| 摘要 |
PROBLEM TO BE SOLVED: To obtain a nitration and denitrification method capable of simplifying equipment, capable of obtaining high treatment capacity and capable of withstanding long-term use by adding porous particles composed of polyvinyl acetal to a nitration tank and/or a denitrification tank as a microorganlsm carrier when nitrogencontaining waste water is biologically nitrated and denitrified. SOLUTION: Raw water l being nitrogen-containing waste water is successively passed through a denitrification tank 3 denitrifying a nitration soln., nitration tank 3 nitrating org. nitrogen and ammonia nitrogen in waste water and a sedimentation tank 4 subjecting the nitrated soln. flowing out of the nitration tank 3 to solid-liquid separation. At this time, porous particles composed of polyvinyl acetal having an almost spherical shape with a diameter of 1-10 mm and a pore size of 0.5-20μm are added to the tanks 2,3 as a microorganism carrier, for example, in an amt. of 10v/v%. Since these microorganism carriers are common carriers circulating between the tanks 2, 3, the carrier is prevented from flowing out of the carrier separator 5 provided. to the outflow end of the nitration tank 3 and circulated to the inflow end of the denitrification tank 2 by an air lift pump 10.
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