WO2016111370A1 - Procédé de traitement d'eau - Google Patents

Procédé de traitement d'eau Download PDF

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Publication number
WO2016111370A1
WO2016111370A1 PCT/JP2016/050576 JP2016050576W WO2016111370A1 WO 2016111370 A1 WO2016111370 A1 WO 2016111370A1 JP 2016050576 W JP2016050576 W JP 2016050576W WO 2016111370 A1 WO2016111370 A1 WO 2016111370A1
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WIPO (PCT)
Prior art keywords
water
semipermeable membrane
rejection
rate
liquid
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PCT/JP2016/050576
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English (en)
Japanese (ja)
Inventor
寛生 高畠
谷口　雅英
杉田　和弥
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東レ株式会社
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Priority to JP2016510866A priority Critical patent/JPWO2016111370A1/ja
Publication of WO2016111370A1 publication Critical patent/WO2016111370A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B01D63/10—Spiral-wound membrane modules
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/56—Polyamides, e.g. polyester-amides
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/138—Water desalination using renewable energy
    • Y02A20/144—Wave energy

Definitions

  • the present invention relates to a water treatment method using a semipermeable membrane. More specifically, the present invention relates to a water treatment method using a composite semipermeable membrane that has been processed to improve the rejection rate of a semipermeable membrane, particularly a rejection rate of a nonionic substance.
  • Semi-permeable membranes such as nanofiltration membranes and reverse osmosis membranes can efficiently remove inorganic electrolytes and neutral molecules, and therefore, desalination of seawater and brine, production of medical and industrial pure water, ultrapure water, It is used in a wide range of fields such as wastewater treatment and food industry.
  • improvement in the blocking rate of the semipermeable membrane is required.
  • these semipermeable membranes are adversely affected by substances present in the treated water. For example, oxidative degradation due to an oxidative substance or alkaline hydrolysis due to a strong alkaline liquid causes membrane degradation over a long period of time or suddenly, and the required treated water quality cannot be obtained.
  • Patent Document 1 A blocking rate improver and a blocking rate improving method that can improve the blocking rate for a soluble solute have been proposed.
  • Patent Document 2 a semipermeable membrane treatment agent for improving the salt rejection rate of the semipermeable membrane, a semipermeable membrane treatment containing a vinyl polymer having an organic group having an acetoxy group and a terminal carboxyl group as a side chain as a main component An agent has been proposed (Patent Document 2).
  • the pH of the raw water is adjusted to 9.5 or higher, and further, a water for obtaining high-quality treated water by adding a blocking rate improver having a polyalkylene glycol chain.
  • a treatment device and a water treatment method have been proposed (Patent Document 3). Then, the non-ionic surfactant is brought into contact with the membrane surface against the reverse osmosis membrane having anion charge with increased permeation flux, and the permeation flux is lowered to a range of + 20% to ⁇ 20% at the start of use.
  • a performance recovery method is proposed (Patent Document 4).
  • a performance recovery method has been proposed in which iodine and / or iodine compounds having a redox potential of 300 mV or higher are brought into contact with a reverse osmosis membrane having a reduced removal rate (Patent Document 5).
  • the reverse osmosis membrane is brought into contact with a strong mineral acid aqueous solution such as phosphoric acid, phosphorous acid, sulfuric acid, etc., and the temperature is raised, and then an exclusion rate improver such as hydrolyzable tannic acid
  • an exclusion rate improver such as hydrolyzable tannic acid
  • Patent Document 7 a method has been proposed in which a semipermeable membrane that performs a rejection improvement process is selected based on a measured rejection rate of a labeling substance such as a salt, and the selected semipermeable membrane is focused on the improvement of the rejection rate.
  • Patent Document 8 a method of supplying the rejection rate improver to the primary side of the semipermeable membrane, measuring the amount of the rejection rate improver taken out from the primary side, and controlling the supply rate of the rejection rate improver based on the measurement result It has been proposed (Patent Document 8).
  • the present invention provides a composite semipermeable membrane, such as a nanofiltration membrane or a reverse osmosis membrane, subjected to a treatment for improving the rejection of the composite semipermeable membrane, in particular, the rejection of nonionic substances.
  • An object of the present invention is to provide a water treatment method for obtaining concentrated water and permeated water from water.
  • the present invention provides a method for easily and accurately grasping the progress of the rejection rate improvement process and executing the rejection rate improvement process quickly and accurately.
  • a blocking rate improving liquid containing a blocking rate improving agent is supplied to the primary side of a semipermeable membrane unit composed of one or a plurality of semipermeable membrane elements, and at least a part of the blocking rate improving liquid is half
  • It is a water treatment method for obtaining a permeated water and a concentrated water by supplying a raw water to the primary side of the semipermeable membrane that has been processed to improve the rejection rate by passing through the permeable membrane
  • the rejection rate improvement process is a rejection rate improvement process in which at least the supply pressure and / or the permeate flow rate at the time of supply of the rejection rate improvement liquid is measured, and the supply of the rejection rate improvement liquid is stopped based on the measured value.
  • a water treatment method (2) The water treatment method according to (1), wherein the permeated water when the raw water is supplied is treated again using a semipermeable membrane different from the semipermeable membrane. (3) The measured value is a measured value of the permeate flow rate when the rejection rate improving liquid is supplied, and the rejection rate improving liquid is supplied to the semipermeable membrane unit so as to have a substantially constant supply pressure.
  • the water treatment method according to (1) or (2) wherein when the measured value of is lower than a predetermined value, the supply of the rejection rate improving liquid is stopped.
  • the predetermined value is approximately the same salt concentration as that of the rejection rate improving liquid, and the liquid containing no rejection rate improving agent is reduced to a substantially constant supply pressure.
  • the water treatment method according to (3) which is supplied to the permeable membrane unit and has a value of 0.7 to 0.95 times the measured value of the permeable water flow rate at that time.
  • the measured value is a measured value of the supply pressure when the rejection rate improving liquid is supplied, and the rejection rate improving liquid is supplied to the semipermeable membrane unit so as to have a substantially constant permeate flow rate.
  • the predetermined value is substantially the same salt concentration as the blocking rate improving liquid, and the liquid containing no blocking rate improving agent has a substantially constant permeate flow rate.
  • the water treatment method according to (6) which is supplied to the semipermeable membrane unit and has a value 1.05 to 1.4 times the measured value of the supply pressure at that time.
  • the predetermined value supplies raw water to the semipermeable membrane unit before supplying the rejection rate improving liquid, and at least two of the supplied water, permeated water, and concentrated water at that time, the salt concentration, and the water temperature.
  • the pure water permeability coefficient A0 is calculated as the initial water permeability from them, and is a predetermined value determined based on at least the pure water permeability coefficient A0, the salt concentration of the rejection rate improving liquid and the water temperature (3)
  • a blocking rate improving liquid containing a blocking rate improving agent is supplied to a primary side of a semipermeable membrane unit composed of one or a plurality of semipermeable membrane elements, and at least a part of the blocking rate improving liquid is half It is a water treatment method for obtaining a permeated water and a concentrated water by supplying a raw water to the primary side of the semipermeable membrane that has been processed to improve the rejection rate by passing through the permeable membrane,
  • the rejection improving process measures at least the supply pressure and / or the permeate flow rate when supplying the rejection improving liquid, and changes the permeate flow rate when supplying the rejection improving liquid based on the measured value.
  • the water treatment method which is a rejection improvement process which performs at least one chosen from the change of the density
  • the measured value is a measured value of the supply pressure and / or the permeated water flow rate when the rejection rate improving liquid is supplied, and when the change rate of the measured value becomes small, the permeated water flow rate and / or the blocked rate.
  • the semipermeable membrane unit is a semipermeable membrane unit provided with a permeate flow rate adjustment valve for adjusting the flow rate of permeate in the permeate line, and when the rate of change of the measured value becomes small,
  • the rejection improvement process stops supply of the raw water to the semipermeable membrane unit, supplies a rejection improvement agent containing a rejection improvement agent to the primary side of the semipermeable membrane, and improves the rejection
  • a process for improving the rejection of a semipermeable membrane in which at least a part of the liquid permeates the semipermeable membrane and measuring at least one selected from a supply pressure, a permeate flow rate, and a permeate quality at the time of supplying raw water. Based on the value, at least one selected from the permeate flow rate at the time of supplying the rejection improvement liquid, the concentration and / or composition of the rejection improvement agent in the rejection improvement liquid, and the water temperature of the rejection improvement liquid (1 ) To (11).
  • the rejection improvement process supplies at least a part of the rejection improvement liquid by supplying a rejection improvement liquid containing a rejection improvement agent to the primary side of the semipermeable membrane element different from the semipermeable membrane element. From the permeate flow rate at the time of supply of the rejection improving liquid, the concentration and / or composition of the rejection improving agent in the rejection improving liquid, and the water temperature of the rejection improving liquid.
  • the relationship between at least one selected and the change in the pure water permeability coefficient A and / or the solute permeability coefficient B before and after the rejection rate improvement treatment is determined in advance, and at least of the supply water, permeate water, and concentrated water at the time of raw water supply at least two flow, salt concentration, and measures the temperature, calculates the pure water permeability coefficient a current and / or solute permeability coefficient B current at the time the raw water supply, the pure water permeability coefficient a current upon the raw water supply And / or melt Permeability coefficient B current and permeate flow rate during rejection enhancing fluid supplied from said relationship, determining at least one selected from the temperature of the concentration and / or composition, rejection enhancing solution rejection enhancing agent in the rejection enhancing solution
  • the rejection rate improving liquid is composed of a first rejection rate improving liquid and a second rejection rate improving liquid, and the first rejection rate improving liquid is supplied to the semipermeable membrane unit.
  • a semipermeable membrane blocking rate improving process for performing a second semipermeable membrane blocking rate improving process for supplying a second blocking rate improving liquid, wherein the measured value is at least a supply pressure at the time of supplying raw water, a permeated water One or more measured values selected from the flow rate and permeate quality, and when the measured value does not fall within a predetermined range, the second rejection rate improving liquid is changed to the first rejection rate improving liquid.
  • the rejection rate improving liquid is different from the composition of the rejection rate improving agent, and the concentration of the rejection rate improving agent in the second rejection rate improving liquid.
  • the supply pressure at the time of supplying the blocking rate improving liquid is higher or lower than the supply pressure at the time of supplying the first blocking rate improving liquid, and the permeate flow rate at the time of supplying the second blocking rate improving liquid is
  • the flow rate of the permeated water at the time of supply of the first rejection rate improving liquid is set to be higher or lower than the flow rate of the permeated water at the time of supplying the first rejection rate improving liquid.
  • the rejection rate improving liquid is any one of (1) to (14), wherein the rejection rate improving liquid is prepared by adding a rejection rate improving agent to the permeated water and / or raw water of the semipermeable membrane unit.
  • the water treatment method as described in any one of.
  • An aqueous solution having a pH of 3 or lower or 10 or higher is supplied to the semipermeable membrane unit, and the aqueous solution is brought into contact with the semipermeable membrane for a predetermined time, and then the inhibition rate improving liquid is supplied to the semipermeable membrane unit ( The water treatment method according to any one of 1) to (15).
  • the rejection rate improver is a rejection rate improver in which the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 0.9 to 1.1.
  • Item (1) The water treatment method according to any one of (16).
  • (18) The water treatment method according to any one of (1) to (17), wherein a weight average molecular weight of the blocking rate improver is 6,000 or more and 100,000 or less.
  • the composite semipermeable membrane after the start of operation in the water treatment facility can improve the removal rate of the composite semipermeable membrane when the permeated water quality deteriorates due to a decrease in the removal rate, and the inorganic electrolyte or The water quality of substances to be removed such as neutral molecules can be improved.
  • the progress of the rejection rate improvement process can be grasped easily and accurately, and the rejection rate improvement process can be executed quickly and accurately.
  • FIG. 1 is a flowchart showing an example of a semipermeable membrane separation apparatus (two stages of concentrated water) according to the present invention.
  • FIG. 2 is a flowchart of the semipermeable membrane separation apparatus when the rejection rate improving process according to the present invention is performed.
  • FIG. 3 is a flow diagram showing another example (two stages of permeated water) of the semipermeable membrane separation apparatus according to the present invention.
  • FIG. 4 is a process flow diagram of a test apparatus used for sampling an embodiment of the semipermeable membrane blocking performance improving method according to the present invention.
  • FIG. 5 is a graph showing the temporal change of the permeate flow rate and the permeate EC during the rejection improvement process according to the first embodiment.
  • FIG. 6 is a graph showing changes in permeate flow rate and permeate EC over time during the rejection improvement processing according to Example 2.
  • the water treatment method of the present invention can be applied to a semipermeable membrane separation apparatus using a semipermeable membrane, an example of which is shown in FIG.
  • the semipermeable membrane separation apparatus shown in FIG. 1 obtains pretreated water after raw water 1 is once stored in the raw water tank 2 and then sent to the pretreatment unit 4 by the raw water supply pump 3 and pretreated. .
  • the pretreated water passes through the intermediate water tank 5, the pretreated water supply pump 6, and the safety filter 7, and after being pressurized by the booster pump 8, is treated by a semipermeable membrane unit 9 (9 a, 9 b) composed of a semipermeable membrane module.
  • the permeated water 10 (10a, 10b) having a lower salt concentration than the raw water 1 and the concentrated water 11 (11a, 11b) having a higher salt concentration are separated.
  • the permeated water 10 is stored in the permeated water storage tank 12, and the concentrated water 11 is discharged.
  • the permeated water 10 is often used as production water, but the concentrated water 11 may be used as production water for recovering valuable materials.
  • the raw water and application to which the present invention is applied are not particularly limited, and can be applied to various purposes such as turbidity and desalination of river water and groundwater, desalination of seawater and brine, and reuse of sewage and wastewater. It is.
  • the pretreatment unit 4 is mainly applied for the purpose of removing the solid content contained in the raw water 1.
  • screens in units of cm to mm, sand filtration capable of high-precision solid-liquid separation on the submillimeter to micrometer level, fiber filters, non-woven fabric filters, sand filtration, and high precision, microfiltration membranes, ultra-fine A filtration membrane or the like can be used depending on the quality of raw water, and various pretreatment processes such as sedimentation separation and flotation separation can be exemplified.
  • a coagulant, an adsorbent, a bactericide, and a drug such as pH adjustment may be used in combination.
  • the pretreatment unit 4 can be omitted.
  • the pretreated water obtained from the pretreatment unit 4 is preferably temporarily stored in the intermediate water tank 5 in order to facilitate maintenance, but the intermediate water tank is used for the purpose of reducing the site area and effectively utilizing the pressure of the raw water supply pump 3. 5 can be omitted.
  • the pretreatment water supply pump 6 is not particularly limited as long as a predetermined amount of pretreatment water can be supplied to the semipermeable membrane unit 9 via the booster pump 8, and a commercially available pump can be used.
  • the booster pump 8 is not particularly limited as long as it can apply a pressure sufficient to separate the treated water from the treated water in the semipermeable membrane unit 9, and a commercially available pump can be used.
  • these pumps for example, a plunger type, a spiral type, a magnet type and the like can be appropriately selected and used according to the required output and characteristics.
  • the semipermeable membrane unit 9 includes a cylindrical pressure vessel that houses one or more semipermeable membrane elements, and a part of the supplied pretreatment water permeates the semipermeable membrane provided in the semipermeable membrane element. By doing this, it is a structure which can obtain the permeated water 10 which is the water which permeate
  • the semipermeable membrane unit 9 includes one or more cylindrical pressure vessels, and in a plurality of cases, the semipermeable membrane unit 9 can be provided in series or in parallel. When one or more cylindrical pressure vessels are installed in parallel and the same supply water is treated as a semipermeable membrane unit, it is possible to install the semipermeable membrane units in multiple stages. .
  • semi-permeable membrane units are installed in two stages, and pre-treated water is first treated by a semi-permeable membrane unit (first semi-permeable membrane unit) 9a to obtain permeated water 10a and concentrated water 11a.
  • the concentrated water 11a may be further processed by the next semipermeable membrane unit (second semipermeable membrane unit) 9b to obtain the permeated water 10b and the concentrated water 11b.
  • the concentrated water three-stage method in which the concentrated water 11b is further treated with another semi-permeable membrane unit, or the semi-permeable membrane unit 9c is further treated with the permeated water 10a as shown in FIG.
  • a permeate two-stage method may be used.
  • the permeated water two-stage method (FIG. 3)
  • most of the components to be removed are removed from the raw water by the treatment by the first-stage semipermeable membrane unit 9a, and the second-stage semipermeable membrane unit 9c is used.
  • This is a technique for improving the water quality of the permeated water 10c to a target level by removing the remaining components to be removed.
  • the method for improving the rejection rate of the present invention is applied to the first semipermeable membrane unit 9a of the two-stage permeated water method.
  • the permeate flow rate is particularly achieved to achieve the permeate quality. More important. This is because even if the permeated water quality does not reach the target water quality, it can be handled by the second-stage semipermeable membrane unit 9b, but when the permeate flow rate is reduced, the second-stage semipermeable membrane unit 9b can handle it. This is because it becomes difficult.
  • the present invention measures the supply pressure and / or the permeate flow rate when the rejection rate improving liquid is supplied, and changes the permeate flow rate when supplying the rejection rate improving liquid based on the measured value.
  • the present invention is applied to the first-stage semipermeable membrane unit 9a. By applying it, it is possible to secure the permeate flow rate and ensure the permeate flow rate and achieve the permeate quality as the entire semipermeable membrane separator.
  • the present invention supplies a blocking rate improving liquid containing a blocking rate improving agent to the primary side of a semipermeable membrane unit composed of one or a plurality of semipermeable membrane elements as described above.
  • Water treatment for obtaining a permeated water and a concentrated water by supplying a raw water to the primary side of the semipermeable membrane subjected to the treatment for improving the rejection rate by at least partially passing through the semipermeable membrane to improve the rejection rate of the semipermeable membrane.
  • the rejection rate improving process measures at least a supply pressure and / or a permeate flow rate at the time of supplying the rejection rate improving liquid, and stops the supply of the rejection rate improving liquid based on the measured value.
  • the permeated water in the permeated water storage tank 12 is transferred to the rejection rate improving liquid adjusting tank 13, and the rejection rate improving agent 14 is added thereto and stirred to adjust and create the rejection rate improving liquid.
  • pretreated water in the intermediate water tank treated by the raw water 1 or the pretreatment unit 4 may be used.
  • the recovery rate is improved.
  • pretreated water since it is after the solid content has been removed, there is little concern about blockage of the flow channel in the semipermeable membrane element, which is preferable.
  • the pretreated water supply pump 6 and the booster pump 8 are stopped to stop the supply of the water to be treated, and the raw water (pretreated water), the permeated water 10 and the concentrated water 11 in the semipermeable membrane unit and the piping are drained. Then, the adjusted rejection rate improving liquid is supplied to the primary side of the semipermeable membrane unit 9 through the water supply line to the semipermeable membrane unit 9 by using the rejection rate improving liquid supply pump 15 and permeated by allowing the membrane to permeate. Get water and concentrated water. The permeated water 10 and the concentrated water 11 are returned to the rejection rate improving liquid adjusting tank 13 to contact the semipermeable membrane while circulating the rejection rate improving liquid, thereby improving the rejection rate of the semipermeable membrane.
  • the pressure when the blocking ratio improving liquid is contacted with the semipermeable membrane is preferably equal to or lower than the pressure when water to be treated is passed through the composite semipermeable membrane (10 MPa or less). It is more preferable that the pressure is not more than the pressure (1 MPa or less) operated in the cleaning facility.
  • the permeation flux is in the range of 0.01 to 2 m / day, because the blocking rate improving agent can be brought into contact with the inside of the semipermeable membrane. . If the permeation flux is 0.01 m / day or less, the treatment effect is low, and if it is 2 m / day or more, the semipermeable membrane may be damaged by excessive operating pressure.
  • the permeation flux is the amount of water that permeates the semipermeable membrane per unit time and unit area.
  • the amount of water that permeates the semipermeable membrane of a known area is measured by a flow meter such as an electromagnetic flow meter or a float type flow meter. Or a weight measuring instrument such as an electronic balance, and calculated by the following formula.
  • Permeation flux Permeated water amount / (Membrane area x Sampling time)
  • the concentration of the blocking rate improver may be appropriately determined from its composition, environmental conditions, etc., but is preferably 10 to 1000 mg / L, more preferably 10 to 500 mg / L.
  • the time for passing the blocking ratio improving liquid is preferably 0.1 to 24 hours, and more preferably 0.25 to 3 hours.
  • the supply pressure and / or the permeate flow rate when the rejection rate improving liquid is supplied are measured, and based on the measured value, the change of the permeate flow rate when the rejection rate improving liquid is supplied, the rejection rate improving liquid At least one selected from a change in the concentration or composition of the rejection improving agent, a supply stop of the rejection improving liquid, and a change in the water temperature of the rejection improving liquid.
  • the measurement of the supply pressure is not particularly limited as long as it can measure the blocking rate improving liquid or raw water pressure supplied to the semipermeable membrane unit 9.
  • FIG. 2 illustrates the case where the supply water pressure gauge 16 is installed in the upstream main pipe of the semipermeable membrane unit 9, it may be installed after the rejection rate improving liquid supply pump on the circulation line before the main pipe joins. .
  • a semi-permeable membrane unit is configured in multiple stages as shown in FIG. 2, it is also preferable to install a pressure gauge on the concentrated water 11a line in order to measure the supply pressure in the subsequent stage.
  • the measurement of the permeate flow rate is not particularly limited as long as the permeate flow rate obtained by the semipermeable membrane unit 9 can be measured.
  • the semipermeable membrane unit is installed in multiple stages as shown in FIG. 2, the case where the permeate flow rate after the permeate flows 10 a and 10 b merge with the permeate flow meter 17 is described in FIG. 2.
  • a permeated water flow meter may be installed so that 10a and 10b can be measured, or the permeated water flow rate may be calculated from the difference between the feed water flow rate and the concentrated water flow rate.
  • the supply pressure and / or the permeate flow rate at the time of supply of the rejection rate improving liquid is measured, and when the change rate of the measured value becomes small, the permeate flow rate or the rejection rate improver concentration increases, and different inhibitions occur. It is preferable to execute at least one selected from the addition of a rate improver and the change of the water temperature of the rejection rate improving liquid.
  • the blocking rate improving liquid When the blocking rate improving liquid is brought into contact with and transmitted through the semipermeable membrane, the holes in the semipermeable membrane are filled with the blocking rate improving agent contained in the blocking rate improving solution. The rejection rate is improved and the water permeability is lowered. Therefore, when the blocking rate improvement treatment is performed under certain conditions, the probability of contact between the blocking rate improver and the pores of the semipermeable membrane is gradually decreased, the processing speed is gradually decreased, and the water permeability decreasing rate is gradually decreased. To do. That is, the rate of change of the measured value, which is the rate of increase of the supply pressure with respect to time and the rate of decrease of the permeate flow rate with respect to time, gradually decreases.
  • the measured values of supply pressure and permeate flow during the rejection rate improvement process are recorded at regular intervals of several seconds to several minutes, and the rate of change of the measured value at any time is calculated from the relationship between the time and the measured value.
  • the rate of change of the measured value at an arbitrary time may be calculated as a difference from the measured value at the previous time, or as the slope of a linear approximation including the measured values up to multiple points before. Also good.
  • the measured value at an arbitrary time is represented by a moving average value obtained as an average value of a plurality of previous points, and the measured value at an arbitrary time is represented based on the moving average value.
  • the rate of change may be calculated.
  • the permeated water flow rate and / or the rejection rate improver when the rate of change of the measured value at any time obtained in this way is reduced to a predetermined rate compared to the rate of change at the start of the rejection rate improvement process. It is preferable to execute at least one selected from an increase in concentration, addition of a different blocking rate improver, and a change in the water temperature of the blocking rate improving liquid.
  • the predetermined ratio may be arbitrarily determined, but is preferably 70%, more preferably 50%.
  • a permeate flow rate adjustment valve is provided in the permeate line of the semipermeable membrane unit to adjust the permeate flow rate. It is further preferable to increase the opening of the regulating valve. Thereby, even if the pump which applies supply pressure, such as a rejection rate improvement liquid supply pump, does not comprise the inverter, the permeated water flow rate can be adjusted appropriately.
  • the ratio and degree of increase in the permeate flow rate can be determined as appropriate. In particular, when the permeate flow rate gradually decreases, it is preferable to increase the permeate flow rate level at the start of the rejection improvement process.
  • the rejection improving agent when the concentration of the rejection improving agent is increased, the rejection improving agent may be added to the rejection improving liquid adjusting tank shown in FIG. 2 or may be injected into the pipe. However, in the latter case, it is preferable to install a line mixer downstream of the line injection point and stir to ensure mixing.
  • the ratio and degree of increasing the rejection rate improver concentration can be determined as appropriate, but in particular, it is preferably increased by 10% or more, more preferably increased by 50% or more.
  • the blocking rate improving agent may be added to the blocking rate improving liquid adjusting tank shown in FIG. 2 or may be injected into the pipe.
  • the different blocking rate improvers include not only the case where the components are different, but also the case where the weight average molecular weight and molecular weight distribution are different.
  • the water temperature of the rejection rate improving liquid when changing the water temperature of the rejection rate improving liquid, it is possible to heat or cool by installing a heater or a cooler in the rejection rate improving liquid adjustment tank of FIG. 2 or passing a heat exchanger or the like. preferable. Moreover, it is preferable to install a water temperature meter in the supply pipe of the rejection rate improving liquid, etc., to monitor the water temperature of the rejection rate improving liquid, and to heat and cool to the target temperature.
  • the degree of heating / cooling may be appropriately determined in view of the affinity between the rejection rate improver and the semipermeable membrane, the upper limit value of the water temperature of the plant, etc.
  • the blocking rate improving liquid is supplied to the semipermeable membrane unit so as to have a substantially constant supply pressure, the permeate flow rate at that time is measured, and the permeate flow rate measurement value falls below a predetermined value.
  • the supply of the blocking rate improving liquid is stopped, or the blocking rate improving liquid is supplied to the semipermeable membrane unit so that the flow rate of the permeated water is substantially constant, the supply pressure at that time is measured, and the supply pressure measurement value
  • the blocking rate improving liquid is supplied to the semipermeable membrane unit so as to have a substantially constant supply pressure, the permeate flow rate at that time is measured, and the permeate flow rate measurement value falls below a predetermined value. It is particularly preferable to sometimes stop the supply of the rejection improving liquid, and it is further preferable that the rejection improving liquid is a rejection improving liquid having a salt concentration of 5,000 mg / L or less.
  • a method of making the discharge pressure of a pump, which is a pressurizing means such as a rejection rate improving liquid supply pump, substantially constant can be mentioned.
  • the permeate flow rate is measured, and the pump serving as a pressurizing means so that the measured value falls within a certain range.
  • Substantially constant as described above means that a measured value at a given time (may be a moving average value for a certain period) does not vary greatly and does not show a clear increasing or decreasing tendency. Specifically, in the present invention, it means that a measured value of 90% or more is included in the range of ⁇ 10% of the average value of the measured value of the time during which the rejection rate improving liquid is supplied to the semipermeable membrane.
  • the semipermeable membrane unit is configured so that a liquid having substantially the same salt concentration as the blocking rate improving liquid and containing no blocking rate improving agent is at a substantially constant supply pressure.
  • the permeated water flow rate is set to 0.7 to 0.95 times the permeated water flow rate measured in advance, or substantially the same as the rejection rate improving liquid before the rejection rate improving liquid is supplied.
  • a liquid that has a salt concentration and does not contain a blocking rate improver is supplied to the semipermeable membrane unit so as to have a substantially constant permeate flow rate, and a predetermined value of the supply pressure is 1. It is preferably from 05 to 1.4 times. By setting the predetermined value within this range, it becomes a range in which the water permeability of the semipermeable membrane can be prevented from excessively decreasing and the processing cost can be avoided, and the rejection rate improvement effect by the rejection rate improvement process can be exhibited.
  • a liquid having substantially the same salt concentration as the rejection rate improving liquid and not containing the rejection rate improving agent means that the rejection rate improving liquid is added to the semipermeable membrane permeated water, for example.
  • the semipermeable membrane permeated water corresponds to the raw water
  • the raw water corresponds to the raw water added with the blocking rate improver. That is, the liquid utilized for the dilution / dissolution of the blocking rate improver is applicable.
  • the liquid may be created artificially so that the salt concentrations are substantially the same.
  • the salt concentration being substantially the same is preferably within ⁇ 10% of the salt concentration of the rejection improving liquid, more preferably within ⁇ 5%.
  • At least the raw water (including pretreated water) is passed through the semipermeable membrane before the rejection improvement process, and at least two of the supply water, permeated water, and concentrated water at that time are measured for flow rate, concentration, and water temperature. From these, pure water permeability coefficient A 0 is calculated as the initial water permeability, and then at least 2 of supply water, permeated water and concentrated water at that time while supplying and passing the blocking rate improving liquid to the semipermeable membrane.
  • One flow rate, concentration, and water temperature are measured, and a pure water permeation coefficient A 1 is calculated from them as initial permeation performance. If A 1 / A 0 is equal to or less than R A , the rejection rate improving process is terminated. It is preferable.
  • R A is more preferably 0.7 to 0.95.
  • At least the components other than containing the rejection improvement agent are passed through the semipermeable membrane using the same liquid. Measure at least two flow rates, concentrations, and water temperature, and calculate pure water permeability coefficient A 0 as initial water permeability and solute permeability coefficient B 0 as blocking performance, and then use a semipermeable membrane to improve the blocking rate.
  • the flow rate, concentration, and water temperature of at least two of the supply water, permeated water, and concentrated water at that time were measured while the water was being supplied and passed through, and the pure water permeability coefficient A 1 and the blocking performance were measured as the initial water permeability.
  • solute permeability coefficient B 2 if a 1 / a 0 is B 1 / B 0 is equal to or less than a predetermined value R B in which when equal to or less than R A1, exit rejection enhancing treatment, B 1 / B 0 exceeds the RB If continues the rejection enhancing treatment, or B 1 / B 0 is equal to or less than R B, when A 1 / A 0 is decreased to R A2, it is preferable to adopt the method of stopping the process. More specifically, R A1 is set to 0.9 or less and R A2 is set to 0.7 or more, and the rejection rate improving process is performed so that R B is set to 0.3 or more and 0.7 or less. It is preferable to apply.
  • the pure water permeability coefficient and the solute permeability coefficient can be obtained by the following equations.
  • Jv A ( ⁇ P ⁇ (Cm)) (1)
  • Js B (Cm ⁇ Cp) (2)
  • Cm ⁇ Cp) / (Cf ⁇ Cp) exp (Jv / k) (3)
  • Cp Js / Jv (4)
  • A ⁇ ⁇ A25 ⁇ ⁇ 25 / ⁇ (5)
  • B ⁇ ⁇ B25 ⁇ ⁇ 25 / ⁇ ⁇ (273.15 + T) / (298.15) (6)
  • the pure water permeability coefficient A and the solute permeability coefficient B under the measured conditions are obtained. Can be sought. Further, based on ⁇ and ⁇ obtained in advance, the pure water permeability coefficient A25 and the solute permeability coefficient B25 at 25 ° C. can be obtained from the equations (5) to (6). Furthermore, the equation (5) Using (6), a pure water permeability coefficient and a solute permeability coefficient at an arbitrary temperature T can be obtained.
  • the pure water permeability coefficient A and the solute permeability coefficient B are values corrected to the same temperature, but the most severe for water permeability, that is, the pure water permeability coefficient A is the lowest. the most stringent for the lowest operating temperature T L, and rejection performance of the semipermeable membrane, i.e. the solute permeability coefficient B is corrected to a value at the maximum operating temperature T H of the largest becomes a semi-permeable membrane, or the performance of each is within the allowable range It is very preferable because it is easy to understand.
  • the rejection rate improving process stops supply of the raw water to the semipermeable membrane unit, and supplies a rejection rate improving liquid containing a rejection rate improving agent to the primary side of the semipermeable membrane
  • a semipermeability improvement process for a semipermeable membrane in which at least a part of the rejection rate improving liquid permeates the semipermeable membrane, and at least one selected from a supply pressure, a permeate flow rate, and a permeate quality at the time of supplying raw water is measured. Based on the measured value, at least one selected from the flow rate of permeate when supplying the rejection improving liquid, the concentration and / or composition of the rejection improving agent in the rejection improving liquid, and the water temperature of the rejection improving liquid is determined. Water treatment method.
  • the rejection rate improving process performs the first semipermeable membrane rejection rate improving process for supplying the first rejection rate improving liquid to the semipermeable membrane unit
  • the raw water is supplied to the semipermeable membrane unit.
  • the measured value is one or more measured values selected from the supply pressure, the permeated water flow rate, and the permeated water quality when the raw water is supplied, and the measured value does not fall within a predetermined range
  • the improving liquid is a blocking ratio improving liquid different from the composition of the blocking ratio improving agent of the first blocking ratio improving liquid, and the concentration of the blocking ratio improving agent in the second blocking ratio improving liquid is the first blocking ratio improving liquid.
  • the supply pressure at the time of supplying the second rejection rate improving liquid is higher or lower than the supply pressure at the time of supplying the first rejection rate improving liquid, the second rejection rate
  • the permeate flow rate at the time of supplying the improvement liquid is set higher or lower than the permeate flow rate at the time of supplying the first rejection rate improving liquid, and the supply direction to the semipermeable membrane element at the time of supplying the second rejection rate improving liquid. It is also preferable to execute at least one selected from the direction opposite to the direction of supply to the semipermeable membrane element when the first blocking rate improving liquid is supplied.
  • the treatment performance of the semipermeable membrane is affected by various factors such as pressure, raw water quality, water temperature, permeation flux, raw water supply water flow rate, and concentrated water flow rate. Therefore, the performance during the rejection improvement process and the performance during the raw water treatment may be different. Therefore, the state of the semipermeable membrane is estimated from values such as supply pressure at the time of raw water supply, permeate flow rate, permeate quality, and the permeate flow rate at the time of supply of the rejection rate improving liquid, By determining the method and conditions of the rejection improvement process such as the concentration and / or composition, the water temperature of the rejection improvement liquid, etc., the rejection improvement process can be carried out more appropriately and efficiently.
  • the following method is preferable.
  • a blocking rate improving liquid containing a blocking rate improving agent is supplied to the primary side of the semipermeable membrane element different from the semipermeable membrane element, and at least a part of the blocking rate improving liquid permeates the semipermeable membrane and blocks the blocking rate.
  • At least one selected from the flow rate of permeated water when supplying the liquid for improving the rejection rate during the improvement treatment, the concentration and / or composition of the agent for improving the rejection rate in the liquid for improving the rejection rate, and the water temperature of the liquid for improving the rejection rate, and improving the rejection rate Predetermined relationship with the change in pure water permeability coefficient A and / or solute permeability coefficient B before and after treatment, and at least at least two flow rates, salt concentration, and supply water, permeated water, and concentrated water at the time of raw water supply , by measuring the water temperature, to calculate the pure water permeability coefficient a current and / or solute permeability coefficient B current at the time the raw water supply, the pure water permeability coefficient a current and / or solute permeation coefficient B current and said at raw water supply From relationship Permeate flow rate during stop-enhancing liquid supply, concentration and / or composition of the rejection enhancing agent in the rejection enhancing liquid, for determining at least one selected from a water temperature of rejection enhancing solution.
  • a pre Pure water permeability coefficient A [m 3 / m 2 / Pa / s] before rejection improvement processing
  • a post Pure water permeability coefficient A [m 3 / m 2 / Pa / s] after the rejection improvement process
  • B pre Solute permeability coefficient B [m / s] before the rejection improvement process
  • B post Solute permeability coefficient B [m / s] after the rejection improvement process It is.
  • Pure water permeation coefficient A current and solute permeation coefficient before rejection improvement processing based on information including at least two flow rates, concentrations, and water temperatures among the feed water, permeate, and concentrated water during raw water treatment prior to rejection improvement B current is calculated according to the above-described equations (1) to (6). Then, the pure water permeation coefficient A target and the solute permeation coefficient B target desired to be achieved by the rejection improvement process are determined from the permeated water flux, the supply pressure, and / or the permeated water quality desired by the above formulas (1) to (6). To determine.
  • the rejection rate improvement processing conditions necessary to satisfy A target / A current and B target / B current are the same as the rejection rate improvement processing conditions and the rejection rate improvement processing effects (A post / A pre , B post / B pre ) is determined based on the relationship.
  • the performance of the semipermeable membrane in the semipermeable membrane treatment using raw water is evaluated by the amount of permeated water, the supply pressure, and the quality of the permeated water, and when it does not fall within the predetermined performance range, the semipermeable membrane is treated again. Accurately grasp membrane performance and achieve target performance with higher accuracy. However, if the second semipermeable membrane rejection rate improving process is performed under the same conditions as the first semipermeable membrane rejection rate improving process, the result is higher than the rejection rate improvement result of the first semipermeable membrane rejection rate improving process.
  • the blocking rate improving liquid is different from the composition of the blocking rate improving agent of the first blocking rate improving liquid,
  • the concentration of the rejection rate improving agent in the second rejection rate improving liquid is made larger or smaller than the concentration of the first rejection rate improving agent, and the water temperature of the second rejection rate improving liquid is changed to the first inhibition rate.
  • the second The permeate flow rate at the time of supplying the rejection rate improving liquid is higher than the permeate flow rate at the time of supplying the first rejection rate improving liquid.
  • the supply direction to the semipermeable membrane element at the time of supplying the second rejection rate improving liquid is opposite to the supply direction to the semipermeable membrane element at the time of supplying the first rejection rate improving liquid.
  • the combination of the composition of the rejection ratio improving agents of the first and second rejection ratio improving liquids may be a combination selected from those having different components as described later, and the weight average molecular weight and molecular weight distribution of the same component are the same. It may be a combination of different things.
  • concentration of a rejection rate improving agent it is preferable to make it 20% or more large or small, and it is still more preferable to make it 50% or more large or small. Decreasing the concentration can also be expected to improve the rejection because the diffusion rate of the rejection rate improver is different, but increasing the concentration not only changes the diffusion status but also the probability of contact between the rejection rate improver and the film surface. Is particularly preferable because of a high value.
  • the water temperature when changing the water temperature, it is preferably 5 ° C. higher or lower, more preferably 10 ° C. higher or lower. Even if the water temperature is lowered, the diffusion rate of the rejection rate improver is different, so the improvement of the rejection rate can be expected.However, by increasing the water temperature, the reaction rate of the rejection rate improver increases not only, but also the diffusion rate is different. preferable.
  • the supply pressure and / or supply flow rate of the rejection rate improving liquid when changing the supply pressure and / or supply flow rate of the rejection rate improving liquid, it is preferably 20% or more, more preferably 50% or more. Decreasing the supply pressure and / or flow rate can also be expected to improve the rejection rate because the diffusion rate of the rejection rate improver differs. However, increasing the supply pressure and / or supply flow rate only changes the diffusion state. This is particularly preferable because the amount of the blocking rate improver that permeates the membrane increases.
  • the concentration and amount of the blocking rate improving liquid that is in contact with the position of the membrane element varies, so the supply direction to the semipermeable membrane element when the rejection rate improving liquid is supplied This is particularly preferable since the semi-permeable membrane element having a small processing effect can be more effectively subjected to the blocking rate improving process in the first blocking rate improving process.
  • the permeated water quality includes electrical conductivity (EC), total dissolved solids (TDS), total organic carbon concentration (TOC), chemical oxygen demand (COD), biochemical oxygen demand (BOD), Examples are absorbance, salt concentration by ion chromatography, emission spectroscopic analyzer (ICP), and the like.
  • EC that is quickly and easily obtained on site is most preferable.
  • the permeated water quality may be measured online by installing a meter or the like, or a sample may be collected and evaluated by an analyzer or the like. By measuring the permeated water quality, it is possible to grasp the degree of the rejection rate of the target permeated water component and to determine the rejection rate improvement processing condition with higher accuracy. It is more preferable to determine the rejection improvement processing conditions based not only on the quality of the permeated water but also on the measured values of the supply pressure of the raw water and the amount of permeated water.
  • an aqueous solution having a pH of 3 or less or 10 or more is supplied to the semipermeable membrane unit, and the aqueous solution is brought into contact with the semipermeable membrane for a predetermined time. It is also preferable to perform the treatment for improving the rejection rate of the semipermeable membrane by supplying.
  • the rejection improvement process is performed, removing the membrane contaminants on the surface of the composite semipermeable membrane in advance before the contact treatment allows the rejection improvement agent to be evenly contacted with the entire semipermeable membrane. Can obtain a high recovery effect.
  • chemicals generally used as cleaning chemicals for these films can be used.
  • metals such as iron and manganese adhering to the film surface can be effectively washed with an acidic solution such as citric acid, oxalic acid, hydrochloric acid, sulfuric acid, etc.
  • an acidic solution such as citric acid, oxalic acid, hydrochloric acid, sulfuric acid, etc.
  • the effect can be enhanced.
  • cleaning with an alkaline solution such as caustic soda or ethylenediaminetetraacetic acid tetrasodium is effective, and the cleaning effect can be enhanced by using a pH of 10 or more. it can.
  • the cleaning with these cleaning chemicals may be a method of cleaning using each chemical alone or a method of cleaning using a plurality of chemicals alternately.
  • the blocking rate improver used in the present invention is not particularly limited as long as it is a component having a function of adhering to the semipermeable membrane and improving the blocking rate of the semipermeable membrane, but a polymer having a vinyl polymer or a polyalkylene glycol chain.
  • vinyl polymers include polyvinyl acetate, polyvinyl alcohol, vinyl acetate-ethylene copolymer, Bolipier alcohol, vinyl acetate-ethylene copolymer, vinyl chloride copolymer, styrene-vinyl acetate copolymer, and N vinyl pyrrolidone.
  • -A vinyl acetate copolymer etc. can be illustrated.
  • examples of the polyalkylene glycol chain include a polyethylene glycol chain, a polypropylene glycol chain, a polytrimethylene glycol chain, and a polytetramethylene glycol chain.
  • These glycol chains can be formed by, for example, ring-opening polymerization of ethylene oxide, propylene oxide, oxetane, tetrahydrofuran or the like.
  • the rejection rate improver applied to the present invention is required to contain other solutes, but as its components, it adsorbs to oxidants and turbids that affect the performance of the semipermeable membrane, and the performance. It should be noted that components such as surfactants, organic solvents and oils that cause a decrease are not included, but there is no particular limitation.
  • the compound having a polyalkylene glycol chain of the present invention a compound in which an ionic group is introduced into the polyalkylene glycol chain can be used.
  • the ionic group include a sulfo group, a carboxy group, a phospho group, an amino group, and a quaternary ammonium group.
  • a water-soluble polymer compound having anionic or cationic characteristics can be obtained.
  • the polyalkylene glycol chain in the present invention is particularly preferably a polyethylene glycol chain. That is, the rejection rate improver preferably contains polyethylene glycol as a main component. Since the compound having a polyethylene glycol chain is highly water-soluble, it is easy to handle as a blocking rate improver and has a high affinity for the composite membrane surface, so that there is little deterioration in performance over time after treatment.
  • the blocking rate improver used in the present invention has a weight average molecular weight of 6,000 to 100,000, more preferably 7,500 to 50,000. If the weight average molecular weight of the blocking rate improver is less than 6,000, the blocking rate of the semipermeable membrane is not sufficiently improved, and the fixability after processing may be lowered. By suppressing the weight average molecular weight within 100,000, it is possible to suppress extreme permeation flux reduction and maintain good solubility in water and perform simple handling. This effect is particularly remarkable when the rejection rate improver is a rejection rate improver having a polyalkylene glycol chain.
  • a weight average molecular weight can be calculated
  • GPC gel permeation chromatography
  • the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the rejection rate improver is preferably in the range of 0.9 to 1.1.
  • the molecular weight distribution of the blocking rate improver contained in the blocking rate improving solution is analyzed by GPC, and the weight average molecular weight and the number average molecular weight are determined by converting the obtained chromatogram into the molecular weight of a polyethylene oxide standard product. Can be measured.
  • Mw / Mn is also called polydispersity.
  • composition has a uniform molecular weight and small variation. Constructing a blocking rate improver with components having a small molecular weight distribution in this way makes the blocking rate improving liquid evenly diffused and improves the blocking rate uniformly throughout the semipermeable membrane in the semipermeable membrane unit.
  • the agent can be contacted.
  • polymer materials such as cellulose acetate polymer, polyamide, polyester, polyimide, vinyl polymer can be used.
  • the membrane structure was formed of another material on an asymmetric membrane having a dense layer on at least one side of the membrane and having fine pores with gradually increasing pore diameters from the dense layer to the inside of the membrane or the other side.
  • a composite semipermeable membrane having a very thin separation functional layer can be used.
  • the translucent film preferably contains polyamide as a main component.
  • the translucent film preferably contains polyamide as a main component.
  • polyamide semipermeable membrane a composite semipermeable membrane having a separation functional layer of a crosslinked polyamide obtained by polycondensation reaction of a polyfunctional amine and a polyfunctional acid halide is suitable.
  • the semipermeable membrane element can be used as a semipermeable membrane element shaped for actual use.
  • the semipermeable membrane is a flat membrane, it can be used by incorporating it into a spiral, tubular, or plate-and-frame module.
  • Such a channel material is incorporated in the module, and is particularly preferably used as a composite semipermeable membrane element designed for high concentration and high pressure.
  • the decrease in the permeation flux after treatment is within the range of 10 to 30%.
  • the content is within the range of 10 to 25%.
  • the water to be treated is supplied to one semipermeable membrane unit (first semipermeable membrane unit) to obtain permeated water and concentrated water, and at least part of the obtained concentrated water is used as the other semipermeable membrane.
  • first semipermeable membrane unit the average water permeability of the first semipermeable membrane unit is the average water permeability of the second semipermeable membrane unit. It is also preferable to make it smaller than the property. Since the concentrated water that has not permeated through the former semipermeable membrane element becomes the raw water of the latter semipermeable membrane element, water having a higher salt concentration is treated in the latter stage.
  • the effective pressure available for permeation through the semipermeable membrane is decreased.
  • the permeate flow rate increases, clogging of the semipermeable membrane and accumulation of impurities on the membrane surface increase, and the burden on the semipermeable membrane increases.
  • the semipermeable membrane of the first semipermeable membrane unit is the same as that of the second semipermeable membrane unit.
  • the burden tends to be greater than that of a semipermeable membrane. Therefore, as in the present invention, by making the average water permeability of the first semipermeable membrane unit smaller than the average water permeability of the second semipermeable membrane unit, the semipermeable membrane of the first semipermeable membrane unit The burden can be reduced and the frequency of membrane exchange and the like can be reduced as a whole.
  • the target water permeability of the predetermined rejection rate improvement process it is possible to set the target water permeability of the predetermined rejection rate improvement process so that the first semipermeable membrane unit is smaller than the second semipermeable membrane unit.
  • the target value of the supply pressure of the first semipermeable membrane unit is set to the second semipermeable membrane unit. This can be achieved by making it larger than the unit.
  • the water permeability refers to the A value obtained by the above formula (5).
  • the rejection rate improving method of the present invention can improve the rejection rate with repetitive effects on the same semipermeable membrane in the same water treatment facility, the treatment method of the present invention is periodically implemented.
  • a constant removal rate can be maintained for a long time.
  • the effect of improving the removal rate of uncharged substances is greater than that of inorganic electrolytes that have an effect of eliminating membrane charges.
  • the non-charged substance include non-electrolyte organic substances and substances that are not separated in the neutral region (for example, boron and silica). Since these are contained in a large amount in seawater and groundwater, more stable operation can be continued by applying the method of the present invention to a water treatment plant for treating these raw waters.
  • the rejection improvement process of the present invention can suppress the permeation of both the solvent and the solute from the composite semipermeable membrane, particularly when the composite semipermeable membrane is deteriorated and the permeation flux is increased.
  • the recovery of the rejection rate it is possible to prevent the water quality from deteriorating due to an excessive decrease in the operating pressure for protecting the permeation flux as designed by reducing the permeation flux.
  • the water treatment method using the composite semipermeable membrane treated by the method for improving the rejection rate as described above prevents deterioration of the permeated water quality, provides good permeated water quality for a long time, and provides a new composite semipermeable membrane.
  • the exchange rate can be reduced.
  • Example 1 The test was performed using an apparatus as shown in FIG.
  • the raw water in the raw water tank 2 is temporarily stored in the intermediate water tank 5 after being subjected to ultrafiltration using a Toray UF membrane module as the pretreatment unit 4.
  • the raw water is supplied to the semipermeable membrane unit 9 by the booster pump 8 through the safety filter 7 by the pretreatment water supply pump 6, and the concentrated water and the permeated water obtained are totally recirculated to the raw water tank. It is a device that keeps the concentration constant.
  • a permeate flow meter 17 and a permeate EC meter (electric conductivity meter) 18 were attached to the permeate line to monitor the permeate flow rate and the permeate water quality.
  • RO element reverse osmosis membrane element TM810V (hereinafter referred to as RO element) manufactured by Toray Industries, Inc. was used.
  • TM810V reverse osmosis membrane element
  • TDS salt concentration
  • the test was performed under the conditions of 5 [MPa], supply flow rate 90 [m 3 / day], and temperature 25 [° C.]. As a result, the permeate flow rate was 4.90 [L / min], and the permeate water quality (EC) was 181.6 [ ⁇ S / cm].
  • RO elements were forcibly deteriorated by immersing them in a 10 mg / L sodium hypochlorite aqueous solution.
  • One RO element after forced deterioration was loaded into the semipermeable membrane unit 9a and tested under the same conditions as before forced deterioration.
  • the permeate flow rate was 5.64 [L / min] and the permeate water quality (EC). was 233.5 [ ⁇ S / cm].
  • the blocking rate improvement process was applied to the RO element after this forced deterioration as follows.
  • This blocking rate improving liquid is supplied to the semipermeable membrane unit 9a loaded with the forcedly deteriorated RO element under the conditions of a supply pressure of 0.5 [MPa], a supply flow rate of 34 [m 3 / day], and a temperature of 25 [° C.].
  • the concentrated water and permeated water were refluxed to the raw water tank.
  • the permeate flow rate value and the permeate water quality (EC) value measured by the permeate flow meter 17 and the permeate EC meter (electric conductivity meter) 18 at this time were recorded every 10 seconds.
  • the permeated water flow rate continued to gradually decrease from 1.41 [L / min], and became 1.24 [L / min] after 30 minutes of the rejection improvement process.
  • the permeated water EC gradually decreased from the initial value of 3.7 [ ⁇ S / cm] to about 3.0 [ ⁇ S / cm] for about 10 minutes after the start of the treatment, but decreased to about 3.0 [ ⁇ S / cm]. After that, it was almost flat.
  • the progress of the rejection rate improvement process can be grasped by measuring the permeate flow rate, it is difficult to grasp the progress of the rejection rate improvement process by measuring the permeate water quality.
  • a supply pressure of 5 with a NaCl aqueous solution (not containing a blocking rate improver) prepared at a salt concentration (TDS) of 32,000 [mg / L] as raw water for the RO element after the 30-minute blocking rate improving process is completed.
  • TDS salt concentration
  • Example 2 Using the RO element that was forcibly deteriorated simultaneously with Example 1, the rejection rate improvement process was performed under the same conditions as Example 1 except for the following rejection rate improvement process conditions.
  • the rejection rate improving liquid a solution obtained by adding NaCl to the rejection rate improving solution used in Example 1 so that the salt concentration TDS is 5000 [mg / L] is used as the rejection rate improving solution. Under the conditions of 0 [MPa] and a supply flow rate of 38 [m 3 / day], it was supplied to the semipermeable membrane unit 9a loaded with the RO element that was forcibly deteriorated.
  • the water treatment method of the present invention can easily and safely recover the performance of the composite semipermeable membrane whose performance has been reduced by use at a place where the membrane is used.
  • the present invention is particularly effective in improving the rejection rate of non-electrolyte organic substances and low molecular weight substances that do not deviate in neutral regions such as silica and boron, and is used when a composite semipermeable membrane is used repeatedly over a long period of time. Useful.
  • Raw water 2 Raw water tank 3: Raw water supply pump 4: Pretreatment unit 5: Intermediate water tank 6: Pretreatment water supply pump 7: Security filter 8: Booster pump 9: Semipermeable membrane unit 10: Permeated water 11: Concentrated water 12: Permeated water storage tank 13: Rejection rate improving liquid adjustment tank 14: Rejection rate improving agent 15: Rejection rate improving liquid supply pump 16: Supply water pressure gauge 17: Permeated water flow meter 18: Permeated water EC meter

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Abstract

Selon l'invention, une solution d'agent améliorant le taux de blocage contenant un agent améliorant le taux de blocage est introduite du côté primaire d'une unité à membrane semi-perméable qui est composée d'un ou plusieurs éléments à membrane semi-perméable et alimentée en eau brute pour obtenir de l'eau ayant perméé et de l'eau concentrée. La pression d'alimentation et/ou le débit d'eau ayant perméé sont mesurés pendant l'introduction de la solution d'agent améliorant le taux de blocage et, sur la base des valeurs mesurées, au moins une action choisie parmi la modification du débit d'eau ayant perméé pendant l'introduction de la solution d'agent améliorant le taux de blocage, la modification de la concentration et/ou de la composition de l'agent améliorant le taux de blocage dans la solution d'agent améliorant le taux de blocage, l'arrêt de l'introduction de la solution d'agent améliorant le taux de blocage et la modification de la température de la solution d'agent améliorant le taux de blocage est exécutée.
PCT/JP2016/050576 2015-01-09 2016-01-08 Procédé de traitement d'eau WO2016111370A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018108550A (ja) * 2016-12-28 2018-07-12 三菱重工業株式会社 塩分濃縮装置及び塩分濃縮装置のスケール検知方法
JP2018122267A (ja) * 2017-02-02 2018-08-09 オルガノ株式会社 逆浸透膜の改質方法、逆浸透膜、および、非荷電物質含有水の処理方法
WO2019180789A1 (fr) * 2018-03-19 2019-09-26 三菱重工エンジニアリング株式会社 Dispositif de traitement d'eau et procédé de traitement d'eau

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JPH06254553A (ja) * 1993-03-08 1994-09-13 Shinko Electric Co Ltd 純水製造装置
JPH08309350A (ja) * 1995-05-17 1996-11-26 Hitachi Plant Eng & Constr Co Ltd 逆浸透膜を用いた水処理方法
JP2008155123A (ja) * 2006-12-22 2008-07-10 Kurita Water Ind Ltd 透過膜の阻止率向上方法、透過膜処理方法および透過膜装置
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018108550A (ja) * 2016-12-28 2018-07-12 三菱重工業株式会社 塩分濃縮装置及び塩分濃縮装置のスケール検知方法
JP2018122267A (ja) * 2017-02-02 2018-08-09 オルガノ株式会社 逆浸透膜の改質方法、逆浸透膜、および、非荷電物質含有水の処理方法
WO2019180789A1 (fr) * 2018-03-19 2019-09-26 三菱重工エンジニアリング株式会社 Dispositif de traitement d'eau et procédé de traitement d'eau

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