Patent ID: 7704733

Claim:
A nitrogen removing apparatus, comprising: a nitrification tank comprising a nitrification carrier containing ammonia-oxidizing bacteria, the nitrification tank being for bringing the nitrification carrier into contact with water containing ammonic nitrogen under aerobic conditions to convert the ammonic nitrogen to nitrite and nitrate by the ammonia-oxidizing bacteria to produce nitrified water; a heat-treatment tank connected to the nitrification tank by a channel for circulating part or all of the nitrification carrier from the nitrification tank to the heat-treatment tank and back to the nitrification tank, and during the circulating, subjecting the nitrification carrier to heat treatment at a temperature of 30 to 80° C. in the heat-treatment tank to accumulate ammonia-oxidizing bacteria for nitrifying ammonic nitrogen to nitrite and nitrate and to suppress accumulation of nitrite-oxidizing bacteria; and a denitrification tank arranged downstream of the nitrification tank, the denitrification tank being for removal of nitrate remaining in the nitrified water; wherein the nitrification carrier is made by a method in which ammonia-oxidizing bacteria for nitrifying ammonic nitrogen to nitrite and nitrate are accumulated and accumulation of nitrite-oxidizing bacteria is suppressed, comprising the steps of: entrapping and immobilizing sludge by polymerizing a monomer or a prepolymer in presence of the sludge selected from the group consisting of sediment from a lake, sediment from a river, sediment from a sea, soil from a surface of the earth, and activated sludge from a sewage-treatment plant; and then subjecting the entrapped and immobilized sludge to heat treatment at a temperature of 30 to 80° C. to produce the nitrification carrier containing accumulated ammonia-oxidizing bacteria.