| 摘要 |
<p>PURPOSE:To increase the rate of settling and to decrease the surface area in a separating part by preparing media having different grain sizes, charging the medium of samllest grain sizes first then increasing stepwise the grain size of the medium to perform in this way a biological treatment of waster water using a fluid medium. CONSTITUTION:In a biological treatment method of a fluid medium type, >=2 kinds of media having different grain sizes, such as sand, active carbon, anthracite, or the like are prepared. A medium of the smallest grain size is charged in the initial period when the operation is started, and when activated sludge sticks to the medium a medium of the grain size larger than the grain sizes charged in the 1st time is charged in the 2nd time. When the activated sludge sticks to these media as well, the media of further larger grain sizes are charged and such operations are repeated plural times, whereby the biological treatment is accomplished. According to the above-mentioned method, the sufficient activated sludge is stuck to the media in about 15-20 days after the start of the operation.</p> |
