Study On Pollution And Control Of Rainwater Pipe Network In A Southern City

With the development of urbanization in China,the urban water problems with high concentration of population and highly developed economy have attracted more and more attention.For SZ City,the Overflow Pollution of drainage pipes in rainy season has been an urgent environmental problem.This paper focuses on the partial rainwater pipe network in the overflow pollution,and conducts corresponding research around the diversion rainwater pipe network around FT River in the downtown area of SZ.Due to the related literature,the sediment will cause a large pollution load.Therefore,the investigation of the sediment in the rainwater pipe network in dry season shows that there are different siltation conditions in the pipeline network,with the deposition range ranging from 14%to 43%.The pollution nature of the sediment in the pipeline is related to the surface functional area,among which the NH₃-N and TP content of the sediment in the three functional areas of living area,commercial area and traffic area are related.The results show that heavy metals in living and commercial areas are moderate pollution and have high risk.By comparing the pollutant content between surface particles and sediment in different functional areas,it is found that the correlation degree is high.According to the actual investigation on the pollution amount of pipeline outlet in rainy season,the maximum concentration of ammonia nitrogen and total phosphorus at the outlet of the pipeline can reach 5.80 mg/L and 3.41 mg/L,and the scouring effect in the initial stage of rainfall process is closely related to rainfall and rainfall intensity.The highest contribution rate of ammonia nitrogen and total phosphorus is about 30%and 42%respectively.In order to know more about the pollution law of the discharge outlet,the SWMM model was constructed according to the measured data.Through the model analysis,the EMC of ammonia nitrogen and total phosphorus reached the peak value at the return period of P=0.3 a and P=0.1 a,respectively,and the EMC of water quality ammonia nitrogen exceeded the V water limit only when P=0.3 a,while the EMC of total phosphorus was always above the V water limit.According to the current pollution situation and the specific areas investigated,this study puts forward several feasible control methods,which are:increasing the management and supervision of the surrounding construction units,increasing the frequency of dredging and dredging,laying green roofs on the corresponding commercial floors of residential buildings,and changing the cleaning tools of cleaning personnel.The model was used to simulate the effect of laying green roof and changing cleaning tools.The results showed that the removal rate of ammonia nitrogen and total phosphorus was up to 20%and 19%,which could keep the EMC concentration of ammonia nitrogen at the outlet of the pipeline under the water limit value of class V.Under the rainfall pattern with return period P=0.7 a and greater rainfall,the EMC concentration of total phosphorus was always controlled under the water index of class V.In this study,the situation of rainwater pipe network in dry season and rainy season around FT River in SZ City was investigated,and a set of solutions was provided for the current problems,so as to provide reference for related research and control scheme in SZ City in the future.