Method and device for the removal of nitrogen from nitrogen-containing and organic compounds containing wastewater

摘要

1432667 Activated sludge process SOUTH AFRICAN INVENTIONS DEVELOPMENT CORP 16 July 1973 [4 Aug 1972] 33817/73 Heading C1C A 4- or 5-stage activated sludge process for removing nitrogen (and possibly phosphates) from organic waste water (e.g. sewage) comprises: (1) mixing the influent water with recycled liquor from stage 2 and recycled sludge from stage 5 and applying anaerobic or slightly aerobic conditions, preferably at a pH of at least 6À2 to effect bacterial denitrification; (2) aerating the product from stage 1 (optionally in admixture with further sludge recycled from stage 5) to effect bacterial nitrification; (3) subjecting the product from stage 2 (optionally in admixture with a carbon source, e.g. methanol) to anaerobic or slightly aerobic conditions to effect bacterial denitrification; (4) optionally aerating the product from stage 3 with the possible result of nitrification and/or phosphate precipitation; and (5) separating the product from stage 3 or 4 into activated sludge and clarified effluent. At any stage of the process, the liquor or sludge may be treated with time, alum, aluminate or iron slats to effect phosphate removal. Fig. 3 shows stages 1-5 of the above process being effected in zones 14.3, 16.3, 18.3, 20.3 and 22.3 respectively, where zones 16.3 and 20.3 are concentric endless annular channels through which the liquor is propelled by the rotation of surface aeration discs 44; and zones 14.3 and 18.3 have stirrers 36.3. Fig. 4 (not shown) is similar to Fig. 3 but with three central zones and only one annular channel. Fig. 5 (not shown) shows stages 1-4 being effected in adjoining rectangular tanks (with surface or submerged aeration for stages 2 and 4) and a separate -circular clarifier for stage 5. Fig. 2 (not shown) is a diagrammatic flow sheet.