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对水日益增长的需求的有效对策。但在某些情况下，推广水循环可能会增加能源消耗，因为为此目的通常需要对废水进行深度处理，从而导致环境污染负荷增加。本研究的目的是提供一个建立低能耗的完全水循环系统的程序。研究结果表明：1）通过问卷调查的方式，对工业废水处理与回用能耗现状进行了调查。分析了能耗与处理工艺、待处理原水特性、出水水质、回用状况等的关系。2）以CO2排放为指标，采用生命周期评价法对生活污水特别是建筑污水回用系统进行评价。结果表明，膜过滤工艺对环境的影响相对较大，出水水质要求较高。3）比较了活性污泥法、氧化沟法、序批式活性污泥法等厌氧生物处理工艺的能量利用效率，并分析了不同工艺的能量利用效率。对生物活性炭法和膜过滤法进行了评价和比较。对废水脱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.