Wastewater treatment can be divided into three types based on its functions: physical method, biological method, and chemical method.

① Physical method: mainly uses physical action to separate non soluble substances in wastewater, without changing chemical properties during the treatment process. Commonly used methods include gravity separation, centrifugal separation, reverse osmosis, air flotation, etc. The physical method for treating structures is relatively simple and economical, and is used in situations where the water volume in villages and towns is large, the self purification capacity is strong, and the level of sewage treatment is not high.

② Biological method: By utilizing the metabolic function of microorganisms, dissolved or colloidal organic matter in wastewater is decomposed and oxidized into stable inorganic substances, purifying the wastewater. The commonly used methods include activated sludge method and biofilm method. The degree of biological treatment is higher than that of physical treatment.

③ Chemical method: It is a method of treating or recovering dissolved or colloidal substances from wastewater through chemical reactions, and is commonly used in industrial wastewater. Commonly used methods include coagulation, neutralization, oxidation-reduction, ion exchange, etc. The chemical treatment method has good treatment effect and high cost, and is often used as the effluent after biochemical treatment for further treatment to improve the quality of the effluent.