A method and system for reversibly converting water between an initial ionic strength and an increased ionic strength, using a switchable additive, is described. The disclosed method and system can be used, for example, in distillation-free removal of water from solvents, solutes, or solutions. Following extraction of a solute from a medium by dissolving it in water, the solute can then be isolated from the aqueous solution or “salted-out” by converting the water to a solution having an increased ionic strength. The solute then separates from the increased ionic strength solution as a separate phase. Once the solute is, for example, decanted off, the increased ionic strength aqueous solution can be converted back to water having its original ionic strength and reused. Switching from lower to higher ionic strength is readily achieved using low energy methods such as bubbling with CO.sub.2, CS.sub.2 or COS. Switching from higher to lower ionic strength is readily achieved using low energy methods such as bubbling with air, heating, agitating, introducing a vacuum or partial vacuum, or any combination or thereof.

Draw compounds and draw solutions comprising said draw compounds for use in forward osmosis solvent purification systems. The draw compound may be a linear random, sequential, or block molecular chain consisting of at least one oxide monomer or diol monomer and have a temperature-dependent affinity with a feed solvent. The draw compound may further include a first terminal group and a second terminal group, at least one of the first terminal group and the second terminal group selected from the group consisting of a hydroxyl group, an amine group, a carboxylic group, an allyl group, and a C1 to C14 substituted and unsubstituted alky group. The draw compound may also be a branched random, sequential, or block molecular chain consisting of at least one oxide monomer or diol monomer.

An online cleaning system for micro-polluted nanofiltration membranes uses forward osmosis, and a process of the online cleaning system, and relates to the field of water treatment membrane separation technique. The online cleaning system includes a nanofiltration raw water tank, a nanofiltration membrane assembly, a pure water tank, a forward osmosis feed solution tank, a forward osmosis draw solution tank, a first saline water tank, a second saline water tank and a water bath temperature control device. Compared with convention techniques, some embodiments include efficient cleaning of the nanofiltration membranes that is realized by using forward osmosis as a nanofiltration membrane cleaning system, and cyclic regeneration of the nanofiltration membranes can be realized, so that the purposes of removing dissolved organic matters in micro-polluted raw water, reducing hardness of calcium and magnesium and prolonging the service life can be achieved.

The invention relates to a system and method of use for concentrating a solution that is eluted from an ion exchange process (elution solution) during an ion exchange regeneration using the osmotic pressure of the salt saturator. This method recovers solvent from the elution solution that could be used in a future ion exchange regeneration process. The concentration of the elution solution may include the precipitation and removal of solids from the elution solution.

Disclosed herein is a forward osmosis module for concentration and/or crystallization salts from an aqueous feed solution, the feed solution including seeds that surround an open semi-permeable membrane having free membrane portions forming an enclosure with a distribution pipe that introduces draw solution inside said enclosure. The feed solution penetrates into the enclosure as permeate from the feed side of the membrane to the draw solution side according to a Forward Osmosis process based on net driving pressure. The draw solution with permeate is evacuated from the enclosure via an outlet. A generator applies, at least periodically, a plurality of directional gauge pressure strokes PGs, directed from at least one of the draw solution inlet and outlet thereby effecting mechanical shaking of the free membrane portions for detachment of foulant.

The high water recovery hybrid membrane system for desalination and brine concentration combines nanofiltration, reverse osmosis and forward osmosis to produce pure water from seawater. The reject side of a nanofiltration unit receives a stream of seawater and outputs a brine stream. A permeate side of the nanofiltration unit outputs a permeate stream. A feed side of a reverse osmosis desalination unit receives a first portion of the permeate stream and outputs a reject stream. A permeate side of the reverse osmosis desalination unit outputs pure water. A draw side of at least one forward osmosis desalination unit receives the reject stream and outputs concentrated saline solution. A feed side of the at least one forward osmosis desalination unit receives a second portion of the permeate stream and outputs a dilute saline stream, which mixes with the first portion of the permeate stream fed to the reverse osmosis desalination unit.

An ocean alkalinity enhancement (OAE) system that reduces atmospheric CO.sub.2 and mitigates ocean acidification by electrochemically processing feedstock solution (e.g., seawater or brine) to generate an alkalinity product that is then supplied to the ocean. The OAE system includes a base-generating device and a control circuit disposed within a modular system housing deployed near a salt feedstock. The base-generating device (e.g., a bipolar electrodialysis (BPED) system) generates a base substance that is then used to generate the ocean alkalinity product. The control circuit controls the base-generating device such that the alkalinity product is supplied to the ocean only when (1) sufficient low/zero-carbon electricity is available, (2) it is safe to operate the base-generating device, and (3) supplying the alkalinity product will not endanger sea life. Modified BPED systems include features that facilitate autonomous system operations including enhanced maintenance cycle operations and a reduced reliance on external fresh water sources.

A method of recovering draw agent utilised in a forward osmosis membrane cell, the method comprising the steps of passing diluted draw agent to a vapour-liquid separator; using the vapour-liquid separator to separate draw agent vapour and solvent; and condensing draw agent vapour.

Systems and processes for purifying and concentrating a liquid feed stream are disclosed. In the systems, the concentrated liquid output from the high pressure side of a reverse osmosis stage is used as the draw solution in the low pressure side of the reverse osmosis stage in a configuration called osmotically assisted reverse osmosis. This reduces the osmotic pressure differential across the membrane, permitting high solute concentrations to be obtained, hastening the purification of the liquid. Reduced system pressures are also obtained by arranging multiple osmotically assisted reverse osmosis stages in a cross-current arrangement. Overall system energy consumption is reduced compared to conventional thermal processes for high concentration streams.

The present invention relates to a device and to a method for producing dialysate, wherein the device comprises a first part and a second part designed as a circuit, wherein the first part comprises a water connection or a water container and the primary side of a filter, wherein the filter is designed to produce purified water from the water by forward osmosis, and wherein the second part comprises the secondary side of the filter, a reservoir, a filtrate line which leads from the secondary side of the filter to the reservoir, and a return line leading from the reservoir to the secondary side of the filter, wherein an electrodialysis unit comprising a diluate chamber and a concentrate chamber is further provided, wherein the concentrate chamber is fluidically connected to the secondary side of the filter.