Metaanikäymisellä

Metaanikäymisellä, also known as anaerobic digestion, is a natural biological process where organic matter is broken down by microorganisms in the absence of oxygen. This process occurs in environments like the digestive tracts of animals, in swamps, and in engineered digesters. The primary products of methanogenesis are biogas, a mixture of methane and carbon dioxide, and digestate, a nutrient-rich residue.

The process typically occurs in several stages. First, complex organic compounds like carbohydrates, fats, and proteins are hydrolyzed into simpler molecules. These are then fermented by acidogenic bacteria into volatile fatty acids, alcohols, hydrogen, and carbon dioxide. In the next stage, acetogenic bacteria convert these products into acetate, hydrogen, and carbon dioxide. Finally, methanogenic archaea convert acetate and hydrogen/carbon dioxide into methane and carbon dioxide.

Biogas produced through anaerobic digestion is a valuable renewable energy source. It can be used for heating, electricity generation, or upgraded to biomethane, which is chemically similar to natural gas and can be injected into existing gas grids or used as vehicle fuel. The digestate can be used as a fertilizer, providing essential nutrients for plant growth. Anaerobic digestion is also employed for waste management, reducing the volume of organic waste and mitigating the release of methane from landfills.