Process Design And Operation Effect Analysis Of Wastewater Treatment Plant In Northeast Small Town

In this paper,the Bajiazi Wastewater Treatment Plant was taken as example to design the applicable treatment process for the wastewater treatment in northeast small town.Based on the analyzing of the current situation of water supply and drainage in the service area of Bajiazi Wastewater Treatment Plant,the construction scale,design water quality and treatment process were reasonably determined.After that,the cost of investment and operation were analyzed.All the wastewater in the town,major was the domestic sewage,were collected and treated in the Bajiazi Wastewater Treatment Plant.The designed average daily flow(Q_average)was 2000m³/d,and the acceptable maximum flow(Q_max)was 125 m³/h.According to the flow and composition of wastewater,the designed qualities of the influent were as follows:COD was350 mg/L,BOD₅ was 200 mg/L,SS was 300 mg/L,TN was 50 mg/L,NH₃-N was 40 mg/L,TP was 8.0 mg/L,and pH was 6⁹.The effluent qualities were complied with the“urban sewage treatment plant pollutant discharge standard”（GB 18918-2002）level A standard.BIOCOS process was chosen as the main process,which combined with coarse grille,fine grille,sediment pool,buffer pool,filter room,disinfection pool.According to the analysis of operation results,we found that the qualities of effluent were stable,and all the indexes met the requirements of level A standard.At the same time,the changing of the seasons and temperature had little impact on the effluent qualities.Even in winter,the effluent could still met the requirements,indicating that the process was suitable for sewage treatment in northeast small town.The total investment of the plant was RMB 6.7738 million,including the project cost of5.3952 million,other expenses of 0.8554 million,preparatory expenses of 0.50 million,and the working capital of the foundation was 0.0232 million.The annual operating cost was RMB 0.87million,and the operating cost was RMB 1.19/m³,indicating that the process was highly economic and suitable for practical application.BIOCOS process is simplified and costly,it needs less operating equipment and maintenance,and has a wide application range.Meanwhile,it is suitable for most domestic water quality and exhibits strong resistance to temperature changing.Therefore,the BIOCOS process is suitable for sewage treatment in northeast small town.This project provided the basis and demonstration for the construction of sewage treatment plant in northeast small town.