JP2010131478A - Organic fluorine compound treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic fluorine compound treatment system capable of inexpensively detoxicating an organic fluorine compound in water to be treated. <P>SOLUTION: The organic fluorine compound treatment system 2 is provided with: an ion exchange treating apparatus 300 being a concentrating means for concentrating the water to be treated containing the organic fluorine compound; and a super critical water oxidation treatment apparatus 100 for oxidizing the concentrated liquid obtained by treating the water to be treated with the concentration means under a super critical state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic fluorine compound processing system.

  Organic fluorine compounds such as perfluorooctane sulfonic acid, perfluoroalkyl sulfonic acid, and perfluorooctanoic acid have been used in various industrial fields such as photographic photosensitive agents, semiconductor antireflection films, and photoresist production. However, these organofluorine compounds have high stability, so degradation in the ecosystem does not proceed and environmental persistence has become a problem. It is hoped that the organofluorine compounds will be rendered harmless by decomposing them. It is rare.

In general, methods for decomposing pollutants in water include a method that uses a Fenton reagent, a method that uses ozone, a method that uses hydrogen peroxide and ultraviolet rays, and a method that decomposes pollutants by an oxidation reaction. However, the method using the Fenton reagent has a problem that sludge from iron salt is generated. In addition, both the method using ozone and the method using hydrogen peroxide and ultraviolet rays have a problem that the decomposition ability is weak and it is difficult to decompose a highly stable organic fluorine compound.
There is also a method of directly incinerating these. For example, as a method for treating pollutants and organic compounds, methods using supercritical water with high decomposition efficiency have been proposed (see Patent Documents 1 to 3).
JP 2003-6997 A JP 2006-175392 A JP 2003-245679 A

  However, usually the organic fluorine compound contained in industrial wastewater or the like is dilute. Such a method of incinerating waste water or the like has a problem that a large amount of fuel is required and costs are high. In addition, in any of the above-described methods, there is a problem that it is difficult to efficiently treat and dilute a dilute organic fluorine compound contained in industrial wastewater discharged in large quantities.

  This invention is made | formed in view of the said situation, and aims at the organic fluorine compound processing system which can detoxify the organic fluorine compound in to-be-processed water at low cost.

  The organic fluorine compound treatment system of the present invention comprises a concentration means for concentrating treated water containing an organic fluorine compound, and a concentrated liquid obtained by treating the treated water with the concentration means as a supercritical state for oxidation treatment. And a supercritical water oxidation treatment apparatus.

In the organofluorine compound treatment system of the present invention, the concentration means is preferably an ion exchange treatment device, a synthetic adsorption device or an activated carbon treatment device.
In the organic fluorine compound processing system of the present invention, it is preferable that the concentration means is an electrodialysis apparatus, an evaporation concentration apparatus, or a membrane processing apparatus.

  According to the organic fluorine compound treatment system of the present invention, the organic fluorine compound in the for-treatment water can be detoxified efficiently at low cost.

  Hereinafter, although the organic fluorine compound processing system of the present invention will be described with an example, the present invention is not limited to this.

[First embodiment]
<Organic fluorine compound treatment system>
A second embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a schematic diagram of an organic fluorine compound processing system 2 according to a second embodiment of the present invention. As shown in FIG. 1, the organic fluorine compound treatment system 2 includes an ion exchange treatment device 300 and a supercritical water oxidation treatment device 100 as concentration means.
The ion exchange treatment apparatus 300 is connected to the treated water inflow line 15, the treated water outflow line 11, and the concentrated liquid feed line 12. The treated water inflow line 15 is connected to a treated water supply source (not shown).
The supercritical water oxidation treatment apparatus 100 is connected to the concentrated liquid feed line 12, the oxidant inflow line 13, and the drain / exhaust line 14. The oxidant inflow line 13 is connected to an oxidant supply source (not shown).

(Concentration means)
The ion exchange treatment apparatus 300 which is a concentration means is an apparatus for concentrating the water to be treated A containing an organic fluorine compound. In FIG. 1, an ion exchange processing apparatus 300 is provided with an ion exchange tower 311.
To the ion exchange tower 311, the treated water inflow line 15, the treated water outflow line 11, the desorbed solvent inflow line 312, and the concentrated liquid feed line 12 are connected. The desorption solvent inflow line 312 is connected to a desorption solvent supply source (not shown).
In addition, a valve 17 a is attached to the treated water inflow line 15, a valve 17 b is attached to the treated water outflow line 11, a valve 17 c is attached to the desorbed solvent inflow line 312, and the concentrated liquid feeding line 12 is connected. Is equipped with a valve 17d.

  The ion exchange tower 311 provided in the ion exchange processing apparatus 300 is filled with an ion exchanger including an anion exchanger. As the ion exchanger packed in the ion exchange tower 311, for example, an ion exchange resin, an ion exchange fiber, a monolithic porous ion exchanger, or the like can be used. Of these, the most general-purpose ion exchange resin is preferably used.

  As an anion exchanger, what can adsorb | suck the organic fluorine compound contained in the to-be-processed water A can be selected, and it is a strongly basic anion exchanger. Examples include weakly basic anion exchangers. Examples of the anion exchanger include amberlite (trade name, manufactured by Rohm and Haas) which is an anion exchange resin.

  In addition, the anion exchanger is still more preferable if it can desorb the organic fluorine compound with hot water. In general, an alkaline aqueous solution such as sodium hydroxide is used for the desorption solution of the anion exchanger, but there is a concern that the supercritical water oxidation treatment apparatus 100 may be corroded by the alkaline concentrate after the desorption. Therefore, it is necessary to select materials for the constituent members of the supercritical water oxidation treatment apparatus 100, relax operating conditions, and the like. Moreover, when neutralizing a concentrate, there exists a concern of the obstruction | occlusion by precipitation of the salt in the supercritical water oxidation treatment apparatus 100. FIG. For this reason, it is preferable from the viewpoint of device design to use an anion exchanger capable of desorbing an organic fluorine compound with hot water.

  The form of packing of the ion exchanger in the ion exchange column 311 is not particularly limited, and a single bed form in which the anion exchanger is packed alone, a mixed bed form in which the cation exchanger and the anion exchanger are mixed, and a cation exchanger. And a packed bed in which a packed bed of an anion exchanger and a packed bed of an anion exchanger are stacked in the vertical direction. Especially, from a viewpoint which can adsorb | suck the organic fluorine compound in the to-be-processed water A efficiently, the single bed form of an anion exchanger is preferable. In addition, when it is set as the mixed bed form of a cation exchanger and an anion exchanger, or a multiple bed form, the ratio of an anion exchanger is 50 to 100 mass% in the ion exchanger with which the ion exchange tower 311 is packed. It is preferable to make it less than.

  The cation exchanger packed in the ion exchange tower 311 can be determined in consideration of the water quality in the water to be treated A, and examples thereof include a strong acid cation exchanger and a weak acid cation exchanger. Examples of the cation exchanger include amberlite (trade name, manufactured by Rohm and Haas) which is a cation exchange resin.

(Supercritical water oxidation equipment)
The supercritical water oxidation treatment apparatus 100 is an apparatus that oxidizes and decomposes the organic fluorine compound in the concentrated solution obtained by the concentration means and renders it harmless. In the present invention, detoxification means that an organic fluorine compound is decomposed into fluoride ions, carbon dioxide and water, and fluoride ions are isolated.

An example of the supercritical water oxidation apparatus will be described with reference to FIG.
FIG. 2 is a schematic diagram of the supercritical water oxidation treatment apparatus 100. The supercritical water oxidation treatment apparatus 100 includes a pump 111a, a pump 111b, a reactor 112, a cooler 113, and a decompressor 114.
The concentrated liquid feed line 12 and the pipe 124a are connected to the pump 111a. Further, the pipe 124 a is connected to the reactor 112.
The oxidant inflow line 13 and the pipe 124b are connected to the pump 111b. Further, the pipe 124b is connected to the reactor 112.
The reactor 112 and the cooler 113 are connected by a pipe 125. The cooler 113 and the decompressor 114 are connected by a pipe 126. Further, a drainage / exhaust line 14 is connected to the decompressor 114.

  Examples of the reactor 112 include those in which a heater or the like is provided on the outer periphery of a container having heat resistance and pressure resistance (Bessel type). Or the thing (tube type | mold) by which the heater for heating etc. was provided in the outer peripheral part of cylindrical piping or a coiled tube is mentioned. In the case of the vessel type, it is necessary to increase the size of the apparatus when the amount of water to be treated is increased. For this reason, from the viewpoint of efficiently treating a large amount of water to be treated, the reactor 112 is preferably a tube type. In addition, when temperature rises with reaction heat irrespective of the reactor shape, the heater for a heating is not necessarily required.

  The cooler 113 is not particularly limited as long as it can cool the supercritical water heated to a high temperature (374 ° C. or higher) to a supercritical state in the reactor 112 to an arbitrary temperature, and can be converted into a liquid. An exchange or the like can be used.

  The decompressor 114 is not particularly limited as long as it can depressurize supercritical water at a high pressure (22 MPa or more) to be in a supercritical state in the reactor 112 to any pressure, and is of a valve type, a capillary type, or the like. Is used.

<Method of treating organic fluorine compound>
The processing method of the organic fluorine compound contained in the to-be-processed water A using the organic fluorine compound processing system 2 is demonstrated.
First, the organic fluorine compound contained in the to-be-processed water A is concentrated using the ion exchange processing apparatus 300 which is a concentration means (concentration process).
Next, the concentrated liquid obtained in the concentration process is oxidatively decomposed using the supercritical water oxidation treatment apparatus 100 to render the organic fluorine compound contained in the concentrated liquid harmless (oxidation process).

(Concentration process)
First, the valve 17a and the valve 17b are opened, the valve 17c and the valve 17d are closed, and the water to be treated A containing the organic fluorine compound is fed from the water to be treated inflow line 15 and is passed through the ion exchange tower 311. The organic fluorine compound is adsorbed on the ion exchanger in the ion exchange tower 311. The treated water after adsorbing the organic fluorine compound on the ion exchanger is discharged from the treated water outflow line 11.
Next, the valve 17a and the valve 17b are closed, the valve 17c and the valve 17d are opened, the desorption solvent is sent to the ion exchange tower 311 from the desorption solvent inflow line 312, and the organic fluorine compound adsorbed on the ion exchanger is removed. Detach. And let the obtained detachment | desorption liquid be a concentrate.

(Oxidation process)
The valve 17a and the valve 17b are closed, the valve 17c and the valve 17d are opened, the pump 111a is started, and the concentrated liquid obtained in the concentration process is supplied from the concentrated liquid feed line 12 to the reactor of the supercritical water oxidation treatment apparatus 100. 112.
At the same time, the pump 111 b is started, and the oxidizing agent is sent from the oxidizing agent inflow line 13 to the reactor 112 of the supercritical water oxidation treatment apparatus 100.
At this time, the pump 111a sends the concentrated solution while applying pressure. In the pump 111b, the amount of the oxidizing agent fed may be adjusted according to the arbitrary oxidizing agent concentration of supercritical water in the reactor 112.
Thereafter, the concentrated liquid in the reactor is brought into a supercritical state, and the organic fluorine compound is oxidatively decomposed to obtain supercritical water containing fluoride ions, carbon dioxide, water and the like.
The obtained supercritical water is passed through a cooler 113 and a decompressor 114, separated into waste water and exhaust gas, and discharged from the waste water / exhaust line 14.
At this time, the waste water contains fluoride ions, water, and the like, and the exhaust gas contains carbon dioxide and the like.

(Treatment conditions for organic fluorine compounds)
Examples of the organic fluorine compound contained in the water to be treated A include perfluorooctanesulfonic acid (hereinafter referred to as “PFOS”), perfluoroalkylsulfonic acid (hereinafter referred to as “PFAS”), and perfluorooctanoic acid (hereinafter referred to as “PFAS”). Hereinafter, it is referred to as “PFOA”). These may contain only 1 type, or may contain 2 or more types.

  The amount of the water to be treated A to be passed through the ion exchange tower 311 may be determined by the concentration of the organic fluorine compound contained in the water to be treated A and the retention capacity of the ion exchanger. The concentration of the organic fluorine compound contained in the water to be treated A is not particularly limited, but is preferably determined in consideration of the retention capacity of the ion exchanger and the concentration of the concentrate.

The desorption solvent can be determined according to the type of ion exchanger, and for example, sodium hydroxide solution, hot water, etc. can be used.
If a salt is contained in the desorption solvent, the salt may be precipitated in the reactor 112 of the supercritical water oxidation treatment apparatus 100. Therefore, it is particularly preferable to use hot water that does not precipitate a salt.
When a sodium hydroxide solution is used as the desorption solvent, the concentration of sodium hydroxide contained in the concentrated liquid after desorption of the organic fluorine compound is preferably 0.1 to 10% by mass, and 1 to 5% by mass. % Is more preferable. If the concentration of sodium hydroxide is 0.1% by mass or more, the organic fluorine compound can be sufficiently eliminated. On the other hand, if it is 10% by mass or less, it is economical because sodium hydroxide can be efficiently eliminated without being excessive.

In the concentrate, the concentration of the organic fluorine compound is more preferably 1 μg / L to 100 mg / L.
When the concentration of the organic fluorine compound in the concentrate exceeds 100 mg / L, the corrosiveness is remarkably increased, and the progress of the corrosion in the supercritical water oxidation treatment apparatus 100 tends to become remarkable due to the concentrate. On the other hand, when it is less than 1 μg / L, the processing efficiency tends to decrease.

  As the oxidizing agent, hydrogen peroxide, air, oxygen, or the like can be used. Further, when the concentration of the organic fluorine compound in the concentrate is low, the reaction may be carried out using only dissolved oxygen in the concentrate without adding an oxidizing agent.

  The addition amount of the oxidizing agent can be determined in consideration of the organic fluorine compound concentration and the dissolved oxygen concentration in the recycled waste liquid. For example, the oxidant concentration in the regeneration waste liquid is preferably 1 to 2 times the amount of oxidant necessary for the oxidative decomposition of the organic fluorine compound in the regeneration waste liquid into carbon dioxide, water, and hydrofluoric acid. More preferably, the amount is 1 to 1.5 times.

The temperature in the reactor 112 is 374 ° C. or higher, and more preferably 400 to 650 ° C. If the temperature in the reactor 112 is 374 ° C. or higher, the concentrated liquid can be brought into a supercritical state to decompose the organic fluorine compound, and if it is 650 ° C. or lower, the material selection of the reactor is relatively easy.
Moreover, the pressure in the reactor 112 is 22 MPa or more, more preferably 22 to 40 MPa, and particularly preferably 22 to 30 MPa. If the pressure in the reactor 112 is 22 MPa or more, the concentrated liquid can be brought into a supercritical state to decompose the organic fluorine compound, and if it is 40 MPa or less, an apparatus can be produced at a relatively low cost.
The residence time in the reactor 112 is preferably 1 second to 60 minutes, although it depends on the pressure, temperature, and concentration of the concentrated liquid in the reactor 112. If the reaction time is 1 second or longer, the organic fluorine compound can be sufficiently decomposed, and if it is 60 minutes or shorter, it is possible to produce a device at a relatively low cost.

As described above, the organic fluorine compound treatment system 2 includes the ion exchange treatment device 300 and the supercritical water oxidation treatment device 100 as concentration means.
According to the supercritical water oxidation treatment apparatus, an organic fluorine compound can be decomposed and made harmless by fluoride ions, carbon dioxide, water and the like. Since the method of decomposing an organic fluorine compound by this supercritical water oxidation treatment apparatus does not require much energy (fuel) as compared with the conventional combustion method, the cost can be reduced.
In addition, the concentration of organic fluorine compounds in the water to be treated such as waste water discharged from factories, etc., especially the concentration of PFOS, PFAS, and PFOA is low. Large and needed to expand the equipment. On the other hand, if the concentration of these organic fluorine compounds is too high, the organic fluorine compound treatment system 2 may be corroded. However, when the organic fluorine compound is concentrated to a preferred concentration using the concentration means of the present invention, the organic fluorine compound can be efficiently decomposed without imposing a burden on the reactor while minimizing the addition of water.
Further, in the treatment of the organic fluorine compound using the organic fluorine compound treatment system of the present invention as described above, the concentration of the organic fluorine compound in the treated water and the wastewater discharged from the treated water outflow line 11 and the drainage / exhaust line 14. Can be at least 0.1 × 10 ⁻³ mg / L or less, and the influence on environmental persistence can be reduced.
Furthermore, in this organic fluorine compound processing system 2, when an anion exchanger is used as the ion exchanger, the organic fluorine compound can be more selectively removed from the concentrate.

[Second Embodiment]
<Organic fluorine compound treatment system>
A third embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a schematic diagram of an organic fluorine compound processing system 3 according to the third embodiment of the present invention. As shown in FIG. 3, the organic fluorine compound treatment system 3 includes a membrane treatment apparatus 400 and a supercritical water oxidation treatment apparatus 100 which are concentration means.
The membrane treatment apparatus 400 is connected to the treated water inflow line 15, the treated water outflow line 11, and the concentrated liquid feed line 12. The treated water outflow line 11 is installed on the membrane permeation side of the membrane treatment apparatus 400, and the concentrated liquid feed line 12 is installed on the membrane non-permeation side of the membrane treatment apparatus 400. In addition, a to-be-treated water supply source (not shown) is connected to the to-be-treated water inflow line 15, and a supercritical water oxidation treatment apparatus 100 is connected to the concentrated liquid feed line 12.
The supercritical water oxidation treatment apparatus 100 is connected to the concentrated liquid feed line 12, the oxidant inflow line 13, and the drain / exhaust line 14. The oxidant inflow line 13 is connected to an oxidant supply source (not shown).
A valve 18 a and a valve 18 b are attached to the concentrated liquid feed line 12 and the treated water outflow line 11.

(Concentration means)
The membrane treatment apparatus 400, which is a concentration means, brings the water to be treated A into contact with the separation membrane, sends the membrane impermeant that does not permeate the separation membrane as a concentrate, and uses the membrane permeate that has permeated the separation membrane as treated water It is a device to send liquid.
The separation performance of the separation membrane is not limited as long as the organic fluorine compound in the water to be treated A does not permeate and can be concentrated as a membrane-impermeable component, and the kind of the organic fluorine compound contained in the water to be treated A is considered. To select. For example, a separation membrane having a NaCl removal rate of 50 to 99.7% by mass may be selected.

  Examples of the separation membrane include a reverse osmosis membrane and a nanofiltration membrane. The material of the separation membrane is not particularly limited, and examples thereof include a cellulose acetate-based asymmetric membrane and a synthetic polymer-based composite membrane which are natural polymers. Examples of the synthetic polymer composite membrane include those in which the skin layer material includes a polyamide-based material or an aromatic polyamide-based material. The form of the separation membrane is not particularly limited, and examples include a spiral type, a flat membrane type, and a hollow fiber type.

(Supercritical water oxidation equipment)
As the supercritical water oxidation treatment apparatus 100, the same supercritical water oxidation treatment apparatus 100 as that used in the first embodiment is used.

<Method of treating organic fluorine compound>
The processing method of the organic fluorine compound contained in the to-be-processed water A using the organic fluorine compound processing system 3 is demonstrated.
First, the organic fluorine compound contained in the to-be-processed water A is concentrated using the membrane treatment apparatus 400 as a concentration means (concentration step).
Next, the concentrated liquid obtained in the concentration step is oxidatively decomposed using the supercritical water oxidation treatment apparatus 100 to render the organic fluorine compound contained in the concentrated solution harmless (oxidation step).

(Concentration process)
First, with the valve 18a and the valve 18b opened, to-be-treated water A containing an organic fluorine compound is fed from the to-be-treated water inflow line 15 and flows to the membrane treatment apparatus 400 to be concentrated (membrane impermeable). And treated water (membrane permeation). The treated water is discharged from the treated water outflow line 11.

(Oxidation process)
Next, the concentrate obtained in the concentration step is sent to the reactor 112 of the supercritical water oxidation treatment apparatus 100 through the concentrate liquid feed line 12, and the oxidation treatment step is performed in the same manner as in the first embodiment. Do.

(Treatment conditions for organic fluorine compounds)
As an organic fluorine compound contained in to-be-processed water A, the thing similar to 1st embodiment is mentioned.
The amount of water to be treated A flowing to the membrane treatment apparatus 400 can be determined by the type of membrane of the membrane treatment apparatus 400. Further, the concentration of the organic fluorine compound contained in the water to be treated A is not particularly limited, but is preferably determined in consideration of the treatment capacity of the separation membrane and the concentration of the concentrated liquid.
Furthermore, the organic fluorine compound concentration in the concentrate is preferably 1 μg / L to 100 mg / L as in the first embodiment.

  In the oxidation treatment step, the kind of oxidant, the temperature in the reactor 112, the pressure, the residence time, the temperature of the cooler, the pressure of the decompressor, and the concentration of the organic fluorine compound in the treated water and waste water are It is the same as that of the embodiment.

As described above, the organic fluorine compound processing system 3 includes the film processing apparatus 400 and the supercritical water oxidation processing apparatus 100 as concentration means.
In this organic fluorine compound processing system 3, unlike the organic fluorine compound processing system 2, there is no operation to switch between the process of adsorbing and desorbing the organic fluorine compound, and the organic fluorine compound can be processed more easily. It is.

[Other Embodiments]
The present invention is not limited to the first to second embodiments described above.
In the first embodiment to the second embodiment, either an ion exchange treatment device or a membrane treatment device is used as the concentration means. In addition, an activated carbon treatment device, a synthetic adsorption treatment device, an electrodialysis device, An evaporative concentration apparatus may be used.
The activated carbon used in the activated carbon treatment apparatus can be either granular activated carbon or powdered activated carbon, but granular activated carbon is preferred from the viewpoint of ease of regeneration. As the synthetic adsorbent used in the synthetic adsorption treatment apparatus, any of methacrylic and polystyrene synthetic adsorbents can be used. Examples of the evaporative concentration apparatus include a natural circulation type, a forced circulation type, and a liquid film type.

In the first embodiment to the second embodiment, the concentrated liquid of the organic fluorine compound is directly supplied to the decomposition apparatus (supercritical water oxidation treatment apparatus). However, the present invention is not limited to these forms, and for example, a storage tank for temporarily storing the regenerated waste liquid (concentrated liquid) may be provided between the concentrating means and the supercritical water oxidation treatment apparatus. According to such a configuration, after an arbitrary amount of concentrated liquid obtained by the concentration means is stored in the storage tank, the concentrated liquid is supplied from the storage tank to the decomposition apparatus, and the organic fluorine compound in the concentrated liquid is removed. It can be detoxified.
Moreover, in 1st embodiment-2nd embodiment, the obtained concentrate (pretreatment water) is supplied to a decomposition device (supercritical water oxidation treatment device) as it is. However, the present invention is not limited to this form, and the concentrate (pretreated water) may be diluted or further concentrated as necessary and then supplied to the decomposition apparatus.

Further, the configuration of the supercritical water oxidation treatment apparatus 100 is not limited to the first embodiment to the third embodiment. For example, when dissolved oxygen in the concentrate is used as the oxidant, the oxidant flows. The line 13, the pump 111b, and the pipe 124b may be omitted.
In addition, as the reactor 112 in the supercritical water oxidation treatment apparatus 100, a reactor in which a heater for heating is not installed may be used when the concentrated liquid generates sufficient heat due to the oxidative decomposition reaction.

  Further, the organic fluorine compound treatment system may have a configuration in which an inorganic ion removing means or the like is added to the concentration means and the supercritical water oxidation treatment apparatus.

It is a schematic diagram which shows the organic fluorine compound processing system concerning 1st embodiment of this invention. It is a schematic diagram which shows the supercritical water oxidation treatment apparatus used for the organic fluorine compound processing system of this invention. It is a schematic diagram which shows the organic fluorine compound processing system concerning 2nd embodiment of this invention.

Explanation of symbols

1, 2: Organic fluorine compound treatment system 100: Supercritical water oxidation treatment device 300: Ion exchange treatment device 400: Membrane treatment device A: Water to be treated

Claims (3)

A concentration means for concentrating water to be treated containing an organic fluorine compound;
An organic fluorine compound treatment system comprising: a supercritical water oxidation treatment device that oxidizes a concentrate obtained by treating the water to be treated with the concentration means in a supercritical state.   The organofluorine compound treatment system according to claim 1, wherein the concentration means is an ion exchange treatment device, a synthetic adsorption device, or an activated carbon treatment device.   The organofluorine compound treatment system according to claim 1, wherein the concentration means is an electrodialysis apparatus, an evaporation concentration apparatus, or a membrane treatment apparatus.

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