Analysis On The Influence Of Sewage Outfall Into The River Of A Sewage Treatment Plant Relocation And Expansion Project On The Polluted River

Effective monitoring and management of sewage outlets into rivers can not only control the total amount of pollutants into rivers,but also protect water resources,improve water environment and promote sustainable utilization of water resources to a certain extent.According to relevant laws,regulations,standards and local sewage discharge intensity,in order to scientifically support the relocation and expansion project of a municipal sewage treatment plant,this paper analyzes the influence of the sewage outlet into the river of the relocation and expansion sewage treatment plant on the receiving waters.Based on the present situation of the water function area of the relocation and expansion sewage treatment plant and its influence on the total amount of water pollutants in the area,and considering the setting scheme of the sewage outlet,the influence range and degree of the sewage outlet on the regional water system are predicted by using one-dimensional steady-state model and two-dimensional unsteady-state model under different working conditions.Draw the following conclusions:(1)The sewage outlet of a renovated and expanded sewage treatment plant belongs to the sewage outlet of mixed waste water entering the river,which is located at the south bank of Yisi River in a city and 150m west of the intersection with Shahe River.It mainly serves the old city of a city,economic development zone,automobile industrial park,riverside new town and surrounding key towns,mainly treating regional domestic sewage and industrial wastewater,and the tail water is discharged into Yisi River in the form of open channel.(2)According to the analysis of routine monitoring,environmental protection departments and supplementary monitoring data,the water quality of an industrial water use area in the Yangtze River corresponding to the current situation basically meets the water function target requirements,and the overall water quality is excellent,and the water quality of each section is Class Ⅱ.At present,the discharge outlet water function area of sewage treatment plant has a COD inflow of 4691.5 t/a and NH3-N inflow of 634.1t/a.According to the balance analysis of the capacity of water receiving function area and the amount of pollutants entering the river,the amount of main pollutants entering the river in an industrial water area of the Yangtze River is COD:4240.3 t/a,NH3-N:568.4 t/a,and the amount of main pollutants entering the river does not exceed the capacity of pollution receiving.(3)Using one-dimensional steady-state and two-dimensional unsteady-state mathematical models to simulate and predict the influence of tail water under four working conditions on the water quality of sewage receiving area and downstream related water function areas.The prediction results show that under normal working conditions,the actual effluent water quality concentration of tail water can basically reach Class Ⅳstandard,and continuous discharge has little impact on the water environment of the Yangtze River.The accident discharge will seriously affect the local water quality of the Yangtze River,with the water concentration exceeding the standard reaching 7.12 km.It is suggested that the sewage treatment plant should further strengthen its operation to prevent the accident discharge.