ABSTRACT
Composting is the aerobic, biological decomposition and stabilization of solid or semi-solid organic substrates, under conditions that allow development of thermophilic temperatures as a result of biologically produced heat, to produce a final product that is stable, free of pathogens and plant seeds, and can be beneficially applied to land. Most biological stabilization and conversion processes deal with dilute aqueous solutions, and only limited temperature elevation is possible. Biological criteria include the absence of pathogenic bacteria and the inactivation of weed seeds. Maximum composting temperatures are generally limited to about 75 to 85°C because the rates of biological activity become seriously reduced by thermal inactivation at such temperatures. The most common nonreactor processes in commercial use are the windrow and static pile processes. A great number of reactor types have seen at least some commercial application in the long history of composting.
