| 摘要 |
PROBLEM TO BE SOLVED: To maintain high activity of microorganisms and to treat sewage by forming a biodegradable plastic as a fixed bed or a fluidized bed. SOLUTION: In this biological treatment of sewage, a biodegradable plastic previously placed in a treating tank is utilized as the nutrition source of the microorganisms even if the pollution load is extremely low. The plastic is worked into a film or a porous body or the like and used. The plastic is set as a fixed bed 7 in a treating tank consisting of an activated-sludge tank 3 to treat sewage 1. Accordingly, since the microorganisms assimilate org. matter in the sewage more easily, the org. matter in the sewage is preferentially assimilated by the microorganisms, however the plastic present in the environment is utilized by the microorganisms as the nutrition source to maintain its life and for its propagation when its energy source is exhausted. Consequently, the activity of the microorganisms are maintained at all times, and good treated water is obtained.
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