1. What does MLSS stand for?
A. Mixed Liquor Suspended Solids
B. Main Lagoon Sludge System
C. Mechanical Liquid Separation System
✅ Answer: A
2. What is the purpose of aeration?
A. Remove grit
B. Add oxygen for microorganisms
C. Remove chlorine
✅ Answer: B
3. High sludge blanket levels can cause:
A. Better settling
B. Solids washout
C. Lower MLSS
✅ Answer: B
4. Which process removes ammonia?
A. Sedimentation
B. Chlorination
C. Nitrification
✅ Answer: C
5. What happens if DO becomes too low?
A. Biology becomes stressed
B. Clarifiers grow larger
C. pH increases automatically
✅ Answer: A
6. What is SVI used for?
A. Measuring chlorine
B. Evaluating sludge settling
C. Measuring flow rate
✅ Answer: B
7. Which bacteria are slow-growing?
A. Nitrifiers
B. Filaments
C. Coliforms
✅ Answer: A
8. Bulking sludge often causes:
A. Clear effluent
B. Poor settling
C. Lower sludge age
✅ Answer: B
9. What does RAS stand for?
A. Return Activated Sludge
B. Rapid Aeration System
C. Residual Aerobic Solids
✅ Answer: A
10. The main purpose of wasting sludge is to:
A. Increase odors
B. Control solids inventory
C. Raise pH
✅ Answer: B