ABSTRACT
T his chapter describes the three stages of composting (preprocessing processing and postprocessing) for both yard trimmings and MSW composting It examines the operations that must be performed at each step in the process à and describes ways for optimizing those conditions that influence the process. In addition, this chapter discusses the different technologies currently used to compost yard trimmings and MSWfeedstocks in the United States. These can range from simple, low-technology systems that require minimal attention and maintenance to complex systems that use sophisticated machinery and require daily monitoring and adjustment. The design and complexity of a composting operation are determined by the volume, composition, and size distribution of the feedstock; the availability of equipment; the capital and operating finds; and the end-use specifications for the finished product. This chapter also examines the potential problems associated with odor and describes the measures a composting facility can take to prevent or minimize odor. A system flow chart for a typical operation that composts yard trimmings is shown in Figure 4-1. Figure 4-2 outlines a process flow diagram for a typical MSW composting facility. For more information on costs and effectiveness of the equipment described in this chapter, see Appendix B. Two case studies illustrating the process of composting yard trimmings and MSW are included at the back of this chapter.
