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

Objective Since haloacetic acids (HAAs), which are nonvolatile and of high carcinogenic risk, are common species of chlorinated disinfection by-products(DBPs) in drinking water, and little has been known in China, it is necessary to make a survey about the kinds and levels of HAAs in drinking water of the nation. Method HAAs were analyzed using gas chromatography with electron capture detector(GC/ECD) and relatively complex pretreatment process of sample was applied. Five main cities in different areas of China were chosen in the survey. Results Studies showed that the main species of HAAs in drinking water in China were DCAA and TCAA, ranging from 0.4 礸/L to 12.85 礸/L and from 0.56 礸/L to 10.98 礸/L, respectively. MBAA and DBAA were also detected in one city, ranging from 2.20 礸/L to 4.95 礸/L and 1.10 礸/L to 2.81 礸/L, respectively. Therefore, the contents of HAAs varied, usually no more than 25 礸/L. Based on the acquired data to date, it is known that the concentrations of HAAs in drinking water in China were surely under the limits of Sanitary Standard for Drinking Water Quality (China, 2001). Conclusion A wider survey of HAAs in drinking water should be conducted throughout the nation to get adequate data and information, the ultimate aim of which is to control HAAs pollution and keep the balance between microbiological safety insurance and chemical risk control, minimize the formation of DBPs and ensure the safety of water supply at the same time.

Researches on Formation of Haloacetic Acids in Chlorination of Drinking Water by a Novel Technique

Haloacetic acids(HAAs) are formed during the chlorination of drinking water,which are harmful to people′s health due to their carcinogenic and mutagenic effects. In the present study,a detection method combining methyl tert -butyl ether(MtBE) extraction with acid catalysis and gas chromatography coupled with an electron capture detector(GC/ECD) was developed for determining HAAs. The detection limit of this method(MDL) and relative standard deviation(RSD) were below 0.37 μg/L and 6.2%,respectively. The laboratory chlorination experiments were conducted with the purpose of investigating the influences of reaction time,temperature,UV_ 254 ,bromide and ammonia-nitrogen on the formation of HAAs. The results show that the formation amount of HAAs increases with increasing reaction time and temperature,respectively;and there exists a linear relationship between the formation of HAAs and UV_ 254 . The formation amount of HAAs decreases first and then increases as the bromide ion concentration increases,and adding NH +_4 is a possible way to control the formation of HAAs.

Determination of haloacetic acids in hospital effuent after chlorination by ion chromatography

The ion chromatography combined solid phase extraction （SPE） method was developed for the analysis of low concentration haloacetic acids （HAAs）, a class of disinfection by-products formed from chlorination of hospital wastewater. The monitored HAAs included monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, dibromoacetic acid and trichloroacetic acid. The method employed a sodium hydroxide eluent at a flow rate of 0.8 ml/min, electrolytically generated gradients, and suppressed conductivity detection. To analyze the HAAs in real hospital wastewater samples, C18 pretreatment cartridge was utilized to reduce samples＇ turbidity. Preconcentration with SPE and matrix elimination with treatment cartridges were investigated and found to be able to obtain acceptable detection limits. Linearity, repeatability and detection limits of the above method were evaluated. The detection limits of monobromoacetic acid and dibromoacetic acid were 2.61 μg/L and 1.30 μg/L, respectively, and the other three acids are ranging from 0.48 to 0.82μg/L under 25-fold preconcentration. When the above optimization procedure was applied to three hospital wastewater samples with different treatment processes in Tianjin, it was found that the dichloroacetic acid was the major compound, and the growth ratios of the HAAs after disinfection by sodium hypochlorite were 91.28%, 63.61% and 79.50%, respectively.

Behaviour of Haloacetic Acids in Drinking Water Distribution Systems

To guarantee the safety of drinking water quality after chlorination,the formation,distribution and factors influencing the concentrations of haloacetic acids(HAAs)in a water distribution system(WDS) were investigated both on a full-scale WDS(FWDS) and pilot-scale WDS(PWDS) within a city in northern China.The results of both investigations showed that trichloroacetic acid(TCAA) and dichloroacetic acid(DCAA) were the dominating types of HAAs.In the FWDS,variations in the HAA content showed negative correlations with total residual chlorine,pH and non-purgeable organic carbon(NPOC)and positive correlations with temperature and UV_(254).In the PWDS,the concentration of HAAs after rechlorination followed the rule of 'first rise and then fall';therefore,locating an appropriate rechlorination point and lowering the single chlorine dosage could be used as effective measures to control the HAA content in WDSs.

Evolution and Fate of Haloacetic Acids before and after Chlorination within the Treatment Plant Using SPE-GC-MS

The previous research on the occurrence of disinfection by-products (DBPs) in drinking water has focused on trihalomethane (THMs) formation and evolution, in particular within distribution systems. In this study, the variability of occurrence of haloacetic acids (HAAs) before and after treatment was investigated. The investigation focused on point–to-point fluctuations of HAAs in different treatment stages within the treatment plant. The research was also carried out to find out the possible sources for the presence of HAAs before chlorination in the raw water. The results showed that the presence of HAAs from the raw water point until the filtered water occurred due to industrial waste and sewages. Subsequent formation of HAAs from treated point until service reservoir due to disinfection. The HAAs concentration was the highest and most variable in the plant where level of DBP precursor indicators and the chlorine dose were both higher. However, HAAs level and in particular dichloroacetic acids (DCAA) (the preponderant HAAs species in the waters under study), trichloroacetic acids (TCAA) decreased dramatically during filtration, very probably because of the biodegradation within the filter. An ANNOVA test was used to evaluate the level of significance of HAAs between treated water and service reservoir outlet water.

氯消毒过程中水中色氨酸产生THMs和HAAs的特征研究

以氨基酸为代表的溶解性含氮有机物在水源水中广泛存在,成为制水工艺消毒副产物的主要前体物之一.选取色氨酸(Trp)为含氮前体物模型,考察了其在消毒工艺中产生受控消毒副产物的途径及影响因素.结果表明,Trp氯化过程经取代,脱羧,水解等一系列反应,可生成卤乙酸(HAAs),三卤甲烷(THMs)等消毒副产物.THMs和HAAs的生成量随加氯量增加;随接触时间的延长逐渐增加.温度的升高,HAAs的生成量先增大后减少;碱性条件有利于THMs和HAAs的生成.氯胺消毒和遮光条件下可明显减少THMs和HAAs的产生.

Rapid Determination of HAAs Formation Potential of the Reaction of Humic Acid with Chlorine or Chlorine Dioxide

On the basis of gas chromatography（GC） coupled with a short capillary column and an electron capture detector （ ECD）, a simple and rapid method for the determination of five haloaceric acids （ HAAs ） in drinking water was developed by the optimization of derivation conditions and the modification of gas chromatographic program. HAAs formarion potential（HAAFP） of the reaction of humic acid with chlorine was determined via this method. The major advantages of the method are the simplicity of chromatographic temperature program and the short run time of GC. Dichloroaceric acid（DCAA） and Trichloroacetic acid（TCAA）, which were detected in the determination of HAAFP, were rapidly formed in the first 72 h of the reaction of humic acid with chlorine. HAAFP of the reaction of humic acid with chlorine increased with the increase in the concentrations of humic acid and chlorine. The average HAAFP of the reaction of humic acid with chlorine was 39.9μg/mg TOC under the experimental conditions. When the concentration of humic acid was 4 mg/L, the concentration of HAAs, which were produced in the reaction of humic acid with choline, may exceed MCL of 60μg/L HAAs as the water quality standards for urban water supply of China and the first stage of US EPA disinfecrion/disinfection by-products（D/DBP） rule; when the concentration of humic acid was 2 mg/L, the concentration of HAAs may exceed MCL of 30 μg/L HAAs for the second stage of US EPA D/DBP rule. When humic acid was reacted with chlorine dioxide, only DCAA was detected with a maximum concentration of 3.3 μg/L at a humic acid content of 5 mg/L. It was demonstrated that the substitution of chlorine dioxide for chorine may entirely or partly control the formation of HAAs and effectively reduce the health risk associated with disinfected drinking water.

不同消毒方式供水管网中消毒副产物的分布特征

针对我国东南沿海地区4个使用不同类型二次消毒剂(氯、氯胺、二氧化氯)的局部管网水样的中三卤甲烷(THMs)、卤乙酸(HAAs)、卤乙腈(HANs)的分布特征及影响因素进行了分析。结果表明,3座城市DBPs的超标风险整体较低,采集的117份水样中有10份水样THMs超过国标限值,其余DBPs均符合标准。以氯为消毒剂的管网水样中THMs浓度和HANs浓度远高于其他管网,以二氧化氯为消毒剂可以减少消毒副产物THMs的生成,但以氯胺为消毒剂的上海地区HAAs浓度较高,是其他3个系统的5~19倍,可能与原水中HAAs前体物含量较高有关。在SH-NH_(2)Cl系统中,消毒剂浓度与输配距离成反比(r=-0.57),同时该系统中硝酸盐、亚硝酸盐及氨氮浓度也随距离变化,说明饮用水在管网输送过程中余氯被逐渐消耗,同时管网中发生了硝化反应,氨氮被氧化为亚硝酸盐和硝酸盐。WJ-Cl2系统中DBPs与输配距离相关,HANs浓度沿程减少(r=-0.49),HAAs浓度沿程增加(r=0.45)。此外,建筑管网中长停滞时间也会影响水样理化指标。该研究揭示了不同类型二次消毒剂的管网水中DBPs浓度水平和变化规律,研究结果可为不同地区水质安全评价和风险控制提供依据。

生姜对烘烤猪肉饼品质及杂环胺形成的影响

选取猪肉与生姜为研究对象,探究不同生姜浓度(0.5%、1.0%、1.5%)对烘烤猪肉饼品质及杂环胺(heterocyclic aromatic amines,HAAs)生成的影响。结果表明,生姜能够降低猪肉饼的质量损失率并且改善色泽。生姜对8种HAAs(MeIQ、MeIQx、4,8-DiMeIQx、PhIP、IQx、IQ、AαC、Trp-P-2)均具有很好的抑制效果。浓度为1.5%的生姜对烘烤猪肉饼的总HAAs含量抑制率为55.45%。随着生姜浓度的增加,对游离氨基酸的消耗减少。因此生姜对烘烤猪肉饼中的HAAs有很好的抑制活性。

液相色谱-串联质谱法测定生活饮用水中4种卤代乙酸的含量

提出了液相色谱-串联质谱法测定生活饮用水中二氯乙酸、三氯乙酸、一碘乙酸和二碘乙酸等4种卤代乙酸含量的方法。取0.5 mL过滤后的水样,与0.5 mL乙腈混合。以Torus DEA色谱柱为固定相,以体积比10∶90的含1.0 mmol·L^(-1)乙酸铵的2.0%(体积分数)氨水溶液-乙腈混合液为流动相进行等度洗脱。分离后的4种目标物经电喷雾离子源负离子模式扫描,采用多反应监测模式进行检测,外标法定量。结果显示:4种卤代乙酸的质量浓度在5~100μg·L^(-1)内与定量离子峰面积呈线性关系,检出限(3S/N)为0.3~3.0μg·L^(-1);对自来水水样进行3个浓度水平的加标回收试验,回收率为70.1%~114%,测定值的相对标准偏差为(n=6)为0.90%~5.8%;方法用于10份末梢水分析,其中一碘乙酸、二碘乙酸和三氯乙酸均未检出,有8份样品检出二氯乙酸,检出量为2.0~4.4μg·L^(-1)。

饮用水处理中氯化消毒副产物三卤甲烷和卤代乙酸研究进展

三卤甲烷和卤代乙酸是饮用水氯化消毒的典型副产物。该文结合国内外学者对三卤甲烷和卤代乙酸的研究成果对这两类物质的形成的影响因素、主要检测方法及控制方法进行了总结。

供水管网中AOC、消毒副产物的变化规律

以西南L市的供水管网为研究对象 ,以可同化有机碳 (AOC)、三卤甲烷 (THMs)、卤乙酸 (HAAs)为评价指标 ,研究了不同季节给水管网中水质的变化情况。结果表明 :三卤甲烷在管网中只受余氯的影响 ,其含量一般随管道长度的增加而增加 ;卤乙酸和AOC在管网中的变化受余氯和微生物活性的影响 ,其含量一般随管网延伸而先增加后减少 ,温度越高则下降越快。温度和余氯是管网中控制消毒副产物和AOC浓度的重要因素。

饮用水中卤乙酸和三卤甲烷的形成及影响因素研究

以浙江省钱塘江流域的七种水源水为代表,分析了前体物、pH值、投氯量、氯化时间和温度等因素对氯化消毒副产物(DBPs)中三种卤乙酸(HAAs)和三种三卤甲烷(THMs)的影响.研究表明,总有机碳(TOC)和UV-254与HAAs前体物呈正相关,而与THMs前体物的相关性较差;在pH5-10的范围内,pH值对HAAs的形成影响较小,pH值愈高HAAs总量愈小,而对THMs的形成影响较大,THMs总量随pH值的增高而增大;HAAs和THMs的形成量与投氯量、氯化时间均呈正相关;在正常气温条件下,随温度的增加而增加.

氯胺消毒对消毒副产物的控制研究

采用氯胺消毒与自由氯相比能够降低二氯乙酸和三氯乙酸生成量,氯与氨氮比值降至4∶1,总卤乙酸的生成量可以降低69.1%,三卤甲烷的总量降低了89%,减少了一种消毒副产物———二溴一氯甲烷.氯胺消毒所生成的副产物与氯胺的投加量线性相关性好;氯胺消毒增加接触时间对消毒副产物的生成量影响小,三氯乙酸的生成量4 h后基本稳定,二氯乙酸和三氯甲烷的生成量24 h后基本趋于稳定;升高pH有利于降低氯胺消毒副产物的生成量及副产物的种类,当pH至8时没有检测到一溴二氯甲烷,三卤甲烷的总量也比pH=7时减少82.3%,二氯乙酸和三氯乙酸都降低,二氯乙酸减少程度比三氯乙酸减少的程度略大;采用氯胺消毒能够很好的控制自由氯消毒所产生的溴代消毒副产物.

臭氧活性炭工艺中卤乙酸生成潜能与相对分子质量分布关系的研究

通过臭氧生物活性炭和微曝气生物活性炭（O3／BAC和micro—aeration／BAC）2套工艺研究其对不同相对分子质量有机物去除特点和不同相对分子量有机物生成的卤乙酸及其去除特性．结果表明，O3／BAC工艺对相对分子质量区间〉30×10^3的有机物去除率超过90％，O3／BAC与micro—aeration／BAC出水中，UV254值表示相对分子质量〈10^3的有机物超过50％，相对分子量区间在10×10^3～30×10^3的有机物占20％～30％；在O3／BAC和微曝气／BAC工艺出水中，以相对分子质量〈10^3的有机物生成的卤乙酸最多，生成DCAA、TCAA、DBAA分别为97．00、38．55、2．10μg／L和104．00、42．75和2．92μg／L；采用各处理单元不同分子量有机物与氯反应生成的DCAA、TCAA、DBAA和THAAs与相对应的UV254值进行线性拟合，相关系数分别为0．827、0．8513、0．8157和0．878，UV254与臭氧生物活性炭处理工艺出水中的卤乙酸生成潜能具有较好的线性关系，

氯胺消毒对卤乙酸类消毒副产物的控制研究

对影响氯胺消毒副产物的因子进行了研究,结果表明:降低氯与氨氮的比值能够降低卤乙酸消毒副产物生成总量,当氯与氨氮比降至5:1时,氯胺消毒产生卤乙酸的总量比氯消毒能够减少69.1%;消毒副产物的生成量与氯胺的投加量呈很好的线性关系;延长接触时间对氯胺消毒副产物的生成量影响小;pH升高能够减少卤乙酸类消毒副产物的生成量;升高温度对卤乙酸生成量的影响很小。采用氯胺取代氯消毒能够很好控制卤乙酸类消毒副产物。

安全氯化消毒工艺的消毒副产物控制

在天津市某水厂进行了新型安全氯化消毒工艺———短时游离氯后转氯胺的顺序消毒工艺的中试,结果表明,进水相同时安全氯化消毒工艺比传统的游离氯消毒工艺产生的三卤甲烷减少了35.8%～77.0%,卤乙酸减少了36.6%～54.8%。消毒接触池进水水质越差,短时游离氯后转氯胺的顺序消毒工艺在控制消毒副产物方面就越有优势。试验中还获得了含较高浓度溴离子原水的消毒副产物生成特性。

饮用水中卤乙酸生成的影响因素及检测方法

卤乙酸作为已检出的氯化消毒副产物中最具致癌性的一类物质,在饮用水的研究中得到了越来越多的重视。本文从卤乙酸的生成机理及其影响因素、检测方法入手,对卤乙酸的研究进行了概述,并着重分析了影响卤乙酸生成的各种影响因素以及其检测方法的优化。

天津城市供水系统中卤乙酸含量的研究

考察了天津市城市供水系统中卤乙酸的含量及其变化规律。结果表明,各自来水厂的出厂水及管网水中的二氯乙酸和三氯乙酸含量均远远低于《生活饮用水卫生标准》(GB5749—2006)规定的限值;自原水进入自来水厂至最终到达用户自来水龙头的整个过程,水中的二氯乙酸和三氯乙酸含量呈快速上升—保持平稳—快速下降的变化趋势,其中滤后水中的卤乙酸含量最接近或达到峰值;采用预氯化工艺会促进卤乙酸的生成,水温与卤乙酸的生成呈正相关。

常规工艺中消毒副产物季节变化研究

对某给水厂进行了一个水文年的月度监测,重点分析了各工艺段出水的三卤甲烷和卤乙酸浓度变化。结果表明,对消毒副产物控制起关键作用的工艺是预氯化(混凝)、过滤和消毒。预氯化工艺是一个很大的健康隐患,必须严格控制。在过滤工艺中同时存在消毒副产物的生成和去除两种作用,对三卤甲烷的去除率明显较高,而卤乙酸在过滤前后变化不大。在清水池消毒过程中游离氯会与消毒副产物前体物继续反应生成消毒副产物。