抄録
To evaluate the effectiveness of various reactor types for anaerobic ammonium oxidation (anammox), four types of reactor, a sequencing-batch reactor, a fixed-bed reactor with nonwoven carriers, a fluidized-bed reactor with tube-shaped attachment carriers, and a fluidized-bed reactor with methanogenic granules as carriers, were examined. While activity in the sequencing-batch reactor occasionally decreased markedly, a stable nitrogen removal was maintained for 200 days in the fixed-bed and fluidized-bed reactors. It appeared that the biofilm mode was not inhibited by oxygen due to the high biomass density and the existence of oxygen-consuming microorganisms on the biofilm surface. However, overgrowth on the nonwoven and tube-shaped carriers sometimes resulted in gas entrapment and the floatation of carriers. After 173 days of operation, the maximum nitrogen removal rate of the fluidized-bed reactor using methanogenic granules as carriers was 2.87 kg N·m-3·d-1, which was the highest among these four reactors. Considering biomass attachment and hydrodynamic mixing characteristics in addition to treatment efficiency, the use of methanogenic granules as attachment carriers in a fluidized-bed reactor appeared to be the most effective for the anammox process.
