Biogas production is increasingly becoming a suitable renewable
alternative to the use of fossil fuels either for power or heat
generation (Chen et al., 2008;Weiland, 2010). Biogas is the result of
an anaerobic digestion (AD) or fermentation process of biomass
mediated by a consortium of microorganisms. This digestion process
takes place at constant temperature at 35e42 C or 45e60 C
and are called mesophilic or thermophilic, respectively (Weiland,
2010). The final biogas product is a methaneecarbon dioxide
mixture saturated with water and small amounts of ammonia and
hydrogen sulphide, and other trace gases (US-EPA, 2010; Weiland,
2010). Re-using organic wastes (of any kind) as raw input
material in biogas production realizes two principal benefits: (1)
reduction of the amount of organic wastes and (2) reduction of
fossil fuel consumption, and thereby greenhouse gas emission.