Tennessee Wastewater Operator Practice Exam

Increasing the return activated sludge (RAS) flow without equal flow distribution between clarifiers will typically lead to which outcome?

1. Higher sludge volume index

2. Improved settling rates

3. Uneven surface loading rate between clarifiers

4. Lower BOD removal efficiency

The correct answer is: Uneven surface loading rate between clarifiers

Increasing the return activated sludge (RAS) flow without ensuring equal flow distribution between clarifiers often results in uneven surface loading rates between the clarifiers. When RAS flow is not evenly distributed, one clarifier may receive a significantly higher volume of sludge than another. This imbalance can lead to one clarifier being overloaded while another is underloaded, which can disrupt the settling characteristics and overall operational efficiency of the treatment process. When clarifiers operate with uneven surface loading, it can cause one to become ineffective at removing solids due to the excess load, while the other may not be utilized to its full potential. This inefficient distribution may ultimately affect the overall treatment performance of the wastewater facility, but primarily it represents a clear operational concern related to the equalization of flow within the system. Proper flow management is crucial in activated sludge systems to ensure optimal performance and adequate treatment of wastewater.