Tennessee Wastewater Operator Practice Exam

What is an advantage of flow pacing RAS pumps to influent flow?

1. Increased energy consumption

2. Nearly constant RAS concentration

3. Improved effluent quality

4. Increased SVI

The correct answer is: Nearly constant RAS concentration

Flow pacing RAS (Returning Activated Sludge) pumps to influent flow is advantageous because it helps maintain a nearly constant concentration of RAS in the system. When RAS flow is adjusted to match the influent flow rates, it ensures that the biomass concentration in the aeration tank remains stable. This stability is crucial for effective biological treatment, as the microorganisms responsible for breaking down organic matter can operate more efficiently when they are consistently in equilibrium with the incoming wastewater. Maintaining a constant RAS concentration supports optimal conditions for microbial growth and activity, allowing for better treatment performance. It helps the treatment system handle variations in influent load more effectively by ensuring that the amount of biomass available for treatment is proportionate to the amount of incoming wastewater, which leads to better treatment efficiency and can directly influence the overall quality of the effluent produced. In contrast, options related to increased energy consumption or increased SVI (Sludge Volume Index) are less desirable outcomes that may arise from improper RAS flow management, while improved effluent quality can be a result of consistent RAS concentration but is more of a secondary benefit related to biological process stability.