Tennessee Wastewater Operator Practice Exam

What impact does decreased settling velocity have on wastewater treatment effectiveness?

1. Improves treatment efficiency

2. Reduces treatment efficiency

3. Has no impact

4. Only affects sludge retention

The correct answer is: Reduces treatment efficiency

Decreased settling velocity in wastewater treatment indicates that the solids present in the wastewater do not settle effectively during the sedimentation process. This reduced settling velocity can lead to less efficient separation of solids from liquids in processes such as primary and secondary sedimentation tanks. When the solids do not settle properly, they can remain suspended in the liquid, resulting in higher concentrations of suspended solids in the effluent. This can lead to increased turbidity and other negative effects on water quality, consequently making it harder to meet discharge permit requirements. Furthermore, anaerobic conditions may arise if solids accumulate, leading to odors and operational issues. In summary, decreased settling velocity diminishes the effectiveness of wastewater treatment by compromising the removal of suspended solids, thereby leading to reduced treatment efficiency and potentially harm the environment through poor effluent quality.