Estimation of Sewage Production and Discharge Coefficients of Rural Areas in Taihu Lake Basin

A total of 9 farmer households(3 high,3 medium and 3 low in income level),typical of the Taihu Lake basin,were selected for studying quantitatively production and discharge coefficients of various pollutants in sewage from the rural areas of the basin through in-situ monitoring and indoor survey.It was found that income level had no significant influence on production coefficient of TN,NH+4-N and TP in total wastewater,but had on wastewater quantity,COD production coefficient and discharge coefficients of various kinds of pollutants in total wastewater,showing an order of high income household medium income household low income household in effect.The contribution of toilet wastewater to the total pollutant load was very high,reaching 67% or over in COD,and 84% or over in TN,NH+4-N and TP,so the utilization and treatment rates of toilet wastewater are the leading factors influencing discharge coefficient of pollutants,while agricultural income level and septic tank type have significant influence on the two factors.