净水厂全流程控制三氯乙醛副产物技术应用研究

针对部分氯消毒水厂面临三氯乙醛副产物超标风险高的问题,以全面提升深圳市优质饮用水为目标,研发建立了三氯乙醛生成抑制为主、前体物和三氯乙醛去除为辅的多级屏障消毒副产物全流程控制技术,并在深圳市上南水厂进行技术示范。改造后的运行效果显著,出厂水三氯乙醛生成势的去除率提高27%,三氯乙醛平均浓度下降40%,耐氯菌检出率下降23. 5%,出厂水消毒副产物稳定达标,达到保障供水水质安全的目的。     

臭氧-活性炭深度处理工艺控制三氯乙醛的研究

以南方某自来水厂砂滤池、主臭氧和炭滤池出水为研究对象,定期监测臭氧-活性炭深度处理各工艺段对水中天然有机物的去除效果,从而研究其控制三氯乙醛生成的效果。研究结果表明,对砂滤池出水,单独投加臭氧对三氯乙醛没有明显的控制作用,但与活性炭滤池联用后能显著降低出水的三氯乙醛浓度。臭氧-活性炭深度处理工艺对CODMn的平均去除率达41.4%,对UV254的平均去除率达60.9%,对三氯乙醛的平均去除率可达65.3%,有效降低了三氯乙醛生成量。     

不同滤料过滤控制三氯乙醛生成的生产性试验研究

将自来水厂快滤池石英砂滤料更换为活性炭与活性无烟煤,对比这三种滤料过滤对水中有机物的去除效果,以及控制三氯乙醛生成的效果。生产性试验结果表明,活性炭、活性无烟煤过滤对有机物的去除效果明显好于石英砂滤池,TOC、CODMn、UV254去除率均为石英砂滤池的一倍以上。活性炭与活性无烟煤滤池出水的加氯消毒副产物三氯乙醛生成量均远小于石英砂滤池出水。三种滤料过滤后的出水浊度无明显差别,均在0.3NTU以下。     

曝气炭砂滤池对消毒副产物三氯乙醛的控制作用

以我国南方某水源水为研究对象,考察了曝气炭砂滤池对消毒副产物三氯乙醛(CH)的控制作用,并与普通炭砂滤池进行对比分析。结果表明,与普通炭砂滤池相比,曝气炭砂滤池对浊度、COD_(Mn)、UV_(254)、DOC的去除率分别提高了1.10%、1.73%、4.58%、4.38%,同时出水溶解氧提高了0.43 mg/L;在外加较高浓度CH的情况下,曝气和普通炭砂滤池对CH的去除率均在99%以上,活性炭的吸附作用足以满足对CH的去除;曝气炭砂滤池对三氯乙醛生成势(CHFP)的去除率比普通炭砂滤池提高了4.80%。     

氯化与氯胺消毒生成消毒副产物的对比研究

通过小试试验,对比研究利用氯化和氯胺消毒对生成消毒副产物的影响。结果表明,随着次氯酸钠投加量的增加,氯胺消毒和氯化消毒产生的三卤甲烷均呈现逐渐增长的趋势,氯胺消毒产生的三卤甲烷明显比氯化消毒低,可降低76.58%;受限于前体物,氯化消毒产生的三氯乙醛随次氯酸钠投加量增加没有明显的变化趋势,氯胺消毒则呈现逐渐增长的趋势,氯胺消毒产生的三氯乙醛明显低于氯化消毒,可降低83.41%。     

常规工艺和深度处理工艺控制消毒副产物前体物的比较

以南方地区水源水为对象,对比研究常规工艺和深度处理工艺对三卤甲烷、卤乙酸和三氯乙醛消毒副产物前体物的去除效果.试验结果表明,与常规处理工艺相比,增加臭氧活性炭深度处理工艺,可以使三卤甲烷、卤乙酸和三氯乙醛消毒副产物前体物去除率分别提高32.34％、20.59％、24.32％.     

混凝土碳化控制的研究

混凝土的强度和耐久性是混凝土结构的两个重要指标,其中混凝土抗碳化能力是衡量混凝土结构耐久性非常重要的一个指标。由此,通过对混凝土碳化反应机理的探讨,分析导致混凝土碳化的各种因素,提出施工时对混凝土减缓碳化处理的建议。     

气相色谱法测定水中三氯乙醛的方法优化

针对采用气相色谱法测定水中三氯乙醛的标准方法中存在的问题,对其试验条件进行了优化.优化后的试验条件为:平衡时间为40 min,平衡温度为40℃,在水样中加入NaCI并使其饱和,适当提高加碱量,而且对存在背景三氯甲烷的实际样品所造成的三氯乙醛计算浓度误差进行了校正.优化方法的最低检测浓度为0.24μg/L,相对标准偏差≤2.5%,加标回收率为89.2%～100.6%,经,检验证实优化方法与标准方法不存在显著性差异,可用于水中三氯乙醛的测定.     

影响工程造价因素与控制分析

本文研究分析了影响工程造价的各个因素,并且针对这些因素提出相应的解决措施,以提高建筑公司的经济效益。     

氯化消毒副产物的控制研究进展

探讨了CDBPs的形成机理,总结了目前国内外控制CDBPs的方法,并为饮用水高效安全消毒技术的进一步研究提出了意见和建议,以确保饮用水的安全性。     

Occurrence and control of nitrogenous disinfection by-products in drinking water--a review

The presence of nitrogenous disinfection by-products (N-DBPs), including nitrosamines, cyanogen halides, haloacetonitriles, haloacetamides and halonitromethanes, in drinking water is of concern due to their high genotoxicity and cytotoxicity compared with regulated DBPs. Occurrence of N-DBPs is likely to increase if water sources become impacted by wastewater and algae. Moreover, a shift from chlorination to chloramination, an option for water providers wanting to reduce regulated DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs), can also increase certain N-DBPs. This paper provides a critical review of the occurrence and control of N-DBPs. Data collated from surveys undertaken in the United States and Scotland were used to calculate that the sum of analysed halonitromethanes represented 3-4% of the mass of THMs on a median basis; with Pearson product moment correlation coefficients of 0.78 and 0.83 between formation of dihaloacetonitriles and that of THMs and HAAs respectively. The impact of water treatment processes on N-DBP formation is complex and variable. While coagulation and filtration are of moderate efficacy for the removal of N-DBP precursors, such as amino acids and amines, biofiltration, if used prior to disinfection, is particularly successful at removing cyanogen halide precursors. Oxidation before final disinfection can increase halonitromethane formation and decrease N-nitrosodimethylamine, and chloramination is likely to increase cyanogen halides and NDMA relative to chlorination.     

饮用水氯消毒副产物安全控制的研究现状

叙述了饮用水处理过程中消毒副产物（DBPs）的形成机制和变化情况,总结了DBPs的诱发因子,探讨了DBPs安全控制的基本对策,同时为饮用水高效安全消毒方案的进一步探究提出了建议。     

饮用水中氯化消毒副产物的控制研究进展

探讨了DBPs的形成机理及其种类,然后介绍了DBPs对人体的健康风险,并总结了目前国内外控制DBPs的方法,为饮用水高效安全消毒技术的进一步研究提出了意见和建议。     

Controversies about the occurrence of chloral hydrate in drinking water

Besides trihalomethanes (THMs) and haloacetic acids (HAAs), chloral hydrate (CH) is the next most prevalent disinfection by-product (DBP) in drinking water, formed as a result of the reaction between chlorine and natural organic matter (NOM). Chloral hydrate (trichloroacetaldehyde) should be limited in drinking water because of its adverse health effect. The controversies concerning the appearance of CH in disinfected water found in literature are discussed in the present paper. According to some authors the CH yield during chlorination of water depends only on TOC. However, there are other data available that do not confirm this relationship. Another fact requiring clarification is the dependence of CH formation on pH. In the present study, CH formation is analysed in different types of water disinfected with different doses of chlorine. Formation of CH is correlated with the dose of Cl₂ and the contact time. The formation of chloral hydrate takes place as long as chlorine is available in the water. Total organic carbon (TOC) is not considered the main factor influencing the production of chloral hydrate in water treated with Cl₂ as the production depends also on the nature of NOM. Higher levels of CH are observed at alkaline conditions (pH > 7). A significant correlation (R² > 0.9) between the concentrations of chloral hydrate and chloroform has been observed. The preozonation increases significantly the chloral hydrate formation potential in the water treated. Biofiltration process does not remove all of CH precursors and its efficiency depends strongly on the contact time. Chloral hydrate was analyzed by gas chromatography with electron capture detector with the detection limit 0.1 μg L⁻¹.     

预臭氧化CT值对消毒副产物的影响研究

以天津市引滦原水为研究对象,研究了不同臭氧投加量(C)和不同反应时间(T)条件下预臭氧化工艺对THMFP、HAAFP和溴酸盐等消毒副产物指标的影响。结果表明,引滦原水经不同CT值条件下的预臭氧化处理后,出水THMFP和HAAFP均有一定程度的下降,去除率分别为7.3%~32.2%和3.0%~30.9%;生成的溴酸盐含量均符合国家关于饮用水中溴酸盐含量的要求。当初始臭氧含量为2.696 mg/L,反应时间为10 min时,预臭氧化出水的THMFP浓度最低;当初始臭氧含量为1.048 mg/L,反应时间为20 min时,预臭氧化出水的HAAFP浓度最低。     

西北地区地表水处理工艺消毒副产物控制的中试研究

为有效控制西北地区某水厂处理工艺中水合三氯乙醛(CH)的生成,在中试规模条件下,通过降低前加氯量、增大助凝剂中高锰酸钾比例对预氯化工艺进行优化。试验结果表明,当助凝剂中高锰酸钾比例较低时,后加氯72 h后水样中CH含量随前加氯量的增加而升高;当高锰酸钾比例较高时,后加氯72 h后水样中CH含量随前加氯量的增加而降低。当预氯化投加量为0.4mg/L,助凝剂中高锰酸钾比例为1.0%时,对CH形成控制效果最佳,且相对经济,同时也可以更好地控制其他水质指标。     

Disinfectant decay and disinfection by-products formation model development: chlorination and ozonation by-products

Comprehensive disinfectant decay and disinfection by-product formation (D/DBP) models in chlorination and ozonation were developed to apply to various types of raw and treated waters. Comparison of several types of models, such as empirical power function models and empirical kinetic models, was provided in order to choose more robust and accurate models for the D/DBP simulations. An empirical power function model based on dissolved organic carbon and other parameters (Empirically based models for predicting chlorination and ozonation by-products: haloacetic acids, chloral hydrate, and bromate, EPA Report CX 819579, 1998) showed a strong correlation between measured and predicted trihalomethane (THM) and haloacetic acid (HAA) formation for raw waters. Internal evaluation of kinetic-based models showed good predictions for chlorine decay and THM/HAA formation, but no significant improvements were observed compared to the empirical power function model simulations. In addition, several empirical models for predicting ozone decay and bromate (ozonation disinfection by-product) formation were also evaluated and/or developed. Several attempts to develop kinetic-based and alternative models were made: (i) a two-stage model (two separate decay models) was adapted to ozone decay and (ii) an ozone demand model was developed for bromate formation. Generally, internal evaluation of kinetic-based models for ozone decay showed significant improvements, but no significant improvements for the simulation of bromate formation were observed compared to the empirical power function model simulations. Additional efforts were performed to reduce the gaps between specific models and their actual application. For instance, temperature effects and configuration of ozone contactors were considered in actual application.     

Removal of chlorine dioxide disinfection by-products by ferrous salts

Chlorine dioxide when used as an effective disinfectant forms undesirable disinfection by-products, i.e. chlorite and chlorate ions. The aim of this research was to study the removal of these ions by ferrous ions in the presence or absence of oxygen. The efficiency of Fe+2 for ClO2- and ClO3- removal was followed by a determination of their initial and final concentrations, pH and delta Fe+2 consumed/delta ClO2- removed ratios. The optimal weight ratio of delta Fe+2 consumed/delta ClO2- removed for complete ClO2 removal was found to be close to the theoretical calculated value of 3.31. It was proved that ferrous salts can reduce chlorite ions to harmless Cl- ions. This method can be recommended as a part of ClO2 disinfection to ensure safe drinking water, with no harm to water consumers and to the environment.     

Multivariate distributions of disinfection by-products in chlorinated drinking water

Drinking water disinfection by-product (DBP) occurrence research is important in supporting risk assessment and regulatory performance assessment. Recent DBP occurrence surveys have expanded their scope to include non-regulated priority DBPs as well as regulated DBPs. This study applies a Box-Cox transformed multivariate normal model and data augmentation methods for left-censored and missing observations to US EPA Information Collection Rule (ICR) drinking water data to describe the variability in the trihalomethane (THM4), trihaloacetic acid (THAA), dihaloacetic acid (DHAA), and dihaloacetonitrile (DHAN) DBP classes, the relationship between class-sum and the occurrence of individual DBPs within these classes. Inferences about bromine incorporation in these classes are then compared to those made by Obolensky and Singer (2005). Results reported herein show that class-based and individual DBP concentrations are strongly related to bromine substitution, and that speciation and bromine substitution patterns are consistent across DBP classes. In addition, the multiple imputation approach employed reveals that uncertainties related to missing and left-censored DBPs have important implications for understanding bromine substitution in the THAA class. These concerns should be considered through alternative approaches to DBP regulation in subsequent Stage II D/DBP assessment and revisions, where appropriate.