Energy Consumption Evaluation of Completcly Recycling System for Industrial and Domestic Wastewaters

水循环利用是满足工业和经济活动日益增长的用水需求的有效对策。但是，在某些情况下，促进水循环利用可能会增加能源消耗，因为为此目的通常需要对废水进行高级处理过程，从而导致对环境的污染负荷增加。本研究的目的是建立一个低能耗的完全水循环系统的程序。得到了以下结果：1)根据问卷调查的结果，调查了工业废水处理和回收的能耗现状。分析了能耗与处理工艺、待处理原水特性、处理后水质、回用状况等因素的关系。提出了工业废水回用深度处理工艺的选择指南。2)采用生命周期评价方法对生活污水特别是建筑污水回用系统进行二氧化碳排放评价。结果表明，膜过滤工艺对环境的影响较大，出水水质要求较高。雨水利用系统也在成本和能源消耗方面进行了评估。3)对好氧生物处理工艺（如活性污泥法、氧化沟法、序批式反应器法等）、生物活性炭法和膜过滤系统的能效进行了评价和比较。并对废水中除氮除磷技术进行了评价。

Water recycling is an effective countermeasure to meet the increasing need of water for industrial and economic activities. But in some cases, the promotion of water recycling may put energy consumption up because an advanced treatment process of wastewater is usually necessary for this purpose, leading to an increase in pollution load to the environment. The aim of this study was to give a procedure for the establishment of completely water recycling system with low energy consumption. The following results were obtained.1) The present situation of energy consumption for industrial wastewater treatment and recycling was investigated based on the results of a questionnaire. The relationships between energy consumption and treatment techniques used, characteristics of raw wastewater to be treated, quality of treated water, recycling status, etc.were analyzed. A guide to select advanced treatment process for the recycling of industrial wastewater was suggested.2) The recycling system of domestic wastewater, especially of building wastewater was evaluated with life cycle assessment in term of carbon dioxide emission. It was shown that the impact to the environment of membrane filtration process, the effluent water quality of which is very high, is relatively higher than other techniques. A rainwater using system was also evaluated in terms of cost and energy consumption.3) The energy efficiency of acrobic biological treatment processes (such as activated sludge process, oxidation ditch method, sequencing batch reactor process, etc.), biological activated carbon process and membrane filtration system were evaluated and compared. The techniques for nitrogen and/or phosphorus removal from wastewater werc also evaluated.