How much alkalinity is used per 1 lb of ammonia?

• A. 0.72 lbs alkalinity per pound ammonia.
• B. 7.2 grams per pound ammonia.
• C. 7.2 lbs alkalinity per 1 lb ammonia.
• D. 72 lbs per lb ammonia.

Answer: (C)

Nitrification, the biological conversion of ammonia to nitrate, consumes alkalinity as buffering capacity is used to neutralize the acids formed during the process. For every pound of ammonia oxidized, about 7.14 pounds of alkalinity (as CaCO3 equivalents) are consumed. In practice, this is rounded to roughly 7.2 pounds of alkalinity per 1 pound of ammonia, which is why that option is the best choice. The other options don’t fit because they either use the wrong units (grams instead of pounds) or a magnitude far from the established ratio (0.72 or 72), which don’t reflect the typical alkalinity demand of nitrification.