ABSTRACT
The objective of anaerobic sludge digestion is the transformation of wastewater sludges to innocuous and easily dewatered substance. Destruction of pathogenic organisms also is accomplished during anaerobic digestion. The final product is a stable, innocuous sludge that can be used as a soil conditioner or fertilizer. Anaerobic digestion of waste activated sludge also is practiced at many industrial facilities where the excess biological sludge is stored in lagoons or ponds. The composition of the sludge introduced into the anaerobic digested process controls the final products of digestion. The rate-limiting reaction in anaerobic digestion is the conversion of volatile acids to methane gas by methane-forming bacteria, which are strict anaerobes and extremely sensitive to changes in temperature and pH. The final use/disposal of digested sludge will affect the degree of digestion required by current regulations and the feasibility of applying anaerobic sludge digestion.
