Tennessee Wastewater Operator Practice Exam

What is the desired pH range for optimal anaerobic digestion?

1. 4.0 - 5.0

2. 6.0 - 7.0

3. 7.0 - 8.0

4. 8.0 - 9.0

The correct answer is: 7.0 - 8.0

In anaerobic digestion, maintaining the optimal pH range is crucial for the effective breakdown of organic matter by microorganisms. The desired pH range for anaerobic digestion is typically between 6.8 and 7.4, with 7.0 being ideal. This pH range supports the metabolic activities of methanogens, which are the microorganisms responsible for producing methane during the digestion process. A pH around neutral levels ensures that these microorganisms can thrive, thereby enhancing the efficiency of biogas production. When the pH falls below 6.0, the environment can become acidic, which inhibits the activity of methanogens and can lead to a buildup of volatile fatty acids. Conversely, a pH that rises above 7.5 may result in alkaline conditions, which can also be detrimental to microbial activity. Therefore, maintaining a pH that is typically categorized within the range of 7.0 to 8.0 ensures an environment conducive to anaerobic processes, promoting effective nutrient breakdown and biogas production. This understanding underscores why the chosen range of 7.0 to 8.0 is the optimal condition for anaerobic digestion processes.