Generally biogas refers to a gas, which is produced by the biological breakdown of organic matter in the absence of oxygen.
Methanogenic bacteria breakdown biogenic material in the absence of oxygen to produce methane as one of the major constituent of biogas, which is used as biofuel.
Methane, Carbon dioxide, Hydrogen sulphide, Ammonia, Nitrogen, Water vapour, Siloxanes. Carbon dioxide concentration can constitute from 25 to 50% of the biogas produced. This may depend on various factors involved in the process. Carbon dioxide being soluble in water can be removed to give pure methane. Other gases are present in minute quantities and are called impurities.
The most common and well known source of methanogenic bacteria harbour in the rumen of cattle. The cowdung is thus used as a source of methanogenic bacteria.
Cowdung, human and animal waste was initially used as substrates for biogas. However, in order to get a better yield for household purposes high carbohydrate food material such as flour (rice, wheat, maida, etc.) are also being used. Presently, Kitchen wastes for a single house hold, whereas, municipal waste is found to be a good source as substrate to produce biogas.
For the municipal waste, the infrastructure set up would need –
The sludge that is produced form the biogas is non-odouress, composted black sludge which can be sun dried and used as soil enricher in gardens.
Most of the bacterial pathogens are reported to get eliminated within a week of inoculation. Hence, the process is medically safe.
Biogas is presently being used in various areas. The most common includes cooking, generation of electricity, use of compressed methane as vehicular fuel and water heating.