Study On Operation Simulation And Process Optimization Of WETP

The extensive experience management mode of sewage treatment plant in China has been adopted for long time.It was difficult to guide the operation of sewage treatment system economically and reasonably with traditional experience operation mode.Besides,it is also difficult to predict and guide the optimal operation management plan with traditional operation mode.The rapid development of activated sludge model and software provided new methods for the optimization of wastewater treatment process.Take the second sewage treatment plant of Suzhou new area as an example,ASM2D was used to simulate the operation of A²/O process in the wastewater treatment plant with the BioWin software.The model can reflect the real operation status of the plant fairly.The influence of main operation parameters on the biological treatment system was analyzed with the model.To ensure the effluent quality was stable for long time,optimal operation condition of the typical seasonal condition in the sewage treatment plant was formulated.According to the structural characteristics of the process,a series of CSTR was used to simulate anaerobic+anoxic+oxidation ditch process.The steady simulation and dynamic verification were carried out with the average historical data of summer,2015 and the daily dynamic data lasted for one month in April,2014.Results showed,by calibrating influent wastewater characterization?Fus=0.07 g?COD?/g?total COD?,Fup=0.20 g?COD?/g?total COD?,Fbs=0.80 g?COD?/g?total COD??and kinetic parameters(m_AUT=0.6 d^-1,K_O2=0.1 g O2/m³),simulation results of the main effluent quality and the MLSS in the oxidation ditch were matched well with the measured.The model could reflect the process of carbon removal,nitrogen and phosphorus removal in the biological treatment system.In view of the typical seasonal influent conditions during the whole year,a typical seasonal optimization scheme of sewage plant was developed based on the model.The optimal operational condition in summer:SRT=15 d,MLSS controlled at 2500 mg/L,internal recycle ratio 200%,sludge recycle ratio 67%,the influent flow of anaerobic and anoxic is 100:0,DO of 3#aerator controlled at 1.0 mg/L.The optimal operational condition in spring and autumn:SRT=20 d,MLSS controlled at 4300 mg/L,internal recycle ratio200%,sludge recycle ratio 50%,the influent flow of anaerobic and anoxic is 100:0,DO of3#aerator controlled at 2.5 mg/L.The optimal operational condition in winter:SRT=25 d,MLSS controlled at 5500 mg/L,internal recycle ratio 250%,sludge recycle ratio 50%,the influent flow of anaerobic and anoxic is 100:0,DO of 3#aerator controlled at 3.5 mg/L.Under the optimized scheme,the effluent quality of the wastewater treatment plant in the whole year meets the level A discharge standard.