Study On Denitrification And Posphourus Removal By Improved A～2/O Process For Wastewater Of Low Carbon

The wasterwater quality and quantity of public washrooms vary within a large range and, especially in low season, outflow of pretreatment cannot meet the request of carban resource for denitrification and posphourus removal simultaneously using conventional A2/O process. Because Chemical Oxygen Demand decreases in the septic tank., the effecet of nitrogen and posphourus removal is influenced. Using the research achievement of Pro. T. Kuba of Netherlands Delft University of Technology for reference, the new idea that the Denitrifying Phosphorus removal Bacteria is incubated as dominant bacterias and the conventional A2/O process is improved correspondingly. The improved process consists of adding a settling tank, changing the begin and the end of the old sludge return routine and adding the flexible filling into the oxic tank. This process became a two-sludge system to accumulate the DPB so that it can slove the problem that it is difficult for the convetional A2/O process to arrive the high efficiency of denitrification and posphorus remval. The research develops the relevant experiment.The incubation of DPB is the key for the new process, so the two-stage sequencing approach of incubation is adopted, and DPB is incubated successfully.The result of captive test: The value of pH for the filmed nitrobacteria should be controlled at 8.5; the concentration of COD and NO3- influence the effect of the posphourus take-up and release, the concentration of COD should be controlled below 30 mg/L in the posphourus take-up process.The dynamic test is carried out in the condition of three flux and three different sludge return flux to get the optimal value of HRT and the sludge return. The result indicates that when the inflow Q is 10L/h and the sludge return is 0.3Q, the removal rate of TP is 94.2%, the removal rate of NH4+-N is 93.6%, and the removal rate of NO3--N is 91.3%. The research design and carry out the checking up the posphousrus rate of the bacteria so that it proved that the DPB takes an important role in posphourus removal. The results indicate the DPB is in a natural working status.The research shows that it is correct ,simple and practical for this idea to improved A2/O process based on dominant bacteria of DPB, The removal rate of the nitrogen and posphourus arrive more than 90% in the condtion of neither addition extra carbon resource nor increasing the cost.