3.4.3 pH

The optimal pH level varies throughout the different phases of biogas formation. Specifically, the ideal pH range for hydrolysis and acidogenesis is between 5.2 and 6.3. On the other hand, for acetogenesis and methanogenesis, the optimum pH range is between 6.5 and 8. If the entire digestion process occurs in a single digester, the optimal pH is between 6.5 and 8, as methanogenesis is the most crucial step during this biogas production. Usually, the bacteria establish a pH balance. Still, disruption can occur if, for example, excessive amounts of the substrate are introduced, leading to the formation of volatile fatty acids, which cause a pH drop. Or if suddenly changing the feedstock from low to high nitrogen content can lead to increased pH levels.

Monitoring the pH levels provides valuable insights into the stability of the anaerobic process. It helps identify deviations or potential issues, enabling timely troubleshooting and corrective actions.