Biogas is a gas obtained through the decomposition of organic waste.
Biogas is the gas obtained from the decomposition of organic waste anaerobically (that is, without oxygen). This process is carried out by bacteria.
Biogas, therefore, is a fuel generated by the degradation of organic substances . The anaerobic decomposition carried out by microorganisms allows the production of biofuel with the treatment of biodegradable waste. The process effluents, on the other hand, serve as fertilizer .
Methane and carbon dioxide are the main constituents of biogas, which also has nitrogen , hydrogen and other elements. With biogas you can generate energy used by boilers, stoves, ovens and other devices, and it is even possible to produce electricity using a generator.
Biogas and biodigesters
The system that takes advantage of the digestion of bacteria found in manure for the generation of biogas and fertilizer is called biodigester . In its simplest format, a biodigester is a container known as a reactor , where the organic substances that will ferment are stored. In the reactor, which is impermeable and hermetically closed, plant waste and animal excrement can be included so that, with anaerobic fermentation, biogas and fertilizer are generated.
The construction of a biodigester is very simple and economical. That is why in rural regions of Latin America the development of these reactors is promoted to obtain biogas, whose combustion generates little smoke. Farmers, in this way, can produce their own energy at a reduced cost.
The process of obtaining biogas consists of several stages.
Production process
To produce biogas through the anaerobic digestion of organic matter, it is necessary to carry out a process that consists of four well-defined stages, according to experts in biochemistry and microbiology who are dedicated to this activity. Below is the procedure in detail:
- Hydrolysis : it is the first stage of biogas production, and requires that the organic compounds pass through the cell wall so that their organic matter can be used. It is possible to obtain soluble organic compounds from polymeric organic matter thanks to the action of hydrolytic microorganisms, which generate extracellular enzymes that have this capacity. The time the entire process takes is largely determined by this stage, whose success is linked to the dimensions of the particles, temperature, biochemical composition of the substrate and pH, among other factors.
- Acidogenesis : in this stage the conversion of soluble organic molecules into three types of compounds takes place. They are divided into those that cannot take advantage of methanogenic bacteria (such as fatty acids, aromatic compounds and ethanol), and those that can (where we find hydrogen, acetic and formic, as well as propionic, valeric and lactic). These compounds are also responsible for eliminating any trace of oxygen in the biodigester.
- Acetogenesis : any compound that has not been metabolized by methanogenic bacteria is used in this stage, and among them are aromatics, fatty acids and ethanol, which are transformed into others of less complexity, such as hydrogen and acetate . Homoacetogenics also stand out here, a very particular type of acetogenic microorganism that is capable of generating acetate and is used to keep the level of hydrogen gas low, since it does not produce it.
- Methanogenesis : to complete the anaerobic decomposition of the products, methanogenic bacteria come into action , which are responsible for producing methane. It is known that 70% of the methane produced in biodigesters arises when acetic acid loses the carboxyl group of atoms, since acetate can only be used by two types of bacteria.