Generally, there are four kinds of filtration methods of polyaluminum ferric chloride, including lattice screen filtration, deep filtration, microporous filtration and membrane filtration.

Grid screen filtration: the filter medium is grid bar or filter screen, which is used to remove coarse suspended solids, such as weeds, rags, fibers, pulp, etc. The typical equipments are grid, screen and microfilter.

Deep filtration: granular filter media, such as quartz sand, anthracite, etc. Due to the existence of pores between the filter particles, the suspended solids in the water will be intercepted when the wastewater passes through a certain depth of filter layer. In order to distinguish from the above three types of surface or shallow filtration process, this kind of filtration is called deep filtration.

Microporous filtration: it uses shaped filter materials, such as filter cloth, filter piece, sintered filter tube, honeycomb filter element, etc. it can also pre coat a layer of filter aid (such as diatomite) on the filter medium to form a filter cake with fine pores to remove fine particles.

Membrane filtration: the special semi permeable membrane is used as the filtration medium, and the filtration is carried out under certain driving force (such as pressure, electric field force, etc.). Due to the small pore and selectivity of the membrane, bacteria, viruses, organic matter and soluble solutes in water can be removed. The main equipments are reverse osmosis, ultrafiltration and electrodialysis.