Patent ID: 6120688
Filing Date: 2000-09-19
Classification: B01D,C02F,Y02A

Abstract:
A method of purifying impure water to provide drinking water, the method comprising the step of:(a) providing a microfiltration unit in fluid communication with an impure water source and with an air source, the microfiltration unit comprised of:(i) a tank for containing said impure water;(ii) a microfiltration membrane positioned in said tank to filter said impure water to provide a concentrate, the microfiltration membrane comprised of an array of hollow tubular membranes having an inside surface and an outside surface;(iii) an air diffuser located in said tank for diffusing air past said tubular membranes for inducing water movement around said tubular membranes;(b) directing water from said impure water source into said tank;(c) drawing filtered water through said tubular membranes to provide purified water and simultaneously therewith rejecting impurities to provide said concentrate;(d) permitting excess concentrate to flow from said tank;(e) pumping said purified water to a high pressure side of a reverse osmosis module wherein water is permeated through a membrane to a low pressure side of said reverse osmosis module to provide said drinking water and wherein impurities are concentrated in said high pressure side to provide a retentate;(f) returning retentate from the high pressure side of said reverse osmosis module to a CIP (clean-in-place) container;(g) periodically backflushing said hollow tubular membranes with said retentate from said CIP container, said retentate directed to the inside surfaces of said membranes to dislodge foulants from the outside surfaces of said membranes; and(h) continuing production of drinking water during said backflushing by directing flow of retentate to the high pressure side of said reverse osmosis module and recovering drinking water on said low pressure side.