Study On The Performance And Optimum Operation Of CAST Process

With the severe eutrophication question occurred, the standard of wastewater discharge was controlled more strictly. Therefore, the wastewater techniques developed gradually from the period of pure COD removal to the period of simultaneous COD, nitrogen and phosphorus removal. The application and investigation development of the new wastewater treatment process with the function of nitrogen and phosphorus removal has been the study focus. CAST process is a novel wastewater treatment process with the function of nitrogen and phosphorus removal, which has been applied more and more often these years and has a broad marketing prospect in our country, due to many merits such as little floor space, no need for preliminary and secondary sedimentation tanks, low cost of capital construction and operation, preventing sludge bulking effectively and convenient operation and management.To promote the investigation development of CAST process, especially the application in municipal sewage treatment, a series of production tests were carried out. Zhenjiang Zhengrunzhou sewage plant as the experimental field, the performance of CAST process was studied roundly. Study emphases was put on N and P removal of CAST. Based on studying the influence on operation effect of different operation conditions, the optimum controls parameters were put forward. In the meantime, the performance of nitrification and denitrification of CAST sludge was studied through static test.The CAST process of Zhenjiang Zhenrunzhou sewage plant has an stably excellent effect on the removal of organic matter and phosphorus. According to the experimental result, when MLSS was 3500 ～ 4500mg/L, cycle was 4h, DO concentration was 0～0.5 mg/L in influx/aeration phase and 2～3 mg/L in aeration phase, COD load was 0.3～0.8kg/(m³d), SRT was 8～12d and water temperature was 15～21°C, the mean removal efficiencies of TP, NH₃-N and TN were 82.2%, 28.6% and 20.7% respectively; mean concentration of TP, NH₃-N and TN in effluent were 0.25,14.61 and 18.16mg/L respectively.