饮用水加氯消毒后的氯仿、四氯化碳含量及其相关因素的探讨

饮水加氯消毒是一种系统的、经济而又简便的消毒方法,被世界各国广泛采用。我省城市饮用水采用氯化消毒方法。 但据报导:饮水加氯消毒可产生一些含卤有机物,并有致癌的可能。1972—1974年间先后在美国的最大河流—密西西比河的河口城市新奥尔良市的自来水中检出66种有机物。并认为这些物质是由工业废水污染加氯消毒所致。同时认为,饮用新奥尔良市供水的居民癌症患病率比     

太仓市饮用水水源污染现状和对策

根据太仓市饮用水地表水源和地下水的监测数据，分别采用单因子评价和综合评价方法，对饮用水源的水质进行评价。结果认为地表水水源已受到轻度污染，属Ⅲ类水；地下水的水质较差，已不适合于直接饮用。饮用水水源的主要污染物为COD、氨氮、挥发酚、硝酸盐氮和高锰酸盐指数。对饮用水水源的污染成因进行了全面分析，并从四个方面提出了水源安全保护对策：法律法规与行政手段、技术支撑、经济支持和宣传教育.     

液氯对自来水中低碳卤代烃含量的影响

投加氯是饮用水常用的消毒方法.自1972年美国首先报导在自来水检出可疑的致癌物质—氯仿、四氯化碳等低磷卤代烃后,各国都广泛地进行研究.大多数文献报导了自来水中低碳卤代烃来源于水源的河水受城市     

饮用水中隐孢子虫的危害、杀灭及预防对策

介绍了隐孢子虫的特性及其感染病症状 ,探讨了饮用水中隐孢子虫的杀灭和检测。提出了加强净水处理 ,加强对水源的保护 ,合理再利用中水和处理废水等预防隐孢子虫的对策。强调随着经济的发展及供水事业与世界接轨 ,自来水直饮将是饮用水发展的趋势。     

姚江水源及饮用水Ames试验研究

对宁波姚江原水及梅林水厂各净水工艺进行了致突变性研究,研究结果表明,姚江水源已受到污染,传统的净水工艺难以保证饮用水的安全,极需提高受污染原水的净化程度。     

扬中市饮用水源应急监测体系的探索

在调查研究的基础上,分析了扬中市饮用水源的具体特征,结合饮用水源保护的相关方针政策,探索了一条切实可行的扬中市饮用水源应急处置的监测体系.     

饮用水中卤代产物及前驱物的形成与控制

简述了目前国内对饮用水中卤代烃类化合物的研究现状，根据对饮用水中卤代产物的形成及浓度受水源水中前驱物、饮用水消毒处理方法等因素的影响，阐述了控制饮用水消毒过程中卤代烃的形成途径。     

长江口区域饮用水源地有机污染特性研究

以南通市为例,对长江口区域饮用水源地53种挥发性有机物( VOCs)、64种半挥发性有机物(SVOCs)、33种农药、20种多氯联苯等有机污染物进行定性、定量检测,选取汇龙镇水厂、如皋水厂、海门长江水厂3个水厂水源地进行r枯水期、平水期、丰水期3个水期的监测.结果表明:(1)VOCs中仅在枯水期有四氯化碳检出,33种农...     

长三角示范区饮用水水源水质安全与实体性制度协同立法

在对长三角生态绿色一体化发展示范区(以下简称示范区)饮用水水源保护所涉立法和实务部门进行广泛调研的基础上,研究和探讨了示范区饮用水水源的立法现状与水质状况、水质安全问题的主要成因、协同立法的理论基础和有利条件,并就协同立法的形式选择和核心内容提出了具体建议.研究发现,水质安全与相关实体性制度的构建是示范区饮用水水源保护...     

关于常州西郊水厂水源受污后的改善方法探讨

常州西郊水厂水源取自京杭大运河,近年来水源由于受到工业“三废”污染,出现了原水较多指标不符水厂建设水源要求,每到枯水季节污染加剧,水厂往往被迫停产,已直接影响着城市工业生产,人民生活的正常用水需要。当前改善与解决水源受污水厂的方法与途径问题已是各城市地面水厂所共同关心的议题。本文围绕改替水源受污水厂的方法与途径提出初步看法,藉以共同探讨。     

城市给水厂污泥对污水中磷的动态吸附

以城市给水厂污泥为原料,制备了2种不同粒径的颗粒状吸附剂,探讨了这2种颗粒吸附剂不同应用方式动态吸附初沉池水中磷的效果,并对吸附的影响因素进行了探究。结果表明,在使用2 mm粒径的吸附剂进行动态吸附时,在颗粒投加量固液比为20 g·L~(-1)的条件下,运行8 h后,出水磷浓度最低,总磷、可溶性总磷、可溶性活性磷酸盐的出水浓度分别可达到1.52、0.27、0.16 mg·L~(-1)。干化大颗粒的固定床吸附实验结果表明,空床停留时间应控制在30 min左右,有效滤层高度为11.5 cm,滤柱连续运行前80 h,对初沉池水有良好的处理效果,为该吸附剂投入使用提供了初步依据。对给水厂污泥颗粒吸附剂进行了技术经济分析,得出颗粒吸附剂理论上处理初沉池水所需药剂费用为0.021 2元·t~(-1),具有较高的经济效益。以上结果可为给水厂的污泥在实际生产中的应用提供参考。     

Impact of intermittent water supply on water quality in Lebanon

Lebanon in general and its capital, Beirut, suffer from water shortage due to the increasing water demand and the lack of proper management despite its abundant water resources. An intermittent water supply strategy was implemented in order to minimise deficiency problems. This, however, can seriously affect water quality due to the potential suction of non-potable water by negative pressures, biofilm detachment, and microbial re-growth especially when static conditions occur. Intermittent supplies also entail storing water in household tanks to satisfy demand during no-flow periods, and these tanks often encourage bacterial re-growth. Dumping of disinfectants in order to circumvent bacterial presence and the subsequent formation of undesirable byproducts is another concern. A study was conducted in Beirut over an eight-month period, during which samples were collected from household tanks and drinking water taps of Beirut's network. This paper presents the findings of the study and highlights key aspects in intermittent water supply systems.     

Organic contaminates in water

Abstract

The carbon adsorption method was used for separating organic matter from large samples of drainage, river and tap water. The carbon chloroform extract (CCE) was separated into different solubility fractions and the neutral fraction was separated into aliphatic, aromatic and oxy‐compounds using column chromatography. The aromatic fraction was subjected to TLC, IR and UV analysis. The pesticide endrin was present in both river and tap water at concentrations of 0.7 and 1.5 ppb, respectively.     

Perfluorochemicals in water reuse

Faced with freshwater shortages, water authorities are increasingly utilizing wastewater reclamation to augment supplies. However, concerns over emerging trace contaminants that persist through wastewater treatment need to be addressed to evaluate potential risks. In the present study, perfluorinated surfactant residues were characterized in recycled water from four California wastewater treatment plants that employ tertiary treatment and one that treats primary sewage in a wetland constructed for both treatment and wildlife habitat. Effluent concentrations were compared with surface and groundwater from a creek where recycled water was evaluated as a potential means to augment flow (Upper Silver and Coyote Creeks, San Jose, CA). In the recycled water, 90-470 ng/l perfluorochemicals were detected, predominantly perfluorooctanoate (PFOA; 10-190 ng/l) and perfluorooctanesulfonate (PFOS; 20-190 ng/l). No significant removal of perfluorochemicals was observed in the wetland (total concentration ranged 100-170ng/l across various treatment stages); in this case, 2-(N-ethylperfluorooctanesulfonamido) acetic acid (N-EtFOSAA), perfluorodecanesulfonate (PFDS), and PFOS were dominant. Though there is currently no wastewater discharge into the creeks, perfluorochemicals were found in the surface water and underlying groundwater at a total of 20-150 ng/l with PFOS and PFOA again making the largest contribution. With respect to ecotoxicological effects, perfluorochemical release via recycled water into sensitive ecosystems requires evaluation.     

Decomposition of dihaloacetonitriles in water solutions and fortified drinking water samples

An investigation of the decomposition of dihaloacetonitriles (DHANs) in water solutions and fortified drinking water samples was conducted. The concentrations of dichloroacetonitrile (CHCl2CN, DCAN), bromochloroacetonitrile (CHBrClCN, BCAN) and dibromoacetonitrile (CHBr2CN, DBAN) were determined by a gas chromatography mass spectrometry (GC-MS) method at regular time intervals and different temperatures. The effect of sodium thiosulfate (Na2S2O3), which is used as a preservative in water samples, was also examined. The rates of decomposition were determined for each compound. The results show that the reactions are faster in fortified drinking water samples than in ultrapure water solutions. They are also favored at higher temperature, especially when sodium thiosulfate is present. The highest decomposition rate is shown by DCAN, followed by BCAN and DBAN, while at the presence of sodium thiosulfate the decomposition of DBAN is the fastest.     

Differential water quality in confined and free-flowing water bodies, Lebanon

Integrated management of water resources is a major critical issue to be addressed in combating water stress in developing countries, such as Lebanon. At present, surface water is not properly used in Lebanon. This emphasises the importance of assessing surface water quality as a projected means to increase water availability. This study involves two different water bodies, the freely flowing Nahr-Ibrahin River and the Qaraaoun Reservoir, an impoundment of the Litani River. Water samples were collected from 16 chosen sites of each water body at four different dates during the dry season. Measured water parameters were temperature, pH, conductivity, BOD, HCO₃^-, Ca²⁺, Mg²⁺, Cl^-, SO₄^2-, PO₄^3-, NO_{3-, NH3, Fe, Mn, Zn, Pb, and Cd. Statistical analysis of the data revealed significant differences in water quality. The differences could be attributed to the fact that whereas the Qaraaoun reservoir is receiving domestic waste discharges that lead to an increase in the CO2 content and a pH decrease, the Nahr-Ibrahim River is influenced by agricultural runoffs and industrial discharges that increase the pH values. Consequently, the water metal speciation of the two water bodies was different. The study indicated that the differential quality of the two water bodies could be attributed to the nature of the water resources and exposure to contaminants. This is crucial in recommending intervention studies to protect quality and promote the role of surface water use, as an integrated component of water management in Lebanon.}     

Partitioning of polychlorinated biphenyls in octanol/water, triolein/water, and membrane/water systems

The use of the octanol/water partition constant (Kow) as a surrogate parameter for lipid/water partitioning of persistent organic pollutants (POPs) was reassessed by comparing the measured Kow of 12 selected polychlorinated biphenyl congeners (PCBs) with partition constants in triolein/water (Ktw) and membrane/water (Kmw) systems. Kow and Ktw were measured by the slow-stirring method. Kmw was measured by an adaptation of the slow-stirring method using suspensions of phosphatidylcholine and phosphatidylserine liposomes. Partitioning of POPs to octanol, triolein, and liposomes is similar but not equal. The log-log correlation for Kow and Ktw is excellent (r2 = 0.982) and that for Kow and Kmw is somewhat weaker (r2 = 0.856). Ktw values are greater than Kow by a factor of 1.6. Kmw of some PCB congeners exceed both Kow and Ktw by an order of magnitude. The differences are attributed to different PCB activity coefficients in the different lipid phases. The results imply that Kow can be used as a reasonable conservative estimate of lipid/water partitioning. But the observed differences between Kow and Kmw also indicate that using Kow to predict accumulation of POPs, particularly highly hydrophobic ones, in the polar lipids of organisms will underestimate their concentrations at equilibrium.     

多水源供水管网中铁释放规律

针对水源切换而引起的水质超标现象,开展了多水源联合供水条件下管网中铁释放规律的研究。分析了北方某城市2种水源(滦河水和长江水)的水质特点,利用实验模拟反应器分别研究了水源完全置换和供水分界线处水源混合区域的铁释放规律。结果表明,多水源供水管网的铁释放速率与水源水质密切相关,特别是水中含高浓度SO2-4和氯化物时会加快铁的释放。不同水源之间的频繁切换会破坏管垢表面的钝化层,使铁释放速率迅速变化,随后会有所缓解,但新的平衡的形成需要较长时间。供水分界线处的水源混合区域,由于水质的不断变化造成管垢表面很难形成稳定的钝化层,铁释放速率持续偏高,只有当长江水所占比例高达75%以上时才能得到抑制。     

Photodegradation of phosphonates in water

Phosphonates are widely used as chelating agents, e.g., in water cooling systems, in bleaching baths or as scale inhibitors in deflocculation agents. They are considered to be difficult to degrade and produce aminomethylphosphonic acid (AMPA) as a metabolite. As the fate of phosphonates in the environment is not very well known the present work aims at simulating the time dependent photodegradation of four selected phosphonates: nitrilotris-methylenephosphonic acid (NTMP), ethylenediamine-tetra-methylenephosphonic acid (EDTMP), diethylenetriaminepenta-methylenephosphonic acid (DTPMP) and hexaethylenediamine-tetra-methylenephosphonic acid (HDTMP), at concentrations of 1 mg/l (i.e. 3.2 microM NTMP, 2.3 microM EDTMP, 1.7 microM DTPMP and 2.0 microM HDTMP) irradiated by a middle pressure mercury lamp emitting between 190 and 600 nm. The influence of iron under different pH ranges (3, 5-6 and 10) are tested. The degradation of phosphonates is measured by the release of orthophosphates (PO4-P) and aminomethylphosphonic acid (AMPA). This study shows that phosphonates are substances that undergo UV light conversion, which is enhanced in the presence of iron. The half-life without iron is between 15 and 35 min at pH 3, between 10 and 35 min at pH 5-6 and between 50 and 75 min at pH 10. The half-life in the presence of 3.6 microM iron is between 5 and 10 min at pH 3, between 5 and 15 min at pH 5-6 and between 35 and 60 min at pH 10. The individual substances do not significantly influence the reaction rates whereas the presence of iron and the pH have significant effects. The total conversion of phosphonates after 90 min is 75-100% for pH values of 3 and 5-6 and 55-75% for a pH of 10 dependent on the presence of iron. In the environment longer degradation times are to be expected since natural light is weaker by a factor between 125 and 300 in the UVB, a factor between 3 and 8 in the UVA and of the same intensity in the visible range than the light in our study. Although orthophosphates are the major products, AMPA is also shown to be a by-product of the photodegradation of phosphonates that is later converted into orthophosphate.