Improved Simulation And Experimental Research On Sewage Recycling Process

Energy saving after meeting the discharge standards is a common problem of wastewater treatment plants.Since resources and energy recovery from sewage is beneficial for saving energy and reducing consumption,upgrading sewage treatment process based on resource recovery is becoming a hot topic of research and application.Therefore,this study aims to develop“Beijing standard A”resource-based technology,with focusing on experimental and simulation research.Based on TUD model,several domestic sewage treatment processes are modeled and each of the static simulations is provided by using the default values of the model and the actual influent water quality of a small wastewater treatment plant in Beijing.Comparative simulations demonstrate that UCT can accumulate more DPB in the system,which would enhance simultaneous N&P removal remarkably.Compared with external carbon addition,UCT with phosphate recovery in side stream has different approaches but equally satisfactory results,which the effluent TP would meet the need of the strict local standards of Beijing A and also save a great quantity of external carbon and chemical agent.As for energy recovery,especially for excess sludge treatment and disposal,a series of biochemical methane potential(BMP)batch tests are conducted to verify the feasibility of co-digestion between excess sludge and municipal solid waste,as well as the assessment of increased potential of methane production.The BMP tests demonstrate that the best positive synergistic effect happens when controlling VS ratio of dewatering sludge and food waste at1:1.5 respectively,which can increased methane production up to 21.4%.The semi continuous start-up experiments is suitable for organic loading rate(OLR)of 1 g VS/L/d.When increasing OLR to 1.5 g VS/L/d after stable gas production,the average methane content increased slightly(About 1%,the amount is to 70.6%).Based on calibrated anaerobic digestion model No.1(ADM1),the start-up phase(low OLR)in semi continuous culture of co-digestion between dewatering sludge and food waste could be well simulated and predicted by the calibrated model.The simulation results indicate that the biogas production and methane content in co-digestion system were affected by substrate ratio and hydrolysis rate constant(k_h).While the biogas production is most significantly affected by k_h of the mixed substrates,in the contrast,methane content is more sensitive to the ratio of each substrate.Moreover,increasing OLR after stable gas production is benificial to further improving methane content in biogas.