Extended aeration is aerobic biological treatment process used in wastewater treatment. This process is principally modified version of most commonly used and proven technology i.e. activated sludge process. Extended aeration systems are simpler in construction and operation. The wastewater is brought directly to the aeration basin after screening and grit removal.
In aeration basin the aeration is carried out for extended period of time thus mineralizing the sludge solids sufficiently hence the sludge produced is completely digested. Extended aeration is a method of sewage treatment using acclimatized active biomass, the oxygen for bioprocess is provided from mechanical aeration system of blowers and fine bubble diffusers. The suitable ratio of food to microorganism (F : M) is maintained for effective process operation. The microorganisms maintained in reactor carries out digestion of oxygen demanding impurities present in wastewater and hence the treated water is with very low concentration of biological and chemical oxygen demand. The clarifier or tube settler downstream is used to carrying out solid- liquid separation, settled sludge at bottom of reactor is partly recycled back for process, excessive sludge is sent for sludge dewatering treatment.
The ability of absorbing flow and qualitative shock loads due to higher detention time makes it preferred and reliable treatment process. This type of treatment process is very commonly used worldwide and in major industrial applications of wastewater/ effluent treatment.