The second step in most publicly owned waste treatment systems in which bacteria consume the organic parts of the waste. It is accomplished by bringing together waste, bacteria, and oxygen in trickling filters or in the activated sludge process. This treatment removes floating and settleable solids and about 90 percent of the oxygen-demanding substances and suspended solids. Disinfection is the final stage of secondary treatment.
The removal of organic matter from waste water in a sewage treatment plant using aerobic biological processes.
The treatment provided after preliminary and primary treatment. Secondary treatment involves "biological" treatment - using bacteria to break down the biodegradable matter in waste water. After secondary treatment there is further settlement. Secondary treatment should comply with the standards of the Directive.
Keywords:  category, needs, see
See Categories of Needs: Category I.