煮沸对自来水中氯仿含量的影响

为了解管网末梢自来水及其在加热煮沸过程中致癌有机物——氯仿（CHCl3）含量的变化，采用不同的加热器、运用不同的加热方式对我国南方某地区管网末梢的自来水进行了加热煮沸处理，并对不同加热煮沸时间的水样进行了色质联机分析。结果发现，氯仿含量与热水器的功率、加热煮沸的方式及水中自由余氯含量均有关系。不管采用何种原水、何种加热器和加热方式，若煮沸后使水保持数分钟的沸腾状态均可使水中的氯仿含量降低到5μg／L以下的安全水平。     

芳香类有机物在氯化反应过程中的特性研究

选择几种在受污染水源水中常见的、具有代表性的芳香类有机物进行氯化试验,测定三卤甲烷和卤乙酸的生成特性,并分析芳香类有机物的化学结构对生成消毒副产物的影响,结果表明：（1）各试验物质氯化生成消毒副产物的生成量和反应速率大小排序为：间苯二酚〉对苯二酚〉邻苯二酚〉苯酚〉苯胺〉苯甲酸〉硝基苯;（2）芳香类有机物苯环上官能团的性质、数量和位置等影响消毒副产物的生成;（3）邻苯二酚的氯化反应可分为快速反应阶段和慢速反应阶段。     

A pilot plant evaluation of the Magnetic Ion EXchange® process for the removal of dissolved organic carbon at Draycote water treatment works

Natural organic matter (NOM) in water sources is undesirable for customers because it reacts with chlorine to form trihalomethanes (THMs), which can be harmful to health, and other organochlorine compounds that can cause taste complaints. A new Magnetic Ion EXchange process (MIEX^® DOC) has been reported as being successful in removing NOM from raw water. The aim of this research was (a) to evaluate the performance of the MIEX^® process in removing NOM from hard, lowland water on a pilot plant scale and (b) to compare the performance of the MIEX^® process with low pH coagulation DAF, in particular, with respect to reducing THM levels. A 45 and 40% reduction in the amount of NOM and in the levels of THMs, respectively, in chlorine‐dosed water was achieved when the MIEX^® process was used with dissolved air flotation (DAF).     

配水管网水质变化的研究(Ⅲ)--三卤甲烷的研究

以腐殖酸为三卤甲烷形成的前驱物质,确定ＴＨＭ生成的反应级数为二级。引入了ＴＨＭ生态能（ＴＨＭＦＰ）的概念,将ＴＨＭ的自下而上作为ＴＨＭＦＰ、余氯浓度、滞留时间及温度的函数,开创性提出了三卤甲烷浓度分布的水质模型。利用此模型结合配水管网的水力分析与计算可以求出配水管网中任一节点的ＴＨＭ浓度。三卤甲烷浓度分布的水质模型用于实际的配水管网,计算值与观测值取得了较好４的一致性,证明了本研究方法及所提出的水     

Iodoform taste complaints in chloramination

Iodoform (CHI₃) plus four of six possible iodo derivatives, CHClBrI, CHBr₂I, CHClI₂ and CHBrI₂ have been found in chloraminated drinking water. The presence of iodoform in concentrations > 5 μg l⁻¹ was associated with an objectionable medicinal taste in the water. Production of iodoform was dependant on the order of addition of the chlorine and ammonia.Throughout the report the order of addition of chlorine and ammonia will be defined by:—ammonia first then chlorine or —chlorine first then ammonia—implemented at Mundaring Weir from 12/5/86.     

Effect of bromide ions on genotoxicity of halogenated by-products from chlorination of humic acid in water

Genotoxicity of halogenated by-products obtained by chlorination of humic acid in water was evaluated in the presence of bromide ions (Br⁻). After the halogenated humic acid solution was made to flow through CSP800 cartridge, absorbed substances were eluted with dimethyl sulfoxide or acetone, and subjected to mutagenicity assays and to analysis of trihalomethanes (THMs). Mutagenic activity was measured by Ames tests using S. typhimurium TA100 strain without metabolic activation, and by the frequencies of micronuclei formation using cultured Chinese hamster lung cells (CHL/IU) in vitro. A powerful effect of bromide ions in chlorinated humic acid solutions was observed on the reverse mutation and micronuclei formations. The formations of total THMs and more brominated THMs were also enhanced in the presence of bromide ions. The ratio of [Br⁻/Cl⁻] regulated the composition and concentrations of THMs intensely, and the rate of substitution of Br⁻ was greater than that of chloride ions (Cl⁻). The increments of the mutagenicity and total THMs formed in chlorinated solutions were observed in parallel with the concentration of Br⁻ or Cl⁻. From the observations, it was concluded that the increasing mutagenicity might be caused by the increasing chlorinated and/or brominated by-products.     

Fenton试剂与粉末活性炭联用去除微污染原水中的THMFP

三卤甲烷等消毒副产物是致癌物质，饮用水中的三卤甲烷含量超标会对人体健康造成危害．为了降低饮用水中的三卤甲烷的浓度，笔者从改变水处理工艺入手，采用强氧化剂和粉末活性炭联用技术去除三卤甲烷前体物(THMFP)．按一定顺序在原水中投加少量Fenton试剂和粉末活性炭，可在保证常规出水水质指标的情况下，有效去除三卤甲烷前体物(THMFP)，从而大大降低饮用水中三卤甲烷的浓度．     

氯胺消毒对管网中消毒副产物的控制

相对氯消毒,氯胺具有消毒副产物生成量低的特点。本试验模拟管网,取典型的停留时间2d,考察了氯胺消毒时,pH和C12：N对管网中的消毒副产物（三卤甲烷和卤乙酸）浓度的影响。试验表明,消毒副产物的浓度及其含溴的程度基本上随着pH降低、C12：N升高而增大。试验条件下,氯胺生成的卤乙酸量大都高于三卤甲烷,并且以二卤乙酸为主,这和自由氯时所生成三卤甲烷多、卤乙酸以三卤乙酸为主的倾向正好相反。     

Determination of several common disinfection by-products in frozen foods

Disinfected water and/or disinfectants are commonly used by the freezing industry in such processes as sanitising, washing, blanching, cooling and transporting the final product. For this reason, disinfection by-products (DBPs) can be expected in frozen foods. This study focused on the presence of DBPs in a wide variety of frozen vegetables, meats and fish. For this purpose, the 14 halogenated DBPs more prevalent in disinfected water were selected (four trihalomethanes, seven haloacetic acids, two haloacetonitriles and trichloronitromethane). Up to seven DBPs were found in vegetables, whereas only four DBPs were present in meats and fish, and at lower concentrations, since their contact with disinfected water is lower than in frozen vegetables. It is important to emphasise that trichloronitromethane (the most abundant nitrogenous DBP in disinfected water) was found for the first time in foods. Finally, it was concluded that the freezing process can keep the compounds stable longer than other preservation processes (viz. sanitising, canning) and, therefore, frozen foods present higher DBP concentrations than other food categories (minimally processed vegetables, or canned vegetables and meats).     

The removal of algal biomass and extracellular products from water

Abstract

The removal of algal biomass and algal extracellular products (ECPs) from eutrophic water is studied using various physical chemical methods including coagulation/precipitation, powdered activated carbon (PAC) adsorption and combination of coagulation/ precipitation and activated carbon adsorption. The removal efficiencies of algae and TOC are 96% and 81%, respectively, by coagulation/ precipitation method. Moreover, dissolved organic carbon (DOC) is divided into four groups based on molecular weight distribution. It is found that coagulation/ precipitation process has good DOC removal efficiency for high molecular weight groups whereas PAC adsorption is particularly effective of the removal of DOC of low molecular weight. It is also discovered that the removal efficiency is synergistic by coagulation/ precipitation followed by PAC adsorption. The formations of THMFP/ DOC and AOXFP/DOC are higher with high molecular weight groups than those with low molecular weight groups.