ABSTRACT
This chapter provides a brief description of the available types of composting systems. It is necessary to have a basic understanding of the types of processes before proceeding too far into fundamental concepts. The chapter introduces the general nature of composting systems, and describes their basic similarities and differences. Composting of municipal solid waste represents the opposite extreme from municipal sludge. Windrow composting has been applied to a variety of relatively dry substrates, but in particular yard and "green" wastes. Application of the windrow process to yard waste composting has seen its own evolution, as was the case with sludge composting reactor type, solids flow mechanisms, bed conditions in the reactor, and manner of air supply. Designers and operators of composting systems have a limited number of areas over which to exercise control of the process. Composting is often divided into a first stage, high-rate phase and a second stage, curing phase.
