Abstract: The present invention provides a method for analyzing a halogenated structure in a composite semipermeable membrane. The method for analyzing a composite semipermeable membrane according to the present invention includes: a step A for immersing the composite semipermeable membrane in a solution containing alkali and at least one of nicotinamide and a derivative thereof; and a step B for performing fluorescence analysis on the solution obtained in step A.

Abstract: An efficient method is provided for cleaning hollow fiber membrane modules, the method being capable of efficiently removing substances accumulated inside hollow fiber membrane modules. The internal liquid on the raw liquid side of the hollow fiber membrane module (3) is discharged from a lower end face nozzle (19) of the hollow fiber membrane module (3) while air-cleaning is performed. The method for cleaning hollow fiber membrane modules is characterized in that the rate of liquid discharge from the lower end face nozzle of the hollow fiber membrane module (3) when discharging the internal liquid from the lower end face nozzle is adjusted so that the air supplied from the lower end face nozzle of the hollow fiber membrane module (3) through the aeration holes is supplied to the hollow fiber membrane module (3).

Abstract: The present invention provides a submerged type membrane separation device and a membrane separation method which allow long-term stable filtration. In the submerged type membrane separation device including a membrane module having membrane units stacked on top of each other in stages, in each of which flat sheet membrane element each having a separation membrane are arranged, the membrane module is constructed of various membrane units differing in sludge-filtration resistance or pure-water permeation resistance, whereby it becomes possible to extend a device operation period of time lapsing before transmembrane plugging occurs, or equivalently, the necessity to clean membranes arises. Further, it also becomes possible to design to synchronize timings with which a plurality of membrane units require cleaning.

Abstract: Disclosed is a method of enhancing a rejection performance of a semipermeable membrane by pressurizing and feeding a liquid containing a rejection performance enhancer to a primary side of the semipermeable membrane to come into contact with a membrane surface thereof, the method including: a step of changing, at least once during the feeding, a pressure or an osmotic pressure of the liquid containing the rejection performance enhancer at a fluctuation rate of 0.05 MPa/s or more, or a feed flow rate to the semipermeable membrane, thereby changing at least either a pressure acting on the membrane surface or a permeation flow rate from that at the time of normal treatment, followed by maintaining.

Abstract: Provided is a fresh water generation system which filters biotreated water produced by microbiologically treating waste water via a primary semi-permeable membrane (8), and then mixes concentrated water rejected by the filtration with seawater, thereby to filter the mixed water via a secondary semi-permeable membrane (14). This system enables frequencies of chemical cleaning and replacement of the secondary semi-permeable membrane to be reduced. The fresh water generation system comprises: a primary semi-permeable membrane apparatus (9) which separates microorganism treating waste water into permeated water and concentrated water; a secondary semi-permeable membrane apparatus (13) which filters mixed water prepared by mixing the concentrated water into seawater. In the fresh water generation system, the primary semi-permeable membrane (8) has an equal to or a higher microorganism adhesive property than the secondary semi-permeable membrane (14).

Abstract: The present invention provides a submerged type membrane separation device and a membrane separation method that can deal with a temporary increase of a treatment flow rate by taking advantage of the filterability of the constituent separation membranes of the device. In submerged type separation device including a membrane module having stacked therein membrane units in which flat sheet membrane elements having a separation membrane are arranged, a membrane unit having the highest filtration resistance or the highest pure-water permeation resistance is placed at the lowermost stage of the membrane module, thereby setting a high temporary filtration flux for the membrane module as a whole. This makes it possible to deal with a short-term flow rate increase.

Abstract: Provided is, in a fresh water generation system, a bactericide dosing method for suppressing growth of biofouling by mixing waters to be treated having different water qualities from each other in order to reduce the amount of energy required to generate fresh water. The present invention relates to a fresh water generation system and a fresh water generation method for obtaining fresh water from water to be treated A1 and dilution water B1 having different osmotic pressures from each other as raw waters, using desalination technique.

Abstract: Provided is a fresh water production method applying a combined water-treatment technology employing a plurality of semi-permeable membrane units, the method enabling prevention of problems caused by growth of a biofilm and allowing effective use of an injected chemical agent and an injected neutralizing agent. The fresh-water production method produces fresh water by treatment of source water by a semi-permeable membrane treatment device, the concentrated water resulting from the treatment by the semi-permeable membrane treatment device is mixed with other source water, and the water mixture is treated by a second semi-permeable membrane treatment device. A first chemical agent is injected continuously or intermittently into the source water and a second chemical agent is injected continuously or intermittently into the source water.

Abstract: An efficient method is provided for cleaning hollow fiber membrane modules, the method being capable of efficiently removing substances accumulated inside hollow fiber membrane modules. The internal liquid on the raw liquid side of the hollow fiber membrane module (3) is discharged from a lower end face nozzle (19) of the hollow fiber membrane module (3) while air-cleaning is performed. The method for cleaning hollow fiber membrane modules is characterized in that the rate of liquid discharge from the lower end face nozzle of the hollow fiber membrane module (3) when discharging the internal liquid from the lower end face nozzle is adjusted so that the air supplied from the lower end face nozzle of the hollow fiber membrane module (3) through the aeration holes is supplied to the hollow fiber membrane module (3).

Abstract: A water producing system which is provided with a semi-permeable membrane treatment process A100 to produce membrane permeate A3 and concentrate A, a semi-permeable membrane treatment processB200 which is equipped with a treatment target water B branching means for branching treatment target water B2 into two or more to produce a membrane B5 and concentrate B6, and a semi-permeable membrane treatment process C300 which is equipped with a first water mixing means for mixing one of the treatment target water B with at least part of the concentrate A, and subjects the mixed water to the semi-permeable membrane treatment to produce membrane permeate C7 and concentrate C8, thereby producing fresh water from a plurality of kinds of raw water which differ in osmotic pressure.

Abstract: The present invention provides a submerged type membrane separation device and a membrane separation method which allow long-term stable filtration. In the submerged type membrane separation device including a membrane module having membrane units stacked on top of each other in stages, in each of which flat sheet membrane elements each having a separation membrane are arranged, the membrane module is constructed of various membrane units differing in sludge-filtration resistance or pure-water permeation resistance, whereby it becomes possible to extend a device operation period of time lapsing before transmembrane plugging occurs, or equivalently, the necessity to clean membranes arises. Further, it also becomes possible to design to synchronize timings with which a plurality of membrane units require cleaning.

Abstract: Provided is a process for producing water including generating a water to be filtrated wherein a water to be treated is treated to generate a water to be filtrated; filtration wherein the water to be filtrated is filtrated through a separation membrane module having a separation membrane to generate a filtrated water; back washing wherein the substance to be removed by filtration which has blocked the separation membrane in the step of filtration is washed away by using a cleaning water; and drainage wherein cleaning drainage generated in the step of back washing is drained; wherein the step of generating the water to be filtrated has a coagulation substep of adding a first pH adjuster and a cationic coagulant to coagulate the substance to be removed by filtration in the water to be treated to thereby generate the pretreated water; the water to be filtrated used in the step of filtration satisfies the following expression (i); and the step of back washing has at least first back washing substep wherein the se

Abstract: Disclosed is a fresh water generator for fresh water production, which is effective to prevent a membrane life from becoming worse by suppressing the load on the membrane of a second semi-permeable membrane treatment facility when the concentrated water produced by the treatment of a first semi-permeable membrane treatment facility, and water to be treated with different osmotic pressure there from are mixed and treated with the second semi-permeable membrane treatment facility by the fresh water generator which comprises a means for storing the concentrated water produced from the first semi-permeable membrane treatment facility and water (B) to be treated, which is separately supplied in a storage tank A and a storage tank B in such a manner that the flow rate (mixture ratio) of the concentrated water to the water (B) to be treated is maintained constant, and supplying the concentrated water and the water (B) to be treated from each of the storage tanks to the second semi-permeable membrane treatment facili

Abstract: A fresh water generation method using a fresh water-generating device. The fresh water generation method includes a first treatment process for treating sewage and wastewater using a biological treatment unit and a first solid-liquid separation unit; a second treatment process for treating sewage and wastewater with a second solid-liquid separation unit; and a first detection process for detecting the treatment capacity level of the biological treatment unit; and which adjusts the volume of sewage and wastewater treated with the second treatment process on the basis of the results of the first detection process.

Abstract: Provided is a fresh water generation system which filters biotreated water produced by microbiologically treating waste water via a primary semi-permeable membrane (8), and then mixes concentrated water rejected by the filtration with seawater, thereby to filter the mixed water via a secondary semi-permeable membrane (14). This system enables frequencies of chemical cleaning and replacement of the secondary semi-permeable membrane to be reduced. The fresh water generation system comprises: a primary semi-permeable membrane apparatus (9) which separates microorganism treating waste water into permeated water and concentrated water; a secondary semi-permeable membrane apparatus (13) which filters mixed water prepared by mixing the concentrated water into seawater. In the fresh water generation system, the primary semi-permeable membrane (8) has an equal to or a higher microorganism adhesive property than the secondary semi-permeable membrane (14).

Abstract: The present invention relates to a method for separating and recovering a purified alkali metal salt from an aqueous alkali metal salt solution, the method including a treatment step of removing a purification-inhibiting substance from an aqueous alkali metal salt solution with a separation membrane having a glucose removal ratio and an isopropyl alcohol removal ratio simultaneously satisfying the following expressions (I) and (II) when each of a 1000 ppm aqueous glucose solution having a temperature of 25° C. and pH of 6.5 and a 1000 ppm aqueous isopropyl alcohol solution having a temperature of 25° C. and pH of 6.5 is permeated through the separation membrane at an operating pressure of 0.75 MPa: Glucose removal ratio?90% . . . (I), Glucose removal ratio—Isopropyl alcohol removal ratio?30% . . . (II).

Abstract: A fine bubble diffusing tube that can generate fine bubbles evenly and uniformly even when the diffusing tube has a long length, a fine bubble diffusing device using such a tube and a submerged membrane separation apparatus are produced. The fine bubble diffusing tube is provided with a cylindrical supporting tube 1, and an elastic sheet 2 with fine slits formed therein, with the elastic sheet 2 being placed to cover the outer circumference of the supporting tube 1, so that, upon supplying a gas to a space between the elastic sheet 2 and the supporting tube 1, the fine slits of the elastic sheet 2 are opened to generate fine bubbles, and the supporting tube 1 has a length L of 1000 mm or more in the longitudinal direction, with gas supply units 4 serving as gas flow inlets being attached to the two ends of the supporting tube.

Abstract: A method is provided for producing fresh water, the method including feeding raw water to a semipermeable membrane to obtain fresh water, in which water having a solute concentration different from that of the raw water is fed and mixed with the raw water according to changes of a flow rate of fresh water of the semipermeable membrane unit and/or operating pressure of the semipermeable membrane unit.

Abstract: A method is provided for precisely predicting the temporal variation of a membranous filtration resistance, a transmembrane pressure, a membranous filtration flowrate, or a membranous filtration flowrate as occurs in filtrating a liquid with a membrane, in a membranous filtration method wherein the liquid is filtrated by the separation membrane with the transmembrane pressure as a driving force. The method includes calculating: a constituent component quantity value of the liquid that attaches on a surface of the separation membrane at a time t+?t; a constituent component quantity value of the liquid that exists in pores of the separation membrane; a consolidation degree of a constituent component of the liquid that attaches on the separation membrane surface; a membranous filtration resistance value; a transmembrane pressure value; and a membranous filtration flowrate value.

Abstract: A water producing system is provided that produces fresh water by treating treatment target water A at a first semipermeable membrane treatment plant, that mixes concentrate resulted by the treatment carried out at the first semipermeable membrane treatment plant with treatment target water B, and that treats the mixed water at a second semipermeable membrane treatment plant to produce fresh water. A bypass line allows the treatment target water A to be mixed with the treatment target water B or the concentrate while bypassing the first semipermeable membrane treatment plant, so that the second semipermeable membrane treatment plant can operate even when any trouble occurs at the first semipermeable membrane treatment plant and treatment cannot be carried out thereby.