A proposal for managing wastewater in Harare, Zimbabwe

This paper deals with wastewater management in Harare, in the Lake Chivero catchment area of Zimbabwe. It aims at developing a sustainable system for managing water and nutrients and is based on the literature and a water quality monitoring study conducted from June 2000 to December 2001. This study has shown serious water pollution problems due to urbanisation in the catchment. A ‘three‐step strategic approach’ to urban (waste)water management was used as a basis for formulating solutions. The short‐term solutions include reduction of wastewater volume in industries and households, reducing wastewater flows by 24% and total phosphorus by 5%. The medium‐term solutions involve treating wastewater to high standards, resource recovery and reuse, and controlling upstream sources of pollution, and thus would reduce the lake total nitrogen and total phosphorus levels to about 0.4 and 0.07 mg/L, respectively. A long‐term solution was suggested based on pollution prevention and direct reuse, treatment at onsite and decentralised levels followed by reuse, and minimal disposal of the remaining effluents combined with the stimulation of the self‐purification capacity of the receiving rivers. It was concluded that it is feasible to reduce pollution levels in the catchment by applying these phased developments.     

城市供水保障体系的建设

城市因水而产生、因水而发展,也可能因水而衰败。城市的生产、生活等活动都离不开水,当城市的规模和地位达到一定程度时,城市的供水保障要求也提出来了。随着城市的发展、扩大,如何保证城市安全供水要求呢,必须建立供水保障体系。为此,从目前我国城市供水面临的问题和困难出发,提出了围绕供水体系的水质、水量、水压等三个方面开展建立城市供水保障体系活动的观点。     

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.     

Statutory Water Quality Objectives on the River Cam

The Government has announced its wishes to gradually introduce statutory water quality objectives in pilot catchments, commencing in late 1993. The River Cam is one of the catchments under consideration.
The paper describes the main physical features of the River Cam and its uses, which include salmonid and cyprinid fisheries, agricultural and industrial abstraction, and recreational pursuits.
Significant sewage and industrial discharges in the catchment, and their impact on water quality, are discussed, and current river quality is compared with established river quality objectives, EC requirements and proposed statutory water quality objectives. Procedures for setting the latter objectives are considered, together with monitoring and compliance assessment. Future effluent discharge standards are proposed, and options to achieve long-term water quality targets are suggested as part of a catchment management action plan.     

城市化进程中水资源供需趋势分析

在阐述我国城市化发展特点及现状的基础上，从总用水量、用水结构及用水设施的变化几个方面，探讨了我国总体水资源供需变化趋势及城市用水量总体变化趋势，为进一步制定城市水资源规划及管理政策提供借鉴。     

四川省2010年城镇污水处理总体需求分析

分析了四川省各流域和区域的水环境容量，根据四川省供水排水现状，预测了四川省2010年城镇污水排放量和污水水质，将水环境容量、水环境功能区水体水质要求、水污染物总量控制和削减污染物总量等环保领域的要求与城镇污水处理的需求预测和规划布局相衔接，确定了水体接纳未处理城市污水所占最大允许排放量的比例为40％，并以污水中氨氮浓度为25mg／L为最不利条件，利用水环境容量的计算结果确定了四川省2010年城镇污水处理的总体需求。     

The Impact of Intensive Dairy Farming Activities on River Quality: The Eastern Cleddau Catchment Study

Pollution from farm wastes has been one of the principal causes of deterioration in river quality in recent years. However, little is understood of how, and which, farming activities affect the chemical and biological quality of rivers. To address this problem, a field study has been initiated in the Eastern Cleddau catchment, West Wales, to investigate relationships between land use, farm waste management practices and river quality.
Water quality of small tributaries in this area is poor, and intensive chemical monitoring has shown that discharges from farmyards are a major source of pollution. Rainfall has been shown to exacerbate this effect either through field runoff or wastes washing directly from the farmyards. The status of benthic macroinvertebrate communities in these tributaries is poor and, typically, only a few pollution-tolerant species are present.
Small tributaries from farms appear to affect both the water chemistry and biology of larger watercourses, although this effect may be quite localized.
Future research will look at ways to reduce the impact of farm wastes on river quality. This will provide the basis for producing recommendations and guidelines for catchment management aimed at minimizing pollution of rivers from farming practices.     

Microbiological water quality along the Danube River: Integrating data from two whole-river surveys and a transnational monitoring network

The River Danube is with 2780 km the second longest river in Europe. Its catchment area covers 801 500 km², with approximately 81 million inhabitants in 19 countries. River water for anthropogenic use, transportation and recreation is of major importance in all of these countries. Microbiological contamination from faecal pollution by anthropogenic sources is considered to be a crucial problem throughout the Danube River basin. Thus, detailed knowledge on the extent and the origin of microbial pollution is essential for watershed management. The determination of faecal indicator concentrations along the Danube and its major tributaries during two whole-river surveys and 16 permanent stations allowed for the first time to draw a clear picture of the faecal pollution patterns along the whole longitudinal profile of this important international river. By including a variety of environmental variables in statistical analysis, an integrative picture of faecal pollution in the Danube River basin could be evolved. Four hot spots and six stretches of differing faecal pollution were identified, mainly linked with input from large municipalities. Significant decline of microbiological pollution was observed in the upper and lower Danube stretches over the investigation period. In contrast, a significant increase in the middle part was evident. The planned implementation of new wastewater treatment plants and advanced wastewater treatment measures according to the European Union urban wastewater directive will have a great potential to reduce microbial faecal pollution in the Danube and thus improving water quality.     

Regional water quality management for the Karun–Dez River basin, Iran

To achieve water quality goals in a river basin, a water quality management model (WQMM) has been developed through the geographic information system (GIS) approach and a mathematical water quality model. The developed model has been applied to the Karun and Dez Rivers, where water quality has decreased due to heavy pollutant loads from Khuzestan province cities and surrounding areas. Pollution sources, land use, geographic features and measured water quality data of the river basin were incorporated into the Arc‐View GIS database. With the database, the management model calculated management type and management cost for each management project in the river basin. Until now, river management policy for polluted rivers in Iran first penalizes pollution sources and then constructs treatment plants for the pollution sources whose wastewater is released untreated and for which the wastewater quality goal of the Iranian Department of Environment is not met. Different management projects with a time programme were proposed and they were compared with the results of the river quality without any management approach. It became clear that the results based on the management approach were much better than those for the unmanaged condition from the viewpoint of the achievement of water quality goals and cost optimization.     

Hydrology and the ecological quality of Scottish river ecosystems

Hydrology is a primary control on the ecological quality of river systems, through its influence on flow, channel geomorphology, water quality and habitat availability. Scottish rivers are widely perceived to be of high ecological quality, with abundant flow volumes and high water quality. However, historical and current river flow regulations, and land use change have altered the physical and chemical characteristics of Scottish rivers, with adverse consequences for aquatic biota. Baseline hydrological, geomorphological and water quality conditions in Scottish rivers are thus summarised. The impacts of river regulation and land use change on the hydrology, geomorphology and water quality of Scottish rivers are then discussed. Consequences of these changes for aquatic habitat are examined, with particular reference to the economically significant salmonid species (Salmo salar and Salmo trutta). Policy and management issues relating to the future ecological quality of Scottish rivers are reviewed. These include the impacts of climate change on ecological quality, the calculation and implementation of ecologically acceptable flows, and river restoration and best management practices within integrated catchment planning.     

Assessing the impact of changes in landuse and management practices on the diffuse pollution and retention of nitrate in a riparian floodplain

In many European lowland rivers and riparian floodplains diffuse nutrient pollution is causing a major risk for the surface waters and groundwater to not achieve a good status as demanded by the European Water Framework Directive. In order to delimit the impact of diffuse nutrient pollution substantial and often controversial changes in landuse and management are under discussion. In this study we investigate the impact of two complex scenarios considering changes in landuse and land management practices on the nitrate loads of a typical lowland stream and the riparian groundwater in the North German Plains. Therefore the impacts of both scenarios on the nitrate dynamics, the attenuation efficiency and the nitrate exchange between groundwater and surface water were investigated for a 998.1 km(2) riparian floodplain of the Lower and Central Havel River and compared with the current conditions. Both scenarios target a substantial improvement of the ecological conditions and the water quality in the research area but promote different typical riparian landscape functions and consider a different grade of economical and legal feasibility of the proposed measures. Scenario 1 focuses on the optimisation of conservation measures for all natural resources of the riparian floodplain, scenario 2 considers measures in order to restore a good status of the water bodies mainly. The IWAN model was setup for the simulation of water balance and nitrate dynamics of the floodplain for a perennial simulation period of the current landuse and management conditions and of the scenario assumptions. The proposed landuse and management changes result in reduced rates of nitrate leaching from the root zone into the riparian groundwater (85% for scenario 1, 43% for scenario 2). The net contributions of nitrate from the floodplain can be reduced substantially for both scenarios. In case of scenario 2 a decrease by 70% can be obtained. For scenario 1 the nitrate exfiltration rates to the river drop even below the infiltration rates from the river, the riparian floodplain in that scenario represents a net sink for river derived nitrate. As the nitrate contributions from the investigated riparian floodplain represent only a small proportion of the total nitrate loads within the river (1% p.a.) the overall impact of the scenario measures on the nitrate loads at the river outlet remains small. However, during the ecologically most sensitive summer periods under current conditions nitrate contributions from the riparian groundwater of the Lower and Central Havel River (which covers only 5% of the area of the Havel catchment) represent more than 20% of the river loads. By the implementation of the investigated landuse changes within the research area the groundwater derived nitrate contributions could be halved to only 10% during summer baseflow conditions.     

我国城市供水面临的主要问题及对策

介绍了我国城市的供水概况,从水质、水量、水处理工艺等方面与发达国家进行了比较,并对如何提高我国城市供水质量、保护水源等提出了建议     

南明河流域治理中污水处理厂布局与建设模式探讨

在贵阳市南明河流域综合治理中,结合城市河流生态补水需求以及城市建设用地条件限制,采用污水收集处理系统与河流治理统筹、污水厂分散布局和地下污水厂的建设模式,实现了污水收集系统一体化、污水处理的协同化、污水的资源化、污水厂建设生态化以及用地集约化、污水厂地上地下土地资源的最大化综合利用,同时实现了污水厂与城市的和谐共生,达到了污水与河流同治的效果,创造了城市流域治理典范。     

探索城乡供水水质问题

本文通过饮用水源监测管理、净水工艺改造、絮凝荆试验选用、配水管网建设与管理、水质检测能力建设等方面探索城乡供水水质问题的解决途径。     

Analysis of chemicals and energy consumption in water and wastewater treatment,as cost components: Case study of Oslo,Norway

Adopting a systems-approach to an urban water and wastewater system, while applying a triple bottom line strategy to management, entails a careful analysis of all the sub-systems and components thereof with a view to improving service levels, optimising expenditure, augmenting investments, and also reducing the life-cycle environmental impacts associated with setting up, maintaining and operating the system. The scope for optimising expenses is system-wide, though it varies from one sub-system to another, depending on inherent lock-ins and external factors beyond the direct control of the water and wastewater utility. Optimising the consumption of energy and chemicals and improving the cost-efficiency thereof, is always on the agenda of water treatment plants (WTPs) and wastewater treatment plants (WWTPs). This paper analyses the consumption of and the expenditure on chemicals and energy at Oslo's WTPs and WWTPs over time. Energy and chemicals for water and wastewater treatment, on an average account for 10.8% of the total operational expenses in the water supply sub-system and 13.7% for the wastewater handling sub-system. There is a perceptible increase in this share from 5.2% in 2004 to 14.9% in 2009 for water and 12.3% to 14.2% for wastewater. Chemicals cost more than energy for the WWTPs, while it was the other way round for the WTPs. The total real cost of energy and chemicals per cubic metre, in year-2007 currency, was between 4 and 5.2 Euro cents for the WTPs, and between 1 and 4.5 Euro cents for the WTPs. The total (WTP + WWTP) per-capita real costs of energy and chemicals, expressed in year-2007 currency, rose from around 10 Euros in year 2000 to about 12.2 Euros in year 2007.     

深圳市茅洲河流域(宝安片区)黑臭水体治理研究

从目标层、子目标层、方案层3个层面建立了深圳市茅洲河流域(宝安片区)黑臭水体治理系统构架,以2020年底茅洲河流域基本做到水清岸绿、鱼翔浅底为最终目标导向,过程中实现污水不入河、河水不入厂、污染清出河、清水补入河四项子目标,具体采取源头分离、迁移隔离、终端处理、闸门改造、管网改造、泵站改造、漂浮物清理、淤泥清理与处置及清水补给九项措施,从全局着手,做到流域统筹、系统治理。     

Modelling the urban water chain: Incentives and cost recovery in wastewater treatment in developing countries

To improve surface water quality in developing countries new approaches to design wastewater treatment schemes have been developed. We identify a compliance problem in these schemes which threatens their success. To analyze this problem, we integrate a compliance game into a model of the urban water chain. We illustrate the model with a numerical example on small scale leather processing. We find that the compliance problem indeed threatens the overall success of the treatment scheme and show under which conditions this is so. With an empirical calibration our model is a ready to use tool to provide quantitative results that can inform planners of urban wastewater treatment schemes.     

The impact of new developments on river water quality from an integrated system modelling perspective

New housing areas are a ubiquitous feature of modern life in the developing and developed world alike built in response to rising social, demographic and economic pressures. Inevitably, these new developments will have an impact on the environment around them. Empirical evidence confirms the close relationship between urbanisation and ambient water quality. However, what is lacking so far is a detailed and more generalised analysis of environmental impact at a relatively small scale. The aim of this paper is to quantify the impact of new developments on river water quality within an integrated system modelling perspective. To conduct the impact analyses, an existing integrated urban wastewater model was used to predict water flow and quality in the sewer system, treatment plant and receiving water body. The impact on combined sewer overflow (CSO) discharges, treatment plant effluent, and within the river at various reaches is analysed by ‘locating’ a new development on a semi-hypothetical urban catchment. River water quality is used as feedback to constrain the scale of the new development within different thresholds in compliance with water quality standards. Further, the regional sensitivity analysis (RSA) method is applied to reveal the parameters with the greatest impact on water quality. These analyses will help to inform town planners and water specialists who advise them, how to minimise the impact of such developments given the specific context.     

Managing Agricultural Pollution Using a Linked Geographical Information System and Non-Point Source Pollution Model

This study documents the development of a link between a geographical information system (GIS) and a non-point source pollution model. The GIS ARC/INFO was linked to the agricultural non-point source pollution model and ORACLE data sources. Application of the system is demonstrated using the Bedford-Ouse catchment as a suitable case study. Water quality impacts are predicted from source data describing topography, soils, land use and river network. The model results were in agreement with observed nitrate concentrations at the catchment outlet, and more appropriate data sources are considered to be the main priority for improving model predictive ability. Management scenarios were established to assess the impact of changing agricultural management practices on predicted water quality. The approach has significant potential for the management of agricultural pollution in the UK.     

Dynamic modelling and control applications in water quality maintenance

The purpose of this paper is to develop and illustrate a unified, systematic approach to problems of water quality management. In order to achieve this a water quality system is defined as the following group of component features: the abstraction, purification, and supply of potable water from a river: consumer effluent, rainfall-runoff from an urban land surface, and the sewer network; the wastewater treatment plant: the river itself. A systems analysis approach to the study of the dynamic and control aspects of the system is discussed, with particular reference to the practical limitations of instrumentation and technology. In an attempt to blend the theory with the practice recent studies on the dynamic modelling and control of parts of the water quality system are reviewed. Special attention is paid to the practical application of techniques of system identification and parameter estimation. Finally, piecing together several individual results, it is possible to give a good indication of the manner in which control studies should be directed in the near future.