ABSTRACT
The principal purposes of sludge stabilization are to reduce pathogens, eliminate offensive odors, and control the potential for putrefaction of organic matter. Sludge stabilization can be accomplished by biological, chemical, or physical means. Selection of any method depends largely on the ultimate sludge disposal method. Various methods of sludge stabilization are anaerobic digestion, aerobic digestion, chemical stabilization, and thermal conditioning. This chapter discusses these methods because of the increasing use of anaerobic and aerobic sludge digestion. It presents step-by-step design procedure, design details, and operation and maintenance for an anaerobic digester in design example. The key factor for selection of a sludge stabilization process is the ultimate sludge disposal. The federal, state, and local regulatory agencies have regulations that directly impact the process selection, design criteria, redundancy requirements, and ultimate disposal restrictions. In the standard-rate digestion process, the digester contents are usually unheated and unmixed. The sludge is fed intermittently.
