Experiment Research On The Water Drip Gravity Heavy Sand Filter Tank

The water drip gravity sinking sand filter tank is a new type of heavy sand filter tank which is composed of sedimentation tank, filter, clean-water reservoir, it has advantages of no power consumption, control area is large and low operating cost. On the basis of predecessors’ study of sand basin, this paper focus on using model test to study the sediment motion law and the water sediment separation efficiency of the water drip gravity sinking sand filter tank under different overflow weir length and different length. The main research results are as follows:(1) In the positive gradient slope with lateral overflow weir tank, the change of the average flow velocity along the longitudinal section can be divided into three stages: velocity quickly reduce, the velocity is constant, slow phase.(2) Sinking sand filter tank structure size can be determined by the test: under 0.05m3/s to water flow, in the three length of sedimentation tank, 20 m is more appropriate, in the 2 m, 3 m, 5 m length of lateral overflow weir, 3 m is more appropriate.(3) Under the flow rate of 0.05m3/s, the maximum sediment concentration of imports is about 1.5kg/m3, when the clear water reserviors export sediment content is 0.5 ~ 0.6 kg/m3.(4) Settling basin sediment average processing efficiency can reach 34.08%, average filter sediment rate at about 18.55%, clear water sediment average rate of about 11.28%, the total water sand separation efficiency can reach 52.75% on average.(5) The study found that, to the end of sedimentation tank, the longitudinal section of the average sediment concentration change trend. To set the lateral overflow weir here is so inappropriate that can stir up the sediment and take it out the tank easily. To do this, it can consider moving the lateral overflow dam to upstream of mobile location.