| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an activated sludge treatment method for org. sewage which is low in ozone cost, obviates the overflow of sludge by foaming, does not require a treating device for waste gaseous ozone and is capable of greatly reducing the excess sludge and an apparatus therefor. SOLUTION: The separated sludge 14 obtd. by subjecting org. sewage 11 to an activated sludge treatment, then to sepn. of solid from the liquid is partly subjected to ozone oxidation then, to aeration with an oxygen-contg. gas and thereafter, this sludge is returned to the activated sludge treatment stage in the method for returning the separated sludge 14 obtd. by the sepn. of the solid from the liquid to the activated sludge treatment stage. The apparatus having a sewage treating aeration tank 1B, a means 2 for separating the solid from the liquid and a sludge returning means 4 has an ozone oxidation section 6 for subjecting part of the separated sludge 14 to the ozone oxidation and an oxidized sludge aeration tank 1A for aerating the sludge subjected to the ozone oxidation with the oxygen-contg. gas and is so constituted as to admit the self-digested sludge 16 digested in this oxidized sludge aeration tank 1A into the sewage treating aeration tank 1B.</p> |
