Texas Wastewater Class B Practice Exam

Which are important control parameters in the activated sludge process?

1. Temperature, pH level, and effluent flow

2. Dissolved oxygen level, aerator solids level, and wasting rate

3. Only the rate of returned sludge

4. Inflow and outflow rates only

The correct answer is: Dissolved oxygen level, aerator solids level, and wasting rate

The choice highlighting dissolved oxygen level, aerator solids level, and wasting rate as important control parameters in the activated sludge process is indeed correct. Dissolved oxygen is crucial because it directly affects the respiration of the microorganisms in the activated sludge, which are essential for breaking down organic matter in wastewater. If the oxygen levels are too low, the bacteria cannot perform their function effectively, leading to incomplete treatment. Aerator solids level refers to the concentration of suspended solids in the aeration tank, which indicates the amount of biomass available for treatment. Maintaining the right concentration is key to ensuring that there are enough microorganisms to efficiently process the incoming waste. The wasting rate, or the amount of sludge that is removed from the system, must be carefully managed to maintain a balance in the system. Over- or under-wasting can disrupt the biological treatment process, as it affects both the solids retention time and the overall health of the microbial community. The other options lack the comprehensive considerations needed for effective control of the activated sludge process. Specifically, simply relying on temperature and pH is not sufficient on its own, nor is focusing only on inflow and outflow rates. The process requires a holistic approach that incorporates several factors, including but not limited to dissolved oxygen