Tennessee Wastewater Operator Practice Exam

What occurs when the SLR is too high?

1. The effluent quality improves

2. Blanket depth will increase

3. RAS flow decreases

4. SVI stabilizes

The correct answer is: Blanket depth will increase

When the SLR, or Solid Loading Rate, is too high, it can lead to an increase in the blanket depth within the clarifier. This occurs because a higher solid loading can cause an accumulation of solids that the clarifier is unable to effectively remove from the process. As the concentration of solids increases beyond the optimal level for settling, the sludge blanket—comprised of settled solids—grows thicker. This can impact various aspects of the wastewater treatment process. An increased blanket depth can lead to poor clarifier performance and potential carryover of solids into the effluent, thereby degrading the overall effluent quality. Moreover, it can create challenges with the return activated sludge (RAS) flow and stability of the mixed liquor. Monitoring and maintaining the SLR within appropriate limits is crucial to optimize treatment efficiency and ensure that the solids remain adequately settled and managed within the system.