A CLOSED WATER REUSE SYSTEM FOR POWER PLANT COOLING AND DIGESTER HEATING1

ABSTRACT: A model consisting of closed water reuse and productive use of various types of wastes for energy generation is presented. The sewage after treatment would be used as the cooling water for power plants, and the condenser discharge therefrom be used as heating water for sludge digesters. The water is then purified for municipal water supply for continuous use. The advantages of this system are that water resources and energy are conserved while various types of wastes including waste heat are controlled. With a preliminary system analysis, it appears that the design for power plant based on the total heating value of wastes and digester capacity based on sewage sludge generation is feasible in terms of acquisition and full utilization of various types of wastes as generated in a single metropolitan area. The system as shown in this design is in balance among various factors such as the generation rate of municipal refuse, municipal sewage, waste heat in the condenser discharge, and raw sewage sludge.     

Environmental and economic analysis of management systems for biodegradable waste

The management system for solid and liquid organic waste affects the environment and surrounding technical systems in several ways. In order to decrease the environmental impact and resource use, biological waste treatment and alternative solutions for sewage treatment are often advocated. These alternatives include increased agricultural use of waste residuals. To analyse whether such proposed systems indicate improvements for the environment and its sustainability, systems analysis is a useful method. The changes in environmental impact and resource use is not only a result of changes in waste treatment methods, but also largely a result of changes in surrounding systems (energy and agriculture) caused by changes in waste management practices. In order to perform a systems analysis, a substance-flow simulation model, the organic waste research model (ORWARE), has been used. The results are evaluated by using methodology from life cycle assessment (LCA). An economic analysis was also performed on three of the studied scenarios. The management system for solid organic waste and sewage in the municipality of Uppsala, Sweden, was studied. Three scenarios for different treatments of solid waste were analysed: incineration with heat recovery, composting, and anaerobic digestion. These three scenarios included conventional sewage treatment. A fourth scenario reviewed was anaerobic digestion of solid waste, using urine-separating toilets and separate handling of the urine fraction. The results are only valid for the case study and under the assumptions made. In this case study anaerobic digestion result in the lowest environmental impact of all the solid waste management systems, but is costly. Economically, incineration with heat recovery is the cheapest way to treat solid waste. Composting gives environmental advantages compared to incineration methods, without significantly increased costs. Urine separation, which may be implemented together with any solid waste treatment, has great advantages, particularly in its low impact on the environment. However, there is a large increase in acidification.     

上海市污泥集装化运输可行性研究

随着上海市生活垃圾集装化运输系统的逐步完善和发展,上海市污泥的集装化运输逐渐被提上日程。本文通过对上海市中心城区的10座城市污水处理厂的污泥产量、污泥含水率、污泥运输道路和装卸环境等进行系统调研,综合分析和研究了上海市各污水处理厂污泥集装化运输的可行性,并进一步研究了污泥性质对集装化运输的影响。结果表明,上海市中心城区仅白龙港污水处理厂含水率约为60%的深度脱水污泥符合污泥集装化运输的要求;深度脱水污泥性质较为稳定,对各种钢材料的腐蚀性为0.00016~0.00125 mm/a,对集装化运输影响较小,但污泥释放的氨气浓度高达173.66 mg/m3,影响集装化运输,需采取水雾喷洒等措施进行控制。     

A new system for groundwater contamination hazard rating of landfills

In developing countries, several unregulated landfills exist adjacent to large cities, releasing harmful contaminants to the underlying aquifer. Normally, landfills are constructed to hold three types of waste, namely hazardous waste, municipal solid waste, and construction and demolition waste. Hazardous waste and municipal solid waste landfills are of greater importance as these pose greater hazard to groundwater, in comparison with landfills holding waste from construction and demolition. The polluting landfills need to be prioritized to undertake necessary control and remedial measures. This paper assesses existing site hazard rating systems and presents a new groundwater contamination hazard rating system for landfills, which can be used for site prioritization. The proposed system is based on source-pathway-receptor relationships and evaluates different sites relative to one another. The system parameters have been selected based on literature. The Delphi technique is used to derive the relative importance weights of the system parameters. The proposed system is compared with nine existing systems. The comparison shows that the site hazard scores produced by the existing systems for hazardous waste, municipal solid waste, and construction and demolition waste landfills are of the same order of magnitude and tend to overlap each other but the scores produced by the proposed system for the three types of landfills vary almost by an order of magnitude, which shows that the proposed system is more sensitive to the type of waste. The comparison further shows that the proposed system exhibits greater sensitivity also to varied site conditions. The application of different systems to six old municipal solid waste landfills shows that whereas the existing systems produce clustered scores, the proposed system produces significantly differing scores for all the six landfills, which improves decision making in site ranking. This demonstrates that the proposed system makes a better tool for prioritization of landfills for adopting control measures and remediation.     

Composting and compost application in China

The current situation of municipal solid waste (MSW) and sewage sludge production (in terms of volume as well as composition) in China is introduced. Composting and compost application in China are reviewed. In China, the production of municipal solid waste and sewage sludge is changing rapidly along with economic development. Composting is mainly applied for treating MSW, about 20% of the total amount of MSW being disposed. MSW composting is mainly co-composted with night soil or sewage sludge. Compost is used in agriculture, forestry and horticulture. Compost application is the key factor influencing the composting development in China. To promote composting and compost application in China, a state-wide survey on the production, composition and physical and chemical properties of MSW and sewage sludge should be carried out. More effort should be made to develop low cost and high efficient composting technologies according to China's conditions. The environmental impact of compost application should also be given more attention.     

The maturity tests during the composting of municipal solid wastes

This study investigated at first the evolution of co-composting process of municipal solid waste and sewage sludge under Tunisian pedo-climatic conditions.Results showed that the temperature profiles established in the system revealed three classical steps, the mesophilic phase during the first 25 days, the thermophilic phase between 30 and 130 days and the cooling phase began after the 14th week in the two windrows W1 (100% of municipal solid wastes) and W2 (60% of municipal solid wastes and 40% of dried sewage sludge). Potential toxic heavy metal content appeared generally more important in W2 than W1, and both finished products of compost obtained in this study satisfied most parts of the recommended norms of agronomical use. The presence or absence of nitrifying activity allowed determining that the compost W1 was more mature than the compost W2.Composting cannot only transform waste by reducing its harmful effect but also corrects when added to soil, the deficit in organic matter. The nature of the raw material used in composting may affect the quality of the final product. There is a significant need for the amendment of soils by compost. The quality of the amendment may have a significant impact on environment.     

OPTIMUM ALTERNATIVES FOR CONTROLLING COMBINED SEWAGE OVERFLOWS - A CASE STUDY1

ABSTRACT: Frequent high quantity overflows of combined sewage entering the Mississippi River near the city of Red Wing, Minnesota, have degraded water quality and caused concern among federal and state environmental agencies. The city of Red Wing was required to conduct a comprehensive waste control study, as part of the sewer system Construction Grant (Section 201 of PL 92–500), to identify alternative waste control and treatment measures and to recommend the optimum combination of alternatives in terms of both cost and waste control effectiveness. The study involved these basic steps: determination of present and future (year 2020) sanitary flow rates and volumes, storm runoff discharges, frequencies and volumes, and combined sewage bypass volumes; identification of alternative waste control measures; elimination of unfeasible alternatives; detailed analysis of the hydrologic, economic, and waste control feasibility of the promising alternatives; selection of the optimum combination of alternative waste control measures to satisfy the study objectives, and determination of construction priorities for the optimum control measures. Because of an uncertain budget and undetermined conditions of state and federal assistance, the city has not yet selected the optimum waste control measure for its needs. When the decisionmaking process between representatives of the city and the state commences, the optimum combination of waste control alternatives can be easily identified using the results of this study.     

钟村镇城市污水处理问题及对策探讨

钟村镇城市污水处理要解决的主要问题是选址、污水现状调查(主要为水质情况)、出水水质确定、环境评价、规划、治理工艺选择、废气处理、污泥处置、噪声防治、投资评估及融资方式、污水处理收费、招标等.本文试图就这些问题结合钟村的实际进行分析探讨.     

Assessment of waste management technology using BATNEEC options, technology quality method and multi-criteria analysis

Best Available Techniques Not Entailing Excessive Costs (BATNEEC) options, technology quality method and multi-criteria analysis were proposed as means of developing indices for evaluating municipal waste management systems. The proposed indices can be treated as a tool for ranking the system taking into account technical, environmental, economic, social and other objectives, bearing in mind specific features of the area involved. The analysis was made for three different incineration plants (Spittelau in Vienna, Warsaw and Tarnobrzeg) together with alternative waste disposal versions (with or without biogas burning and with MBP Mechanical-Biological Process) and the waste management infrastructure. The results showed that incineration of waste is much more beneficial than disposal. These results conform to the waste hierarchy identified in EU Directive 2008/98, but the indices created are easy to interpret and useful as a tool for communicating with the public, which is often a crucial factor in determining the location of investment.     

BETTER WATER RESOURCES THROUGH SEWERLESS SANITATION1

ABSTRACT: The water-flushed sewage system represented an advance in human sanitation when adopted in the nineteenth century but is coming under increasing criticism because it wastes water of drinking quality and sewage treatment plants do not completely clean the effluent. A number of on-site waste disposal systems are now available or under development which may eliminate the need for sewers and central treatment plants: aerobic, biological, composting, incinerating, oil-flushed, and vacuum or pressure systems. Official agencies should test them to determine if one or more can replace central sewer systems. As part of the program, the kitchen garbage grinder should be phased out.     

城市污水处理厂市场化运营的思考

根据目前城市污水处理厂建设与管理中存在的主要问题，以博兴县城市污水处理厂为实例，提出了城市污水处理厂建设、管理、与运营的一些思考，对污水处理厂的规范化建设管理，完善有关法律制度，推进城市污水处理市场化、产业化健康发展有着积极的指导作用。     

Multi-objective optimization of waste and resource management in industrial networks – Part I: Model description

This article presents a general multi-objective mixed-integer linear programming (MILP) optimization model aimed at providing decision support for waste and resources management in industrial networks. The MILP model combines material flow analysis, process models of waste treatments and other industrial processes, life cycle assessment, and mathematical optimization techniques within a unified framework. The optimization is based on a simplified representation of industrial networks that makes use of linear process models to describe the flows of mass and energy. Waste-specific characteristics, e.g. heating value or heavy metal contamination, are considered explicitly along with potential technologies or process configurations. The systems perspective, including both provision of waste treatment and industrial production, enables constraints imposed upon the systems, e.g. available treatment capacities, to be explicitly considered in the model. The model output is a set of alternative system configurations in terms of distribution of waste and resources that optimize environmental and economic performance. The MILP also enables quantification of the improvement potential compared to a given reference state. Trade-offs between conflicting objectives are identified through the generation of a set of Pareto-efficient solutions. This information supports the decision making process by revealing the quantified performance of the efficient trade-offs without relying on weighting being expressed prior to the analysis. Key features of the modeling approach are illustrated in a hypothetical case. The optimization model described in this article is applied in a subsequent paper (Part II) to assess and optimize the thermal treatment of sewage sludge in a region in Switzerland.     

城市污泥干燥焚烧一体化处理工艺的研究

城市污泥的产量日益增加,若不进行处理,不仅浪费土地资源而且污染环境。对污泥中的水分形式和污泥的处理工艺进行了分析,认为污泥的干燥和焚烧是最完全、稳定的处理工艺。提出一种城市污泥干燥焚烧一体化处理工艺,利用污泥自身焚烧产生的热值,提供干燥系统所需的热量,达到整个污泥处理系统能量的基本自给。对该系统的流程和各工艺进行了分析,结果表明该系统的污泥减量大、干燥效率高、运行成本低、尾气排放有效控制。     

城市生活垃圾处理的现状与管理研究

城市生活垃圾的处理与资源化是环保领域的一个难点,在管理上我国也缺乏相关的法律依据。本文介绍了城市生活垃圾处理的现状,同时针对构建我国城市生活垃圾管理体系提出了建议。     

Nutrient processing capacity of a constructed wetland in western Ireland

In Ireland, constructed wetland systems are increasingly being used to perform tertiary treatment on municipal waste effluent from small towns and villages located in areas whose receiving waters are deemed sensitive. The bedrock formation in the west of Ireland is primarily karst limestone and where the overburden-soil cover is very shallow, such waters are highly sensitive to pollution sources, as little or no natural attenuation and/or treatment will occur. Constructed wetland technology has been seen to offer a relatively low-cost alternative to the more conventional tertiary treatment technologies, particularly when dealing with low population numbers in small rural communities. This paper examines the waste treatment performance, in terms of nutrient (P and N) reduction, of a recently constructed surface-flow wetland system at Williamstown, County Galway, Ireland. Performance evaluation is based on more than two years of water quality and hydrological monitoring data. The N and P mass balances for the wetland indicate that the average percentage reduction over the two-year study period is 51% for total N and 13% for total P. The primary treatment process in the wetland system for suspended solids (between 84 and 90% reduction), biological oxygen demand (BOD) (on average, 49% reduction), N, and P is the physical settlement of the particulates. However, the formation of algal bloom during the growing season reduces the efficiency of the total P removal.     

我国城市污水回用现状及前景

通过对我国水资源状况和不处理状况的论述，说明了我国城市污水回用的紧迫性、必要性，分析了我国城市污水利用的现状和回用水利用的模式，提出了下一步应解决的问题的思路，展望了我国城市污水回用的前景，以实现水资源开发利用的可持续性发展。     

Effects of deodorants on treatment of boat holding-tank waste

A literature search and survey of Virginia, USA, campgrounds with RV pump-out stations were used to determine whether boat holding-tank deodorant chemicals would have deleterious effects on marina septic systems or package treatment plants. Laboratory studies reported in the literature indicate that these chemical additives could affect septic system function in three ways: (1) active ingredients in the additives can impair sewage degradation in septic tanks, causing sludge buildup and overflow of solids into the drainfield, (2) additive chemicals might enter the drainfield and, in high enough concentrations, reduce the drainfield's ability to degrade waste, or (3) toxic additive chemicals might migrate from the drainfield to ground or surface water. Laboratory studies also show that some ingredients added to holding tanks interfere with functioning of activated sludge treatment process. Experience in the field and in other laboratory studies suggests that factors such as dilution of treated waste with untreated waste and the characteristics of the sewage to be treated can reduce the possibility of damage to septic and activated sludge systems. The campground owners surveyed indicated that they have few problems with their septic systems in spite of the presence of chemical additives in the RV waste. However, most of them practice good septic system maintenance and have devised other means of ensuring that their systems function efficiently. In addition, the survey indicates that most Virginia campgrounds get only seasonal use (as would marinas in Virginia), allowing their systems to recover between peak seasons.     

Decision making under uncertainty using PEES–fuzzy AHP–fuzzy TOPSIS methodology for landfill location selection

The location selection for landfill municipal solid waste is an important issue in waste management. Selection of the optimal location requires consideration of multiple alternative solutions and evaluation factors because of system complexity. Further, ranking of the alternative locations and selection of the most optimal and efficient locations for landfill waste are an important multi-criteria decision-making problem. In this study, the candidate locations for landfill are determined based on Political, Economical, Environmental and Social factors are assessed through decision-makers’ opinion and by the methodology that incorporates fuzzy analytic hierarchy process (fuzzy AHP) and fuzzy technique for order preference by similarity to ideal solution (fuzzy TOPSIS). Specifically, the fuzzy AHP technique is applied to determine the weights of selected criteria impacting the location selection process, and the fuzzy AHP is adapted to model the linguistic vagueness and ambiguity, which can also be expressed as triangular fuzzy numbers. Furthermore, fuzzy TOPSIS technique is employed to rank the alternative locations. The applicability of this methodology is demonstrated by a case study of landfill waste location selection in the region of Casablanca, Morocco, and the results are compared with other techniques. Finally, to complete the treatment, a sensitivity analysis is performed to examine the impact of the preferences given by decision-makers to choose the best location.     

城市污水处理厂环境影响评价中的问题探讨

针对城市污水处理厂项目的特点，分析探讨了此类项目环境影响评价中应注意的几个问题。     

系统科学视角下的城市污水可持续管理研究

立足于城市污水可持续管理思想,利用系统科学方法,理清、分析对城市污水可持续管理的影响因素。以南京市为例,给出了不同政策组合下的城市污水管理的动态结果,并对结果进行了讨论。结果表明,要实现城市污水管理的可持续发展,必须在源头上通过政策设计（如收费）促进污水排放者参加到城市污水管理系统中,注重提高资源化和无害化能力的同时,要加强源头减量的力度。