A biodigester is a natural system that takes advantage of the anaerobic digestion (in the absence of I oxygenate) the bacteria that already live in the dung, to transform this into biogas and fertilizer. Biogas can be used as fuel in the kitchens, or illumination, and in great facilities it is possible to be used to feed a motor that generates electricity. The fertilizer, biol, initially considered as a secondary product, but at the moment is being considered of the same importance, or major, that biogas since it provides farmers with a natural fertilizer that strongly improves their yield on harvests.
The family biodigesters of low cost have been developed and are widely implemented in south-east Asian countries, but in South America, only countries like Cuba, Colombia and Brazil have developed this technology. These models of familiar biodigesters, constructed from tubular polythene sleeves, characterized by its low cost, easy installation and maintenance, as well as the need of only local materials for their construction.
The lack of firewood to cook in many world regions, turn these into interesting systems for its diffusion, spreading and dissemination on a large scale. Families dedicated to agriculture, usually are proprietors of small amounts of cattle (two or three cows for example) and can, therefore, take advantage of their dung to produce their own fuel and an improved natural fertilizer. It is to consider that the accumulated dung near the houses supposes a center of infection, scents and flies will disappear if fertilizer is introduced in the biodigester.
Also it is important to remember the amount of respiratory diseases that women suffer by the inhalation of smoke when cooking with dry firewood or bosta in closed spaces. The combustion of biogas does not produce visible smoke and its ash load is infinitely smaller than the originating smoke of the wood burning fire.
They are the three basic limits for biodigesters: the water availability to make the mixture with the dung that will be introduced in the biodigester, the amount of cattle that owns the family (three cows is enough) and the appropriation of the technology by the family.