소규모 도시 합류식하수관거의 초기월류수와 오염부하량과의 관계

Abstract

In combined sewer systems, rainwater is transported to the wastewater treatment plant together with domestic and industrial waste water, but during rainy seasons, the rainwater is not transported, and overflows into rivers. This overflow of rainwater is called combined sewer overflow (CSO). These CSOs can cause higher pollutant loads than the treated plant effluent, due to washed-out pollutants accumulated in pipes. In addition, initial concentrations of pollutants are higher in CSOs than in measurements taken afterward. This study evaluates the importance of initial CSOs. Maximum CSO concentrations of BOD, CODCr, and T-N are 54 mg/L, 120 mg/L and 14.2 mg/L respectively. These concentrations were shown to increase with overflow rainwater in CSOs due to accumulated pollutants in pipes. The precise pollutant load entering the river was BOD 43.5 kg, CODCr 97.6 kg, and SS 222.4 kg in this study. In accumulated loading and overflow, concentration ratios increased to 40% before decreasing. Results of this study show that because initial loading of pollutants is higher than later levels, control of initial CSOs is important.