The domestic sewage treatment process can be divided into primary, secondary and tertiary treatment processes according to the degree of treatment.

The primary treatment process is to set up a fence at the entrance of the sewage treatment facility, which mainly uses physical methods to intercept larger floating objects, so as to reduce the load of the subsequent treatment structures and enable them to operate normally.

The secondary treatment process mainly removes the organic substances in the colloidal and soluble state in the sewage, and usually adopts the biological treatment method. Primary and secondary treatment processes are conventional treatment methods.

The tertiary treatment process is used to further treat the organic substances that are difficult to degrade, and the soluble inorganic substances such as phosphorus and nitrogen that can lead to the enrichment of water body oxidation after the primary and secondary process treatment.