A Study On Environmental Benefits Of Urban Wastewater Treatment Applying Life Cycle Assessmcnt

Urban sewage treatment works has played an important role in environmental protection, the traditional method for evaluation and analysis of sewage treatment works is mainly environmental impact assessment and economic evaluation, although these methods have been widely used, But a drawback is the quantitative of environmental benefits in sewage treatment works is difficult.Life Cycle Assessment (LCA) is an environmental assessment and management approach. It can evaluate the the whole process of a product or a process from raw material acquisition to waste disposal, by identification and quantification of material and energy use and environmental waste disposal. It was known as a "from cradle to grave" analysis method, widely used in environmental impact analysis and evaluation of product system. The development of LCA in China is still at an early stage, and also need further practice and improvement. The combination of Life cycle assessment method and wastewater treatment is mainly reflected in sewage treatment plant's life-cycle assessment process, that is to treat sewage treatment plants as a product, the construction, running and the final removal of scrap is the product's entire life-cycle process, this analysis and evaluation processes get the environmental impact throughout the life cycle of sewage treatment works.This paper aimed at quantitative analysis of environmental benefits in sewage treatment works, proposed a LCA model of urban sewage treatment system on the environmental impact. On the basis of objective, in the context of defined, we investigated and calculated the material and energy inputs and outputs, and also the emissions on the environment, classified different inventory data to different types of environmental impact, through characterization and quantification, the environmental impact of sewage treatment works attributed to a single indicator characterized by unit energy consumption efficiency. This method was used to Xi'an Beishiqiao wastewater treatment center and the Third Sewage Treatment Plant in Xi'an, the Final results were 843.8/t(Coal)/d and 979.4/t(Coal)/d, This value showed the degree of environmental improvement per unit cost in daily operation, larger values means the ability of environmental improvement is stronger. The method had great significance and reference value on optimazing sewage treatment plant process and choosing different sewage treatment processes.