WASTEWATER TREATMENT WITH AEROBIC GRANULES

摘要

A wastewater treatment system using aerobic granules has a large number of sequencing batch reactor tanks with high volumetric exchange rate, a variable cycle length and constant batch volume. The batch reactors are operated for C, N removal and P is removed chemically. SS are removed in a downstream separation step. A continuous flow reactor may comprise an aerobic zone, an alternately aerobic and anoxic zone or discrete aerobic and anoxic zones, and a settling zone. An anaerobic zone may be located at the bottom of a mass of settled granules. Feed may be introduced through the settled granules. An aerobic/anoxic zone may be like a CSTR but with aeration varying in space or time. Sludge granules may move intermittently from an aerobic zone to an aerobic/anoxic zone. A settling zone may have an upflow rate to wash off flocculated biomass. A dual sludge process may be used in which a fraction of unsettled floc is recycled to a region upstream of the granules settler. A fermentation zone may be used to pre-treat feed water or to treat a recycled waste stream, for example a waste stream contain floc.