24.During sewage, after significant reduction in BOD of waste water, it is passed into setting tank where bacterial flocs are allowed to sediment. This sediment is known as A. Anaerobic sludge B. Primary sludge C. Activated sludge D. Primary effluent
Option C. Once the BOD is reduced the effluent is then passd inot a setting tank where the bacteria flocs are allowed to settle. This sediment is called acitvated sludge .
