Process and apparatus for purifying impure water using microfiltration or ultrafiltration in combination with reverse osmosis
First Claim
1. A method of purifying impure water contaminated with a filterable impurity and a dissolved impurity, the method comprising:
- filtering the impure water in a primary microfiltration or ultrafiltration unit to remove the filterable impurity and produce impure filtered water contaminated with the dissolved impurity;
directing the impure filtered water through a first fluid line fluidly connecting an impure filtered water outlet of the primary microfiltration or ultrafiltration unit to an inlet of a reverse osmosis unit;
filtering the impure filtered water contaminated with the dissolved impurity in the reverse osmosis unit to produce a potable water stream and a residual reverse osmosis stream;
directing the residual reverse osmosis stream into a second fluid line fluidly connecting a residual reverse osmosis stream outlet of the reverse osmosis unit to an inlet of a secondary microfiltration or ultrafiltration membrane filter;
filtering the residual reverse osmosis stream by passing the stream through the secondary microfiltration or ultrafiltration membrane filter to produce a filtered saline solution;
directing the filtered saline solution into a third fluid line fluidly connecting an outlet of the secondary microfiltration or ultrafiltration membrane filter to the impure filtered water outlet of the primary microfiltration or ultrafiltration unit;
blocking flow of the filtered saline solution from the outlet of the secondary microfiltration or ultrafiltration membrane filter to the inlet of the reverse osmosis unit during backwashing of the primary microfiltration or ultrafiltration unit with the filtered saline solution by closing a valve in the first fluid line during backwashing of the primary microfiltration or ultrafiltration unit; and
backwashing the primary microfiltration or ultrafiltration unit with the filtered saline solution.
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Accused Products
Abstract
A method of purifying impure water contaminated with a filterable impurity and a dissolved impurity, such as seawater, comprising the steps of: providing impure water to a primary microfiltration or ultrafiltration unit to remove the filterable impurity and produce impure filtered water contaminated with a dissolved impurity; providing the impure filtered water contaminated with a dissolved impurity to a reverse osmosis unit to produce a potable water stream and a residual reverse osmosis stream; and treating the residual reverse osmosis stream prior to reuse. The treatment may be in the form of passing through a secondary filter (such as another microfiltration or ultrafiltration membrane or a cartridge filter, and the subsequently treated reverse osmosis reject may be used to backwash the microfiltration or ultrafiltration unit.
652 Citations
25 Claims
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1. A method of purifying impure water contaminated with a filterable impurity and a dissolved impurity, the method comprising:
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filtering the impure water in a primary microfiltration or ultrafiltration unit to remove the filterable impurity and produce impure filtered water contaminated with the dissolved impurity; directing the impure filtered water through a first fluid line fluidly connecting an impure filtered water outlet of the primary microfiltration or ultrafiltration unit to an inlet of a reverse osmosis unit; filtering the impure filtered water contaminated with the dissolved impurity in the reverse osmosis unit to produce a potable water stream and a residual reverse osmosis stream; directing the residual reverse osmosis stream into a second fluid line fluidly connecting a residual reverse osmosis stream outlet of the reverse osmosis unit to an inlet of a secondary microfiltration or ultrafiltration membrane filter; filtering the residual reverse osmosis stream by passing the stream through the secondary microfiltration or ultrafiltration membrane filter to produce a filtered saline solution; directing the filtered saline solution into a third fluid line fluidly connecting an outlet of the secondary microfiltration or ultrafiltration membrane filter to the impure filtered water outlet of the primary microfiltration or ultrafiltration unit; blocking flow of the filtered saline solution from the outlet of the secondary microfiltration or ultrafiltration membrane filter to the inlet of the reverse osmosis unit during backwashing of the primary microfiltration or ultrafiltration unit with the filtered saline solution by closing a valve in the first fluid line during backwashing of the primary microfiltration or ultrafiltration unit; and backwashing the primary microfiltration or ultrafiltration unit with the filtered saline solution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 23)
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16. A method of facilitating the purification of impure water, the method comprising:
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providing a primary microfiltration or ultrafiltration unit to produce impure filtered water; providing a first fluid circuit configured to direct the impure filtered water to an inlet of a reverse osmosis unit in downstream fluid communication from said primary microfiltration or ultrafiltration unit; providing a second fluid circuit fluidly connecting a residual reverse osmosis stream outlet of the reverse osmosis unit to an inlet of a secondary microfiltration or ultrafiltration membrane filter, the second fluid circuit configured to direct a residual reverse osmosis stream from the reverse osmosis unit to the secondary microfiltration or ultrafiltration membrane filter to produce a filtered saline solution; and providing a controllable fluid pathway configured to direct the filtered saline solution from the secondary microfiltration or ultrafiltration membrane filter to the primary microfiltration or ultrafiltration unit to backwash the primary microfiltration or ultrafiltration unit, the first fluid circuit including a valve which prevents flow of the filtered saline solution from the secondary microfiltration or ultrafiltration membrane filter to the inlet of the reverse osmosis unit during backwashing of the primary microfiltration or ultrafiltration unit with the filtered saline solution. - View Dependent Claims (24)
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17. A system for purifying impure water contaminated with a filterable impurity and a dissolved impurity, the system comprising:
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a filtration system including; a primary microfiltration or ultrafiltration unit configured to remove the filterable impurity; a reverse osmosis unit configured to produce a potable water stream and a residual reverse osmosis stream, the reverse osmosis unit including an inlet in downstream fluid communication from the primary microfiltration or ultrafiltration unit; and a first controllable fluid pathway configured to transfer a stream of impure filtered water contaminated with a dissolved impurity from the primary microfiltration or ultrafiltration unit to the reverse osmosis unit; and a backwash system in fluid communication with a residual reverse osmosis stream outlet of the reverse osmosis unit and a permeate outlet of the primary microfiltration or ultrafiltration unit, and including; a fluid line fluidly connecting the residual reverse osmosis stream outlet of the reverse osmosis unit to an inlet of a secondary microfiltration or ultrafiltration membrane filter, the secondary microfiltration or ultrafiltration membrane filter configured to filter the residual reverse osmosis stream to produce a filtered saline solution; a second controllable fluid pathway configured to direct the filtered saline solution to backwash the primary microfiltration or ultrafiltration unit; and a valve disposed in the first controllable fluid pathway which blocks flow of the filtered saline solution from the secondary microfiltration or ultrafiltration membrane filter to the inlet of the reverse osmosis unit during backwashing of the primary microfiltration or ultrafiltration unit. - View Dependent Claims (18, 19, 20, 21, 22, 25)
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Specification