Half-nitrosation achieved by controlling alkalinity in a sequencing batch reactor

The key of obtaining partial nitrification is to control the molar ratio of bicarbonate to ammonium. When 1 mole ammonium is completely oxidized, it must need 2 moles bicarbonate. From the stoichiometric relationship of the influent of anammox, the molar ratio of nitrite to ammonium is 1.32 (Strous et al. 1998). In consideration of the toxicity of nitrite, the ammonium must be adequate, so the stoichiometric relationship should be set as 1. Therefore, in order to oxidize 50% ammonium, the molar ratio of ammonium to bicarbonate should be set as 1.