Patent ID: 7384553

Claim:
A method for operating an anaerobic ammonium oxidation vessel in anaerobic ammonium oxidation in which ammonium and nitrite in water to be treated are simultaneously denitrified by anaerobic ammonium oxidizing bacteria, the method comprising the steps of: withdrawing a part of the anaerobic ammonium oxidizing bacteria from one anaerobic ammonium oxidation vessel in which the anaerobic ammonium oxidizing bacteria have been acclimatized, wherein the withdrawn anaerobic ammonium oxidizing bacteria includes at least a part of an excess amount of unaerobic ammonium oxidizing bacteria acclimatized in the one anaerobic ammonium oxidation vessel and wherein the one anaerobic ammonium oxidation vessel retains an amount of the anaerobic ammonium oxidizing bacteria following the withdrawing such that denitrification performance of the one anaerobic ammonium oxidation vessel is not affected, and introducing the withdrawn anaerobic ammonium oxidizing bacteria into another anaerobic ammonium oxidation vessel in which acclimatization is to be carried out to perform start-up operation, wherein the anaerobic ammonium oxidizing bacteria having been acclimatized in the one anaerobic ammonium oxidation vessel are provided as microbe-immobilized materials in which the bacteria are attached to and immobilized on immobilizing materials or entrapped and immobilized in immobilizing materials.