The fermentation process in which organic material is degraded and biogas (composed of mainly methane and carbon dioxide) is produced, is referred to as anaerobic digestion. Anaerobic digestion processes occur in many places where organic material is available and redox potential is low (zero oxygen). This is typically the case in stomachs of ruminants, in marshes, sediments of lakes and ditches, municipal land fills, or even municipal sewers.
The anaerobic ecosystem is the result of complex interactions among microorganisms of several different species. The major groupings of bacteria and reaction they mediate are:
fermentative bacteria
hydrogen-producing acetogenic bacteria
hydrogen-consuming acetogenic bacteria
carbon dioxide-reducing methanogens
aceticlastic methanogens.
The reactions they mediate are presented in figure 2 and discussed in the following sections.
Introduction
Introduction