Simulation Study On The Particulates In Runoff And Surface Water Utilizing Convex Infiltration Ditch

The non-point source pollution caused by the surface stormwater is the main source of regional water environment pollution,The particles in stormwater runoff are the main host of runoff pollutants,The development of urbanization has provided abundant sources of particulate matter for runoff rainwater,and particulate pollution in urban areas has become more prominent in recent years;Due to many factors such as surface runoff stormwater accumulation and soil erosion,large amounts of sediments and other particulate matter have entered the surface water bodies such as rivers,lakes and reservoirs,resulting in the weakening of their flood capacity and capacity adjustment capacity;The urban landscape water body is easily contaminated due to the fact that it is closed to slow flowing water.The turbidity problem of landscape water caused by suspended particulate matter seriously affects the landscape effect of the water body.Traditional water treatment technology has the disadvantages of low efficiency,large investment,and easy clogging when dealing with suspended particles in surface runoff and surface water bodies.Therefore,it is urgent to develop a stable and efficient solid-liquid separation treatment technology to provide technical support for the purification and utilization of large-volume water bodies.Analyzing and comparing the treatment thchnologies of suspend particles in water bodies at home and abroad,combines the advantages of good horizontal filtration and retention of vertical and horizontal seepage flow retention,hydraulic conditions perpendicular to the direction of movement of the suspended particles and the direction of water seepage,and developed a new type of highly efficient convex infiltration ditch.The numerical simulation of VOF model,porous media model and Euler model in FLUENT software was used to optimize the cross-sectional shape of the convex seepage channel.By analyzing the percolation retention rule of the filter layer in the horizontal direction and vertical direction alone,the conventional filtration was adopted.The system design and seepage wall design provide technical references;the main body of the convex seepage canal is the law of seepage retention of the“convex type permeate”,and the size of each part is optimized.The results of the study are as follows:(1)Using Fluent's Euler model and porous media model to simulate the filtration process,setting the viscosity of the suspended particles themselves has no effect on the results.Setting the particles to receive the filter resistance is 105 times to 108 times that of the water received form filter layer in line with the actual filtration process.(2)The effective head difference H of the seepage wall in the project is within 2m,and the seepage wall thickness L can be designed according to the permeability coefficient k with the following formula:L =(1.5/1.89)H/0.5-1× 2H(0.0072K+ 0.5562)(3)Vertical filter seepage retention,thickness of the retentive layer(N)has nothing to do with the water quality and the structure of the filter layer,only related to the filter depth(H),the relationship is N=0.115H,can reduce the overall depth of the filter tank by increasing the resistance of the filter outlet in the actual engineering filter tank.(4)In the convex infiltration channel,it is recommended that the width of the influent canal be between 0.85m and 1.00m;the width of the outflow canal should be between 0.85m and 0.95m;it is recommended that the height of the seepage wall,namely the water head difference before and after the seepage wall in the engineering design.Take in half the width of the Inlet channel,that is 0.45m?0.50m;The thickness of the seepage wall can be calculated according to the following empirical formula according to the permeability coefficient K and the height H of the seepage wall:L =(0.92-1.00)·(0.0072K + 0.5562)The depth of the base layer is between 1.05m and 1.25m.(5)The recent average flow of Xinhe River in the Xixian New District of Xi'an City is 50000ml/d,and the long-term flow rate is 9000ml/d,which is a poor Class V water body.This study completes the modular infiltration wall for suspended matter removal and the analog design of the ancillary facilities.