Study On The Full Scale Start-up And Opitimization Of Reversed A~2/o Process Of Biological Removal Of Nitrogen And Phosphrous From Municipal Wastewater

Aim at municipal sewage treatment plant for secondary treatment which has disadvantages like larger infrastructure investment and higher operating costs etc.A productive start-up operation and optimization study has been researched in this paper which is for the Reversed A²/O Process sewage treatment plant.At the same time,the construction investment and actual running costs of Reversed A²/O Process sewage treatment plant has been also analysized economically.The start-up of Reversed A²/O Process sewage treatment plant can combine intermittent and continuous flow sludge training methods,adopt by delivering the extra carbon resource to improve the grow speed of activated sludge which under the low influent volume and load conditions.Because of the long generation time,nitrifying bactedas are difficult to be trained in a short period of time.Parameter optimization research shows that:With the actual influent volume and water quality situation in Yuncheng Sewage Treatment Plant,the parameters of Reversed A2/O Process are controlled as:DO is 2mg/L,MLSS is 3000mg/L,Refluence ratio is 200%,SRT is 16d and Fw is 0.10kgBOD₅/kgMLSS·d.Actual productive results which under above operating conditions are indicating that the nitrification,denitrification as well as dephosphorization of Reversed A²/O Process are stable and can get a good effect for this water quality.The average removal rate of COD,TN, NH₃-N,TP were 80.8%,90.6%,78.7%,95.6%and 73.9%,the effluent quality meets the Urban Sewage Treatment Plant Pollutant Discharge Standards(GB18918-2002) A-level standards.On the condition of low tempreture in winter,an appropriate extension of SRT to 20 days, an increase of sludge to 3500mg/L,an improve of the dissolved oxygen content of 3mg/L, will ensure the effluent discharge standards.The sludge can be resumed soon by taking the following measures after sludge poisoning: Blocking the further flow of toxic substances;Stop the output of sludge;Increased return ratio;Yuncheng 40000m3/d Reversed A²/O Process sewage treatment plant construction total cost is 3866 million yuan,unit cost indicators is 991yuan/(m3/d) which is low than the 1350～1120yuan/(m3/d) of other process,operating costs is 0.482yuan/ton·water,unit operating costs is 0.325yuan/ton·water.The investment of project is not only low but also has the low operation cost,the process also have the advantage of simple operation as well as eonvinient maintenance.