Calculation Of Urban Domestic Sewage Loaded And Analysis And Prediction Of Water Quality Characteristics

At present,one of the main environmental problems facing water pollution in cities is that the discharge of domestic source wastewater accounts for an increasing proportion of urban wastewater discharge.The existing coefficients of production and discharge of pollutants from urban living sources cannot reflect the differences between regions and cannot meet the needs of Shanghai ’s environmental protection work.This study divides Shanghai into three levels.By collecting the 2017 manual monitoring data and online monitoring data of the urban sewage treatment plants in the main urban area,Xincheng district and the Xinshi town,the production and discharge coefficients of pollutants from various levels of urban life in Shanghai are calculated.By analyzing the selected sewage treatment plants,the correlation between the pollutants is obtained,and the mathematical model is used to predict the pollutant discharge concentration.The main research results are as follows:(1)The amount of pollutants produced is: CODcr 30.50～75.98 g/cap·d,BOD5 13.91～39.15g/cap·d,NH3-N2.26～7.67g/cap·d,TN 3.41～9.85g/cap·d d,TP 0.43～0.99g/cap·d,SS 24.99～39.18g/cap·d.The pollutant emissions are CODcr 2.70～7.60g/cap·d,BOD50.42 ～ 1.57g/cap·d,NH3-N 0.20 ～ 1.07g/cap·d,TN 0.95 ～3.74g/cap·d,TP 0.04 ～ 0.13g/cap·d,SS 1.00 ～ 2.74g/cap·d.The generation and discharge of pollutants in the main urban area are greater than those in Xincheng district and the Xinshi town.(2)The increase in population will lead to increased emissions of pollutants,of which TN and CODcr are the most affected by population factors.Except that there is no correlation between NH3-N and SS and the economy,the other four types of pollutant emissions are positively correlated with the economy,the other four types of pollutant emissions are positively related to the economy,that is,economic growth will lead to an increase in pollutant emissions,of which TN and BOD5 are most affected by economic factors.Therefore,in order to control the discharge of pollutants,we must strengthen environmental governance while economic growth.(3)The correlation between TN and NH3-N is significant.Linear regression analysis will be conducted and it is found that the degree of fit is average.The linear fit between other variables is very poor,and there is almost no linear relationship.Binary regression equations can be established between TN and NH3-N and TP,and multiple regression equations can be established between TN and CODcr,NH3-N and TP.(4)When predicting the quality of domestic sewage by the time series method,in addition to the TP prediction failure,CODcr,NH3-N,and TN are all successfully predicted,and TN has the best effect.Using BP neural network to predict TN has the best effect,and the model runs stably.TP and NH3-N models are unstable.The quality of the prediction depends largely on the quality of the data.Comparing the relative errors of the two prediction methods,it is found that the prediction effect based on the BP neural network is more ideal and more suitable for domestic sewage water quality prediction.The establishment of a prediction model can timely predict the situation where pollutants in the sewage may exceed the standard,which is convenient for timely adjustment of the operation process to ensure that the effluent quality meets the standard.It is of great significance for promoting the sustainable use and protection of water resources.