| 摘要 |
PURPOSE:To efficiently purify filthy water, in the catalytic treatment of organic filthy water with a phosphorus-removing agent after the step of biological treatment, by exfoliating compounds formed on the surface of the removing agent composed of a granular solid body and returning said compounds to the step of biological treatment. CONSTITUTION:Organic filthy water 1 is biologically treated with active sludge by letting it flow through a primary precipitating pool 2, an aerating tank 4 and a final precipitating pool 6. In succession, outflow water 6' from the pool 6 is introduced into a conditioning tank 13, where slaked lime 11 and gypsum 12 are added to it to adjust its pH and concentration of Ca. This pH-adjusted water 13' is let flow as a descending current through a dephosphorizing tank 14, brought into contact with a calcium phosphate-contg. granular solid phosphorus-removing agent 15 and drained as purified water 19. On the other hand, the removing agent 15 is continuously or intermittently backwashed with backwashing water 17 or the backwashing water 17 and air 18, to exfoliate compounds precipitated thereon. The waste backwashing water 16 containing the exfoliated matter is returned to the step of biological treatment, i.e. at least one of the precipitating pool 6, the aerating tank 4, a sludge-thickening tank 8 and a sludge- dehydrating step 9. |
