Experimental Study On Residual Amount Of Aluminum Salt Flocculant In Grid Flocculation Tank Effluent

In this paper,the optimal coagulation conditions of the grid flocculation tank were used to study the effluent turbidity and residual aluminum content of the grid flocculation tank,analyze and calculate the characteristics of the generated floc,and explore the correlation between the residual aluminum content of each component under different conditions and the turbidity of the post-sedimentation water and the characteristic parameters of the floc during the flocculation process.The following conclusions were reached:1.Under the same chemical conditions,the optimal flow conditions of the mesh flocculation effluent with high turbidity removal rate and low residual aluminum content of each component are different among the five different mesh plates.The 10 mm mesh plate with 32.5% porosity has the highest turbidity removal rate,the lowest residual aluminum content of each component,and the dissolved aluminum content is less than 0.2mg/L at the flow rate of 3.8m 3 /h.In the process of mesh flocculation,the number of large-size flocs formed is larger,the fractal dimension of flocs is larger,the flocs form and size are more uniform,and the flocs have good settling performance.2.Under different raw water temperature and Polyaluminum chloride(PAC)dosage,the variation trend of residual aluminum content and residual turbidity of each component in the water of the grid flocculation tank after sinking is consistent.The variation trend of fractal dimension of floc size is opposite to that of floc size.There is a positive correlation between residual total aluminum and particulate aluminum and the turbidity of submerged water.The average particle size of the floc was negatively correlated with the residual and total aluminum particles.The change of residual dissolved aluminum content was not obvious.There is a strong positive correlation between the size of the floc and the fractal dimension.The better the mesh flocculation effect is,the larger the average particle size and fractal dimension of the flocs generated during the flocculation process,the easier the flocs are to settle,the higher the turbidity removal rate of effluent,and the lower the residual aluminum content of each component.3.There is a weak negative correlation between the residual aluminum content of each component and the average particle size of the floc in the mesh plate with the same mesh size at different flow rates.There was a weak positive correlation between the water turbidity and the water turbidity after sinking.However,in the flow rate range of 3.2-3.8m3/h,the turbidity removal effect of grid plate is good,the residual aluminum content of each component is low,and the flocs formed are larger and more uniform.4.Under the optimal flow rate of mesh plates with different mesh sizes,with the increase of mesh plate size,the change trend of residual aluminum content of each component and the average particle size of floc is basically opposite.The residual aluminum content of each component has a negative correlation with the average particle size of the floc,and a positive correlation with the residual turbidity.There is a strong positive correlation between the size of the floc and the fractal dimension.The better the flocculation effect is,the larger and more uniform the flocs formed,the better the sedimentation performance,the lower the residual turbidity and the lower the residual aluminum content.