A system and method for producing from saline source water a product containing an increased ratio of multi-valent ions to mono-valent ions, which includes multiple nanofiltration units arranged to selectively remove mono-valent ions from the water fed into each nanofiltration stage in the nanofiltration permeate stream while retaining multi-valent ions in the nanofiltration reject stream. The rate at which the increase in the multi-valent ion- to mono-valent ion ratio is obtained may be enhanced by introduction of lower salinity water into the nanofiltration reject between stages, and by recirculating a portion of downstream nanofiltration reject flow into an upstream nanofiltration unit. The enhanced multi-valent ion product is suitable for multiple uses, including irrigation of plants and remineralization of desalinated water. The relative concentrations of the multi-valent ions in the product may be adjusted, for example by selection of nanofiltration membrane technologies which have higher or lower rejection for specific multi-valent ions.

The present invention relates to a membrane separation system including a plurality of separation membrane elements connected to one another, each of the separation membrane elements including a plurality of separation membrane pairs, each separation membrane pair including separation membranes each having a feed-side surface and a permeate-side surface and disposed such that the feed-side surfaces face each other, in which the plurality of separation membrane elements include a first separation membrane element and a second separation membrane element, and at least one first separation membrane element serves as a stage preceding the second separation membrane element.

A process for treating sour water includes combining the sour water with an alkali or alkaline metal hydroxide to produce a sour water mixture, the sour water comprising sulfides, passing an electric current through the sour water mixture, where passing the electric current through the sour water mixture causes at least a portion of the sulfides to react to produce a treated sour water comprising sulfates and having a pH of 7.1 to 9.8, saturating the at least a portion of the sulfates in an aqueous sulfate solution, and separating at least a portion of saturated sulfates from a saturated aqueous sulfate solution.

A method for producing an ethanol solution includes obtaining, from a starting liquid, a liquid feed having less than by weight of constituents and having 3% to 25% by weight of ethanol, supplying the liquid feed to a feed stream inlet of a reverse osmosis separation system having a first pass, wherein (i) each pass has an reverse osmosis membrane filtration unit, each membrane filtration unit having an ethanol rejection percentage of between 50% to 99%, and (ii) each pass has the feed stream inlet for a feed stream, a permeate stream outlet for a permeate stream, and a retentate stream outlet for a retentate stream, operating the system to maintain pressure in one of the membrane filtration units in a range of 1,200 to 4,000 psi, and obtaining retentate that is enriched with ethanol, the retentate differs from the starting liquid by absence of the removed constituents.

Facility for the treatment of a feed gas stream comprising at least methane and carbon dioxide, said facility comprising: an oil-lubricated or water-lubricated vane-type compressor making it possible to compress the feed gas stream, and a membrane separation unit capable of receiving the compressed gas stream and of separating the methane from the carbon dioxide.

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.

The invention provides a water-alcohol separation system and a method for water-alcohol separation for producing a high purity alcohol while achieving energy saving as the whole process. Namely, a water-alcohol separation system including plural separation membrane modules connected in series, a vacuum apparatus for reducing a pressure at a permeated side of each of the separation membrane modules, and a condenser for condensing a vapor that has passed through a membrane, in which plural independent vacuum systems reduce the pressure at the permeated side of the membrane of the separation membrane modules.

A novel multi-stage reverse osmosis system is proposed that allows for following benefits a) reduction in pressure-loss while achieving optimum cross-flow velocities and therefore reducing energy consumption of 4-10%; b) increased flux balance between stages resulting in reduced fouling of the first stage; c) disruption of scale forming conditions resulting in reduced scaling of the last stage; d) reduction in scale potential of the concentrate valve; e) reduction in downtime for CIP by proactively disrupting scaling or fouling through several innovative methods; f) ease-of and effectiveness-of CIP with reduced number of valves and g) to keep system operational via isolation of the last stage for maintenance while the keeping remaining system in production mode. All the above improvements are achieved with process-flow and operational characteristics defined in the Specifications and Claims.

A reverse osmosis main plant which may receive non-potable water and discharge out permeate through a permeate out line and concentrate through a concentrate line is disclosed.

A method for efficient separation and enrichment of lithium includes the following steps: pretreatment: diluting and filtering salina aged brine to obtain pretreated brine; separation: separating the pretreated brine via a nanofiltration separation system to obtain nanofiltration permeate and nanofiltration concentrate, wherein the operation pressure of the nanofiltration separation system is 1.0 MPa5.0 MPa; first concentration: carrying out first concentration on the nanofiltration permeate via a reverse osmosis system to obtain reverse osmosis concentrate and reverse osmosis permeate; and second concentration: carrying out second concentration on the reverse osmosis concentrate via an electrodialysis system to obtain electrodialysis concentrate and electrodialysis permeate, wherein the electrodialysis concentrate is a solution enriching lithium ions. The present application couples several different membrane separation technologies and adopts the monovalent ion selective nanofiltration membrane having good separation performance in the process of nanofiltration.