Study Of Sludge Reduction And Removal Of Nitrogen And Phosphorus In Modified A~2/O Process

Currently, there is a conflict between removal of nitrogen or phosphorus and sludge reduction in a lot of sludge reduction technologies at home and abroad. The sludge reduction technologies needed to be developed is how to achieve a good sludge reduction effect, the premise of the technologies is to ensure a good removal rate of nitrogen or phosphorus.In order to solve the conflict between removal of nitrogen or phosphorus and sludge reduction technologies,we have reformed the conventional A~2/O process on the base of comprehensive analysis on a lot of sludge reduction technologies at home and abroad.There are four stages in tests including conventional A~2/O process,"the conventional A~2/O process + bypass chemical phosphorus removal"system,"the conventional A~2/O process + anaerobic-aerobic"system and modified A~2/O process.The main conclusions through experiments are the following:1.The conclusions of running tests of Conventional A~2/O process show that when the COD of inlet water quality is 347mg/L~490mg/L,the TN is 36.03mg/L~52.00mg/L and the TP is 4.00mg/L~9.00mg/L, their average figure of outlet water quality is separately 34mg/L,15.23mg/L and 0.76mg/L, and the average removed rate of them is separately 91.25%,65.22% and 88.20%,the outlet water quality achieves to the frist Grade B standard of"the standard of pollution emissions in Urban sewage treatment plant"(GB18918—2002).For the excess sludge in 30days,the Cumulative emissions is 563.2g,the productivity Yobs1 is 0.447gMLSS/gCOD.2.The Conclusions of running tests of the"conventional A~2/O process + bypass chemical phosphorus removal"system show that when the COD of inlet water quality is 347mg/L~490mg/L,the TN is 39.33mg/L~50.80mg/L and the TP is 4.30mg/L~8.90mg/L,the poll of bypass chemical phosphorus removal make the removed rate of TN and TP separately add to 4.07% and 2.23% in Conventional A~2/ O process. Recycled of phosphorus in chemical phosphorus removal pool is account for 23.63% in total phosphorus of inlet water.3.The Conclusion of running tests of"the conventional A~2/O +anaerobic-aerobic"system shows Lysis,nitrification,denitrification and other metabolic activities occured in suldge reducing equipment,when the COD of inlet water quality is 369mg/L~480mg/L,the TN is 37.00mg/L~50.89mg/L and the TP is 5.03mg/L~9.00mg/L,the removed rate of COD can keep with the lever with the conventional A~2/O process, but the removed rate of TN increased 3.85%, the removed rate of TP reduced 2.29%,and the TP exceed the one of the frist Grade B standard in"the standard of pollution emissions in Urban sewage treatment plant". The producitity of sludge is 0.278gMLSS/gCOD, and the rate of reduced sludge Yobs3 is 37.9%。4.The Conclusion of running tests of modified A~2/O process shows that when the COD of inlet water quality is 351mg/L~476mg/L,the TN is 38.03mg/L~52.04mg/L and the TP is 4.21mg/L~8.85mg/L,the whole of outlet water quality are good, every index achieved to the demand of discharge in the frist Grade B standard of"the standard of pollution emissions in Urban sewage treatment plant"(GB18918—2002), and the conflict between removal of nitrogen or phosphorus and sludge reduction has been solved by the modified A~2/O process.Compared with the conventional A~2/O process,the removed rate of TN and TP in the modified A~2/O process separately increased 5.65% and 2.37%,the producitity of sludge Yobs3 is 0.276gMLSS/gCOD, the rate of reduced sludge is 38.3%.