ABSTRACT
This chapter aims to discuss the mechanisms by which this occurs during both conventional and nonconventional sludge treatments. Mechanisms of virus inactivation in sludges have been studied by seeding viruses into sludges which are subsequently subjected to various treatments that simulate plant operations. The most common method of sludge stabilization used in sewage treatment plants in the US is anaerobic digestion. One of the most effective methods of stabilizing sludge is composting. Although this method of treating organic waste has been practiced for many years, composting of municipal sludges in the US has only gained major attention since the early 1970s. Viruses in wastewater sludge are inactivated during both conventional and nonconventional treatment processes. The mechanisms of inactivation during these processes depend on factors such as pH, temperature, chemical and biological composition, and moisture content. The effluent recovered after primary sedimentation is normally treated by processes that result in additional sludges also containing high concentrations of infectious viruses.
