1 filter residue layer filtration: the initial filter medium can only retain large solid particles, and the small particles will pass through the filter medium to form the initial filter residue layer. The filter residue layer plays a major role in the filtration. At this time, large and small particles are trapped. For example, the filtration of the plate and frame filter press.
2Deep filtration: The filter medium is thicker, the suspension contains less solid particles, and the particles are smaller than the filter medium. When the particles are filtered, the particles are adsorbed in the pores, such as porous plastic tube filter and sand filter.
3 Screening: The solid particles retained by the filtration are larger than the pores of the filter medium. The inside of the filter medium does not adsorb solid particles. For example, the rotary filter screen removes coarse impurities in the sewage. In the actual filtration process, the three methods are often At the same time or in succession.