Tennessee Wastewater Operator Practice Exam

Why should decanting and solids withdrawal times be kept as short as possible?

1. To increase fermentation

2. To ensure equipment efficiency

3. To prevent diffuser fouling

4. To optimize nutrient recovery

The correct answer is: To prevent diffuser fouling

Decanting and solids withdrawal times should be minimized primarily to prevent diffuser fouling. When solids are allowed to remain in the treatment process for too long, they can accumulate and settle in areas where they are not desired, such as on diffusers. This accumulation can disrupt the even distribution of air, leading to inefficient aeration and less effective biological treatment. When diffusers become fouled, they can fail to deliver the necessary oxygen to the microorganisms responsible for breaking down waste, which can ultimately hinder the treatment process and reduce overall system performance. The focus on preventing diffuser fouling emphasizes the importance of maintaining optimal operation conditions for the aeration system and ensuring that the wastewater treatment process runs smoothly. Keeping withdrawal times short helps maintain the right balance and flow through the system, reducing the likelihood of blockages and enhancing the effectiveness of wastewater treatment.