| 摘要 |
<p>1325323 Treating sewage UNION CARBIDE CORP 1 July 1970 [2 July 1969] 31857/70 Heading C1C A method for treating water containing biochemically oxidizable material comprises introducing into a contact aeration zone, said water having a BOD, sufficient recycling bacterially active sludge from a subsequent sludge stabilization and/or auto-oxidation zone or zones to provide volatile suspended solids content of at least 3000 ppm.; and a first gas comprising at least 50% oxygen (by volume) and mixing same as the aeration gas with the water having a BOD and recycled sludge in the aeration zone for a liquid-solid contact time of at least 5 minutes in sufficient quantity and rate to maintain the dissolved oxygen content (DO) of the mixture at least 0À5 ppm. and form suspended activated sludge; discharging said suspended activated sludge from the aeration zone into a separate sludge stabilization zone or zones; introducing a second gas comprising at least 35% oxygen (by volume) and mixing same with said suspended activated sludge in said sludge stabilization zone or zones in sufficient quantity and rate to form BOD-depleted activated sludge having a lower BOD than said suspended activated sludge, the liquid-solid total contact time in said aeration plus said sludge stabilization zones being 20-90 minutes; discharging said BOLD-depleted activated sludge from the sludge stabilization zone or zones into a separate auto-oxidation zone or zones; introducing a third gas comprising at least 35% oxygen (by volume) and mixing same with said BOD- depleted activated sludge in said auto-oxidation zone or zones in sufficient quantity and rate to maintain the DO of such mixture at least 5 ppm. with liquid-solid contact time of 30-210 minutes to form auto-oxidized sludge; and withdrawing and returning at least part of sludge derived from said sludge stabilization and/or auto-oxidation zones to the aeration zone containing water having a BOD as said recycling sludge.</p> |
