Magnesium Hydroxide Slurry as an Alkalinity Supplement in Nitrification of Biological Wastewater Treatment

Magnesium Hydroxide Slurry as an Alkalinity Supplement in Nitrification of Biological Wastewater Treatment

Industrial processes that produce high ammonia loading in wastewater are common. Biological nutrient removal (BNR) systems employ sequential nitrification/denitrification to convert ammonium into nitrates and harmless N₂ gas.

In nitrification, aerobic nitrifying bacteria convert ammonia to nitrate:

Denitrification then uses microorganisms to convert nitrates to harmless N₂ gas in the absence of dissolved oxygen (DO). Nitrification produces acid, therefore alkalinity must be added or supplemented to buffer the acids produced.

FloMag^® H magnesium hydroxide slurry can be used to provide the 7.14 parts of alkalinity that are required for each part of ammonia to be removed. Alkalinity is the capacity of water to buffer or resist changes in pH in response to introduction of acid or base. Nitrification rates rapidly decrease as pH falls below 7.0, and stops at a pH of approximately 6.0.

FloMag^® H magnesium hydroxide slurry, Mg(OH)₂, represents a good alkalinity supplement for nitrification due to its higher alkalinity per gallon, as compared with caustic soda or hydrated lime. Because alkalinity is released slowly with magnesium hydroxide, there are no large pH excursions to kill nitrifying microorganisms. FloMag^® H magnesium hydroxide slurry provides both alkalinity and pH stability for the biological nitrification process.