The Characteristics And Influence Factors On Effluent Quality Of Wastewater Treatment Plants In Gusu Area

With the rapid development of economics and increasing of population and the expanding of the area of Suzhou City,domestic sewage discharge in the city is increasing continuously.Although there are many rivers in Suzhou,but the environment capacity of surface water is quite limited because of plaint landscape.Even now many wastewater treatment plants were built or expanded,However,the increasing urban sewage discharge is gradually approaching the area's water environment capacity,to bring enormous pressure to the sewage plant.In order to improve and stabilize the effluent quality,the wastewater treatment plants in Gusu Area,namely Chengdong wastewater treatment plants?C.WTP?,Fuxing wastewater treatment plants?F.WTP?and Loujiang wastewater treatment plants?L.WTP?were taken as main research object.The daily record of water quality from Nov.2013 to Oct.2014 were taken for research to concluded the characteristics of effluent quality in different WTP.After analysis on the relationship among the effluent quality,influent quantity,influent quality and temperature,then using the regression equation with stepwise multiple linear regression by “IBM SPSS Statistics 19”,the main influence factors including the main treatment process are analyzed finally.Then put forward the suggestions.The conclusions were following:?1?COD,NH₃-N,TP and TN content in effluent water in C.WTP,F.WTP and C.WTP is unstable,the content of COD and TP is not obvious,content of NH₃-N and TN is less in summer than in winter.After compared,the content of COD and TP in L.WTP is the less,and the content of NH₃-N and TN in C.WTP is the least.?2?The main influence factors of COD and TP in effluent water are mainly the treatment process and human regulation,but not the influence of influent quantity,influent quality and temperature.The main influence factors of NH₃-N and TN are treatment process,human regulation,temperature,influent quality and influent quantity.In C.WTP,temperature is the most influence factor of effluent content of NH₃-N and TN;influent quantity is the second one of effluent content of NH₃-N and influent content is the second one to effluent content of TN.In F.WTP,the most influence factor to the effluent concentrations of NH₃-N and TN is the temperature and the next one is influent content.In L.WTP,the most influence factor of effluent content of NH₃-N is temperature and the next one is influent content,and the mostinfluence factor of effluent content of TN is influent water and the minimal influence is influent quantity of water.?3?Suggestions.It is better to Transform A²/O into inverted A²/O process and build improved type of UNITANK and MSBR process in C.WTP.Besides throwing carbon source and adjusting the influent quantity of water,the anaerobic acidification pond in front of the system and residence time in F.WTP can be increase in biochemical pond,then some agents can be added for phosphorus removal.The residence time in the first stage of UNITANK process can be increased in L.WTP,and it need to be reconstruct and expand when necessary.In addition,all these wastewater treatment plants can be strengthen aeration or be changed the way of aeration at low temperature,and sludge age should be controlled at a higher level when the temperature is less than 15?.The results of stepwise multiple linear regression is the same as the actual.The main influence factors and the inflence level can be determined with these methods in the wastewater treatment plants.The main influence factors of effluent water quality are become clearly based on the research using mathematical method and based on the main treatment process.Therefore,,the suggestion of how to improve the quality of effluent water was presented after the quantitative analysis on influence factors.