What process primarily occurs during anaerobic digestion?

During anaerobic digestion, the primary process that occurs is fermentation. This biological process takes place in the absence of oxygen and involves the breakdown of organic materials by microorganisms, such as bacteria. During fermentation, complex organic matter, like sludge or other waste products, is decomposed into simpler compounds.

In the context of wastewater treatment, anaerobic digestion effectively reduces the volume of organic solids, produces biogas (which primarily consists of methane and carbon dioxide), and stabilizes organic matter, making it less harmful and easier to handle. This process is crucial for managing biosolids and recovering energy from waste materials.

While incineration, oxidation, and condensation are processes that may pertain to waste management or treatment, they do not describe the primary biochemical reactions that occur in anaerobic conditions. Therefore, fermentation stands out as the focal process that defines anaerobic digestion in wastewater treatment.