Optimization Design Of Sedimentation Tank

As one of the most important water treatment structures, sedimentation basinhas great impact on water treatment and saving operation cost of waterplants owingto its rational design. Suspended solids removal efficiency is an important factor tosedimentation basin design and the sedimentation structure parameters and controlparameters according to specific water qualities were optimized using hydraulicsnumerical simulation technology.The source of Zhegao Town Waterplant of Chaohu City is Zhegao River, andthe daily output of the plant is about15thousand m~3. By the backwater influenceof Chaohu Lake, the mobility of Zhegao River is poor, and the pollution is serious,removal of suspended solids has been the difficulty of the water plant.Accord-ing to the dynamic monitoring results of water samples, the particle size of sus-pended solids in the raw water is mainly in the range of5-15μm and20-30μm.Asthe particle size is measured of the suspended solids, establish a numericalsimulation of multiphase flow model of the sedimentation tanks. The flow fieldsin different circumstances(different water inlet heights, different horizontaldistances between water baffle and water inlet, different submerged depths of waterbaffle and different locations of arc-shaped flow-interceptor) and the concentrationfields were analyzed in comparative ways using fluid dynamic software FLUENT.It is shown that:(1) The water inlet height changes within a certain range has someinfluence on suspended solids removal efficiency. Instance, it is more conductiveto the precipitation when the inlet height is higher than1.0m.(2)The submerged depth of water baffle has great impact on the operatingefficiency of the sedimentation tank. It is more conductive to the precipitation whenthe submerged depth of water baffle is deeper than2.5m.(3)The horizontal distance between water baffle and water inlet also hasapparent impact on the operating efficiency of the sedimentation tank.When thedistance between1.5m to2.5m, there is virtually no recirculation zone behind theinlet baffle, and it is more favor to the precipitation.(4)The setting of arc-shaped flow-interceptor could change the uneven flowpattern of the sedimentation tanks, and the rational location of flow-interceptor isconductive to the operating efficiency of the sedimentation tank. Instance, when the flow-interceptor is apart from the inlet baffle1.6m, the critical concentration is low,and there is virtually no recirculation zone behind the inlet baffle, so that it is moreconductive to the precipitation.