Study On The Pollutant Degradation Model Of Hybrid Biofilm-activated Sludge Process

At present, the water pollution of Songhua river basin is serious, specially in section of industrial park in the icebound season. As a important branch of Songhua River, the feiketu river located at the water source area of Songhua river, its water quality safety immediate influence the water body safety of Songhua river and the water supply safety of Harbin, so it very important to seek a high efficient sewage treatment method. The hybrid biofilm-activated sludge process was studied by a lot of researchers now, but the pollutant degradation model of it was still not mature. This article took industrial park's sewage and the hybrid system of A²/O as the research object, established the sewage treatment model of industrial park and verificationed it.In this paper, using mathematical simulation method, the organic removal model was be researched at normal/low temperature based on the Monod equation, the reactive diffusion model and the ASM model. Established the organic steady formula and the biomass formula in effluent in anaerobic stage, anoxic phase and aerobic stage, and then verified by experiments. The results showed that when the organic concentration of influent was 210³20mg.L-1, under the normal temperature condition, the minimum deviation rate between the theoretical value and the actual value of biomass and organic concentration in effluent in anaerobic stage was 5.1%, 3.7%, and the maximum deviation rate was 9.9%, 9.4%. The minimum/maximum deviation rate in anoxic phase was 8.1%, 2.2%/10.4%, 7.9%. And The minimum/maximum deviation rate in aerobic stage was 7.9%, 7.1%/12.7%, 16.5%%. The deviation rate was rised under the low temperature condition. The theoretical value of biomass was always higher than the actual value, and the theoretical value of organic concentration was always lower than the actual value.Based on the material balance equation of nitration and denitrification stage, the model of nitration and denitrification was be studied at normal/low temperature, established the NH3-N steady formula in effluent in anaerobic stage, anoxic phase and aerobic stage, and the NO3--N steady formula in effluent in anoxic phase. Then verified by experiments, it shown that when the NH3-N concentration in influent was 30⁵4mg.L-1, the minimum/ maximum deviation rate between the theoretical value and the actual value of NH3-N in anaerobic stage was 12%/ 16% under the normal temperature condition, and the minimum/ maximum deviation rate was improved 1%/ 2.5% under the low temperature condition. The the minimum/ maximum deviation rate in anoxic phase was 11%/ 16.5% when the temperature is normal, and the minimum/ maximum deviation rate was improved 2.1%/ 1.7% when the temperature is low. Under the normal temperature condition in aerobic stage, the the minimum/ maximum deviation rate was 10.5%/ 15.2%, and under the low temperature condition, the minimum/ maximum deviation rate was improved 4%/ 4.1%. The minimum/ maximum deviation rate between the theoretical value and the actual value of NO^3--N in anoxic phase was 12.5%/ 15.8% at normal temperature, and the minimum/ maximum deviation rate was improved 4%/ 5.6% at low temperature.This paper also studied the process of phosphorus removal, established the model of absorption and release of phosphorus in hybrid system at normal/low temperature. The comparison of theoretical value and the actual value indicated that the minimum/ maximum deviation rate between the theoretical value and the actual value in anaerobic stage, anoxic phase and aerobic stage were9.3%/ 14.6%, 9.1%/ 12.4%, 7.6%/ 9.5% at normal temperature, and the minimum/ maximum deviation rate in anaerobic stage, anoxic phase and aerobic stage were 14.4%/ 19.4%, 12.4%/ 14.9%, 10.4%/ 13.6%at low temperature.The hybrid system pollutant degradation model's establishment can to guide the industrial park sewage factorys'monitoring and working, it deserves the demonstration effect of the wastewater treatment of Songhua river basin and Northeast various provinces. It can improve the pollution status and water environment of songhua river basin, and it is also a signality to water quality improvement during the icebound season.