① Filtration Filter: Filter medium can only intercept large solids particles, small particles with filtrate through filtration media. After the formation of the initial residue layer, the filter plays a major role in the filtration, when large, small particles are trapped, such as plate filter press filtration.
② Deep Filtration: filtration medium thick, the suspension contains solid particles less, and particles less than the filtration medium channel. When filtering, particles are adsorbed into the pores, such as porous plastic pipes, filter sand filters.
③ Sieve Filter: Filter retention of solid particles are larger than the filter media pores, filtration medium does not absorb solid particles, such as rotary filter sieve filter to the coarse impurities in sewage. In the actual filtration process, the three methods are often simultaneously or successively.