ABSTRACT
Anaerobic treatment of solids and biosolids is commonly referred to as anaerobic digestion (AD). Mono digestion is where the feedstock consists of only one type of substrate. Co-digestion involves the digestion of more than one type of feedstock. Co-digestion can improve biogas production when the main source of feedstock is in limited supply, thereby making single feedstock digestion unsustainable. Biogas production rate will depend on several parameters, notably, organic content, reactor type, and operational characteristics. The standard rate system or digester consists of a single-stage operation without mixing. High-rate digesters are designed and operated to maximize biogas. These systems can consist of one or more stages. High-solids digestion is characterized by lower water usage, reactor size, space and heating requirements, and higher bio gas production per unit volume of reactor than the low-solids digestion. Mixing is however less effective than in low-solids digestion, and therefore it requires greater attention.
