紫外线-茶多酚联用对供水管网的消毒效果

针对传统消毒技术的安全风险问题,以维护供水管网水质安全为目标,引入茶多酚作为辅助消毒剂和紫外线消毒联用,模拟供水管网系统探究不同管材和水力停留时间下紫外线-茶多酚联合消毒的消毒效果,分析管壁生物膜形貌和菌落分布的变化.结果表明,75mg/L是紫外线-茶多酚联合消毒时茶多酚的较优投加量,可保持48h消毒效果.模拟管网运行过程中整体水质较好,但管材对管网消毒效果的影响较大,30d内球墨铸铁和UPVC管网中细菌量超过100CFU/mL的频率分别为80%和0%,紫外线-茶多酚联合消毒在UPVC管网中消毒持续性较强.与紫外线消毒相比,紫外线-茶多酚联合消毒对管壁生物膜的破坏效果更明显,且对生物膜中的蓝藻菌和肠道致病菌杀灭效果更强,有利于保障管网水质的安全性.     

三角孔多孔板水力空化杀灭原水中病原微生物

利用自主研发的新型三角孔多孔板水力空化装置对胜利河原水进行消毒处理,采用压力数据采集系统采集水力空化工作段压力、显微镜观察菌体形态变化、平板计数法计数菌落总数、酶底物法检测总大肠菌群和大肠埃希氏菌;研究了三角孔多孔板的水流空化数、孔口大小、孔口数量、孔口排列和原水浓度梯度对水力空化杀灭原水中病原微生物的影响.结果表明：选择适当的原水浓度、增大孔口数量、减小孔口大小以及改进孔口排列方式（如交错式）时,均可进一步提高原水中病原微生物杀灭率.菌群杀灭率在5min时可达到稳定高效杀灭值,15min时菌落总数杀灭率可达80%以上,总大肠菌群和大肠埃希氏菌杀灭率均可达90%以上,甚至完全杀灭.     

合流制排水系统污水溢流污染控制技术进展

合流制污水溢流(Combined Sewer Overflows，CSOs)内含有大量污染物质，在未经处理后排入水体，造成了极大的危害，因此对CSOs的污染控制极其必要。本文分析了CSOs污染的影响因素、特点，综述了CSOs污染控制技术的进展。     

What's wrong with animalby-products?

Without looking beyond the conditions under which laying hens typically live in the contemporary U.S. egg industry, we can understand why the production and consumption of factory farmed eggs could be judged immoral. However, the question, What (if anything) is wrong with animal by-products? cannot always be adequately answered by looking at the conditions under which animals live out their productive lives. For the dairy industry looks benign in those terms, but if we look beyond the conditions under which milk cows live, we can better understand some animal rights activists' reasons for objecting to dairy products. The contemporary U.S. dairy industry requires a slaughter industry between one-seventh and one-third the size of the contemporary beef industry. Today, beef slaughter is vastly more humane than poultry slaughter, but if today's beef slaughter industry is judged emmoral, the contemporary dairy industry should be judged similarly immoral, because the two are wedded. This is the deep reason for moral suspicion of the dairy industry.     

Formation of nitrogenous disinfection by-products from pre-chloramination

A sampling survey investigated the formation of nitrogenous disinfection by-products (N-DBPs) and carbonaceous DBPs (C-DBPs) from pre-chloramination, an increasingly common treatment strategy in China for regulated C-DBP control, followed by subsequent conventional water treatment processes, i.e., coagulation, sedimentation, and filtration. Dihalogenated N-DBPs typically peaked in the summer and early autumn with a relatively higher temperature, with the maximum levels of dichloroacetamide (DCAcAm), dichloroacetonitrile (DCAN), bromochloroacetonitrile, dibromoacetonitrile and dichloroacetone at 1.8, 6.3, 6.0, 2.6 and 1.8 μg L⁻¹ in the finished water, respectively. Also, the levels of all the dichlorinated N-DBPs were correlated with the ratio of dissolved organic nitrogen (DON) to dissolved organic carbon, implying autochthonous DON played an essential role in the formation of these DBPs. In contrast, the yields of trihalogenated DBPs [chloroform (CF), trichloronitromethane (TCNM) and trichloroacetone (TCAce)] appeared not to be significantly affected by seasons. CF and DCAN were the dominant species in trihalomethanes (THMs) and dihaloacetonitriles (DHANs), respectively. Bromine was more readily incorporated into DHANs to form brominated DBPs than THMs during pre-chloramination. Although pre-chloramination can ensure the finished water to meet with the current Chinese THM regulatory limits, the increased levels of TCNM and TCAce may be a new water quality concern.     

Effects of dissolved oxygen and iron aging on the reduction of trichloronitromethane, trichloracetonitrile, and trichloropropanone

Iron metal (Fe(0)) is a potent reductant capable of reducing a wide variety of halogenated organic compounds including disinfection byproducts (DBPs). These reduction reactions may play a role in DBP fate in iron water mains and potentially could be exploited to remove DBPs from drinking water or wastewater in a packed-bed configuration. Oxidants (i.e., dissolved oxygen (DO) and chlorine) present in the water, however, may decrease the DBP degradation rate by competing for reactive sites and rapidly aging or corroding the iron surface. Thus, batch experiments were performed to investigate the effect of DO on the degradation rates of selected DBPs by Fe(0). Experiments were performed under anaerobic conditions, in initially oxygen saturated buffer without DO control, and under controlled DO (approximately 4.0 or 8.0 mg l⁻¹) conditions. The effect of short-term (25–105 min) iron aging in DO-containing buffer on DBP degradation rate also was investigated in separate experiments. For fresh Fe(0), the degradation rates of trichloronitromethane (TCNM) and trichloroacetonitrile (TCAN) in initially oxygen saturated buffer were similar to their respective rates under anaerobic conditions. The degradation rate of 1,1,1-trichloropropanone (1,1,1-TCP), however, decreased significantly in the presence of DO and the effect was proportional to DO concentration in the controlled DO experiments. For a DO concentration of 4 mg l⁻¹, the degradation rate of the three DBPs was greater for longer aging times as compared to their respective rates after 25 min, suggesting the formation of a mineral phase that increased reactivity. For a DO concentration of 8 mg l⁻¹, the effects of increasing aging time were mixed. TCNM degradation rates were stable for all aging times and comparable to that under anaerobic conditions. The TCAN and 1,1,1-TCP degradation rates, however, tended to decrease with increasing aging time. These results suggest that the reduction of highly reactive DBPs by Fe(0) will not be affected by the presence of DO but that the reaction rates will be slowed by DO for DBPs with slower degradation kinetics.     

Formation of iodo-trihalomethanes, iodo-haloacetic acids, and haloacetaldehydes during chlorination and chloramination of iodine containing waters in laboratory controlled reactions

Iodine containing disinfection by-products (I-DBPs) and haloacetaldehydes (HALs) are emerging disinfection by-product (DBP) classes of concern. The former due to its increased potential toxicity and the latter because it was found to be the third most relevant DBP class in mass in a U.S. nationwide drinking water study. These DBP classes have been scarcely investigated, and this work was performed to further explore their formation in drinking water under chlorination and chloramination scenarios. In order to do this, iodo-trihalomethanes (I-THMs), iodo-haloacetic acids (I-HAAs) and selected HALs (mono-HALs and di-HALs species, including iodoacetaldehyde) were investigated in DBP mixtures generated after chlorination and chloramination of different water matrices containing different levels of bromide and iodide in laboratory controlled reactions. Results confirmed the enhancement of I-DBP formation in the presence of monochloramine. While I-THMs and I-HAAs contributed almost equally to total I-DBP concentrations in chlorinated water, I-THMs contributed the most to total I-DBP levels in the case of chloraminated water. The most abundant and common I-THM species generated were bromochloroiodomethane, dichloroiodomethane, and chlorodiiodomethane. Iodoacetic acid and chloroiodoacetic acid contributed the most to the total I-HAA concentrations measured in the investigated disinfected water. As for the studied HALs, dihalogenated species were the compounds that predominantly formed under both investigated treatments.     

Concentration levels of disinfection by-products in 14 swimming pools of China

Swimming has become a popular exercising and recreational activity in China but little is known about the disinfection by-products (DBPs) concentration levels in the pools. This study was conducted as a survey of the DBPs in China swimming pools, and to establish the correlations between the DBP concentrations and the pool water quality parameters. A total of 14 public indoor and outdoor pools in Beijing were included in the survey. Results showed that the median concentrations for total trihalomethanes (TTHM), nine haloacetic acids (HAA9), chloral hydrate (CH), four haloacetonitriles (HAN4), 1,1-dichloropropanone, 1,1,1-trichloropropanone and trichloronitromethane were 33.8, 109.1, 30.1, 3.2, 0.3, 0.6 µg∙L⁻¹ and below detection limit, respectively. The TTHM and HAA9 levels were in the same magnitude of that in many regions of the world. The levels of CH and nitrogenous DBPs were greatly higher than and were comparable to that in typical drinking water, respectively. Disinfection by chlorine dioxide or trichloroisocyanuric acid could substantially lower the DBP levels. The outdoor pools had higher TTHM and HAA9 levels, but lower trihaloacetic acids (THAA) levels than the indoor pools. The TTHM and HAA9 concentrations could be moderately correlated with the free chlorine and total chlorine residuals but not with the total organic carbon (TOC) contents. When the DBP concentration levels from other survey studies were also included for statistical analysis, a good correlation could be established between the TTHM levels and the TOC concentration. The influence of chlorine residual on DBP levels could also be significant.     

E. coli and bacteriophage MS2 disinfection by UV,ozone and the combined UV and ozone processes

The combination of low-dose ozone with ultraviolet （UV） irradiation should be an option to give benefit to disinfection and reduce drawbacks of UV and ozone disinfection. However, less is known about the disinfection performance of UV and ozone （UV/ozone） coexposure and sequential UV-followed-by-ozone （UV- ozone） and ozone-followed-by-UV （ozone-UV） expo- sures. In this study, inactivation of E. coli and bacterioph- age MS2 by UV, ozone, UV/ozone coexposure, and sequential UV-ozone and ozone-UV exposures was investigated and compared. Synergistic effects of 0.5-0.9 log kill on E. coli inactivation, including increases in the rate and efficiency, were observed after the UV/ozone coexposure at ozone concentrations as low as 0.05 mg-L-1 in ultrapure water. The coexposure with 0.02-mg.L-1 ozone did not enhance the inactivation but repressed E. coli photoreactivation. Little enhancement on E. coli inactivation was found after the sequential UV-ozone or ozone-UV exposures. The synergistic effect on MS2 inactivation was less significant after the UV/ozone coexposure, and more significant after the sequential ozone-UV and UV-ozone exposures, which was 0.2 log kill for the former and 0.8 log kill for the latter two processes, at ozone dose of 0.1 mg. t-1 and UV dose of 8.55 mJ. cm 2 in ultrapure water. The synergistic effects on disinfection were also observed in tap water. These results show that the combination of UV and low-dose ozone is a promising technology for securing microbiological quality of water.     

紫外线消毒技术的发展及应用分析

介绍了紫外消毒技术的发展及其与传统加氯消毒的对比分析,并提及紫外线消毒在工程设计中应注意的几个问题,对紫外消毒技术的应用前景作了一个简单的预测。