Three ways of filter

(1) Filtration of filter residue layer: In the initial stage of filtration, the filter medium can only intercept large solid particles, and small particles pass through the filter medium with the filtrate. After the formation of the initial filter slag layer, the filter slag layer plays a major role in the filtration. At this time, large and small particles are intercepted, such as the filter of plate and frame press.

(2) Deep filtration: the filter medium is thicker, the suspension contains fewer solid particles, and the particles are smaller than the channel of the filter medium. When filtering, the particles are absorbed into the channels, such as the filtration of porous plastic tube filters and sand filters.

(3) Screening: The solid particles intercepted by filtration are larger than the pore of the filter medium, and the solid particles are not adsorbed in the filter medium, such as rotary filter to remove coarse impurities in sewage. In the actual filtration process, the three methods often appear simultaneously or successively.