Patent ID: 6676836
Filing Date: 2004-01-13
Classification: C02F,Y02W

Abstract:
An integrated sludge reduction method for biooxidation of wastewater comprising the steps of:providing an anaerobic wastewater treatment zone, an anoxic waste water treatment zone, and one or more aerobic wastewater treatment zones, wherein the volume of the anaerobic treatment zone comprises from about 20 to about 40 percent, the volume of the anoxic treatment zone comprises from about 10 to about 40 percent, and the volume of the one or more aerobic treatment zones comprises from about 20 to about 60 percent of the total processing volume of the anaerobic, anoxic and aerobic tanks, introducing wastewater having BOD5 and suspended solids to be treated into the anaerobic treatment zone and settling at least a portion of the suspended solids to an anaerobic settled solids zone in the lower portion of the anaerobic treatment zone, circulating fluid from the anaerobic zone to the anoxic treatment zone, from the anoxic treatment zone to the aerobic treatment or zones, and from the anoxic treatment zone and/or the aerobic treatment zone(s) back to the anaerobic treatment zone, wherein at least about 50 percent by weight of the microbial sludge and other solids content (TSS) of the waste liquor recycled to the anaerobic zone is settled to the anaerobic settled solids zone in the lower portion of the anaerobic treatment zone together with settled influent wastewater solids, anaerobically digesting at least 50% by weight of the settled mixture of raw influent solids and the recycled microbial sludge solids to produce anaerobically digested solid, soluble and gas components in the anaerobic treatment zone which are conducted to the anoxic and aerobic treatment zones for microbial oxidation, and discharging treated water from the aerobic treatment zone.