Typical urban sewage treatment process mainly includes mechanical treatment, biochemical treatment, sludge treatment and other sections. The system consisting of mechanical treatment and biochemical treatment is a secondary treatment system, in which the removal rate of BOD5 and SS can reach 90% - 98%. The treatment system set after the secondary treatment belongs to the tertiary treatment, such as chemical phosphorus removal, activated carbon adsorption, etc. The current popular sewage treatment processes include AB method, SBR method, oxidation ditch method, ordinary aeration method, membrane separator, etc.