Patent ID: 6485645
Filing Date: 2002-11-26
Classification: C02F,Y02W

Abstract:
A process for treating water to remove phosphorous and nitrogen comprising the steps of:(a) providing an anaerobic zone having an anaerobic mixed liquor having organisms which release phosphorous into the anaerobic mixed liquor and store volatile fatty acids from the anaerobic mixed liquor; (b) providing an anoxic zone having an anoxic mixed liquor having organisms which metabolize stored volatile fatty acids, uptake phosphorous and denitrify the anoxic mixed liquor; (c) providing an aerobic zone having an aerobic mixed liquor having organisms which metabolize stored volatile fatty acids, uptake phosphorous and nitrify the aerobic mixed liquor; (d) flowing water to be treated into the anaerobic zone; (e) flowing anaerobic mixed liquor to the anoxic zone; (f) flowing anoxic mixed liquor to the anaerobic zone; (g) flowing anoxic mixed liquor to the aerobic zone; (h) flowing aerobic mixed liquor to the anoxic zone; (i) contacting aerobic mixed liquor against the feed side of a membrane filter; (j) producing a treated effluent lean in phosphorous, nitrogen, BOD OR COD, suspended solids and organisms from a permeate side of the membrane filter; and, (k) removing some or all of the material rejected by the membrane filter from the process, wherein the steps above are performed substantially continuously and substantially simultaneously and wherein the MLSS is between 3 and 30 g/L.