Tennessee Wastewater Operator Practice Exam

Where are digested solids typically removed from an aerobic digester?

1. From the top

2. Near the bottom

3. From the sides

4. From the inlet

The correct answer is: Near the bottom

Digested solids are typically removed from near the bottom of an aerobic digester. This is because during the digestion process, the solids settle at the bottom of the digester due to gravity. The digestion process reduces organic matter and stabilizes the solids, resulting in sludge accumulation primarily at the bottom. By removing the solids from near the bottom, operators can efficiently manage the accumulation and maintain proper function within the digester. It's important to note that other removal locations, such as the top or sides, would be inefficient for this purpose since the denser, digested materials naturally settle down. Removing solids from the inlet would also not be effective, as the materials there have not yet undergone digestion. Therefore, opting to remove solids from the bottom ensures that the operation remains optimized and that the sludge is adequately processed.