In activated sludge, what condition leads to bulking and how is it typically corrected?

• A. Bulking is caused by excessive nitrification and is corrected by reducing nitrification.
• B. Bulking is caused by insufficient food for bacteria and is corrected by adding more aeration.
• C. Bulking is caused by excessive filamentous bacteria that reduce sludge settleability; corrected by adjusting mixed liquor suspended solids, DO, aeration, wasting rate, and sometimes seeding with bulking-tolerant cultures.
• D. Bulking is caused by excessive nitrification.

Answer: (C)