Biological conversion technologies rely on microorganisms to digest biodegradable waste, producing
biogas generally containing methane as a primary component as well as other byproducts (Pham et
al., 2015). Waste inputs must be biodegradable, and thus feedstock is generally restricted to fibers
(paper), food waste, yard wastes, biosolids/sludges, and select rubber and textile wastes (Pham et
al., 2015; Jenkins and Legrand, 2005). Waste input properties such as material type, moisture
content, average particle size, and overall feedstock consistency (as well as pre-treatment process
type and duration) significantly affects output product and byproduct quantity and quality. There are
two primary types of biological conversion commonly used in solid waste applications: anaerobic
digestion and fermentation.