Research On Silts Properties And Silts Erosion In Mountain Town Sewage Treatment System

With the rapidly development of urbanization,water environment pollution in China becomes increasingly serious.The mountain town sewage treatment is difficult due to the complex and variable composition with plenty of silts.Therefore,it’s extremely practical significance for efficient treatment of urban sewage.to study the properties of sewage silts and the mechanism of silts erosion.This paper takes the silts of sewage treatment plant in Chongqing as a research object.The size distribution,surface morphology and element composition about silts were studied.The wear law of different size distribution and concentration on the impeller and the silts erosion mechanism were analyzed.The properties of silts in mountain town sewage were analyzed.The particle size distribution of sewage silts was normal distribution.After the high temperature burning,the particle size distribution was greatly changed and the distribution range was significantly reduced.The rainy days had a great influence on the particle size distribution of sewage silts in the sewage inlet.Through the study of the morphology and element composition of the silts,it is found that the organic matter will make the surface of the silt particles become rough,the particle size increases and the content of C is higher.After the organic matter was burned at high temperature,the particle size was significantly reduced,the surface profile became clear,and the relative contents of Si and O were obviously increased.Compared with sewage silts,the river sand particle size is greater,the shape is more rules.Through the simulation of laboratory test platform,the wear law of the silts concentration and silts particle size on the impeller was obtained.With the increase of the running time of the impeller,wear rate will increase significantly with the increase of silt concentration,and the increase of wear rate increases with the increase of sediment concentration.The effect of silt particle size on wear rate is less affected than concentration.According to the wear experiment,the wear rate correlation function can be obtained,which can predict the wear rate of the mud on the impeller under the actual working condition.This paper analyzes the silts erosion mechanism of mountain town sewage.The changes of the impact angle make impeller bear different levels of scouring force and vertical scouring force.The impact angle has a great influence on the erosion process and mechanism.When silt particles scour in small impact angle(about 11 °),erosion is coursed by shearing action.When silt particles scour in big impact angle(close to 90 °),erosion is coursed by impact action.When silt particles scour in normal impact angle,erosion is affected by the interaction of shearing and impact.The maximum wear rate in this experiment occurred at an impact angle of approximately 90 °.In the actual production,the alternating action or the compound repetitive effects of silts on the impeller cause the impeller to be worn and damaged after the shearing and impact,and eventually lead to impeller failure.