Anhui BaoLu photoelectric technology company told you sewage treatment is mainly divided into three steps: one of the first level of sewage treatment is to remove the sewage is suspended solid pollutants, most of the physical treatment method can only complete the first level of treatment requirements. After Baolu sewage treatment equipment for primary treatment of sewage, BOD can generally remove about 30%, not up to the discharge standards. Primary sewage treatment belongs to the secondary sewage treatment pretreatment secondary sewage treatment, the main removal of sewage in the colloidal and dissolved state of organic pollutants so that organic pollutants to meet the discharge standards. Tertiary sewage treatment, refers to the further treatment of difficult to degrade organic matter, nitrogen and phosphorus and other soluble inorganic substances that can lead to eutrophication of water bodies. The main methods are biological nitrogen and phosphorus removal method, coagulation and precipitation method, sand rate method, activated carbon adsorption method, ion exchange method and electro-osmosis analysis method.