A process treats high temperature produced water by passing a stream to an electrocoagulation unit and then to a membrane distillation (MD) unit where the stream contacts a hydrophobic membrane on a feed side and deionized water contacts the membrane on a product side. A distilled water stream is recovered and collected with the product side stream to form a volume-depleted exit produced water stream on the feed side of the hydrophobic membrane. The exit product side stream is passed through a heat exchanger to form a stream that is returned to a location upstream of the MD unit for an additional pass through the MD unit, thereby recovering additional water. The stream can be returned multiple times to achieve high recovery and to form a final stream leaving the MD unit having a temperature from 40-60 ? C., a total oil and grease content no greater than 500 mg/L, and a suspended solids content no greater than 200 mg/L. A portion of the distilled water stream from the membrane distillation unit can be used to form a brine solution used to regenerate used ion exchange resin in a water softening system.

A process treats high temperature produced water by passing a stream to an electrocoagulation unit and then to a membrane distillation (MD) unit where the stream contacts a hydrophobic membrane on a feed side and deionized water contacts the membrane on a product side. A distilled water stream is recovered and collected with the product side stream to form a volume-depleted exit produced water stream on the feed side of the hydrophobic membrane. The exit product side stream is passed through a heat exchanger to form a stream that is returned to a location upstream of the MD unit for an additional pass through the MD unit, thereby recovering additional water. The stream can be returned multiple times to achieve high recovery and to form a final stream leaving the MD unit having a temperature from 40-60 C., a total oil and grease content no greater than 500 mg/L, and a suspended solids content no greater than 200 mg/L. A portion of the distilled water stream from the membrane distillation unit can be used to form a brine solution used to regenerate used ion exchange resin in a water softening system.

Lithium recovery processes are described using concentration and conversion techniques. A vaporizer or membrane can be used to concentrate lithium and precipitate impurities. A conversion process can be used to replace anions in lithium bearing streams by adding a second anion and precipitating lithium in a salt with the second anion. Rotary separation can be used to separate the precipitated lithium salt.

The invention relates to a process for separating a composition of matter with the aid of a membrane cascade having at least two stages, in which a separation is effected in each stage at at least one membrane at a separation temperature set for the particular stage. The invention further relates to a corresponding membrane cascade, to the use of said membrane cascade for catalyst separation from homogeneously catalyzed mixtures, and to a process for hydroformylation, in which the catalyst is separated by means of a membrane cascade. The problem addressed thereby is that of specifying a membrane-based process for separating compositions of matter, which has a minimum membrane area requirement and nevertheless fulfills the separation task and separation performance required. This problem is solved by the use of a membrane cascade with falling separation temperature.

Provided herein are systems and methods for removing radon from a natural gas stream. The system includes a radon permeable membrane. The radon permeable membrane is configured to separate a natural gas stream into a radon rich permeate stream and a radon reduced retentate stream. The radon rich stream can be stored for a period of time to yield a decayed permeate stream or reinjected into the source formation. The system can include a second radon permeable membrane configured to separate the radon reduced retentate stream into a second permeable stream and a second retentate stream. The decayed permeate stream and second retentate stream can be combined to form a sales gas.

A method is disclosed for concentrating and purifying an eluate brine and producing a purified lithium compound. An extraction eluate, rich in lithium, is directed to a nanofiltration unit or a softening process that removes sulfate and/or calcium and magnesium. Permeate from the nanofiltration unit or the effluent from the softening process is directed through an electrodialysis unit. As the lithium-rich solution moves through the electrodialysis unit, lithium, sodium and chloride ions pass from the solution through a cation-transfer membrane and an anion-transfer membrane to concentrate compartments. A dilute stream is directed through the concentrate compartments and collects the lithium, sodium and chloride ions. The electrodialysis unit also produces a product stream which contains non-ionized impurities, such as silica and/or boron. Concentrate from the electrodialysis unit is subject to a precipitation process that produces a lithium compound that is subsequently subjected to a purification process.

Air flows across an air-liquid interface such that liquid desiccant flowing through the interface absorbs water from the air and is thereby diluted to form an output stream. The output stream is circulated through an electrodialytic stack having a central ionic exchange membrane and first and second outer ionic exchange membranes. A redox shuttle loop circulates around the first and second outer ionic exchange membranes. A voltage is applied across the electrodialytic stack, which regenerates the liquid desiccant.

The method of verifying an RO membrane of an RO installation is characterised in that the conductivity values of the supplied raw water and of the permeate and the amount of the raw water inflow and the concentrate outflow are continuously or cyclically measured and that the efficiency of the RO membrane, its retention rate and/or filtration efficiency are calculated from the measured values.

Provided are electrodialysis systems comprising a plurality of electrodialysis devices, wherein each electrodialysis device of the plurality of electrodialysis devices has a product inlet stream, a product outlet stream, a brine inlet stream, and a brine outlet stream. The product inlet stream for a first electrodialysis device comprises the brine outlet stream of a second electrodialysis device. Further, a first portion of a feed stream is the brine inlet stream for the first electrodialysis device and a second portion of the feed stream is the brine inlet stream for the second electrodialysis device or a third electrodialysis device.

A purification system is for purifying a mixture containing a first solvent, a second solvent, and an impurity. The purification system includes a first membrane separation device including a pervaporation membrane and a second membrane separation device including a filtration membrane. The pervaporation membrane separates the mixture into a first permeated fluid and a first concentrated fluid. The first permeated fluid has a lower concentration of the impurity than that in the mixture, and the first concentrated fluid has a higher concentration of the impurity than that in the mixture. The filtration membrane separates the first concentrated fluid into a second permeated fluid and a second concentrated fluid. The second permeated fluid has a lower concentration of the impurity than that in the first concentrated fluid, and the second concentrated fluid has a higher concentration of the impurity than that in the first concentrated fluid.