Tennessee Wastewater Operator Practice Exam

Which issue can cause a floating cover in an anaerobic digester to tilt?

1. Excessive temperature fluctuations

2. Improper weight distribution

3. High levels of methane production

4. Inadequate mixing of tank contents

The correct answer is: Improper weight distribution

A floating cover in an anaerobic digester plays a crucial role in maintaining the appropriate conditions for digestion processes, including the capture of biogas. When the weight distribution on this cover is improper, it can lead to tilting, creating an imbalance that affects the operation of the digester. For instance, if one side of the cover is significantly heavier due to uneven accumulation of solids or an uneven distribution of gas pressure, it can cause the entire cover to tilt. This tilting may prevent the cover from sealing properly, leading to gas leaks and reducing the efficiency of the biogas collection system. This scenario highlights the importance of monitoring load distribution on the cover and ensuring that it is designed to handle the expected fluctuations in weight due to changing operational conditions. Proper maintenance and adjustments can help prevent such tilting issues, ensuring the floating cover functions effectively and maintains the integrity of the anaerobic digestion process.