Design Of Phase I Project Of Eastern Wastewater Treatment Plant In Shenyang City

Due to the distribution of Shenyang City's urban sewage treatment plant and the city's drainage network planning development,this paper has carried out the design and research work for the first-phase project of eastern wastewater treatment plant in Shenyang Citythe with 50 million m³/d sewage.The influent water quality of the plant is COD_Cr 350 mg/L,BOD₅150 mg/L,suspended solids 210 mg/L,total nitrogen 40 mg/L,ammonia nitrogen 30 mg/L and total phosphorus 5 mg/L,which is biodegradable Better high turbidity water.Therefore,the wastewater treatment process designed in this paper is:first-level pretreatment+second-level biochemical treatment+advanced treatment+disinfection.Among them,the primary treatment uses coarse grid?sewage lifting system?fine grid?aeration grit chamber?fine grid.The secondary treatment selects the A²/O process,which has the advantages of efficient removal of nitrogen and phosphorus,high stability of operation,and convenient operation and maintenance,and can achieve the goal of efficiently removing sewage from the eastern sewage treatment plant.The advanced treatment was compared and analyzed through the"A²/O process+advanced treatment process"and"A²/O process+MBR membrane process".MBR membrane process was selected to efficiently remove refractory organic pollutants.It can directly reuse water,produce a small amount of mud,the process is simple and smooth and concentrated,small footprint,easy to expand the modular design,mobility,high degree of automation advantages,effectively overcome the traditional secondary sedimentation tank and conventional depth disadvantages such as wasted energy consumption.Ultraviolet light sterilization was chosen as disinfection treatment with less land area,fast effect,low risk,no secondary pollution advantages.Therefore,the wastewater treatment process of the plant's optimal plan was finally determined:Incoming sewage main pipe?coarse grid?sewage lifting system?fine grid?aerated grit chamber?fine grid?A²/O biochemical pool?MBR membrane The pool?UV disinfection?tail water disinfection into the Huishan open channel.Sludge treatment process:biochemical pond surplus sludge+MBR membrane pool sludge?sludge buffer pool?sludge thickening and dewatering?sludge shed?mud cake transporte?shipped to Shenyang Sludge Treatment Plant.The quality of the effluent treated by this process can reach the Class A standard in the?Emission Standard of Pollutants for Municipal Wastewater Treatment Plants??GB18918-2002?.Among them,the specific parameters of the design are as follows:3 rough grids,75°installation angle,20 mm grid gap,1200 mm front grid depth,2.2 kW power;3 fine grid grids,1,500 mm channel width,90°installation inclination,Grating gap 3.0mm,water depth before hatching 1400mm,1.5kW power;aeration grit chamber aeration 0.2m3 air/m3 sewage;grit deposition 0.03L/m3 sewage;fine membrane grid with 3 installation inclination 90°,grid gap 1.0mm,water depth before the grid 1500mm,1.5kW power.2 A²/O biochemical tanks,anaerobic tank residence time 1.51h,anoxic tank residence time 4.32h,aerobic tank residence time6.87h,lack of-abuse mixture reflux ratio 200%,good-absence mixture reflux ratio400%;two MBR bioreactors,some adopting AAO process,with a nominal membrane flux of 15.5 L/m²·h,a scrub gas/water ratio of 12.37:1,a chemical phosphorus removal amount of 1.35 mg/l,and a PAC dosage of 15.42 mg/l,Membrane-good sludge return ratio is 500%.One ultraviolet disinfection tank,with a UV transmission rate of at least 55%,a suspension content of TSS of no more than10 mg/L,a sludge thickening and dewatering chamber,a moisture content of 99.0%before dewatering,and a moisture content of 80%after dewatering.Dry sludge volume reach 8000 kg/d.The process plan of the wastewater treatment plant in this paper can reduce the BOD₅ volume by about 2738.02 tons/year,the COD_Crr volume by about 5475.9tons/year,and the SS volume by about 2552.25 tons/year.The total investment of the plant is 165,881,700 yuan,the profit rate of investment can reach 2.91%,and the profit rate of capital can reach 11.21%.The profitability of this investment and its contribution to the accumulation of the country have reached the average level of the same industry.And can effectively improve the status of drainage engineering in the eastern part of Shenyang and improve the quality of life of local residents.Therefore,according to the economic accounting of this plant and the evaluation of engineering benefits,this project has strong feasibility and good environmental,economic and social benefits.