ABSTRACT
A major problem in designing wastewater treatment plants is the disposal of biosolids into the environment without causing damage or nuisance. Untreated biosolids is even more difficult to dispose of. Untreated raw biosolids must be stabilized to minimize disposal problems. Biosolids digestion is a process in which biochemical decomposition of the organic solids occurs; in the decomposition process, the organics are converted into simpler and more stable substances. Digestion also reduces the total mass or weight of biosolids solids, destroys pathogens, and makes it easier to dry or dewater the biosolids. Biosolids may be digested under aerobic or anaerobic conditions. The purpose of both aerobic and anaerobic digestion is to stabilize organic matter, to reduce volume, and to eliminate pathogenic organisms. Most large municipal wastewater treatment plants use anaerobic digestion. Aerobic digestion finds application primarily in small package-activated biosolids treatment systems.
