What is the main difference between aerobic and anaerobic digestion?

The main difference between aerobic and anaerobic digestion lies in the presence of oxygen. In aerobic digestion, microorganisms break down organic matter in the presence of oxygen, which is essential for their metabolic processes. This process results in the production of carbon dioxide, water, and biomass, leading to an efficient breakdown of waste materials.

On the other hand, anaerobic digestion occurs in environments devoid of oxygen. In this process, different groups of microorganisms, adapted to anaerobic conditions, decompose organic matter and produce biogas, primarily consisting of methane and carbon dioxide, along with digestate, which can be solid or liquid.

This fundamental distinction regarding oxygen availability is vital for understanding the operational parameters and outcomes of each digestion type. Aerobic processes are typically faster because they leverage the higher energy yield from organic substrates in the presence of oxygen, while anaerobic processes tend to take longer and produce different end products.