BIOGAS
When a non-lignious Bio-mass is kept in a closed chamber for a few days , it ferment and produces an inflammable gas that consists of mostly Methane and Carbon-di-oxide . This gas is known as biogas with Methane comprising about 50%of it. This process is called anaerobic fermentation or bio-methanation or bio-gasification.
Decaying bio-mass and animal wastes are broken down to elementary nutrients and soil humus by decomposer organisms , fungi and bacteria. The processes are favoured by wet , warm , and dark conditions. The final stages are accomplished by many different species of Bacteria classified as either anaerobic or aerobic. Aerobic bacteria are favoured in the presence of Oxygen with the biomass carbon being fully oxidised too Carbon-di-oxide. In closed conditions with no Oxygen available from the Environment , anaerobic bacteria are able to exist by breaking down general carbohydrate material. Nutrients such as soluble Nitrogen compounds remain available in the solution, so providing excellent fertiliser and humus. Being accomplished my micro-organisms , the reactions are all classified as fermentations , but in anaerobic conditions yielding Methane , the term Digestion is preferred.
The series of complex reactions involved in the digestion of Organic wastes to Biogas can be broadly divided into two main phases. First, an acidogenic phase [Hydrolysis and acid formation stages combined and called Phase I] in which all organic wastes are converted mainly to Acetate. Secondly the Methanogenic phase called Phase II in which Methane and Carbon-di-oxide are formed. The first two steps are the essential processes in which bonds are broken and acid is formed. Methane is produced through anaerobic fermentation.