| 摘要 |
<p>PURPOSE:To reduce the volume of sludge to be discharged for curtailing the consumption amount of a chemical coagulant, by coagulating filthy water with excess sludge aerated by oxygen-contg. gas, further coagulating it with said chemical coagulant and then treating it with activated sludge. CONSTITUTION:Filthy water is sent into a coagulation tank 1 divided into the first and second coagulation compartments 1a, 1b. Herein, the filthy water is mixed with preaerated excess sludge, and most of SS and colloidal substance in the filthy water are adsorbed onto the surface of the excess sludge. Thereafter, the mixture of the filthy water and the excess sludge is mixed with a chemical coagulant inside the second coagulation compartment 1b, to coagulate residual SS and colloidal substance. The filthy water having passed through said coagulation step is sent into a flotation tank 2 to separate solid matter from it. The filthy water after being separated is introduced into an aeration tank 3, wherein organic substance is decomposed by microbes. Oxygen-contg. gas such as air is injected into the aeration tank 3 using a blower 7.</p> |
