Tennessee Wastewater Operator Practice Exam

What short-term solution may be applied if the secondary clarifier at a small facility is overloaded?

1. Increase the RAS rate

2. Adjust SVI with chemicals

3. Reduce influent flow

4. Install an additional clarifier

The correct answer is: Adjust SVI with chemicals

In situations where the secondary clarifier at a small facility is overloaded, adjusting the Sludge Volume Index (SVI) with chemicals can be an effective short-term solution. SVI is a critical parameter that indicates the settleability of the biomass in the clarifier. By utilizing chemicals, such as flocculants or coagulants, the settling characteristics of the activated sludge can be improved. This will enhance the density and settling rate of the sludge particles, allowing for more efficient clarification and reducing the likelihood of washout or effluent quality issues. This approach can quickly and temporarily address the overload situation, enabling the current clarifier to handle the existing load more effectively. It acts to optimize the performance of the existing infrastructure rather than requiring significant capital investment or construction time, which would be the case if an additional clarifier were to be installed.