Patent ID: 6406629
Filing Date: 2002-06-18
Classification: C02F,Y02W,Y10S

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; (k) removing some or all of the material rejected by the membrane filter from the process; (l) removing anaerobic mixed liquor to a reaction zone; (m) treating the removed anaerobic mixed liquor to form a liquid rich in insoluble phosphates; (n) treating the liquid rich insoluble phosphates in a hydrocyclone to separate out insoluble phosphates and create a liquid lean in insoluble phosphates; and, (o) flowing the liquid lean in insoluble phosphates to the anoxic zone, wherein the steps above are performed substantially continuously and substantially simultaneously.