What is anaerobic digestion

Anaerobic digestion is a biological process in which microorganisms break down biodegradable material in the absence of oxygen. This process produces biogas, which is primarily composed of methane (CH4) and carbon dioxide (CO2), along with small amounts of other gases such as hydrogen sulfide (H2S) and traces of water vapor.

The anaerobic digestion process occurs in several stages:

• Hydrolysis:
  Large organic molecules such as carbohydrates, fats, and proteins are broken down into smaller molecules by enzymes.
  
  
• Acidogenesis:
  The smaller molecules are converted into volatile fatty acids and alcohols by acidogenic bacteria.
  
  
• Acetogenesis:
  Acetogenic bacteria further break down the volatile fatty acids into acetic acid, hydrogen, and carbon dioxide.
  
  
• Methanogenesis:
  Methanogenic archaea convert the acetic acid, hydrogen, and carbon dioxide into methane and carbon dioxide.

The biogas produced during anaerobic digestion can be used as a renewable energy source for heating, electricity generation, and as a vehicle fuel. The remaining material after digestion, called digestate, can be used as a nutrient-rich fertilizer. Anaerobic digestion helps reduce greenhouse gas emissions by capturing methane that would otherwise be released into the atmosphere during the decomposition of organic waste.