The Study Of Rural Domestic Wastewater Treatment Plan Optimization In Three Gorges Reservoir Area

Nowadays, the agricultural non-point source pollution has become one of the main reasons for water pollution, to which rural domestic wastewater contributes a lot. The Three Gorges reservoir area is one of the most important area for environmental protection in Yangtze River. Therefore, effective control of rural domestic wastewater pollution becomes very urgent. The study evaluates the technologies for rural domestic wastewater treatment by Grey Correlation model combining Subjective Weight with Objective Weight and puts forward recommended technologies according to the results of the evaluation. In addition, the study also comes up with several suggestions about rural domestic wastewater management and finally proposes a plan for rural domestic wastewater controlling, which provides a theoretical basis for rural pollution management in Three Gorges reservoir area. The main conclusions of the paper are summarized as follows:(1)With the influence of economic development and population changing, the daily discharge per capita of rural residents in Three Gorges reservoir area increases little by little and stays from 50 to 60 L/d. According to the results of the research about water quantity and quality, we put forward the per capita emissions and water quality parameters scope of rural domestic wastewater in three gorges reservoir area.(2) In this paper, the technologies for decentralized treatment of rural domestic wastewater are divided into two types. As for type one, we recommend the septic-tank and household biogas digesters. As for type two, we put forward the priorities of the evaluated technologies by Grey Correlation model combining Subjective Weight with Objective Weight. And the priorities are as follows, Constructed wetland systems, Stabilization pond, The combination of constructed wetland and stabilization pond, Land infiltration filter, Aeration biological filter, Household biogas digesters. On the whole, Constructed wetland systems is the most suitable technology for decentralized treatment of rural domestic wastewater in Three Gorges reservoir area. Moreover, Stabilization pond and The combination of constructed wetland and stabilization pond are recommended for the advantages over other technologies. In addition, considering the construction fundament of household biogas digesters in this area, we suggest that we can use constructed wetland systems as a post-treatment technology of biogas processing so as to improve the rural wastewater treatment effect.(3) At present, we have lots of problems on rural domestic wastewater management, including unclear subject of operation and management; lack of corresponding laws and standards; lack of effective financing guarantee system; incomplete mechanism of management, supervision and examination; lack of professional operation staff and public participation. In view of the insufficiency of present management and future needs, we need to expand the financing channels for the construction of rural wastewater facilities, optimize its operation mode and strengthen the public participation. In addition, from the perspective of resource utilization and material circulation, we may make full use of the existing local biogas facilities, with which farmers can carry out a variety of courtyard ecological models. Finally, based on the study on engineering and managing practices, we put forward a plan for rural domestic wastewater controlling in Three Gorges reservoir area.