Does public ownership of utilities matter for local government water policies?

What differentiates local governments that implement water policies on equity and the environment? Analyzing a 2015 national survey of 1,897 U.S. municipalities, we find municipalities that own their water utilities are more likely to report policies to protect low-income residents from disconnection and implement water resource management. Respondents from 8% of municipalities report protecting residents from disconnection. State economic regulation of municipally owned utilities and Democrat-majority municipal governments are positively associated with local policies to protect low-income households from shutoffs but bear no association with resource management. Both municipal ownership of utilities and state economic regulation may play a role in meeting certain local water policy goals.     

Development and validation of a drinking water temperature model in domestic drinking water supply systems

Domestic drinking water supply systems (DDWSs) are the final step in the delivery of drinking water to consumers. Temperature is one of the rate-controlling parameters for many chemical and microbiological processes and is, therefore, considered as a surrogate parameter for water quality processes. In this study, a mathematical model is presented that predicts temperature dynamics of the drinking water in DDWSs. A full-scale DDWS resembling a conventional system was built and run according to one year of stochastic demands with a time step of 10 s. The drinking water temperature was measured at each point-of-use in the systems and the data-set was used for model validation. The temperature model adequately reproduced the temperature profiles, both in cold and hot water lines, in the full-scale DDWS. The model showed that inlet water temperature and ambient temperature have a large effect on the water temperature in the DDWSs.     

居住小区管道直饮水系统的设计探讨

本文就居住小区管道直饮水设计的一些问题进行探讨,并提出一些具体看法,使设计做到既符合国情又能提高供水水质,达到供给居民优质直饮水的目的。     

Adaptation and evaluation of the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) for use as an effective tool to characterize drinking source water quality

Protecting drinking source water quality is a critical step in ensuring a safe supply of drinking water. Increasingly, drinking source water protection programs rely on the active participation of various stakeholders with differing degrees of water science knowledge. A drinking source water quality index presents a potential communication and analysis tool to facilitate cooperation between diverse interest groups as well as represent composite water quality. We tested the effectiveness of the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) in capturing expert assessments of drinking water quality. In cooperation with a panel of drinking water quality experts we identified a core set of parameters to reflect common source water concerns. Drinking source water target values were drafted for use in the index corresponding to two basic treatment levels. Index scores calculated using the core parameter set and associated source water target values were strongly correlated with expert assessments of water quality. We recommend a modified index calculation procedure to accommodate parameters measured at different frequencies within any particular study period. The resulting drinking source water CCME WQI provides a valuable means of monitoring, communicating, and understanding surface source water quality.     

Laboratory study on the adsorption of Mn²⁺ on suspended and deposited amorphous Al(OH)₃ in drinking water distribution systems

Manganese (II) is commonly present in drinking water. This paper mainly focuses on the adsorption of manganese on suspended and deposited amorphous Al(OH)₃ solids. The effects of water flow rate and water quality parameters, including solution pH and the concentrations of Mn²⁺, humic acid, and co-existing cations on adsorption were investigated. It was found that chemical adsorption mainly took place in drinking water with pHs above 7.5; suspended Al(OH)₃ showed strong adsorption capacity for Mn²⁺. When the total Mn²⁺ input was 3 mg/L, 1.0 g solid could accumulate approximately 24.0 mg of Mn²⁺ at 15 °C. In drinking water with pHs below 7.5, because of H⁺ inhibition, active reaction sites on amorphous Al(OH)₃ surface were much less. The adsorption of Mn²⁺ on Al(OH)₃ changed gradually from chemical coordination to physical adsorption. In drinking water with high concentrations of Ca²⁺, Mg²⁺, Fe³⁺, and HA, the removal of Mn²⁺ was enhanced due to the effects of co-precipitation and adsorption. In solution with 1.0 mg/L HA, the residual concentration of Mn²⁺ was below 0.005 mg/L, much lower than the limit value required by the Chinese Standard for Drinking Water Quality. Unlike suspended Al(OH)₃, deposited Al(OH)₃ had a much lower adsorption capacity of 0.85 mg/g, and the variation in flow rate and major water quality parameters had little effect on it. Improved managements of water age, pipe flushing and mechanical cleaning were suggested to control residual Mn²⁺.     

Measuring the concentrations of drinking water disinfection by-products using capillary membrane sampling-flow injection analysis

A capillary membrane sampling-flow injection analysis method is presented for selectively measuring the concentrations of total trihalomethanes (THMs) and total haloacetic acids (HAAs) in drinking water. The method is based on the reaction between nicotinamide and THM or HAA species to yield a fluorescent product. Two configurations are presented, one selective for total THMs and another selective for total HAAs. The construction of a capillary membrane sampler is described, and the results of method detection limit, accuracy and precision studies are reported for each method. Interference, selectivity and linearity studies are reported as well as the effect of temperature and ionic strength changes. Drinking water samples were analyzed by each proposed method and the results were compared to USEPA methods 502.2 and 552.3.     

小康住宅生活给排水设计中若干问题的分析与探讨

本文是针对小康住宅生活给排水设计及施工方面所遇到的问题的分析与探讨 ,并提出施工中常用的一些方法。现在的小康住宅中 ,水压的控制、给排水管道的敷设、直饮水的供应、节水等问题都比较明显 ,有些问题也易于被人们忽视 ,因此 ,在给排水设计中应尽量作好设计 ,避免这些问题的出现     

Influence of water quality on the presence of off-flavour compounds (geosmin and 2-methylisoborneol)

Geosmin and 2-methylisoborneol are off-flavour compounds related to poor organoleptics and a decrease in consumer satisfaction with drinking water. The relationship between these off-flavour compounds and 39 parameters of water quality (chemical, physical and biological) for three different surface waters from lotic systems that supply potable water to Quebec City and Lévis (Canada) was studied using principal component analysis. The objective of this study was to show that a multidimensional approach with principal component analysis using the component matrix serves to differentiate the processes involved in the appearance of the olfactory compounds from those not involved or little involved and to extract the most representative data of these processes. Our study shows that the presence of geosmin can be explained, in the case of the water studied, by a process associated primarily with the eutrophication of water and, to a lesser degree, by an allochthonous origin. However, the presence of 2-methylisoborneol may be linked to two processes with different origins, but of equal importance: a winter origin – most likely allochthonous – involving anthropic contributions and an autochthonous bacterial origin.     

Biostability analysis for drinking water distribution systems

The ability to limit regrowth in drinking water is referred to as biological stability and depends on the concentration of disinfectant residual and on the concentration of substrate required for the growth of microorganisms. The biostability curve, based on this fundamental concept of biological stability, is a graphical approach to study the two competing effects that determine bacterial regrowth in a distribution system: inactivation due to the presence of a disinfectant, and growth due to the presence of a substrate. Biostability curves are a practical, system specific approach for addressing the problem of bacterial regrowth in distribution systems. This paper presents a standardized algorithm for generating biostability curves and this will enable water utilities to incorporate this approach for their site-specific needs. Using data from pilot scale studies, it was found that this algorithm was applicable to control regrowth of HPC in chlorinated systems where AOC is the growth limiting substrate, and growth of AOB in chloraminated systems, where ammonia is the growth limiting substrate.     

Elimination of microcystins by water treatment processes-examples from Sulejow Reservoir, Poland

Eutrophication is a serious problem in Polish freshwaters. Mass occurrences of toxic cyanobacteria in reservoirs cause problems in the production of safe drinking water and the diversity of produced toxins complicates monitoring of freshwaters. The aim of this study was to estimate the efficiency of water treatment processes in the removal of microcystins (MCs), cyanobacterial hepatotoxins. Elimination of microcystins was studied at two waterworks, which supply drinking water to the city of Lodz from Sulejow Reservoir. The consecutive steps of pre-oxidation, coagulation, sand filtration, ozonation and chlorination used in the water treatment showed effective elimination of microcystins in water from Sulejow Reservoir in 2002 and 2003. The highest total concentration of microcystin (variants MC-RR, MC-YR, MC-LR) amounted to 6.7 microgl(-1) in raw water and was detected on the 13th of August 2002. In 2003 the water utility decided to increase the contribution of ground water in the production of drinking water. This resulted in a decrease of microcystin in water during and after the treatment process. The current management strategy of the waterworks company includes mixing of surface water and ground water, which reduces the hazards caused by toxic cyanobacterial blooms in the reservoir.     

Using QMRA-based regulation as a water quality management tool in the water security challenge: Experience from the Netherlands and Australia

Innovation in the water sector is at play when addressing the global water security challenge. This paper highlights an emerging role for Quantitative Microbial Risk Assessment (QMRA) and health-based targets in the design and application of robust and flexible water quality regulation to protect public health. This role is especially critical as traditional supply sources are subject to increased contamination, and recycled wastewater and stormwater become a crucial contribution to integrated water supply strategies. Benefits and weaknesses of QMRA-based regulation are likely to be perceived differently by the multiple stakeholders involved. The goal of the current study is to evaluate the experience of QMRA-based regulation implementation in the Netherlands and Australia, and to draw some lessons learned for regulators, policy makers, the industry and scientists. Water experts from regulatory bodies, government, water utilities, and scientists were interviewed in both countries. This paper explores how QMRA-based regulation has helped decision-making in the Netherlands in drinking water safety management over the past decade. Implementation is more recent in Australia: an analysis of current institutional barriers to nationally harmonized implementation for water recycling regulation is presented. This in-depth retrospective analysis of experiences and perceptions highlights the benefits of QMRA-based regulation and the challenges of implementation. QMRA provides a better assessment of water safety than the absence of indicators. Setting a health target addresses the balance between investments and public safety, and helps understand risks from alternative water sources. Challenges lie in efficient monitoring, institutional support for utilities, interpretation of uncertainty by regulators, and risk communication to consumers.     

Characterization of elemental and structural composition of corrosion scales and deposits formed in drinking water distribution systems

Corrosion scales and deposits formed within drinking water distribution systems (DWDSs) have the potential to retain inorganic contaminants. The objective of this study was to characterize the elemental and structural composition of extracted pipe solids and hydraulically-mobile deposits originating from representative DWDSs. Goethite (α-FeOOH), magnetite (Fe₃O₄) and siderite (FeCO₃) were the primary crystalline phases identified in most of the selected samples. Among the major constituent elements of the deposits, iron was most prevalent followed, in the order of decreasing prevalence, by sulfur, organic carbon, calcium, inorganic carbon, phosphorus, manganese, magnesium, aluminum and zinc. The cumulative occurrence profiles of iron, sulfur, calcium and phosphorus for pipe specimens and flushed solids were similar. Comparison of relative occurrences of these elements indicates that hydraulic disturbances may have relatively less impact on the release of manganese, aluminum and zinc, but more impact on the release of organic carbon, inorganic carbon, and magnesium.     

Investigation of Lake Sapanca water pollution,Adapazari, Turkey

Lake Sapanca has been the only source of drinking and recreational water for the city of Adapazari, Turkey. This paper reports a study of the variation of nutrient loading and trophic state of the lake, and also water quality parameters of Lake Sapanca compared to those of the neighbouring Lake Iznik. Through one year, samples were taken every three months from 15 different points on the streams feeding and draining off the lake. Nitrate, NO₂‐N, NH₃‐N, TKN, PO₄‐P concentrations on the 12 streams fe and three draining off points were determined. Then, loading, discharge, and accumulation amounts of nitrogen and phosphorus causing eutrophication were calculated and the trophic state of the lake was determined. A simple model was used to analyse the response of Lake Sapanca when the phosphorus loading rate was changed. Through this model, the variation of different parameters (t, M, K, Q, V and A) with respect to phosphorus concentration (C) was studied to identify effects and results. The consequences of an eutrophic state and measures to protect the lake are also discussed.     

倡导中的美国分用途供水系统

美国现存供水管网系统的管径是按照消防用水最大流量确定的.由于现在火灾频率已变得很低,使得管网流速变缓,导致供水被输送到用户端时水质下降、甚至恶化.为此,美国已开始倡导并应用分用途供水的双管道供水系统,以小管径的不锈钢管输送直饮水,并保留传统管道作为消防等非饮用水之用.这样不仅可以达到供应直饮水的目的,而且可大大降低非饮用水的处理成本.另外,中水也可纳入传统管道系统,使分用途供水第二条管道铺设成本有所降低.     

欧美及日本对饮用水评价的研究

如何从有益健康和可口的角度对饮水进行评价是人们最关心的几个问题之一．综述了国外对饮用水在有益健康和口感方面的研究及评价方法,同时对我国某些地方的水质进行了测试与分析