Research On The Key Technical Of Upgrading And Reconstruction For The Municipal Sewage Treatmental Process

On the basis of a systematic analysis of the problems of the current sewage treatment works such as high SS content in inflow water, discharge of out of water TN without reaching standard and high content of water in excess sludge, in a method combining field research with experiment and actual measurement, the author points out the reasons of high SS content in influent and puts forward increasing a horizontal flow grit chamber for pretreatment to reduce SS content in effluent so as to alleviate its negative effect on organisms. The author finds the reasons why out of water TN is out of limit and puts forward the measures of reducing sludge loading, prolonging hydraulic retention time and adding dominant bacteria PCN etc. after observing the results of biological nitrification and denitrification to effectively improve the biological nitrification and denitrification efficiency and realize the standard discharge of out of water TN. The author also uses related software packages to analyze the correlations of water quality parameters of influent and effluent. The following correlations of water quality parameters between influent and effluent are discovered:there is a moderate negative correlation between BOD₅/TN of influent and two TN variables of effluent, there is a low negative correlation between BOD₅/TP of influent and two TP variables of effluent, there is a very low correlation between BOD₅/COD of influent and TP of effluent and there is almost no correlation between SS/BOD₅ of influent and TN of effluent. These correlations provide reference for upgrading and reconstruction of sewage treatment works. The author also analyzes the reasons of high content of water in excess sludge and puts forward improving dewatering units to lower the water content in sludge.Through analyzing the operation of the system after process improvement, the author finds that all the water quality indexes improve substantially. The removal rates of COD, TN, NH3-N, TP and SS are respectively more than 84%,30%,94%,76% and 95%. All the effluent parameters reach A discharge standard of first grade as stipulated in Pollution Discharge Standards Of Sewage Treatment Works In Cities And Towns ?GB18918-2002?. The water content in sludge is below 60%. Meanwhile, the improved process runs steadily and is resistant to impact load.