The removal of organic pollutants and ammonia nitrogen by series sewage treatment equipment mainly relies on the AO biological treatment process in the equipment. The working principle is at level A. Due to the high concentration of organic matter in sewage, microorganisms are in a state of hypoxia. At this time, microorganisms are facultative microorganisms. Therefore, level A tanks not only have the function of removing organic matter, reducing the organic load on subsequent aerobic tanks, and reducing the concentration of organic matter, but there are still a large amount of organic matter and high NH3-N present. In order to further oxidize and decompose organic matter, and ensure smooth nitrification under carbonization, an aerobic biological contact oxidation tank with low organic load is set up at level O. There are mainly aerobic microorganisms and autotrophic bacteria (nitrifying bacteria) in the O-level pool. Aerobic microorganisms decompose organic matter into CO2 and H2O; Autotrophic bacteria (nitrifying bacteria) use inorganic carbon produced by the decomposition of organic matter or CO2 in the air as a nutrient source to convert NH3-N in wastewater into NO-2-N and NO-3-N. The effluent from the O-grade tank is returned to the A-level tank, providing an electron acceptor for the A-level tank and ultimately eliminating nitrogen pollution through denitrification.

6. Chlorine dioxide generator (disinfection equipment)