Study On Water Quality Simulation And Regulation Scheme Of Urban River In Chengdu

Urban rivers are the constraints of urban development,affecting the city's economy,culture,landscape,environmental protection and so on.Nowadays,the pollution situation of urban rivers is becoming more and more serious,which forms the black and odorous water body.The harm of the black and odorous water body greatly restricts the development of the city and also leads to the health problems of the people.Therefore,the treatment of urban black and odorous water has aroused discussion and research from all walks of life.On the basis of water quality simulation,this paper formulates the urban river pollution control scheme,and forms a more rational evaluation of the treatment scheme with quantitative results and intuitive graphics,so as to avoid inadequate treatment measures or excessive economic investment in the treatment scheme.Taking the comprehensive harnessing project of Modi River as an example,the water environment simulation of Modi River is studied in this paper.Based on the monitoring data provided by Chengdu monitoring station,the current situation of the section of"New Hope Hotel"and"Huangzhong"in the upper reaches of the river is evaluated.The results show that ammonia,nitrogen and total phosphorus in the water body exceed the IV water body standard,while CODcr has an obvious trend of exceeding the standard.According to the correlation analysis of water quality indicators,the main pollution sources of the Modi River are feces and detergents in catering wastewater and domestic sewage.Based on the water quality model,this paper plans to formulate an effective treatment plan.One-dimensional water quality model can be established for medium and small rivers.On the basis of the selected model,the water quality data collected are used to generalize the water quality model.Then,according to the monitoring data,K₁?oxygen consumption coefficient?is calculated to be 1.536d^-1,K_N=0.245d^-1?nitrification coefficient?,and K_P?total phosphorus degradation coefficient?is first set up by analogy with literature.It's 0.8d^-1.After that,a one-dimensional water quality model was established in the reach from"New Hope Hotel"to"Huangzhong Section"of the Modi River.The water quality parameters were checked and calibrated by comparing the calculated values with the monitored values.The calculated values of K₁ and K_N were determined as the above-mentioned values.After repeated debugging,the measured and simulated values of K_P reached the best fitting effect,and finally the K_P was determined to be0.55d^-1.According to the determined water quality parameters,the changes of COD,ammonia nitrogen and total phosphorus in the whole reach of the Moudi River during dry and flat water periods are simulated.It is concluded that the poor water quality of the Moudi River in these two periods is generally inferior V-type water body.In general,the four factors that have the greatest impact on the water quality of the Moudi River are sorted according to their degrees as follows:the discharge of external pollutants,the concentration of pollutants from rivers,and the generation of pollutants.Water content and pollutant degradation coefficient.According to the experiences and cases of black and odorous water treatment at home and abroad,the water quality control scheme of Modi River is put forward.The water quality simulation results show that the scheme can make the water quality of Modi River meet the IV water body standard and the water quality at the entrance of Modi River meet the III water body standard.Finally,according to the design parameters of the planned Huangzhong Sewage Treatment Plant,the environmental capacity of COD,ammonia-nitrogen and total phosphorus in the Moudi River is7748.48 kg/d,391.05 kg/d and 70.33 kg/d respectively.