Differentiate nitrification and denitrification in wastewater treatment.

• A. Nitrification is anaerobic oxidation of ammonia to nitrate; denitrification is aerobic oxidation of nitrate to nitrogen gas.
• B. Nitrification is aerobic oxidation of ammonia to nitrite and nitrate; denitrification is anoxic reduction of nitrate to nitrogen gas.
• C. Nitrification and denitrification are identical processes.
• D. Nitrification occurs in primary clarifiers; denitrification occurs in aeration basins.

Answer: (B)