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典型水源水及其处理工艺中的umu遗传毒性变化特征
Alternative TitleThe umu Genotoxic Characteristics of Typical Raw Water and Water during Treatment Processes
许志珍
Subtype博士
Thesis Advisor王东升
2012-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline环境工程
Keyword遗传毒性 溶解性有机物 溴离子 磁离子交换树脂 混凝 Genotoxicity Dissolved Organic Matter Bromide Magnetic Ion Exchange Resin Coagulation
Other Abstract      随着我国经济的不断发展,饮用水源污染日益严重,饮用水可能存在潜在的安全风险, 进行饮用水遗传毒性调查分析, 对保证水生态安全和人体健康具有重要的现实意义。本文应用umu/SOS 方法对位于我国不同流域的七个典型水源地不同季节的原水及出厂水的遗传毒性特征进行调查, 结合溶解性有机物(DOM) 的表征, 分析了饮用水遗传毒性效应的成因, 并研究了有效降低饮用水遗传毒性效应的处理工艺, 得出以下主要结论:
      ( 1) 对于饮用水umu 遗传毒性实验方法优化得出, 富集1-2 L水样较为合适,pH 调节到酸性条件(pH 2),乙酸乙酯作为洗脱溶剂洗脱, 水样显示的遗传毒性诱导效应较高; 氯化过程中随氯化时间和氯剂量的增加, 饮用水的遗传毒性效应逐步增大;
      ( 2)七个典型水源地原水及出厂水遗传毒性效应调查发现,七个水厂的原水在不同季节的TEQ4-NQO 值范围是0.01-0.21 μg L-1, 而出厂水的TEQ4-NQO 值范围是0.11-1.03 μg L-1, 自来水厂出厂水的遗传毒性效应明显高于原水, 暴露剂量为300 mL/板或小于300 mL/板时, 大部分出厂水在不同季节均显示遗传毒性阳性; 水厂的氯化消毒过程是造成出厂水遗传毒性效应升高的主要原因水厂混凝-沉淀-砂滤处理工艺主要去除水体中大分子量腐殖酸和富里酸类物质, 不能有效去除溶解性微生物代谢产物和芳香类蛋白类物质;
      ( 3)氯化过程中,原水中Br-会促进DOM 降解,增加小分子量物质的生成,促进消毒副产物(DBPs)由氯代组分向溴代组分转化,增大饮用水遗传毒性效应;DOM 和Br-是氯化过程中重要的遗传毒性物质前驱物, 在氯化消毒之前, 去除DOM 和Br-是控制饮用水遗传毒性风险的有效措施;
      ( 4)磁离子交换树脂(MIEX)可同时有效地去除水体中的DOM和Br-, 同时DOM 和Br-也存在竞争关系,MIEX 与DOC 的亲和力大于其与Br-的亲和力,在低投加量下( < 4 mL/L),MIEX 主要去除DOC,在投加量> 4 mL/L 时,Br-与DOM 竞争,降低DOC 的去除效果;小分子量DOM 与MIEX 的亲和力较小,在低投加量下,水体中Br-的存在会影响小分子量DOM 及微生物代谢产物和类蛋白类物质的去除效果;大分子量( 2900-3500 Da)腐殖酸类物质与MIEX 的亲和力较大, 在低投加量下被优先去除, 在高投加量下, Br-与其竞争降低其去除效率; 与混凝相比,MIEX 可去除较宽范围的DOM, 混凝对小分子量DOM 和微生物代谢产物类物质的去除效果较差。MIEX预处理与混凝结合可显著提高对浊度、DOM 和Br-的去除效果, 且所需的混凝剂的剂量可大大降低;
      ( 5)MIEX 可有效降低三卤甲烷生成势(THMFP) 和卤乙酸生成势(HAAFP),包括其溴代组分,可明显降低氯化消毒后水样的遗传毒性物质生成势(GFP); 混凝在一定程度上可以降低GFP, 但其去除GFP 的潜力有限; 混凝可以降低氯代THMFP 和HAAFP, 但降低其溴代组分的效果较差。MIEX 预处理与混凝结合可以有效地降低THMFP、HAAFP 和GFP, 且大大降低混凝剂的使用量。MIEX 预处理与混凝结合提供了一种有效降低浊度、DOM、Br-和饮用水遗传毒性效应的处理工艺。;        In China, the safety of drinking water becomes a significant issue due to serious aquatic environmental pollution. It is imperative and of practical significance for assessing the genotoxic effect of drinking water to ensure aquatic ecosystem safety and human health. This research evaluated the genotoxicity level of raw water and finished water in selected waterworks located in the four basins of China during different seasons using the umu test. The reason for drinking water genotixic effect was analyzed. On this basis the purification method for decreasing drinking water genotoxic effect was investigated. The main results were outlined as follows:
      (1) During sample preparation, 1 or 2 L waters concentrated were suitable for the umu test and the highest yield for genotoxic compounds was obtained from acid solution (pH 2) when ethyl acetate served as the eluant. During disinfection, as chlorination time and chlorine dose increased, drinking water genotoxicity increased.
      (2) Most of the selected finished water presented genotoxicity at or lower than 300 mL water sample exposure dose. The genotoxic effects of finished water were significantly higher than those of raw water. The treatment processes could increase the genotoxic effects of finished water, especially for the chlorination treatment.
       (3) Bromide in waters could promote the oxidation and decomposition of the dissolved organic matters (DOM) fluorescent
constituents during chlorination and dramatically increase the
trihalomethanes (THMs), haloacetic acids (HAAs) and genotoxic effect of waters. Increasing bromide concentration could markedly shifted THMs and HAAs toward bromine-containing species. DOM and bromide were the major precursors of genotoxin during chlorination. Removing DOM and bromide in raw water before chlorination was the effective measure to control drinking water genotoxic risk.
      (4) Magnetic ion exchange resin (MIEX) could remove dissolved
organic matters (DOC) and bromide effectively when coexisting in raw water. The affinity of MIEX for DOM was higher than that for bromide.The high molecular-weight (MW) humic acid presented greater affinity with MIEX. MIEX could remove a wider range of DOM than ferric coagulation in raw water. Soluble microbial byproduct-like organic compounds with low MW were recalcitrant to coagulation. MIEX pretreatment significantly improved the removal of turbidity and DOM when compared with ferric coagulation alone and the ferric demand could be reduced substantially.
      (5) As MIEX dosage increased, the formation of THMs and HAAs, including brominated species and the genotoxic formation potential (GFP) of DY and XHD waters could be decreased clearly. Coagulation could decrease GFP of waters at some extent but the potential was limited. The chloro-disinfection by-products (DBPs) could be preferentially removed by coagulation and the removal of bromo-DBPs by coagulation was poor. With MIEX pretreatment, coagulation could substantially decrease GFP, THMFP and HAAFP of source water and the requisite coagulant dosage was significantly reduced. Coagulation with MIEX pretreatment implied an efficient process capable of decreasing the genotoxic risk and DBPs formation of drinking water.
Document Type学位论文
Identifierhttp://ir.rcees.ac.cn/handle/311016/7209
Collection环境水质学国家重点实验室
Recommended Citation
GB/T 7714
许志珍. 典型水源水及其处理工艺中的umu遗传毒性变化特征[D]. 北京. 中国科学院研究生院,2012.
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