Separation processes using osmotically driven membrane systems are disclosed generally involving the extraction of solvent from a first solution to concentrate solute by using a second concentrated solution to draw the solvent from the first solution across a semi-permeable membrane.

A forward osmosis process for concentration of lithium-containing salt solutions is described. A difference in osmotic pressure between a lithium-containing salt solution and a second salt solution of higher osmotic pressure is used as a driving force to pass water through a semi-permeable forward osmosis membrane from said lithium-containing salt solution of lower osmotic pressure to the salt solution of higher osmotic pressure. Also, a two-part operation is described wherein reverse osmosis process technology and forward osmosis process technology are used in tandem to concentrate lithium-containing salt solutions and to recover water that can be recycled to the process. The forward osmosis process is conducted without requiring (i) use of superatmospheric pressure or (ii) use of subatmospheric pressure or (iii) use of both such pressures, or (iv) use of one or more additives to assist in causing the flow of water through a forward osmosis membrane.

The method of solvent recovery includes using a plurality of solvent recovery units to recover solvent from a dilute solution. The solvent recovery units can include a plurality of reverse osmosis or forward osmosis membrane systems arranged in series. For reverse osmosis, at least some of the concentrate in a last reverse osmosis unit of the series is recycled back to the permeate of that unit to provide a mixed permeate. The mixed permeate is then passed successively to the permeate side of each preceding reverse osmosis unit in the series. For forward osmosis, a draw solution is passed sequentially from the permeate side of each unit to the permeate side of the preceding unit. The draw solution may be prepared by concentrating part of the concentrate stream by evaporation and recycling it back as a draw solution.

An osmotic process comprising for a first period, passing a draw stream and a feed stream through an osmotic unit having a semi-permeable membrane, permitting the passage of water but not salts. The feed stream is an aqueous stream with a lower salinity than the draw stream. The feed stream has a scalant with a concentration above saturation in a region on a feed side of the semi-permeable membrane. The draw stream passes over a draw side of the membrane and the feed stream passes over the feed side so water passes across the membrane from the feed stream to the draw stream. For a second time period, the flow rate of the draw stream is lower than the flow rate in the first time period, and the feed stream passes over the feed side such that the concentration of the scalant in said region is reduced.

A water recovery method for improving water recovery efficiency may include inflowing a low concentration solution including water into an in-series flow path. The in-series flow path may include a plurality of flow paths for a low concentration solution coupled in series. The method may additionally include inflowing a high concentration solution having the same concentration into a plurality of flow paths for a high concentration solution. Each of the plurality of flow paths for the high concentration solution may be connected to each of plurality of flow paths for the low concentration solution via a respective semipermeable membrane being interposed therebetween.

A spiral-wound forward osmosis membrane element (2) includes: a membrane leaf (23) in which an internal flow path extending from a first opening (26A) to a second opening (26B) is formed; and a central tube (31) around which the membrane leaf (23) is wound and which has a feed hole (31A) communicating with the first opening (26A) and a collection hole (31B) communicating with the second opening (26B). The central tube (31) has an interior partitioned to include an inflow region (3A) communicating with the feed hole (31A) and an outflow region (3B) communicating with the collection hole (31B) so that the inflow region (3A) and the outflow region (3B) each form a flow path extending continuously in an axial direction of the central tube (31) from one end to the other end of the central tube (3). Since a liquid fed into the inflow region (3A) is discharged to the outside without passing through two or more internal flow paths (26), the pressure loss in the spiral-wound forward osmosis membrane element (2) is reduced. Thereby, it is possible to provide a spiral-wound forward osmosis membrane element in which the pressure loss of the flow of a fluid is reduced.

Methods and systems for filtering of biological particles are disclosed. Filtering membranes separate adjacent chambers. Through osmotic or electrokinetic processes, flow of particles is carried out through the filtering membranes. Cells, viruses and cell waste can be filtered depending on the size of the pores of the membrane. A polymer brush can be applied to a surface of the membrane to enhance filtering and prevent fouling.

Separation processes using osmotically driven membrane systems are disclosed generally involving the extraction of solvent from a first solution to concentrate a solute by using a second concentrated solution to draw the solvent from the first solution across a semi-permeable membrane. Pre-treatment and post-treatment may also enhance the osmotically driven membrane processes.

The invention relates to a system for separating a product contained as solvent in a solution to be processed, comprising at least one forward osmosis device (816) through which the solution to be processed and a draw solution flow, and a device connected downstream thereof for obtaining the product (56, 62) from the diluted draw solution exiting the forward osmosis device, wherein the forward osmosis device comprises at least one flow channel conducting the solution to be processed and at least one flow channel conducting the draw solution, the inner space of a respective flow channel conducting the solution to be processed is delimited at least partially by a semi-permeable membrane wall that is permeable to the solvent of the solution to be processed but not to the substance dissolved therein, and at least one flow channel conducting the draw solution is delimited on opposite sides by membrane walls that are associated with two adjoining flow channels conducting the solution to be processed, such that solvent from the solution to be processed passes through the membrane walls into the adjoining flow channels conducting the draw solution.

Fluid desalination systems that include an FO reactor and an electrodeionization reactor with improved membranes and solvents, and a method of using such systems, are provided. A fluid having a first salt concentration is directed to the FO reactor, which uses a solute to draw salt away from the fluid across a membrane into the solute, where the electrodeionization reactor is salinized solute fluid and (i) generate substantially desalinated fluid and (ii) regenerate the solute for return to the forward osmosis reactor. The electrodeionization reactor is configured to draw positive and negative ions of the solute across cationic and anionic membranes, respectively, by applying a voltage across electrodes sandwiching the cationic and anionic membranes. In some cases, the cationic and anionic membranes are porous gelled polymer electrolyte membranes, wherein a saturated solution of the salinized solute fluid is absorbed.