Evaluation and Optimization of Rural Sewage Treatment Technologies in the Middle Reaches of the Yangtze River Based on Group Decision Making and Analytic Hierarchy Process

Abstract

Rural sewage treatment in the Yangtze River basin is an important link to achieve the great protection of the Yangtze River, but the existing treatment technologies are difficult to choose and have various techniques and a lack of evaluation. Therefore, this study researched and collected the case information of rural sewage treatment projects in the middle reaches of the Yangtze River, analyzed the application of each treatment technology under different collection modes and discharge standards, constructed the evaluation index system of rural sewage treatment technologies, and then conducted a classification evaluation of processing technologies for each application scenario based on group decision making and the Analytic Hierarchy Process. The results showed that:the collection modes of rural sewage in the middle reaches of the Yangtze River were mainly single village or small-scale joint village, the treatment scale was mainly concentrated below 200 m3·d-1, the treatment technology was most applied by the anaerobic+ecological process (28.05%), and the application of integrated equipment was also more widely used (22.47%). The technical performance in the criterion layer had the largest weight (0.5039) in the evaluation index system, followed by those of economic benefits (0.2474), operation and management (0.1559), and environmental impact (0.0928), respectively; the four indicators of TP removal rate, ton water operation cost, ammonia nitrogen removal rate, and maintenance difficulty had higher weights. The evaluation and optimization results showed that the enhanced ecological and anaerobic+ecological treatment technologies were suitable for promotion and application in the rural areas of the middle reaches of the Yangtze River. The results of this study can provide scientific basis and reference for the selection of rural sewage treatment technologies in the middle reaches of the Yangtze River.