An aqueous solution flows through a desalination system that separates the aqueous solution into purified water and concentrated brine. The concentrated brine is directed into an electrodialysis system that includes an anode and a cathode and at least two monovalent selective ion exchange membranes between the anode and the cathode. At least one of the monovalent selective ion exchange membranes separates at least one diluate channel from at least one concentrate channel in the electrodialysis system, and this membrane selectively allows at least one monovalent ion to pass through the membrane while blocking or inhibiting the transport therethrough of multi-valent ions. The concentrated brine flows through at least the concentrate channel while a voltage is applied to the anode and cathode; and additional aqueous solution flows through the diluate channel.

Provided are: an economically superior protein crystallization method capable of efficiently finding conditions for crystallization by using a small amount of protein; and a crystallization device used for the method. According to the present invention, a transparent sealed container 1 is filled with a solution of protein, a part of the transparent sealed container 1 being formed of a semipermeable membrane 2 with a molecular weight cut-off that inhibits passage of the protein while allowing passage of a precipitant, and then, a precipitant solution with changed concentration and/or pH of the precipitant is continuously supplied to the semipermeable membrane 2, to crystallize the protein with the precipitant that infiltrates from the semipermeable membrane 2 into the sealed container 1.

A method of producing lithium hydroxide using a variety of aqueous solutions as a source liquid. The method includes: providing a lithium ion extraction liquid, including a first mixing of an aqueous solution containing lithium and at least one kind of an element other than lithium and a base in a reaction tank, with a pH regulated to 6 or more and 10 or less, a second mixing of the aqueous solution and the base, with a pH regulated to 12 or more, and removal of a hydroxide of the element other than lithium formed through the first and second mixing; recovering only lithium ion from the lithium ion extraction liquid to a recovery liquid with an electrochemical device including a Li-selectively permeable membrane; and performing the regulation of pH by returning the lithium ion extraction liquid after recovering lithium ion with the electrochemical device to the reaction tank.

A new method for producing D-allulose crystals that allows for a continuous production process and ensures a high yield. Also, new D-allulose crystals. Further, the use of a nanofiltration unit in a method for producing D-allulose crystals to improve the yield and/or quality of the resulting crystals.

A process for the recovery of sodium sulfate from water, in particular from water deriving from a silica manufacturing process.

A scale detection device of a concentrating device comprises: a reverse osmosis membrane device 13 that is a concentrating device including a reverse osmosis membrane 13a, which is a filtering membrane for concentrating salt in a water to be treated 11, containing at least calcium sulfate to obtain reclaimed water 12; and a scale detection unit 15 disposed in a branched line L.sub.14 branched from a concentrated water line L.sub.13 discharging concentrated water 14 having a high concentration of salt, the scale detection unit further concentrating the salt in the concentrated water 14 to obtain reclaimed water for detection 16, and including a detection membrane 15a detecting the absence or presence of scale component deposition in the concentrated water 14.

Provided is a method for processing a feed solution, which is an organic solution containing a small amount of water, using forward osmosis under a non-heated condition to obtain a dehydrated feed solution without causing degradation or change in quality of a solute. This method is for dehydrating a feed solution containing a first organic solvent, water, and a first solute, and comprises a dehydration step for bring the feed solution and an organic draw solution containing a second organic solvent into contact with each other through a forward osmosis membrane to obtain a dehydrated feed solution that has the moisture content thereof reduced to less than 1 mass % through dehydration. In one mode, the initial moisture content of the feed solution in the dehydration step is not less than 1 mass % but less than 30 mass %, and the initial moisture content of the organic draw solution is less than the initial moisture content of the feed solution.

A process for preparing a metal hydroxide comprising (i) at least one metal chosen from nickel and cobalt and optionally (ii) at least one metal chosen from manganese, lithium and aluminum. The process comprises: reacting a metal sulfate comprising (i) at least one metal chosen from nickel and cobalt and optionally (iii) at least one metal chosen from manganese and aluminum with sodium hydroxide and optionally a chelating agent in order to obtain a solid comprising the metal hydroxide and a liquid comprising sodium sulfate; separating the liquid and the solid from one another to obtain the metal hydroxide; submitting the liquid comprising sodium sulfate to an electromembrane process for converting the sodium sulfate into sodium hydroxide; and reusing the sodium hydroxide obtained by the electromembrane process for reacting with the metal sulfate.

The present invention discloses a process for preparing high-purity raffinose from defatted wheat germ comprising the steps of percolate extraction of raffinose from defatted wheat germ, decoloration by extraction from the abstraction liquid, electrodialysis desalination, impurity removal by simulated moving bed, concentration and crystallization, with the absolute purity of raffinose as high as 98% and the recovery up to 75%. The process is not only reliable and easy to operate, but also easy to realize industrial production and control the parameters.

A reverse osmosis desalination system for treating feed water, the feed water containing minerals, the system comprising a reverse osmosis unit comprising a first reverse osmosis stage (21) and a second reverse osmosis stage (22), each of the reverse osmosis stages (21, 22) having a feed water input, a product water outlet and a brine outlet, and a fluidized bed crystallizer (30), configured to remove minerals from the water, wherein the fluidized bed crystallizer (30) receives brine from the first reverse osmosis stage (21) and passes treated water to the feed water input of the second reverse osmosis stage (22).