Patent attributes
In treating water containing ammonium-nitrogen by a combination of a nitrification process and autotrophic denitrification bacteria, high efficiency denitrification treatment is achieved by providing adequate ratio between nitrite and ammonia in effluent of the nitrification process. Ammonium-nitrogen concentration of the raw water introduced to a nitrification reactor and the ammonium-nitrogen concentration of the nitrified liquid from the nitrification reactor is measured, and on the basis of the measurement, the flow volume for aeration by a blower would be controlled. From the difference in NH4—N concentration between the influent and the effluent of the nitrification reactor, nitrite concentration A in the nitrified liquid is calculated, and ratio A/B of the nitrite concentration A with the ammonia concentration B in the nitrified liquid is calculated. The flow volume for aeration by the blower to the nitrification reactor is controlled such that the A/B becomes 1.1 or more, preferably from 1.1 to 2.0.
