Analysis of Water Quality and Quantity Change Characteristics and Influencing Factors of Typical Sewage Treatment Plants in Kunming

In order to explore the characteristics of changes in sewage volume and water quality concentration at the end of the sewage pipe system in Kunming urban area, their characteristics and the correlation of each pollutant were systematically analyzed using the monitoring data of a typical sewage treatment plant from 2017 to 2019. The analysis results showed that the volume of sewage at the end of the pipe network over the years was significantly correlated with rainfall, which was significantly higher than that of the dry season, while the mean values of BOD₅, COD_Cr, SS, TN, TP and NH₃-N mass concentrations were lower than that of the dry season, which was characterized by the “W” type of change, and the most frequent values were 250～300 mg/L, 140～140 mg/L, 200～250 mg/L, 30～35 mg/L, 3～4 mg/L, 22～24 mg/L, and the correlation between the concentrations of each index was highly significant. The ratio of the mass concentrations of BOD₅/COD_Cr, BOD₅/TN, BOD₅/TP, and TN/TP showed that the influent water was good in terms of biochemistry, and the nitrogen and phosphorus in the incoming wastewater could meet the nutritional demand of microorganisms. The nitrogen and phosphorus contained in the incoming sewage basically met the nutrient demand of microorganisms, but in the anoxic stage of the sewage treatment in December of the dry season, denitrification was added with exogenous carbon to solve the problem of insufficient source water in order to improve the effect of phosphorus removal.