Pilot-scale Study On Biological Phosphorus Removal In Upward Continuous Flow Reactor Of Anaerobic-aerobic System

According to the principles of simplicity, energy saving, high efficiency and practicability, design and development of upward-continuous-flow reactor of anaerobic-aerobic system and biological phosphorus removal efficiency of the reactor from municipal wastewater are studied in this paper.The tentative experiment firstly compares the phosphorus removal efficiency of four anaerobic-aerobic reactors using the mode of different inflow and outlet(Reactor using the mode of intermittent transient inflow and intermittent outlet；Reactor using the mode of intermittent slow inflow in anaerobic stage and intermittent outlet；Reactor using the mode of continuous inflow and intermittent outlet, and Reactor using the mode of continuous inflow and continuous outlet). In terms of testing result of Reactor using the mode of continuous inflow and continuous outlet, a new phosphorus removal reactor-upward-continuous-flow reactor of anaerobic-aerobic system-is designed. Two sets of operating behavior are performed in phosphorus removal study of the reactor of anaerobic-aerobic system. Results show that:①with sludge mid-loading of 0.47～0.63kgCOD/(kgMLSS·d), inflow of 6.90～7.68L/h, reflux ratio of 84～88%, SRT of 12d, the ratio of diameter to deepness of anaerobic column of 1:2.7 and aerobic column of 1:4, the average removal efficiency of PO43--P is 93.89% and in effluent, total phosphorus(TP) is less than 0.72mg/L and organic matter(COD) is less than 40mg/L; ② with sludge low-loading of 0.15～0.38kgCOD/(kgMLSS·d), inflow of 3.70～7.20L/h, reflux ratio of 89～112%, SRT of 15～30d, the ratio of diameter to deepness of anaerobic column of 1:5.5 and aerobic column of 1:11, the average removal efficiency of PO43--P is 93.51% and COD is less than 30mg/L in effluent. The above results demonstrate that: phosphorus removal efficiency of this reactor is almost equal to SBR (sequence batch reactor). Meanwhile it can be easily employed because of the mode of continuous inflow and continuous outlet.Based on CSTR cascade (CSTR continuous stirred tank reactor) theory and Eckenfelder's organic matter degradation model, COD and PO43-－P degradation mathematical model of upward-continuous-flow reactor of anaerobic-aerobic system areestablished according to the testing result. Some suggestions on operating control and optimization in this process are put forward in this paper.