Design Scheme And Technical Research Of Municipal Sewage Treatment Project In D City

With the rapid development of D economy,the density of urban population is increasing,and the level of urbanization is rising.The sewage discharge in a town of D continues to increase,but the drainage facilities are backward and lack of funds and channels for sewage treatment.Most of the untreated sewage is discharged directly into the rural River and most of the water body in the town is polluted.It is imminent to study and develop the processing technology suitable for the treatment of sewage water treatment in small towns.Through investigation and analysis,there are two problems in the sewage discharge status of the town in D City:on the one hand,the sewage collection system is now a system of rain and pollution,almost no drainage pipe network in the town,the receiving water is the central lake of the town;on the other hand,there is no sewage treatment plant in the town,only a small amount of septic tanks are discharged directly to the water body.In view of the above problems,the design is divided into two parts:first,the sewage pipe network is reformed,the rain and pollution confluence system is changed into the rain and sewage diversion system.The two is to design a set of economical and reasonable sewage treatment system according to the water quality and water condition of the town and the local related planning requirements,and the water quality is required to reach the first grade A standard.First of all,the prediction of sewage volume in this town is 4000m~3/d in the recent2017-2025 years and 8000m~3/d in the last 2026-2030 years.The sewerage network specifically changes the former confluence pipeline into a rainwater pipe,laying a sewage pipeline underneath,and redesigning the sewer network.In this paper,the technical and economic comparison and demonstration of various two grade biological treatment,depth treatment,phosphorus removal and disinfection process were carried out.Finally,the sewage treatment process was determined as:coarse grille+lifting pump room+fine grille+sand sedimentation tank+CASS biological pool+grid flocculation sedimentation tank+fiber disc filter+disinfection,two stage treatment process selection CASS The coagulation and sedimentation+filtration process is adopted in the process and the advanced treatment.The grid flocculation tank and the inclined tube settling tank are jointly constructed,and the effluent reaches the first grade A standard of the national standard.The design is small in scale,less in sludge yield,directly concentrated and dehydrated,and water content is up to 60%.According to the comparison results of the above sewage and sludge treatment processes,the total design scale of the sewage treatment plant is 8000m~3/d,and the drainage system in the near future is 4000m3/d.The long term total variation coefficient should be 1.66,the recent total variation coefficient should be 1.80,the long term maximum flow rate is553.4m~3/h,the maximum flow rate is 300m3/h in the near future,and the connected pipe and canal etc.are calculated according to the maximum time flow.The whole plant area is divided into three parts.The factory front area is located on the south side of the factory area,and the sewage treatment area and sludge disposal area are located on the north side of the factory area.The structures in the production area are arranged in several shapes according to the technological process according to the direction of water entry and exit.