Research on rural domestic sewage discharge, influencing factors and pollution loads in the Yangtze river basin

Abstract In this study, the characteristics of rural domestic wastewater discharge in the Yangtze River Basin, China, are analysed via geographic information visualization, pollutant load assessment, and correlation analysis. Through the use of a geographic information visualization system, this study intuitively presents the characteristics of rural domestic wastewater discharge in the Yangtze River Basin. In pollutant load assessment, the pressure caused by rural domestic wastewater discharge on maintaining the target water quality standards in the tributaries and main stream of the Yangtze River is comprehensively analysed. Correlation analysis reveals the social and natural factors influencing the levels of rural domestic wastewater discharge. The findings indicate that the average discharge level of rural domestic wastewater in the Yangtze River Basin remains low, with an average water discharge level of 39.24 L/(capita·day), a chemical oxygen demand (COD) of 27.50 mg/(capita·day), an ammonia nitrogen (NH3-N) content of 1.53 mg/(capita·day), a total nitrogen (TN) amount of 2.74 mg/(capita·day), and a total phosphorus (TP) content of 0.22 mg/(capita·day). Based on the current levels of rural domestic wastewater discharge and the concentrations of the above substances in the natural environment, the impact of rural domestic wastewater discharge on maintaining water quality functions in the tributaries and main stream of the Yangtze River can be considered negligible, although regional differences exist. Discharge levels are significantly influenced by various social factors, including educational level, per capita disposable income, and consumption expenditures, as well as natural factors such as average annual temperature, average annual humidity, and average annual rainfall. Overall, this study provides reference data for the analysis and management of rural domestic wastewater discharge in both similar regions in China and globally.