| 摘要 |
<p>PURPOSE:To prevent filtration velocity from being reduced by mixing an inorganic flocculating agent with treatment water before separating sludge and allowing it to adsorb COD. CONSTITUTION:Organic waste water is subjected to biological treatment with activated sludge while aerating it in a biological treatment tank 30. Water to be treated which is deaerated in a deaeration tank 31 is sent to a flocculation tank 32 and an inorganic flocculating agent (e.g. aluminum sulfate and ferric chloride, etc.,) for flocculating activated sludge is mixed with the water to be treated. COD contained in the water to be treated is reduced by allowing the flock of flocculated activated sludge to adsorb COD. The water discharged from the flocculation tank 32 is separated from sludge and a part of the separated sludge is returned to the biological treatment tank 30, and the residual part is drawn out as excess sludge. Thereby filtration velocity can be enhanced.</p> |
