When the solid particles in the suspension are large and uniform, the pores of the filter bed are relatively smooth, and the speed of filtrate passing through the filter bed is relatively large. The application of coagulant to gather fine particles into larger agglomerates is beneficial to improve the filtration speed.

For the suspension with fast settling speed of solid particles, it is applied to the filter with feeding at the upper part of the filter medium to make the filtering direction consistent with the gravity direction. The coarse particles settle first, which can reduce the blockage of the filter medium and the filter residue layer; the coarse solid particles such as diatomite and expanded perlite are mixed into the suspension (such as colloid) that is difficult to filter, which can make the filter residue layer loose; the filtrate viscosity is large The suspension can be heated to reduce viscosity. All of these measures can speed up filtration.