Patent ID: 7879238

Claim:
A process for treating an aqueous nitrogeneous liquor containing ammonium nitrogen, comprising the steps of: providing a reaction vessel containing a biosludge comprising anammox bacteria and ammonia-oxidizing bacteria; charging 40-60% of a batch treatment amount of a liquor containing ammonium nitrogen into the reaction vessel; supplying an oxygen-containing gas into the reaction vessel to oxidize the ammonium nitrogen into nitrite nitrogen by the ammonia-oxidizing bacteria; stopping the supply of the oxygen-containing gas at a point in time at which the observed value of the dissolved oxygen concentration of the liquor in the reaction vessel increases by at least 20% relative to the steady state value during the oxidation of ammonium nitrogen to nitrite nitrogen; and charging the remainder of the batch treatment amount of the liquor containing ammonium nitrogen into the reaction vessel and mixing the remainder of the batch treatment amount of the liquor with the reaction liquor present in the vessel to react the nitrite nitrogen in the reaction liquor with the ammonium nitrogen by anammox reaction and effect denitrification thereof.