三种饮用水消毒副产物形成模型对比研究

选取反应时间(t)、水温(T)、pH、总有碳(TOC)、特别紫外吸光度(UV254)、溴离子浓度(Br-)及反应的氯剂量(Cl2)等相关的水质参数,构建了三卤甲烷及卤乙酸两大类消毒副产物的多元线性回归、非线性回归及神经网络预测模型。结果表明,消毒副产物的多元线性回归模型能逐步筛选回归因子,得出影响消毒副产物形成的主要因素及影响程度,各消毒副产物的多元线性回归方程的线性非常显著(p≤0.05);消毒副产物的非线性回归模型能分析预测各种对消毒副产物的影响不呈线性关系的因素;各消毒副产物神经网络预测的判定参数均大于0.83,表明采用神经网络预测消毒副产物的形成可以获得较精确的预测值。     

A retrospective cohort study of trihalomethane exposure through drinking water and cancer mortality in northern Italy

A few epidemiologic studies have suggested that consumption of drinking water with high trihalomethane content increases the risk of cancer. We investigated the mortality of a cohort of 5144 residents in Guastalla, northern Italy, who were supplied tap water with high chloroform and trihalomethane content between 1965 and 1987. Using death rates of a nearby community as reference rates, the standardized mortality ratio from all cancers between 1987 and 1999 was slightly increased for both males (1.2, 95% confidence interval 1.1-1.4) and females (1.1, 95% confidence interval 1.0-1.3). This was mainly due to a higher mortality from stomach, liver, lung, prostate and bladder cancer in males and from stomach, pancreas, breast and ovarian cancer and lymphocytic leukemia in females. We also noted excess mortality from melanoma in both males and females. Overall, our findings were consistent with an association between trihalomethane exposure and increased cancer risk at some sites. However, the point estimates were statistically imprecise, due to the limited number of deaths for some site-specific cancers. In addition, we were unable to rule out the possibility of confounding due to smoking and other life-style factors with regard to some of the excess rates.     

Multivariate statistical relationships between routine water plant data and trihalomethane levels. Implications for studies of human health

Routine water treatment plant data were used to construct a mathematical/statistical model of trihalomethane formation during lime-soda ash softening. Chemical characteristics of the raw water, such as temperature and color, and several treatment parameters, including chlorine dose, were significant predictors for chloroform and total trihalomethanes. The pattern of prediction was notably different for the brominated species. The results of this preliminary study support the view that routine water plant data can be used to estimate retrospectively, and with accuracy, trihalomethane levels for past time periods in which only the routine plant data are available. Possible limitations of the approach and the prospects for improving epidemiologic health effects studies of trihalomethanes in drinking water are discussed.     

A predictive model for the reactor inorganic suspended solids concentration in activated sludge systems

A simple predictive model for the activated sludge reactor inorganic suspended solids (ISS) concentration (excluding that from chemical precipitant dosing) is presented. It is based on the accumulation of influent ISS in the reactor and an ordinary heterotrophic organism (OHO) ISS content (fiOHO) of 0.15 mg ISS/mg OHO organic (volatile) suspended solids (VSS) and a variable phosphate accumulating organism (PAO) ISS content (fiPAO) proportional to their P content (fXBGP). Organism ISS content is conceptualized as the uptake of dissolved inorganic solids by active organisms, which when dried in the total suspended solids (TSS) test procedure, precipitate and manifest as ISS. The model is validated with data from 22 investigations conducted over the past 15 years on 30 aerobic and anoxic-aerobic nitrification-denitrification (ND) systems and 18 anaerobic-anoxic-aerobic ND biological excess P removal (BEPR) systems variously fed artificial and real wastewater, and operated from 3 to 20 days sludge age. The predicted reactor VSS/TSS ratio reflects the observed relative sensitivity to sludge age, which is low, and to BEPR, which is high. To use the model for design, two parameters need to be known: (1) the influent ISS concentration, which is not commonly measured in wastewater characterization analyses and (2) the P content of PAOs (fXBGP), which can vary considerably depending on the extent of anoxic P uptake BEPR that takes place in the system. Some guidance on the measurement of influent ISS concentration and selection of the PAO P content to calculate the mixed liquor VSS/TSS ratio for design is given.     

Speciation and variation in the occurrence of haloacetic acids in three water supply systems in England

An investigation into the speciation and occurrence of nine haloacetic acids (HAAs) was conducted during the period of April 2007 to March 2008 and involved three drinking water supply systems in England, which were chosen to represent a range of source water conditions; these were an upland surface water, a lowland surface water and a groundwater. Samples were collected seasonally from the water treatment plants and at different locations in the distribution systems. The highest HAA concentrations occurred in the upland surface water system, with an average total HAA concentration of 21.3 μg/L. The lowest HAA levels were observed in the groundwater source, with a mean concentration of 0.6 μg/L. Seasonal variations were significant in the HAA concentrations; the highest total HAA concentrations were found during the autumn, when the concentrations were approximately two times higher than in winter and spring. HAA speciation varied among the water sources, with dichloroacetic acid and trichloroacetic acid dominant in the lowland surface water system and brominated species dominant in the upland surface water system. There was a strong correlation between trihalomethanes and HAAs when considering all samples from the three systems in the same data set (r ²=0.88); however, the correlation was poor/moderate when considering each system independently.     

A suitable model of combined effects of temperature and initial condition on chlorine bulk decay in water distribution systems

Maintaining a chlorine residual is a major disinfection goal in many water distribution systems. A suitable general model of chlorine decay in the transported bulk water is an essential component for efficiently modelling chlorine concentration in distribution systems. The two-reactant model meets basic suitability criteria, including accurate prediction of chlorine residual over hundreds of hours, commencing with chlorine concentration 0-4 mg/L. This model was augmented with an equation that increases the decay coefficients with temperature according to Arrhenius theory. The augmented model was calibrated against decay-test data sets to obtain a single invariant set of parameters for each water. Model estimates of chlorine residuals over time closely matched decay-test data, over the usual operating ranges of initial chlorine concentration (1-4 mg/L) and temperature (3.5-28 °C). When the augmented model was fitted to partial data sets, it also predicted the data reserved for validation very well, suggesting that this model can accurately predict the combined effect of initial chlorine concentration and temperature on chlorine bulk decay in distribution systems, using a single set of invariant parameters for a given source water.     

Behavior of trihalomethanes and haloacetic acids in a drinking water distribution system

This investigation focused on the seasonal variation and spatial fate of chlorination disinfection by-products (CDBPs) in a drinking water distribution system located in a region where very significant seasonal variations in water temperature and surface water quality occur. The analysis of a large number of collected samples showed that the seasonal and geographical variations of both groups of CDBPs under study—trihalomethanes (THMs) and haloacetic acids (HAAs)—were particularly important in this region. THM levels in summer and fall were, on average, about five times higher than in winter, whereas average HAAs in spring were about four times higher than in winter. THMs increased and stabilized in the extremities of the distribution system, whereas HAAs begin to increase, and then decrease (mainly due to a reduction of dichloroacetic acid). This decrease was significantly higher in warm waters than in cold waters, which led to the hypothesis of microbial degradation of HAAs as water approaches the system extremities. In fact, regression models for the occurrence of both CDBPs showed that the residence time of water was one important parameter in explaining the fate of both CDBPs. The spatio-temporal portrait of both groups of CDBPs that was generated demonstrates that, due to their high intra-seasonal changes, the calculation of average annual levels of these substances for compliance with regulations can vary widely. The results used in the portrait of CDBP behavior are also relevant in terms of exposure assessment for future epidemiological studies on human reproductive outcomes in the region.     

Leakage detection and location in water distribution systems using a fuzzy-based methodology

Loss of water due to leakage is a common phenomenon observed practically in all water distribution systems (WDS). However, the leakage volume can be reduced significantly if the occurrence of leakage is detected within minimal time after its occurrence. This paper proposes a novel methodology to detect and diagnose leakage in WDS. In the proposed methodology, a fuzzy-based algorithm has been employed that incorporates various uncertainties into different WDS parameters such as roughness, nodal demands, and water reservoir levels. Monitored pressure in different nodes and flow in different pipes have been used to estimate the degree of membership of leakage and its severity in terms of index of leakage propensity (ILP). Based on the degrees of leakage memberships and the ILPs, the location of the nearest leaky node or leaky pipe has been identified. To demonstrate the effectiveness of the proposed methodology, a small distribution network was investigated which showed very encouraging results. The proposed methodology has a significant potential to help water utility managers to detect and locate leakage in WDS within a minimal time after its occurrence and can help to prioritise leakage management strategies.     

城市理水景观系统整体协同发展的理想模式

根据目前城市理水的变化趋势和发展动向,构建了城市理水景观系统整体协同发展的理想模式,将水景观规划、水环境保护、水生态恢复、水工程建设、水文化传承与水经济开发等涵盖其中,为水景观的规划设计提供了一定的理论与实践指导和支持。     

Evaluation of suitable chlorine bulk-decay models for water distribution systems

Maintaining the chlorine residual is a major disinfection goal for many water distribution systems. A suitable general chlorine bulk-decay model is required for simulation of chlorine profiles in networks to assist disinfection planning/management efficiently. The first-order model is unsuitable due to inaccuracy and inability to represent rechlorination. Three potentially suitable, simple, reactant models were compared. The single-reactant model was found to be unsuitable, as it was inaccurate when restricted to using a single set of invariant parameters. The two-reactant model was more suitable than the variable-rate-coefficient model, although both models were accurate under the same restriction. The two-reactant model was then calibrated against datasets consisting of multiple decay tests for five distinctly different waters. It accurately predicted data reserved for validation over the chlorine concentration range of 0-6 mg/L, using a single set of invariant parameters, and is therefore the simplest, generally suitable model for simulating chlorine profiles in distribution system networks.     

广西城市供水水质饮用特征的流域地域分布与差异

广西城市水源水的水质特征决定了供水水质的饮用特征,通过对广西主要城市供水水质的饮用特征性指标的全年表现和不同流域地域的比较研究,得到广西城市供水水质的流域地域饮用特征主要呈现为：西江水系流域城市酸碱度偏碱,桂南和沿海诸河流域城市酸碱度偏酸;硬度和溶解性总固体在不同流域地域城市中存在明显的差异性,西江流域城市稍高,桂南和沿海诸河流域城市略低;硫酸盐、氯化物指标在各流域地域城市中保持了较低的水平。结果表明,广西城市供水的饮用特征继承了原水水质中良好的天然特性,其饮用品质和口感俱佳,是广西城市成为宜居城市的基础性条件,值得倍加珍惜和维护。     

Modelling low impact development in watersheds using the storm water management model

ABSTRACT

Low impact development (LID) has been widely used to manage stormwater, but evaluations of the benefits of implementing LID need to extend up to the watershed level. Modelling is an important method and this paper proposes an approach that focuses on modelling LID in watersheds using the Storm Water Management Model (SWMM). There are two ways to simulate LID in a SWMM. The first is using the LID editor, and the second is simply adjusting the parameters in the basic SWMM. In the proposed methodology, these two ways are combined. The methodology was applied to one of China’s pilot sponge -cities, Tsingtao. The results show that the method can improve the efficiency and guarantee the accuracy of the model at the watershed level. Use of LID application in the pilot area can significantly reduce runoff volume, but the effect is different in different sub-watersheds.     

Impact of source waters,disinfectants, seasons and treatment approaches on trihalomethanes in drinking water: a comparison based on the size of municipal systems

This study compares concentrations of trihalomethanes (THMs) in municipal water for 2001–2007 from the small and large systems in two provinces in Canada (Newfoundland and Quebec) based on source waters, disinfectants, seasons and treatment approaches. Approximately 71 and 94%, respectively, of the municipal systems in Quebec and Newfoundland are small systems (serving fewer than 3000 people). The small systems serve approximately 8.6% (0.57 million) and 44.1% (0.18 million) of the populations in Quebec and Newfoundland, respectively. Concentrations of THMs and its variability are much higher in the small systems (Quebec: 0–941 μg/L; Newfoundland: 0–875 μg/L) than in the systems with populations 10 000 or more (Quebec: 0–364 μg/L; Newfoundland: 2.3–205 μg/L). The study reveals that the differences in THMs between the small and medium/large systems are because of different types of source waters, treatments, disinfection strategies and seasons. The results emphasize that regulatory agencies must focus more on the occurrence of DBPs in small systems and identify strategies to reduce their levels in drinking water.     

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.     

我国饮用水水质标准发展及与国际标准的对比

本文结合国际水质标准,与我国现行的GB5749-2006生活饮用水卫生标准进行了比较分析,介绍了我国饮用水标准的发展过程,重点介绍了强制性国家GB5749-2006生活饮用水卫生标准,并提出了指导性建议。     

锅炉房汽水系统CAD开发思路的探讨与实现

探讨了面向方案的概念在开发锅炉房汽水系统ＣＡＤ软件中的具体应用,其中包括开放的设备数据库、三维设计环 境、设计知识的组织和管理等,从而形成了一套完整的ＣＡＤ软件的开发与实现模式。     

An optimization model for water quantity and quality integrated management of an urban lake in a water deficient city

This paper presents an optimization model for water quantity and quality integrated management of an urban lake in a water deficient city. A representative water quantity and quality safeguard system served urban lake, including multi-source water supply facilities, recirculating water purification facilities and surplus water discharge facilities, is widely used in Chinese water deficient cities. Because it is complicated, any mismanagement will result in water quality deterioration, water waste and high operation cost. The presented model attempts to achieve the objectives of controlling water pollution, reducing economic cost and improving water utilization efficiency through an optimized operating water safeguard system. The model is applied to Qingjing Lake in Tianjin, China. Results show that the model plays a more positive role for water quantity and quality integrated management.     

三维渗流模型在李楼铁矿矿坑涌水量预测中的应用

李楼铁矿赋存于新太古界霍邱群周集组片岩、片麻岩及白云石大理岩中,矿体及围岩构造裂隙带,为矿床水的储存与运移通道;矿体上覆周集组风化裂隙含水层、青白口系风化裂隙含水层与第四系孔隙含水层,构成一个分布范围大、厚度大、透水性较差、富水性较弱含水体,为矿坑水的充水来源。矿山开采于深部-200m疏干排水时,地下水向排水点汇聚,第四系底部薄含水层承压水压力迅速释放并向四周扩展,上覆第四系孔隙水越流补给,垂向上存在地下水水头梯度,地下水流场呈现三维空间流场。文章在上述水文地质条件认识的基础上,利用地下水三维观测系统取得的长期动态观测资料和放水试验资料,建立三维流数学模型预测矿坑涌水量,并提出了矿山防治水建议,指导矿山建设。     

北方某市水源更换过程中管网黄水产生机制的探讨

针对北方某市在水源更换过程中管网出现局部黄水的现象,从新旧水源水质特征对比、管网的管材构成、管道内壁腐蚀层结构特征等方面探讨了产生黄水的内在原因,并对水源更换过程中防控黄水应采取的措施提出了建议。     

A review of data-driven approaches for burst detection in water distribution systems

This study focuses on data-driven approaches for burst detection and classifies them into three categories: classification method, prediction-classification method and statistical method. The performance of these methods is discussed. By analysing uncertainty in burst detection, this paper revealed that non-stationary monitoring data and limitations present in these methods challenge the reliability of detection results. Data pre-processing and probabilistic solutions to deal with the uncertainty are summarised. From these findings and discussions, this paper concludes and recommends that: a) data-driven approaches are promising in real-life burst detection and reducing false alarms is an important issue; b) more comprehensive performance evaluation might be necessary, in particular regarding detectable burst size; c) further research on new methods employing multivariate analysis and a new category based on clustering analysis would be beneficial to tackle uncertainty; d) more focus on the use of pressure data might facilitate burst location and reduce investment in burst detection.