higher carcinogenic riskl20), problem of HAAs is worthwhilemuch more attention.City T is near city P, but its source water is from a river. Three main waterworks werechosen as objects and samples were collected from January to March in 2003. There is aprechlorination process. Experimental data showed that in finished water, the concentrationof HAAs was between 5.4 ug/L and 14.1 μg/L. Here there were obviously more TCAA thanDCAA, about 65% -75% of total HAAs. No distinct difference was found between the threechosen water facilities. Compared with the other facilities mentioned above, the levels ofHAAs in drinking water in city T were a bit higher than those in city P and city H.0r口Jan.15 ta Feb.OMar.Waterworks J Waterworks X Waterworks LFIG. 6. Contents of HAAs in finished water from three waterworks in city T.DISCUSSIONSBased on the data acquired in China so far, the content of DCAA was from 1.58 μg/L to6.31 ug/L in finished water and from 0.4 ug/L to 12.85 ug/L in distribution water, and thecontent of TCAA was 0.56 μg/L to 6.89 ug/L in finished water and 1.26-10.98 ug/L indistribution water. MBAA and DBAA were also found in the drinking water, though not ascommon as DCAA and TCAA. Their concentrations were 2.20-4.95 ug/L and 1.10-2.81 ug/L,respectively. The concentrations of HAAs ranged from 3.39 ug/L to 12.30 ug/L in finishedwater and from 3.68 μg/L to 23.09 μg/L in distribution water.It is noticeable that raw water of city M is surface water with large catchment areawhere there are abundant vegetations and the sampling happened to take place in summerwhen rich nutrients were likely to enter water and中国煤化工f water wasrelatively high. So natural bromide level here mayYHCNMHG places andafter chlorine was added, bromide was oxidized to/drolysed tohypobromous acid. Such kind of acid would react with organic matters in the water and thenHALOACETIC ACIDS IN DRINKING WATERform MBAA and DBAA. Since MBAA in the water is more than DBAA, it could besupposed that the concentration of Br is not very high in the raw water. Because of the longdistance between sampling places and lab, it is inconvenient to take more samples fofurther study. If there is other chances, the content of Br should be measured, its specificorigin should be looked for and its effect on HAAs formation should be studied carefully.It could be found that the highest concentrations of DCAA and TCAA occurred irCanadal", 10-60 times higher than those in China and 4-39 times than those in Australial16].But in Australia, there existed a higher content of MCAA in drinking waterl6l. Situation ofUSA indicated that its concentration of HAAS was lower than that in Canada but higher thanthat in Australia and ChinalDifferent kinds of disinfectants, distinct dose of disinfectants or different kinds oforganic materials and pollutants (which may act as precursors of DBPs) in source water arell possible causes for these results in different countries. For example, in USA, total chlorinemight be up to 6.5 mg/L and median value was 2.4 mg/L, and free chlorine maximumconcentration 4.4 mg/L and mean 1.1 mg/L819, much higher than those in China. Becausethere is no enough chlorine, not many reactions between chlorine and organic chemicalshappen, and so less HAAs form.Higher content of HAAS usually happens during single chlorine disinfection. Survey offive cities in different areas of China could also be proof of this phenomenon. Wherechlorine-ammonia disinfection is used (for example, City H), there are relatively lowerlevels of HAAS. It has been testified that chloramine process could obviously decrease theformation of DBPs and higher Cl2-to-N ratios might increase the content of chlorinatedDBPt21.221.On the other hand, where the source water is not river changing with seasons, such as incity H, the contents of HAAs are only a bit affected by seasons. There is different situationwhere river changes with season. For example, in city D HAAs content in summer wasnearly 8 times higher than that in winter. Because in summer, a lot of humic substances maypossibly enter the water body from upstream mountainous areas. So it could be determinedthat the quality of source water is the key factor for HAAs formation.CONCLUSIONSFrom the above results and discussion, it can be concluded that DCAA and TCAA arethe main kinds of HAAs in drinking water of China, though their concentrations are muchlower than those in Canada or Australia. MBAA and DBAA have also been found in thedrinking water, not as common as DCAA and TCAA. Concentrations of HAAs are usually1o more than 25 μg/L in drinking water of China and are certainly under the limits o1Sanitary Standard for Drinking Water Quality in China according to the data obtained.Nevertheless, further information is needed to draw final conclusions about HAAspollution situation because China covers so large an area and regional diversities areimaginable. V arying synthetic pollutants and NOM in different source waters should beconsidered and studied carefully because they are possible precursors of DBPs. A widersurvey of HAAs in drinking water should be conducted in the nation. Keeping the balancebetween microbiological and chemical safety is important in water treatment process tominimize the formation of DBPs and at the same t中国煤化工ter supply3'.It is a stringent challenge for engineers and scient:fHCNMH Ged on waterquality.308ZHOU, ZHANG, AND WANGACKNOWI EDGEMENTSThe authors would like to thank the waterworks personnel for help in sample collecting,sample carrying and experimental site supplying. In addition, the authors also extend theirthanks to Water Corporations for their fund assistance and sincere cooperation cparticipation in city P, city H, city D, and cityT.REFERENCES1. David, T, Williams, Guy, L., Lebel, and Frank, M,. Benoit (1997). Disinfection by-products in Canadiandrinking water. Chemosphere 34(2), 299-316.2. Haas, Charles, N. (1999). Benefits of using a disinfectant residual. Joumal/American Water Works Association91(1), 65-69.3. Haas, Charles, N. (2000). 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