초록 ▼

Apparatus is described for purifying or desalinating relatively small quantities of water using one or a few membrane units with relatively modest power requirements. The apparatus uses a pump, an eductor or a combination of both in recirculating a portion of the feed water through a reverse osmosis

Apparatus is described for purifying or desalinating relatively small quantities of water using one or a few membrane units with relatively modest power requirements. The apparatus uses a pump, an eductor or a combination of both in recirculating a portion of the feed water through a reverse osmosis membrane assembly. The method includes recirculating a portion of the feed water through the membrane assembly and discharging a portion of the recirculated feed water from the system.

대표청구항 ▼

A method for the desalination of sea water and the like to produce potable water, comprising, providing a membrane element with an inlet and an outlet and having a flow cross-section with a width to height ratio of greater than fifty, establishing a feed flow at a pressure in excess of the osmotic p

A method for the desalination of sea water and the like to produce potable water, comprising, providing a membrane element with an inlet and an outlet and having a flow cross-section with a width to height ratio of greater than fifty, establishing a feed flow at a pressure in excess of the osmotic pressure to one side of the membrane element, which feed flow is at a rate less than sufficient to maintain the design minimum flow velocity in the flow cross-section of the membrane, recirculating a portion of the concentrate from the outlet to the inlet of the membrane element at a pressure in excess of the osmotic pressure and in excess of the feed flow pressure at a rate sufficient to cause the flow velocity at the surface of the membrane to exceed the design minimum flow velocity, said concentrate being recirculated at a rate which itself is less than the design minimum flow velocity in the flow cross-section of the membrane, recovering permeate product passing through said membrane while maintaining said feed flow at a rate which is sufficient to maintain salinity in said permeate product at or below a maximum acceptable level, and continuously discharging an amount of said concentrate at a rate substantially equal to the difference between the feed flow rate and the recovery permeate product flow rate, said concentrate discharge rate being less than the design minimum flow velocity in the flow cross-section of the membrane and being greater than [Figure] where P is the product flow rate and R is the theoretical recovery rate of product in a system not employing recirculation wherein the theoretical feed flow rate is equivalent to the sum of the actual feed flow rate and the actual recirculation rate.