ABSTRACT
This chapter considers the different types of anaerobic digestion (AD) plants and processes and how they may affect the choice of feedstock usage. There are two main types of AD process; thermophilic and mesophilic, which are differentiated by their operating temperatures. Thermophilic systems have a faster throughput than mesophilic systems, and faster biogas production, which means a smaller digester can achieve the same biogas output. Mesophilic systems are used where there is a higher manure content and there is likely to be more variation in the quality and quantity of feedstock. The chapter gives an overview of various types and sizes of plants, starting with the most basic and simple type and then moving up the scale to larger industrial-level plants. There are two AD plant types, namely, small-scale plants: hot composting plant and Gobar gas plant, and large-scale AD plants that include packaged AD plant. The packaged AD plant might be considered the first step on the biogas ladder.
