Tennessee Wastewater Operator Practice Exam

Why are anaerobic digesters covered?

1. To help retain heat

2. To prevent air from entering

3. To reduce odorous emissions

4. To facilitate biogas collection

The correct answer is: To prevent air from entering

Anaerobic digesters are covered primarily to prevent air from entering. This is crucial because the digestion process within these systems relies on anaerobic conditions, where microorganisms break down organic materials in the absence of oxygen. If air were to enter the digester, it could disrupt the anaerobic environment, inhibiting the activity of the methanogenic bacteria responsible for converting organic matter into biogas. Maintaining an airtight seal ensures that the digestion process remains efficient and effective. While it is true that covering a digester can also help retain heat, reduce odorous emissions, and facilitate biogas collection, the primary purpose is to ensure that the anaerobic conditions are maintained by preventing the entry of air.