Meaning of Biogas

It is called biogas to the gas obtained from the decomposition of waste type organic by anaerobically (ie, without oxygen). This process is developed 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 effluents from the process, on the other hand, serve as compost.

The methane and carbon dioxide are the main components of biogas, which is also nitrogen, hydrogen and other elements. With biogas, the energy used by boilers, stoves, ovens and other devices can be generated, and it is even possible to produce electricity using a generator.

The system that takes advantage of the digestion of bacteria found in manure for the generation of biogas and compost is called a 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 waterproof and hermetically sealed, plant debris 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. For this reason, in rural regions of Latin America, the development of these reactors to obtain biogas is promoted, the combustion of which generates little smoke. Farmers, in this way, can produce their own energy at a reduced cost.

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 the experts in biochemistry and microbiology who are dedicated to this activity. Below is the procedure in detail:

* Hydrolysis: it is the first stage in the production of biogas, and requires that organic compounds pass through the cell wall so that its 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 that the entire process takes is largely determined by this stage, whose success is linked to the dimensions of the particles, the temperature, the biochemical composition of the substrate and the pH, among other factors;

* Acidogenesis: in this stage, the soluble organic molecules are converted into three types of compounds. 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 could not be 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. Here also the homoacetogens stand out, 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 genera of bacteria.


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