Disinfection By-Products in Water Produced by Ozonation and Chlorination

Water produced by advanced treatment of a groundwater was evaluated to determine the amount of DBPs (Disinfection By-Products) including trihalomethanes (THMs). Both Gas Chromatography (GC) and Gas Chromatography/Mass Spectrometry (GS/MS) were adopted for detection and identification of DBPs such as trihalomethanes (THMs), halo-acetic acids (HAAs) and aldehydes. Two disinfection modes (ozonation followed by chlorination and chlorination alone) were compared to determine the DBPs generation. The mutagenitic acivity of ozonated water, chlorinated water after ozonation and potable water was assessed using the Ames test. Chloroform, dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were the main constituents of THMs and HAAs, respectively. THMs accounted for more than 85% of all DBPs measured, whereas haloacetic acids accounted for around 14%. Ozonation followed by chlorination proved to be better in terms of THMs and HAAs control. The combined system produced 28.3% less DBPs compared to chlorination alone. Ozonation was found capable of reducing mutagenic matter in the groundwater by 54.7%. The combined system also resulted in water with no mutagenicity.     

Fe~(3+)和Cu~(2+)对饮用水氯消毒副产物三卤甲烷形成的影响

为了研究水中存在Br-的情况下,Fe3+和Cu2+对三卤甲烷(THMs)的生成及CHCl3、CHBr Cl2、CHBr2Cl、CHBr34种消毒副产物相对分布的影响,以腐殖酸模拟氯消毒过程中的前体物进行实验。结果表明,在p H为6、7和9 3种条件下,Fe3+抑制了THMs的生成,p H=6时只有CHCl3生成量随着Fe3+浓度的增加逐渐减少,其余3种消毒副产物均在增加,p H=7时4种消毒副产物浓度均减小并在Fe3+浓度为2 mg/L时生成量最低,p H=9时的生成趋势与p H=6时类似。Cu2+能促进THMs的生成,在p H为6、7和9时,当加入0.5 mg/L Cu2+时,THMs总量分别增加了16.7%、22.6%和2.5%,随着p H增加,THMs总量增加。在3种p H环境中,Cu2+对THMs生成的影响大于Fe3+,在偏酸性环境中,Fe3+影响THMs生成,产生的致癌风险高,当金属离子浓度为2.5 mg/L时,致癌风险相差最高为15%,在中性和偏碱性环境中,Cu2+影响THMs生成,产生的致癌风险高。     

两点短时游离氯后转氯胺的顺序氯化消毒工艺研究

基于顺序氯化消毒工艺的原理,采用两点短时游离氯后转氯胺的两点顺序氯化消毒工艺,即在过滤和清水池前的两点分别加氯,并在清水池加氯后立即加氨转化为氯胺消毒的工艺,该工艺在常规处理工艺的给水厂进行了消毒试验.结果表明,加氯点的适当提前,不仅有利于控制消毒副产物的生成量,而且有效抑制了滤池中的生物膜滋生.两点顺序氯化消毒工艺中生成的卤代消毒副产物比相同条件下一次性加入等量的氯消毒剂的消毒方法产生的三卤甲烷(THMs)平均减少了51.6％,卤乙酸(HAAs)平均减少了46.7％.细菌学指标HPC的结果也显示出了该工艺在保障水质的微生物安全方面的优势.     

溶解性有机氮乙酰胺氯化生成饮用水THMs的影响因素研究

氯化消毒可以有效杀灭细菌,但同时会产生危害人体健康的消毒副产物(DBPs).溶解性有机氮(DON)是DBPs的重要前体物,为考察DON对THMs的影响,首次选取乙酰胺(AcAm)作为前体物DON的代表物质,采用Plackett-Burman和Box-Behnken方法设计试验,考察了AcAm初始浓度、加氯量、pH、温度、溴离子浓度和反应时间等因素对三卤甲烷(THMs)生成的影响.结果表明,在AcAm生成THMs的过程中,AcAm初始浓度、pH和反应温度3个因素的影响程度较小,溴离子、有效氯和反应时间3因素的影响较大,其中溴离子的影响最为显著.溴离子浓度一定时,改变有效氯的含量,生成的THMs总量变化不大,溴离子对THMs的生成有一定的催化作用,控制溴离子的浓度是减少AcAm生成THMs的有效措施.在有效氯为8.77 mg/Ｌ、溴离子为0.77 mg/Ｌ及接触时间为6.20 h的条件下,THMs存在最大生成量为45.82 μg/L.随着反应时间的推移,溴分配系数n呈上升趋势,控制消毒反应时间,是减少THMs致癌风险的有效方法.同时探讨了AcAm生成THMs的反应路径,表述了溴离子的催化作用机制.     

哈尔滨土壤提取液中的卤代前驱物

通过连续过滤方法和实验室氯化，臭氧化实验研究了哈尔滨地区土壤提取液中天然有机物的卤代活性以及不同的形态天然有机物的差异，比较了氯化和臭氧化条件下的卤代烃生成量及处理后的7日卤代潜力，研究结果表明，在数分钟的氯化实验中，憎水有机物，腐殖酸类化合物和非腐殖酸类亲水有机物的单位有机碳卤代烃生成量分别为1.46,0.35和4.03μg/mg(C），而7日卤代潜力则分别为6.6,57.2和40.6μg/mg(C)，可见其差别不仅表现在热力学文献，而且反应在反应速率方面，在本实验条件下，臭氧化能够降低大约水样的一半卤代潜力。     

3种典型消毒副产物对细菌抗生素抗性的影响

本文研究了消毒副产物对细菌抗生素抗性的作用.分别选取三卤甲烷类(THMs)、卤乙酸类(HAAs)以及醛类消毒副产物中典型物质一氯二溴甲烷(CDBM)、碘乙酸(IAA)和水合三氯乙醛(CH),研究了细菌经消毒副产物染毒之后,对多种抗生素的抗性变化情况.结果发现,3种消毒副产物均可以诱导野生型铜绿假单胞菌提高对5种受试抗生素的抗性,提高作用IAACHCDBM.IAA对多重抗性也具有一定的提高作用.野生型大肠杆菌的抗生素抗性同样能够被DBPs诱导提高,说明DBPs对抗性的影响具有普遍性.其作用机制可能是DBPs通过氧化胁迫机制诱导细菌发生突变,进而提高细菌抗生素抗性.本研究表明饮用水系统中部分细菌抗生素抗性的获得可能与消毒副产物有关;除毒理学风险外,消毒副产物的流行病学风险同样不容忽视.     

Effects of copper(II) and copper oxides on THMs formation in copper pipe

Little is known about how the growth of trihalomethanes (THMs) in drinking water is affected in copper pipe. The formation of THMs and chlorine consumption in copper pipe under stagnant flow conditions were investigated. Experiments for the same water held in glass bottles were performed for comparison. Results showed that although THMs levels firstly increased in the presence of chlorine in copper pipe, faster decay of chlorine as compared to the glass bottle affected the rate of THMs formation. The analysis of water phase was supplemented by surface analysis of corrosion scales using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX). The results showed the scales on the pipe surface mainly consisted of Cu₂O, CuO and Cu(OH)₂ or CuCO₃. Designed experiments confirmed that the fast depletion of chlorine in copper pipe was mainly due to effect of Cu₂O, CuO in corrosion scales on copper pipe. Although copper(II) and copper oxides showed effect on THMs formation, the rapid consumption of chlorine due to copper oxide made THM levels lower than that in glass bottles after 4 h. The transformations of CF, DCBM and CDBM to BF were accelerated in the presence of copper(II), cupric oxide and cuprous oxide. The effect of pH on THMs formation was influenced by effect of pH on corrosion of copper pipe. When pH was below 7, THMs levels in copper pipe was higher as compared to glass bottle, but lower when pH was above 7.     

Modeling the Formation of Chlorination By-Products During Enhanced Coagulation

Because of increasing need to balance health risks for pathogen control and disinfection by-products (DBP) formation in drinking water supplies, water utilities are forced to closely examine and optimize their disinfection practices. This research was designed to investigate the effects of independent variables of dissolved organic carbon (DOC), ferric chloride dosage, chlorine dose, and reaction time on trihalomethanes (THMs) formation in Terkos Lake Water (TLW) of Istanbul City. A statistically-based empirical model was developed for predicting THM formation during enhanced coagulation. The R ² and F value of model were 0.762 and 460, respectively. The model was found to be statistically significant for all four variables, and model predictions appear to be most accurate for this study. A multiple linear model exhibited the best fit of data. It was observed that THM formation depended primarily on DOC removal. Model calibration, testing and validation were accomplished by using independent data set.     

臭氧-生物活性炭对南方河网典型污染物的去除特性

以我国南方河网原水中有机物和季节性溴化物(Br^-)为对象,研究臭氧-生物活性炭(BAC)工艺净化过程中有机物相对分子质量(M_r)分布变化及溴酸盐(BrO^-₃)和消毒副产物(THMs)的形成规律.结果表明,原水中M_r在10³以下的有机物(DOC)约占总量的80%,常规工艺主要表现为对M_r >100×10³有机物的去除,出水DOC去除率为8%、 SUVA(UV₂₅₄/DOC)值下降14%;臭氧-活性炭工艺主要去除10³<M_r<5×10³的有机物,但亲水性小分子有机物抑制生物降解作用,出水DOC去除率仅提高至30%、SUVA值下降31%.当臭氧投加量高于2 mg/Ｌ时,臭氧氧化出水中BrO^-₃增加明显,氧化过程原水中Br^-浓度升高BrO^-₃生成量增大;生物活性炭对BrO^-₃的去除率平均仅为13%,且波动较大.与常规处理相比,臭氧-生物活性炭处理后各类THMs均有减少,总量减少40%;但氯量和Br^-对溴代副产物影响大,主要为CHBr₃生成量增加.     

污水厂出水DOM的分级及三卤甲烷生成势研究

研究目的在于调查寒冷季节城市污水处理厂出水中天然有机物化学组分分级,探讨各分级组分与消毒副产物生成潜能间之关系。采集污水厂二级出水,以三种不同树脂把污水厂出水中有机物分离成六类不同组分,其中A水厂含量最高的物质为亲水酸性物质(33%)而B水厂的疏水性中性物质含量最多约占总有机物的64%。从总体来看两水厂的疏水性物质含量大于亲水性物质含量,疏水性物质的三卤甲烷生成势也较大,是水体中消毒副产物的主要前驱物质。疏水性有机物质较多,代表受生活污水污染严重,得知该城市污水主要受民生污染较多。