| 摘要 |
<p>PROBLEM TO BE SOLVED: To treat for a long period of time without the degradation in the nitric acid reduction effect of denitrification bacteria by adding an inorganic acid to waste water before the introduction thereof into a denitrification tank, thereby suppressing the deposition of calcium carbonate at the time of the biological denitrification treatment of the nitrogen-containing waste water which contains calcium ions. SOLUTION: In the case of the denitrification treatment of the waste water, a carrier carried with the denitrification bacteria is packed in the denitrification tank 1 and is maintained at a fluidization state by the waste water introduced from the lower part of the tank. At this time, a microbial cell peeling device 3, which is composed of agitating vanes having guides on the circumference and peels part of the denitrification bacteria adhered to the carrier by applying shearing force to the carrier floating to the surface, is actuated. In addition, part of a circulating liquid is withdrawn and the inorganic acid is added in addition to methanol necessary for the denitrification reaction at need in a circulation tank 5. The liquid withdrawn from the circulation tank 5 is again sent by a circulating pump 6 to the denitrification tank 1. The inorganic acid is added into the waste water in the manner described above, by which the deposition of the calcium carbonate is suppressed and the stable denitrification reaction is made possible.</p> |
