Evaluation method for engineering technology of rural domestic sewage treatment based on fuzzy integral model

Abstract: Rural domestic sewage is the main source of pollution of rural water pollution, including all kinds of washing water of daily life, kitchen waste water and animal wastes. Most of the rural domestic sewage flow directly into rivers, lakes and reservoirs. As a result, the content of nitrogen, sulfur, phosphorus increased and leading to the eutrophication of water body. It not only damaged the water environment but also affected the health of human body seriously. The difficulty of rural domestic treatment is that rural domestic sewage is widely distributed and has a big difference between areas. On the other hand, the rural sewage quality and quantity have great fluctuations. Due to the poor infrastructure construction, the sewage pipe network is not perfect in rural area. At the same time, the weak rural economy and the lack of professional sewage treatment technology and management personnel, make the rural sewage treatment and resource utilization degree inferior to the city sewage treatment plants. Currently, the rural domestic sewage emission leads to the problems of agricultural nonpoint source pollution and shortage of water resources in rural areas in China. The protection of rural water environment is the guarantee of the development of agricultural production and construction of beautiful countryside. The wastewater treatment in rural areas is the need to change the disorderly discharge situation of rural life sewage, and improve the living conditions of farmers. Because of different circumstances in thousands of counties, the rural domestic sewage treatment must accommodate one's measures to local conditions and classification guidance. It is very important to put forward the practical domestic sewage treatment methods and measures. The government departments attach great importance to this issue, which means that this question must be addressed in the coming construction and development of rural areas. Scientific research institutions have the responsibility to carry out scientific experiments and studies to support resolving this problem. In this study, a serial surveys were conducted on the status quo of rural domestic sewage pollution, emission characteristics, water quality characteristics and the existing treatment processes and technologies. Also site visits of the typical rural domestic sewage treatment works in the rural areas were carried through to learn and understand the treatment effect, operating conditions and existing problems of the projects. With choosing and analyzing the evaluation indexes from economic, technical characteristics and environmental effects, the evaluation index system of rural domestic sewage treatment technologies was constructed. With integrated analytic hierarchy process and entropy method, the index weights were determined by considering the subjective and objective weighting methods. Based on hierarchical fuzzy integral model, a comprehensive evaluation was made on 15 kinds of domestic sewage treatment engineering techniques existing and commonly used in rural areas. Through sorting the final results, 10 kinds of more excellent treatment technologies were selected, such as ecological filter tank, ecological pond, anaerobic (facultative) pond, constructed wetland, integrated purification tank, anaerobic biological contact oxidation constructed wetland. The research can provide a reference for the construction of rural domestic sewage treatment works.