Physical, such as grates, mixers, pumps and other equipment
Chemical, such as polymerized aluminum chloride, PAM, diatomaceous earth, and so on, added to the water stirring reaction to form a floc precipitation
Biological, such as activated sludge, oxidation ditch, SBR, contact oxidation, UASB anaerobic, etc., are all belonging to the biological class
Two or more of these categories Combined class