BIOLOGICAL WASTE WATER TREATMENT APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide the subject apparatus equipped with a denitrification tank having a fixed filter bed capable of efficiently catching a suspended substance in water to be treated and capable of reducing an org. matter. SOLUTION: In a biological waste water treatment apparatus, a fixed filter bed 28 is constituted of two upper and lower layers and the particle size and specific gravity of the filter material 48 forming the lower filter material bed 29 are made larger than those of the filter material 48 forming the upper filter bed 27. By this constitution, the catching of a coarse suspended substance(SS) and denitrification treatment are performed in the lower filter material bed 29 and the catching of fine SS can be performed in the upper filter material bed 27.