The Mechanism And Processes Study On Denitrifying Phosphorus Removal

The standard of wastewater discharge was controlled more strictly with the severe eutrophication question occurred. Therefore, the wastewater techniques developed gradually from the period of pure COD removal to the period of simultaneous COD, nitrogen and phosphorus removal. Today, the nitrogen and phosphorus removal technology aimed for eutrophication control has been the study focus in the wastewater treatment area. Denitrifying phosphorus removal is the new prominent biological wastewater treatment technique. The Anaerobic-Anoxic/Nitrification (A₂N) system is a continuous-flow, two-sludge process which is fundamentally based on the technique of denitrifying phosphorus removal. The main advantage of A₂N system is the possible saving of COD (50%) and energy (aeration) (30%) and less sludge production(50%).These characteristics benefit significantly for the municipal wastewater treatment, especially for the low influent C/N municipal wastewater treatment where the lack of carbon effects the nutrient removal efficiency.In order to accelerate the investigation development of A₂N process, in particular to accelerate the application of A₂N process for the low C/N wastewater treatment, the continuous model dynamic experiment operated with municipal wastewater combined with batch experiment was carried out. The mechanic of denitrifying phosphorus removal in A₂N system and the effect of different operational factors and influent characteristics on the A₂N system were studied systematically for the first time. Based on this, Effect of added carbon source and nitrate concentration on the denitrifying phosphorus removal by denitrifying phosphorus removal bacteria (DPB) sludge was systematically studied using batch experiments for the first time. Simultaneously the variation of ORP was investigated and further to verify the feasibility of ORP as a process control parameter.The A₂N process was set up in two-sludge system, in which nitrifies were separated from denitrifying phosphorus removal bacteria in a nitrification biofilm reactor, whereas DPB sludge was recalculated between an anaerobic reactor and an anoxic reactor. The process solves the competition of organic substance among Poly-p organisms and denitrifiers as well as the problems of overgrowing of slow...