A system for cleaning feed water of variable quality, the system comprising an inlet for selectively delivering feed water (FW) to one or other of at least two feed chambers (2,4), each feed chamber having a delivery pipe (2i, 4i) for delivering feed water to a reverse osmosis or nanofiltration (8); a pump (6) to deliver the feed water from one of the chambers (2, 4) through its associated delivery pipe (2i, 4i) to the reverse osmosis or nanofiltration (8) to create a concentrated feed stream and a product water stream (PW); return pipes (2R, 4R) for selectively returning the concentrated feed stream to one or other of the at least two feed chambers (2, 4); a product water outlet for removal of the product water (PW); and means for switching the delivery of the concentrated feed stream between the selectable return pipes (2R, 4R) upon detection of a predetermined reduction in the efficiency of the RO or NF process within one or other of the feed chambers (2, 4). The pressure of the concentrated feed stream is reduced to atmospheric pressure prior to its delivery back to the chamber and the feed stream passes through a desaturation unit (20).

A system for cleaning feed water of variable quality, the system comprising an inlet for selectively delivering feed water (FW) to one or other of at least two feed chambers (2,4), each feed chamber having a delivery pipe (2i, 4i) for delivering feed water to a reverse osmosis or nanofiltration (8); a pump (6) to deliver the feed water from one of the chambers (2, 4) through its associated delivery pipe (2i, 4i) to the reverse osmosis or nanofiltration (8) to create a concentrated feed stream and a product water stream (PW); return pipes (2R, 4R) for selectively returning the concentrated feed stream to one or other of the at least two feed chambers (2, 4); a product water outlet for removal of the product water (PW); and means for switching the delivery of the concentrated feed stream between the selectable return pipes (2R, 4R) upon detection of a predetermined reduction in the efficiency of the RO or NF process within one or other of the feed chambers (2, 4). The pressure of the concentrated feed stream is reduced to atmospheric pressure prior to its delivery back to the chamber and the feed stream passes through a desaturation unit (20).

An integrated, membrane-based process to produce purified water and conversion of salt to high value chemicals from oil and gas well produced water is described. A liquid stream including water and dissolved salt is flowed through pretreatment units and one or more desalination and concentration units which remove at least a portion of the water to form a brine enriched in dissolved salt. The purified high-density brine may be subjected to electrically-enforced salt dissociation techniques to produce chemicals from oil and gas produced water.

A system and method for increasing the water production efficiency of a desalination plant and producing concentrated calcium and magnesium is provided. A saline source water is preferably subjected to a first treatment such a passage through a first desalination unit, followed by dual treatment of the first treatment reject stream using physicochemical adsorption and electrodialysis to remove scale-forming calcium and magnesium. The reject stream from the dual treatment may then be received by a second desalination unit. Due to the removal of the majority of the saline source water's scale-forming minerals, the second desalination unit may be operated at higher operating limits than in conventional desalination units without significant concern for fouling due to scaling. The approach of the present system and method efficiently increases the fresh water production ratio from the source saline water while generating commercially attractive concentrated calcium and magnesium products.

A device for the multi-stage, modular purification of drinking water is described, wherein a module comprises a chelating gel or a chelating and a bactericidal gel for heavy metal removal and/or for heavy metal removal and bacterial removal.

Produced water from a crude oil or natural gas production process is purified using a membrane purification system for petroleum production, agricultural, commercial and domestic uses. The produced water is pretreated to remove, at least, particulates and oil from the produced water. The minimally pretreated water is then purified in a membrane purification system, that is operated at conditions such that membrane scaling is reduced or prevented. In particular, the membrane purification system is operated to maintain the turbidity of clarified water feed to the system or intermediate aqueous streams that are cascading through the membrane purification system. Ensuring that the turbidity of the reject streams generated in the membrane system are useful in achieving long membrane operating life.

A water treatment device includes a tubular member configured to allow water to flow between an inlet on one end side and an outlet on the other end side, and a filter member disposed in the tubular member between the inlet and the outlet. The filter member includes a conductive filter having permeable holes through which water can flow, a pair of electrodes configured to apply a voltage to the conductive filter, and an insulator disposed between the pair of electrodes and configured to insulate between the pair of electrodes.

A method for desalination of hot supersaturated water having a temperature of between 40 C. and 80, includes contacting the hot water with a reverse osmosis membrane which is resistant to temperatures of between 40 and 80 C. without a prior cooling step.

An integrated, membrane-based process to produce purified water and conversion of salt to high value chemicals from oil and gas well produced water is described. A liquid stream including water and dissolved salt is flowed through pretreatment units and one or more desalination and concentration units which remove at least a portion of the water to form a brine enriched in dissolved salt. The purified high-density brine may be subjected to electrically-enforced salt dissociation techniques to produce chemicals from oil and gas produced water.

A system and method for producing high quality potable water by re-mineralization of desalinated water is provided. The retentate rejected from a nanofiltration unit becomes a source of mineral-rich divalent ions for mixing with the desalinated water being produced by a desalination unit, thereby reducing or eliminating the need for separate supply from outside sources of chemicals needed to obtain potable water that meets various drinking water standards. The nanofiltration unit may be located in a desalination upstream and/or downstream of the desalination unit, and the amount of flow of the nanofiltration retentate supplied to the re-mineralization unit relative to the amount of desalinated water flow may be adjusted to achieve the desired potable water quality.