| 摘要 |
<p>PURPOSE:To improve sedimentating properties of an active sludge by bringing a returned sludge into contact with an oxygen gas or an oxygen-enriched gas in an enclosed water tank before the returned sludge is mixed with organic waste water. CONSTITUTION:A returned sludge 2 is introduced in a modifying tank 3 to which O2 or an oxygen-enriched gas 8 is being fed, so that the sludge comes into contact with the oxygen dissolved at a high concentration. Thereafter, the sludge flows in a tank 4 for mixing the original water. Original water 1 is allowed to flow in a subsequent air exposure tank 5 through a connecting channel 10', and the pollutants are oxidized by means of exposure to air. After, completion of the oxidation, an active sludge is separated in a sedimentation tank 6. Then, most of the sludge is returned to the modifying tank 3 and the remainder is treated and disposed as an excess sludge 7. Accordingly, sedimentating properties of sludges can be improved greatly.</p> |
