HIGH-DEGREE PURIFICATION OF ORGANIC SEWAGE

摘要

PROBLEM TO BE SOLVED: To stably obtain an extremely high nitrogen removing ratio by oxidizing a part of activated sludge of biological nitrification and denitrification treatment by ozone to subject the same to solidliquid separation and subjecting the separated water to flocculation separation and subsequently supplying the flocculated separated water to a granular filter material packed bed to which denitrifying bacteria are bonded to perform denitrification and SS filtering. SOLUTION: Org. sewage 1 is denitrified and oxidized in a biological nitration and denitrification tank A and a part of the oxidized and nitrated slurry is transferred to a sedimentation tank B as an outflow slurry 2. Herein, the outflow slurry is subjected to solid-liquid separation to be circulated to the denitrification part of the nitration and denitrification tank A as return sludge and a part thereof is transferred to an ozone oxidation tank D. An inorg. flocculant 11 is added to the separated water formed from the soluble sludge 6 oxidized by ozone in the ozone oxidizing tank D and sedimented and separated in a second sedimentation tank E to flocculate phosphorus and these flocs are separated as flocculated sludge 12 in a third sedimentation tank G. Separated sludge 8 is biologically treated in an aeration tank F to be reduced in amt. to elute phosphorus and the remainder is refluxed to the ozone oxidizing tank D as circulating sludge 7.