Wastewater Treatment Operator Certification Practice Test

Which of the following is an improper way to control an anaerobic digester?

1. Control the loading rate or food supply

2. Control the volatile acid/alkalinity relationship

3. Control mixing

4. Control the acid formation so that it is larger than the methane formation

The correct answer is: Control the acid formation so that it is larger than the methane formation

Controlling an anaerobic digester effectively requires balancing the different processes occurring within it, particularly those related to acid production and methane formation. In a well-functioning anaerobic digestion process, it's crucial that methane production outpaces acid formation. This ensures the stability of the digestion environment and encourages the efficient breakdown of organic matter into biogas. When acid formation exceeds methane formation, it creates an unfavorable condition known as acidosis, which can hinder the performance of the microbes responsible for generating methane. Such an imbalance can lead to process instability, reduced biogas production, and potentially system failure, as the accumulation of volatile fatty acids can become toxic to the methanogenic bacteria. In contrast, controlling the loading rate, the volatile acid/alkalinity ratio, and mixing are all critical operational practices to maintain a healthy anaerobic digester. These factors help ensure that the conditions inside the digester remain optimal for the microorganisms, promoting effective degradation of organic material and maximizing biogas production. Therefore, managing acid and methane formation to maintain a proper balance is essential in anaerobic digestion processes.