Sewage treatment in which a portion of decomposer bacteria present in waste is recycled into the beginning of the process

Sewage treatment in which a portion of decomposer bacteria present in waste is recycled into the beginning of the process known as Activated sludge treatment.
The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewater using aeration and a biological floc composed of bacteria and protozoa. It uses air (or oxygen) and microorganisms to biologically oxidize organic pollutants, producing a waste sludge containing the oxidized material.