Operation Investigation Of A Chongqing Downtown Wastewater Collection System And Improvement Measures

As an important part of urban infrastructure,the construction quality of drainage pipe will not only affect the living environment of the city,but also affect the normal operation of sewage treatment facilities,the effect of water pollution control and water environment quality.Whether the planning and design of drainage pipeline is reasonable or not is an important determinant of the construction cost,operation and maintenance cost of drainage system.On the one hand,for a long time,China has attached great importance to the theoretical research of drainage pipeline planning and design,but neglected the follow-up investigation and monitoring of the actual operation condition of the drainage pipeline system after its completionIt is difficult to improve the quality of drainage planning and design because of its rationality,which has become a prominent problem to be solved in drainage field.On the other hand,with the unprecedented attention paid to urban water pollution control in China in recent years,the operation and maintenance of drainage system are also increasingly paid attention to.In this context,it is of great significance and value to investigate the actual operation status of the drainage pipeline system and compare it with the planning and design to find problems and optimize the pipeline design,so as to improve the utilization efficiency of the drainage pipeline and improve the operation and maintenance of the drainage pipeline.Papers on summarizing domestic and foreign about the design of the drainage pipe system and the actual operation situation on the basis of comparative study,a central city in Chongqing city shunt drainage systems of sewage pipe network system as the research object,application of CCTV equipment on the investigation,identify the problems existing in the sewage pipeline in the actual operation,such as congestion,damage,etc.),analyzes its reasons,put forward the corresponding advice about design and operation management;Then,the hydraulic parameters(such as flow rate,water level,flow rate,etc.)are monitored on the spot by using flowmeter and other monitoring equipment,and the statistical analysis and comparative study with the original design are carried out,and the inspiration Suggestions for improving the design are put forward.The specific results are as follows:(1)Screening of the film area,a total of 93 segments section found that,more than 65% of the defects of structural or functional diseases section,refer to the national standards of drainage pipeline monitoring,defects of pipeline are summarized and evaluated,including class I slight defect section 44,15 class II medium defect section and section 2 level III serious defects,mainly for aprons,pipe burst,pipe bottom sediments,scaling,section deformation accumulation,obstacles,joint part disconnects,etc;Problem section of distribution are: shop area > department stores > > residential area office,the survey found sanitation conditions are in good condition and artificial factor will to a certain extent,health,decided to pipe in the construction aspect mainly construction way or improper protection and pipe quality impact the normal operation of pipeline.According to the situation of defective pipeline,the corresponding countermeasures of partial and overall repair are worked out.It is considered that the trenchless technology is more in line with the current reality,and the pipeline management and maintenance technology should be used to improve the pipeline operation.(2)The measured results and analysis of the hydraulic parameters of the sewage pipeline in a central urban area of Chongqing show that the measured values are generally lower than the designed values,among which the flow velocity of sewage in the pipeline basically cannot reach the non-silting velocity of 0.6m/s,and the measured average flow velocity distribution range of each monitoring point is 0.21-0.56 m /s,less than 50% of the designed value.The average filling degree in the pipeline is between 0.2 and 0.3,which is less than 55% of the design value.The total variation coefficient calculated from the flow data of each pipe section ranges from 2.75 to 3.08,which is 12.2% to 31.5% larger than the value of the total variation coefficient in the specification.The above results indicate that the hydraulic utilization efficiency of pipelines is extremely low.From the perspective of water power and water quality,the regulation of minimum drainage pipe diameter of 400 mm in Chongqing will not only cause waste of water carrying capacity of pipelines,but also increase the risk of siltation of pipelines and reduce the organic load of sewage.(3)Will be a center in chongqing urban sewage pipeline hydraulics parameters measured results compared with the original design analysis shows that in addition to the chongqing planning about drainage pipe diameter influence of technical regulations,the values of the design parameters of a other also has certain problem,such as sewage rate of high value,irrational prediction methods or prediction method is too simple,full of degree is too small,etc.With reference to foreign codes and relevant literatures,it is considered that more scientific and reasonable water consumption population and water consumption prediction method should be adopted to make flow prediction results more reasonable.The sewage quota value can be reduced to 200-250[L/(d·cap)],the minimum pipe diameter of sewage pipeline can be reduced to 300 mm,and the design filling degree can be appropriately increased.