| 摘要 |
<p>PURPOSE:To reduce the clogging of a fixed bed and to enhance the production effi ciency of treated water by a method wherein the fixed bed of a predetermined carrier is formed to the upper part of a biological filtering apparatus and a fluidized bed composed of the same carrier is formed to the lower part thereof and raw water is passed through the fluidized bed from the lower part thereof along with oxygen- containing gas as an ascending stream to be biologically treated. CONSTITUTION:The raw water from a raw water supply pipe 2 becomes a violent gas-liquid mixed phase stream along with the oxygencontaining gas from an air diffusion pipe 3 to enter a fluidized bed A constituted of a carrier composed of three- dimensional reticulated granular matter holding bacteria in high concn. and held to a sufficiently freely fluidized state and BOD in the raw water is rapidly removed. In this fluidized bed A, 30-35% of BOD in the raw water is removed and, when the raw water is supplied to a fixed bed B composed of the same carrier, the filtering of SS, the removal of BOD and the nitration of ammonia nitrogen are performed in the fixed bed B and the treated water passes through the carrier outflow preventing member 7 provided to the upper part of the treatment tank 1 under tension to overflow from the overflow weir 8 provided to the uppermost part of the treatment tank 1 and passes through a treated water outflow pipe 10 to be discharged.</p> |
