Which statement about pH and microbial activity in anaerobic digestion is true?

In anaerobic digestion, the activity of methanogens—microorganisms responsible for converting organic materials into methane gas—is significantly influenced by pH levels. Methanogens generally thrive in a pH range of about 6.8 to 7.4, which is considered optimal for their metabolic processes. When the pH levels deviate from this range, either becoming too acidic or too alkaline, it can inhibit the activity of methanogens and consequently reduce the overall efficiency of the anaerobic digestion process.

Moreover, during anaerobic digestion, the breakdown of organic matter occurs in two main stages: fermentation by acid-producing bacteria and subsequent conversion of these acids into methane by methanogens. If pH levels drop due to the accumulation of volatile fatty acids, it can negatively impact the methanogen population, leading to process instability and reduced biogas production. Therefore, monitoring and controlling pH levels is crucial to maintaining optimal conditions for microbial activity in anaerobic digestion.

Understanding this relationship is essential for effective wastewater treatment and optimizing the operational parameters of anaerobic digesters, making this statement about the impact of pH on methanogen activity accurate and relevant.