Research On Multi-objective Optimization Of Combined Overflow Pollution Control System Based On Sponge City Construction

Based on China’s economic development and basic national conditions,the retrofication of combined drainage system and the control of overflow pollution are still major problems needed to be solved in some cities in China.CSO pollution is an important cause of urban water and water environment deterioration.CSO control is a long-term and complicated systematic project,with the continuous development of the concept of sponge of city construction in China and abroad source control facilities of the development of the related research.The sponge construction of city is closely connected with CSO control strategy gradually,the research on the sponge in the course of the construction of urban rivers overflow system control scheme design and optimization of train of thought can offer sponge city water environmental governance construction can draw lessons from the experience.The main purpose of this study is to study the planning,design and scheme optimization of CSO system in the construction process of sponge city,and to summarize relevant governance experience and advanced technology.Combined with the concept of sponge city construction,this study takes the confluence system of sponge city construction in Beijing sponge city pilot area as an example.This study studies the design and optimization of the overflow control system of the confluence system during the construction of sponge city.The main research contents of this study are as follows.Firstly,we analyzed and summarized the geographical information such as the status quo of the study area,the underlying surface,and the climatic characteristics,and build the SWMM model of the study area according to the actual rainfall monitoring data and geographical information,and then rate and verify the model.Then we analyzed the current situation of the research area.According to the sponge city construction objectives and CSO control objectives of the study area,the planning scheme within the sponge city confluence system was designed.Based on the multi-objective optimization theory,with the help of Matlab and other software platforms,the multi-objective optimization model of regional combined flow control system was built and solved to study the optimization idea of the combined flow control strategy.Finally,considering the disadvantages of the gray facilities in the CSO reconstruction in some regions,the multi-objective optimization method and its law of the single sponge city headwaters facility construction were studied.Main research conclusions of this study are as followers.(1)The control system of CSO optimization results,said overall regional CSO cut rate with the increase of construction cost control system there is increased,but the CSO reduction rate is not affected by the construction costs,also affected by the rationality of CSO control system configuration.Under the same construction cost,reasonable planning and design can get a better benefit.(2)In the optimization results of the CSO control system,the construction cost ratio of the source LID facility.The end confluence regulation tank and the intermediate closure pipe network were successively reduced under the condition of design rainfall once every three years.(3)In the multi-objective optimization process of CSO reduction rate,runoff control rate and construction cost based on water quantity control.The optimization results of the sponge city headstream scheme show that the two facilities.The sunken green space have better construction benefits in the facilities involved in the study and account for a large proportion in the optimization results.They should be taken seriously by solution designers.Green roofs have a limited effect on water control.(4)According to the CSO control system composition,step-by-step design the CSO control scheme of the sponge under the city.And further analyzes the intercepting main reform’s influence on system control of the confluence.Found that the reconstruction of intercepting network that network to enhance the drainage ability,affected by upstream and downstream position,more close to the downstream overflow control more difficult.The actual construction will lead to sewage treatment plant load downstream.This study further analyzes the idea of determining the volume of the mixing tank when the CSO control target is the overflow volume control and the overflow frequency control.(5)in the combined pipe network system,the higher the overflow reduction rate is,the closer to the upstream is,and the lower the overflow reduction rate is,the lower the overflow reduction rate is.The CSO control system with three kinds of schemes: source,midway and terminal can achieve better results.All three are necessary in the construction of CSO pollution control system.