Pilot Experimental Study On Efficent Nutrient And Phosphorus Removel Process

Since the reform and opening up,the city of our country increasing the degree, the steps faster and faster, however, city sewage treatment and drainage, especially nitrogen and phosphorus in sewage the processing in City, always an urgent problem. City life sewage is generally characterized by relatively low carbon nitrogen.The main problems existing in the conventional A2/O process is the nitrifying bacteria, denitrifying bacteria and phosphorus accumulating bacteria exist contradictions and competition in the organic loading, sludge age and carbon source demand, it is difficult in the same system, to the removal effect of nitrogen and phosphorus efficient.The process were improved as follows for the A2/O:First, adding a anoxia mixed reflux between anoxic and anaerobic pool, and return sludge from the precipitation pool and the inlet mixture;Second, the anoxic pool is divided into two segments, the mixture of aerobic nitrification after the water pump to pump water back to the first anoxia pool; the anoxic pool through denitrification, composed of a water pump will be mixed liquid from the anoxic tank 2 return to anaerobic pool, increase the generation time of denitrifying bacteria.The following main function of the process:First, strengthen the role of time the denitrifying bacteria in the anaerobic tank; Second, to ease the competition between PAOs and denitrifying bacteria in the anoxic zone, further strengthen the nitrogen and phosphorus removal effect; basicity;The last, make full use of water, to strengthen the functions of denitrifying bacteria.This process through the content of dissolved oxygen in the aerobic pool adjustment,Control of anaerobic pool: anoxic pool:aerobic pool volume ratio,Reflux ratio of nitrification, anoxic mixing liquid reflux ratio, sludge return ratio, hydraulic retention time,etc.The best working parameters to find the process.In the process, Guangzhou wastewater plant fine grid of the wastewater in test water treatment pool, running through the actual research to test the water treatment tank, come out the best condition of the process, as the actual water treatment process operation to provide guidance and reference.The optimum operation parameters of the modified A2/O device were obtained, and were given in the paper. The results showed that the residual of COD、NH4+-N、TN、TP in the effluent from pilot plant were 37.17mg/L, 2.64mg/L, 16.74mg/L, and 0.73mg/L, respectively, when the temperature, dissolved oxygen(DO) of the tail end of aeration pool, hydraulic retention time(HRT), nitrification liquor reflux ratio(R), oxygen-poor mixture reflux ratio(R1), and sludge reflux ratio(r) were 22~28℃, 2mg/L, 8h, 200%, 150%, and 60%~80%, respectively. The final effluent was satisfactory with one-class B criteria of <Chinese discharge standard of pollutants for municipal wastewater treatment plant>(GB18918-2002).