Analysis of the characteristics of major pollutants discharged from wastewater in China’s provinces

Abstract

Abstract In recent years, the discharge of major pollutants in China's wastewater has shown a downward trend, but it is still at a high level. Based on data collected from 31 provinces in China from 2011 to 2020 (except 2018), the entropy method was used to evaluate and analyze the discharge of major pollutants in wastewater in China's provinces. The results showed that the emission of COD, ammonia nitrogen (NH3), total nitrogen (TN) and total phosphorus (TP) decreased by 27.57%, 79.87%, 59.27% and 61.25%, respectively, due to the environmental protection plan of the “12th” and “13th Five-Year Plan”. In terms of regional emission differences, the Northwest region was the lowest compared with other regions, accounting for 4.02%-6.92% of the national pollutant emissions, and the Central China region was the highest, accounting for 20.52%-27.06% of the national pollutant emissions. The average value of pollutant emissions per unit of GDP was decreasing year by year on the whole, but Guangxi and Tibet show a trend of first decreasing and then increasing. Correlation analysis shows that TN and TP were significantly different at the 0.01 level, and TN and TP were the main pollutants in the provincial wastewater discharge in China. Through clustering and MDS analysis, Beijing and Shanghai have been performing quite well in controlling water pollution discharges, while the two provinces of Tibet and Guangxi need to continue their efforts in water pollution control.