| 摘要 |
PURPOSE:To treat conc. organic waste liquor, while saving resources and energy, by evaporating water formed in the biotreatment of organic waste liquor, mixing oil having a boiling point higher than that of water in excess activated sludge formed in the step of biotreatment, and evaporating, drying and then burning said sludge. CONSTITUTION:Scum-removed night soil 1 is biologically nitrified and henitrified 2 without being diluted to remove BOD and N components. The outflow activated sludge slurry is then separated into a liquid and solid matter, and the major part of the separated sludge 5 is circulated as returned sludge 6 to the step 2. On the other hand, the separated liquid 7 is sent to an eveporation step 8, preheated with condensed water 12' obtd. from steam in a heat exchanger 9, evaporated, thickened, discharged as a conc. liquid 11, and then dried or burnt. Mixed slurry 20 obtd. by mixing oil 19, e.g. waste oil, having a boiling point higher than that of water in excess activated sludge 17 formed from the step 2 inside a mixing tank 18 is transferred to an evaporation- drying step 10 equipped with multi-effect evaporator cans 21, 21', 22'' and thickened therein to a water-retaining ratio of about 10%. Thereafter, said slurry is treated with mixed slurry 29 discharged from the can 21''. The separated oil is recovered, while deoidled sludge 32 is burnt in a boiler 22 to recover steam 23. |
