JP6830811B2 - Treatment method and treatment equipment for thickening polysaccharide-containing water - Google Patents

Description

The present invention relates to methods and devices for treating thickening polysaccharide-containing water.

Thickening polysaccharides are polysaccharides that dissolve or disperse in water to produce high viscosity, and are mainly used as food additives for imparting viscosity to foods, beverages, and the like. As the thickening polysaccharide, for example, carrageenan and the like are known (see, for example, Patent Document 1).

A method is known in which a flocculant is added to water containing a thickening polysaccharide discharged from a process for producing a thickening polysaccharide to perform solid-liquid separation (see, for example, Patent Document 2). Further, when the membrane filtration treatment is performed using an ultrafiltration membrane or the like, so-called fouling, in which thickening polysaccharides and the like are adsorbed and adhered to the surface of the membrane and the inside of the membrane pores, is likely to occur.

Tokukousho 64-007602 Gazette Japanese Unexamined Patent Publication No. 60-132649

An object of the present invention is to provide a method and an apparatus for treating thickening polysaccharide-containing water, which can perform a membrane treatment for reducing the TOC component of thickening polysaccharide-containing water while suppressing fouling. ..

The inventors of the present application have found that the TOC component of thickening polysaccharide-containing water can be reduced by an ultrafiltration membrane under predetermined conditions. That is, in the present invention, the water to be treated, which is a dehydration solution containing gelled thickening polysaccharide and inorganic salt , discharged from the manufacturing process of thickening polysaccharide is passed through the ultrafiltration membrane by a cross-flow method. The film material of the ultrafiltration membrane includes a step of treating the ultrafiltration membrane and a step of treating the reverse osmosis membrane in which the permeated water of the ultrafiltration membrane obtained in the step of treating the ultrafiltration membrane is passed through the reverse osmosis membrane. There Ri polysulfone or polyacrylonitrile der, obtained in the reverse osmosis membrane treatment process, a reverse osmosis membrane concentration water containing inorganic salt were collected, reused in the manufacturing process of the thickening polysaccharide, Zonebao This is a method for treating saccharide-containing water.

In the method for treating thickening polysaccharide-containing water, the fractional molecular weight of the ultrafiltration membrane is preferably less than 50,000 Da.

In the method for treating thickening polysaccharide-containing water, it is preferable that the cross-flow linear velocity when passing water through the ultrafiltration membrane is 0.5 m / s or more.

In the method for treating thickening polysaccharide-containing water, the content of the thickening polysaccharide in the water to be treated has a TOC (total organic carbon amount) in the range of 50 mg / L to 100 mg / L, and the inorganic salt. The content of is preferably in the range of 0.2% by weight to 1.0% by weight.

Further, in the present invention, the water to be treated, which is a dehydration solution containing gelled thickening polysaccharide and inorganic salt , discharged from the manufacturing process of thickening polysaccharide is passed through the ultrafiltration membrane by a cross-flow method. The ultrafiltration membrane treatment means and the reverse osmosis membrane treatment means for passing the ultrafiltration membrane permeated water obtained by the ultrafiltration membrane treatment means through the reverse osmosis membrane are provided, and the film material of the ultrafiltration membrane is provided. There Ri polysulfone or polyacrylonitrile der, obtained in the reverse osmosis membrane treatment unit, a reverse osmosis membrane concentration water containing inorganic salt were collected, reused in the manufacturing process of the thickening polysaccharide, Zonebao It is a treatment device for sugar-containing water.

In the thickening polysaccharide-containing water treatment apparatus, the fractional molecular weight of the ultrafiltration membrane is preferably less than 50,000 Da.

In the thickening polysaccharide-containing water treatment apparatus, it is preferable that the cross-flow linear velocity when passing water through the ultrafiltration membrane is 0.5 m / s or more.

In the thickening polysaccharide-containing water treatment apparatus, the content of the thickening polysaccharide in the water to be treated has a TOC (total organic carbon amount) in the range of 50 mg / L to 100 mg / L, and the inorganic salt. The content of is preferably in the range of 0.2% by weight to 1.0% by weight.

The present invention provides a method and an apparatus for treating thickening polysaccharide-containing water, which can perform a membrane treatment for reducing the TOC component of thickening polysaccharide-containing water while suppressing fouling.

It is a schematic block diagram which shows an example of the thickening polysaccharide-containing water treatment apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows another example of the thickening polysaccharide-containing water treatment apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows the apparatus used for the reverse osmosis membrane concentration test of an Example.

Embodiments of the present invention will be described below. The present embodiment is an example of carrying out the present invention, and the present invention is not limited to the present embodiment.

An outline of an example of a thickening polysaccharide-containing water treatment apparatus according to an embodiment of the present invention is shown in FIG. 1, and its configuration will be described. The treatment device 1 includes an ultrafiltration membrane treatment device 12 as an ultrafiltration membrane treatment means for passing water through the ultrafiltration membrane in a cross-flow manner. The membrane material of the ultrafiltration membrane included in the ultrafiltration membrane treatment apparatus 12 is polysulfone or polyacrylic nitrile. The treatment apparatus 1 includes a water tank 10 to be treated for storing water to be treated, an ultrafiltration membrane permeation water tank 14 for storing ultrafiltration membrane permeation water of the ultrafiltration membrane, and an ultrafiltration membrane permeation water. The reverse osmosis membrane treatment device 16 may be provided as a reverse osmosis membrane treatment means for passing water through the reverse osmosis membrane.

In the treatment device 1 of FIG. 1, a water pipe 24 to be treated is connected to the inlet of the water tank 10 to be treated, and a discharge pipe 40 is connected to the discharge port. The water outlet to be treated of the water tank 10 to be treated and the inlet of the ultrafiltration membrane treatment device 12 are connected by a water supply pipe 26 to be treated via a pump 18. The ultrafiltration membrane permeation water outlet of the ultrafiltration membrane treatment device 12 and the inlet of the ultrafiltration membrane permeation water tank 14 are connected by an ultrafiltration membrane permeation water pipe 28. The ultrafiltration membrane permeable water outlet of the ultrafiltration membrane permeable water tank 14 and the inlet of the reverse osmosis membrane treatment device 16 are connected via a pump 22 by an ultrafiltration membrane permeable water supply pipe 30. A reverse osmosis membrane permeable water pipe 32 is connected to the reverse osmosis membrane permeable water outlet of the reverse osmosis membrane treatment device 16, and a reverse osmosis membrane concentrated water pipe 34 is connected to the reverse osmosis membrane concentrated water outlet. The backwash water outlet of the ultrafiltration membrane permeation water tank 14 is connected to the middle of the ultrafiltration membrane permeation water pipe 28 by a backwash pipe 36 via a pump 20. The ultrafiltration membrane concentrated water outlet of the ultrafiltration membrane treatment device 12 and the water tank 10 to be treated are connected by an ultrafiltration membrane concentrated water pipe 38.

The method for treating the thickening polysaccharide-containing water and the operation of the treatment device 1 according to the present embodiment will be described.

The thickening polysaccharide-containing water, which is the water to be treated, is stored in the water tank 10 to be treated as needed through the water pipe 24 to be treated, and then through the water supply pipe 26 to be treated by the pump 18, the ultrafiltration membrane treatment device 12 Is sent to. In the ultrafiltration membrane treatment apparatus 12, the water to be treated is passed through the ultrafiltration membrane by a cross-flow method (ultrafiltration membrane treatment step). The water to be treated is, for example, passed by an upward flow from the lower inlet of the ultrafiltration membrane treatment device 12, and is filtered from the inside to the outside of an ultrafiltration membrane such as a hollow fiber type. The ultrafiltration membrane permeated water that has permeated the ultrafiltration membrane and has reduced TOC components such as thickening polysaccharides is passed from the ultrafiltration membrane permeation water outlet through the ultrafiltration membrane permeation water pipe 28 as needed. The liquid is sent to the ultrafiltration membrane permeation water tank 14 and stored. On the other hand, the concentrated water in which the TOC component and the like are concentrated in the ultrafiltration membrane treatment device 12 is used as circulating water from the ultrafiltration membrane concentrated water outlet at the upper part of the ultrafiltration membrane treatment device 12 to the ultrafiltration membrane concentrated water pipe 38. It is returned to the water tank 10 to be treated through. As the treatment proceeds, TOC components such as thickening polysaccharides are concentrated in the water tank 10 to be treated, so that the water to be treated is discharged from the discharge port to the outside of the system through the discharge pipe 40 after a predetermined treatment time has elapsed. May be good.

The present inventors suppress fouling by passing water through the ultrafiltration membrane by a cross-flow method in the ultrafiltration membrane treatment step and by using polysulfone or polyacrylicnitrile as the membrane material of the ultrafiltration membrane. It was found that the membrane treatment that reduces the TOC component of the thickening polysaccharide-containing water can be performed. The thickening polysaccharide contained in the water to be treated is considered to be less likely to cause clogging because it is less likely to be adsorbed and adhered to the surface or inside the membrane pores of the ultrafiltration membrane made of polysulfone or polyacrylonitrile. ..

The ultrafiltration membrane permeable water stored in the ultrafiltration membrane permeable water tank 14 is sent to the reverse osmosis membrane treatment device 16 through the ultrafiltration membrane permeable water supply pipe 30 by the pump 22, and is passed through the reverse osmosis membrane. It may be (reverse osmosis membrane treatment step). For example, when the water to be treated is wastewater discharged from the manufacturing process of thickening polysaccharides and contains inorganic salts such as potassium chloride (KCl), TOC components such as thickening polysaccharides are treated by ultrafiltration membrane treatment. Is reduced and then treated with a reverse osmosis membrane. The reverse osmosis membrane concentrated water in which the inorganic salt such as potassium chloride is concentrated by the reverse osmosis membrane treatment is discharged through the reverse osmosis membrane concentrated water pipe 34, and the reverse osmosis membrane permeated water in which the inorganic salt such as potassium chloride is reduced is discharged. It is discharged through the reverse osmosis membrane permeated water pipe 32. At least one of the reverse osmosis membrane concentrated water and the reverse osmosis membrane permeated water may be recovered and reused.

When the amount of permeated water in the ultrafiltration membrane treatment device 12 decreases, the pumps 18 and 22 are stopped, the pump 20 is started, and the ultrafiltration membrane permeated water is backwashed from the ultrafiltration membrane permeated water tank 14. As water, the liquid may be sent from the secondary side to the ultrafiltration membrane treatment device 12 through the backwash water pipe 36 and the ultrafiltration membrane permeation water pipe 28 to perform backwashing of the ultrafiltration membrane treatment device 12 ( Backwash process). The backwash drainage may be sent from the ultrafiltration membrane concentrated water outlet on the primary side of the upper part of the ultrafiltration membrane treatment device 12 to the water tank 10 to be treated through the ultrafiltration membrane concentrated water pipe 38, or may be limited. It may be discharged to the outside of the system from the middle of the ultrafiltration membrane concentrated water pipe 38.

Inorganic salts such as potassium chloride and sodium chloride may be used in the process of producing the thickening polysaccharide. For example, in the production of carrageenan, which is one of the thickening polysaccharides, an inorganic salt such as potassium chloride is generally used when alkaline extraction is performed from the raw material red algae and the extracted carrageenan is gelled. When gelled carrageenan is dehydrated by a gel press method, a drum drying method, an alcohol precipitation method, etc., the dehydrated solution contains a TOC component (for example, about 100 ppm) containing a high concentration of thickening polysaccharides and an inorganic salt such as potassium chloride (for example, about 100 ppm). For example, about 0.5 to 0.7% by weight) will be contained. It has been required to recover and reuse an inorganic salt such as potassium chloride from such a dehydrated solution, but it is difficult to recover and reuse the TOC component because a high concentration of TOC component remains. Reduction was an issue. In the thickening polysaccharide-containing water treatment method and the thickening polysaccharide-containing water treatment apparatus 1 according to the present embodiment, the water to be treated containing the thickening polysaccharide and an inorganic salt such as potassium chloride is limited by a cross-flow method. Thickening polysaccharides are produced by an ultrafiltration membrane treatment step in which water is passed through the outer filtration membrane and a reverse osmosis membrane treatment step in which the ultrafiltration membrane permeated water obtained in the ultrafiltration membrane treatment step is passed through the reverse osmosis membrane. The water to be treated containing the water and an inorganic salt such as potassium chloride can be subjected to a membrane treatment that reduces the TOC component of the thickening polysaccharide-containing water while suppressing fouling, and further, an inorganic salt such as potassium chloride can be used. It can be collected and reused.

FIG. 2 outlines another example of the thickening polysaccharide-containing water treatment apparatus according to the embodiment of the present invention.

The treatment device 3 includes an ultrafiltration membrane treatment device 12 as an ultrafiltration membrane treatment means for passing water through the ultrafiltration membrane by a cross-flow method, and a reverse osmosis membrane for passing water permeated through the ultrafiltration membrane through the reverse osmosis membrane. A reverse osmosis membrane treatment device 16 is provided as the treatment means. The membrane material of the ultrafiltration membrane included in the ultrafiltration membrane treatment apparatus 12 is polysulfone or polyacrylic nitrile. The treatment device 3 may include a water tank 10 to be treated for storing water to be treated and an ultrafiltration membrane permeation water tank 14 for storing ultrafiltration membrane permeation water of the ultrafiltration membrane.

In the treatment apparatus 3 of FIG. 2, the water to be treated pipe 24 from the equipment 50 for discharging the water containing the thickening polysaccharide, such as the equipment for producing the thickening polysaccharide, is connected to the inlet of the water tank 10 to be treated. A discharge pipe 40 is connected to the pipe. The water outlet to be treated of the water tank 10 to be treated and the inlet of the ultrafiltration membrane treatment device 12 are connected by a water supply pipe 26 to be treated via a pump 18. The ultrafiltration membrane permeation water outlet of the ultrafiltration membrane treatment device 12 and the inlet of the ultrafiltration membrane permeation water tank 14 are connected by an ultrafiltration membrane permeation water pipe 28. The ultrafiltration membrane permeable water outlet of the ultrafiltration membrane permeable water tank 14 and the inlet of the reverse osmosis membrane treatment device 16 are connected via a pump 22 by an ultrafiltration membrane permeable water supply pipe 30. A reverse osmosis membrane permeable water pipe 32 is connected to the reverse osmosis membrane permeable water outlet of the reverse osmosis membrane treatment device 16, and the reverse osmosis membrane concentrated water outlet and the equipment 50 are connected by a reverse osmosis membrane concentrated water return pipe 52. There is. The backwash water outlet of the ultrafiltration membrane permeation water tank 14 is connected to the middle of the ultrafiltration membrane permeation water pipe 28 by a backwash pipe 36 via a pump 20. The ultrafiltration membrane concentrated water outlet of the ultrafiltration membrane treatment device 12 and the water tank 10 to be treated are connected by an ultrafiltration membrane concentrated water pipe 38.

The thickening polysaccharide-containing water containing the thickening polysaccharide and an inorganic salt such as potassium chloride, which is the water to be treated discharged from the equipment 50 such as the equipment for producing the thickening polysaccharide, is required through the water pipe 24 to be treated. After being stored in the water tank 10 to be treated, the liquid is sent to the ultrafiltration membrane treatment device 12 through the water supply pipe 26 to be treated by the pump 18. In the ultrafiltration membrane treatment apparatus 12, the water to be treated is passed through the ultrafiltration membrane by a cross-flow method (ultrafiltration membrane treatment step). The water to be treated is, for example, passed by an upward flow from the lower inlet of the ultrafiltration membrane treatment device 12, and is filtered from the inside to the outside of an ultrafiltration membrane such as a hollow fiber type. The ultrafiltration membrane permeated water that has permeated the ultrafiltration membrane and has reduced TOC components such as thickening polysaccharides is passed from the ultrafiltration membrane permeation water outlet through the ultrafiltration membrane permeation water pipe 28 as needed. The liquid is sent to the ultrafiltration membrane permeation water tank 14 and stored. On the other hand, the concentrated water in which the TOC component and the like are concentrated in the ultrafiltration membrane treatment device 12 is used as circulating water from the ultrafiltration membrane concentrated water outlet at the upper part of the ultrafiltration membrane treatment device 12 to the ultrafiltration membrane concentrated water pipe 38. It is returned to the water tank 10 to be treated through. As the treatment proceeds, TOC components such as thickening polysaccharides are concentrated in the water tank 10 to be treated, so that the water to be treated is discharged from the discharge port to the outside of the system through the discharge pipe 40 after a predetermined treatment time has elapsed. May be good.

The ultrafiltration membrane permeable water stored in the ultrafiltration membrane permeable water tank 14 is sent to the reverse osmosis membrane treatment device 16 through the ultrafiltration membrane permeable water supply pipe 30 by the pump 22, and is passed through the reverse osmosis membrane. (Reverse osmosis membrane treatment step). The reverse osmosis membrane concentrated water in which an inorganic salt such as potassium chloride is concentrated by the reverse osmosis membrane treatment is returned to the equipment 50 such as a thickening polysaccharide production facility through the reverse osmosis membrane concentrated water return pipe 52, and is returned to the facility 50. Will be reused. The permeated water from which inorganic salts such as potassium chloride have been reduced is discharged through the reverse osmosis membrane permeated water pipe 32. The permeated water may be reused in the equipment 50.

The water to be treated in the thickening polysaccharide-containing water treatment method and treatment apparatus according to the present embodiment is thickening polysaccharide-containing water containing thickening polysaccharide, and contains thickening polysaccharide containing carrageenan. It is preferably applied to water, and more preferably when it further contains an inorganic salt such as potassium chloride. The content of the thickening polysaccharide in the thickening polysaccharide-containing water is, for example, a TOC in the range of 50 mg / L to 100 mg / L, and preferably in the range of 50 mg / L to 70 mg / L. When the water to be treated contains an inorganic salt such as potassium chloride, the content is, for example, in the range of 0.2% by weight to 1.0% by weight, and 0.5% by weight to 1.0% by weight. It is preferably in the range.

The thickening polysaccharide is a polysaccharide that dissolves or disperses in water to produce high viscosity, and examples thereof include carrageenan, guar gum, locust bean gum, tamarind gum, xanthan gum, and curdlan. Carrageenan is a polysaccharide extracted from red algae and is a polysaccharide composed of D-galactose or 3,6-anhydro-D-galactose and sulfuric acid.

The equipment 50 is, for example, a facility for producing a thickening polysaccharide. The thickening polysaccharide production facility is, for example, a carrageenan production facility. The carrageenan manufacturing equipment includes, for example, an alkali extraction means (alkali extraction step) for extracting alkali from raw materials such as red algae, a gelling means for gelling the extracted carrageenan (gelling step), and a gel press for gelled carrageenan. A dehydration means (dehydration step) for dehydrating by a method, a drum drying method, an alcohol precipitation method or the like may be provided, and further, a purification means (purification step), a crushing means (crushing step) or the like may be provided. Thickening polysaccharide-containing water is generated from the dehydration means (dehydration step) of the carrageenan production facility.

The ultrafiltration membrane treatment device 12 may be any as long as it allows water to pass through the ultrafiltration membrane by a cross-flow method, and is not particularly limited. Membrane treatment generally includes a cross-flow method in which water to be treated is circulated in a direction substantially parallel to the surface of the filtration membrane and a dead-end (total amount filtration) method in which the entire amount of water to be treated is filtered. As described above, the cross-flow method was adopted in the thickening polysaccharide-containing water treatment method and treatment apparatus according to the present embodiment.

The ultrafiltration membrane treatment device 12 is, for example, a modular membrane treatment device, which is a pressure type membrane filtration device having a filtration membrane sealed in a cylindrical container (casing) such as a cylinder. Examples of the form of the filtration membrane include a tubular membrane and a hollow fiber membrane, and a hollow fiber membrane is preferable. The water flow method of the filtration membrane may be either an internal pressure type or an external pressure type, but the internal pressure type is preferable. The liquid flow direction in the ultrafiltration membrane treatment device 12 is usually an upward flow, but may be a downward flow.

The membrane material of the ultrafiltration membrane included in the ultrafiltration membrane treatment apparatus 12 is polysulfone or polyacrylic nitrile. Materials other than polysulfone and polyacrylic nitrile, such as polyvinylidene fluoride and polytetrafluoroethylene, tend to adsorb and adhere to the thickening polysaccharides contained in the water to be treated on the surface of the membrane or in the pores of the membrane. It is thought that clogging is likely to occur.

The molecular weight cut-off of the ultrafiltration membrane is preferably less than 50,000 Da, more preferably more than 4,000 Da and less than 50,000 Da, and more preferably 6,000 Da or more and 13,000 Da or less. Is even more preferable. When the fractional molecular weight of the ultrafiltration membrane is 50,000 Da or more, the TOC concentration of the ultrafiltration membrane permeated water becomes high, and when the reverse osmosis membrane treatment is performed after the ultrafiltration membrane treatment, the reverse osmosis membrane is used. Fouling is likely to occur. When the molecular weight cut-off of the ultrafiltration membrane is 4,000 Da or less, the flux when it stabilizes is low, and the treatment efficiency may decrease.

The cross-flow linear velocity at the time of passing water through the ultrafiltration membrane in the ultrafiltration membrane treatment apparatus 12 is preferably 0.5 m / s or more, and is in the range of 0.5 m / s or more and 10 m / s or less. Is more preferable. If the cross-flow linear velocity is less than 0.5 m / s, the flux when stable is low, and the processing efficiency may decrease. If it exceeds 10 m / s, the required film strength and the required film strength and The required pump capacity may increase.

The material of the reverse osmosis membrane provided in the reverse osmosis membrane treatment apparatus 16 is not particularly limited, but for example, a polyamide membrane or the like can be used.

The content of the thickening polysaccharide in the ultrafiltration membrane permeated water is reduced to the range of 1 mg / L to 30 mg / L as TOC, and is contained when the water to be treated contains an inorganic salt such as potassium chloride. The amount is, for example, in the range of 0.5% by weight to 1.0% by weight.

The content of the thickening polysaccharide in the reverse osmosis membrane permeated water is, for example, 1 mg / L or less as TOC, and when the water to be treated contains an inorganic salt such as potassium chloride, the content is, for example, 0. It is reduced to 1 mg / L or less.

The content of the thickening polysaccharide in the reverse osmosis membrane concentrated water is reduced to, for example, in the range of 2 mg / L to 120 mg / L as TOC, and when the water to be treated contains an inorganic salt such as potassium chloride, the content is Is concentrated, for example, in the range of 1.0% by weight to 2.0% by weight.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Ultrafiltration membrane filtration test]
<Example 1>
A filtration test using an ultrafiltration membrane (hollow fiber membrane, membrane material: polysulfone) was performed using the processing apparatus shown in FIG. The water to be treated was supplied to an internal pressure type ultrafiltration membrane (UF membrane, see Table 1), and the filtration treatment was performed by a cross-flow method. The amount of circulating water was adjusted so that the linear velocity of the cross flow (the amount of water supplied to the membrane (the amount of filtered water + the amount of circulating water) / the cross-sectional area of the membrane) was 2 m / s. Filtration was performed at a pressure of 100 kPa, and when a stable flux was measured, it was stable at 70 LMH (L / m ² · h). Table 2 shows the water to be treated and the quality of the treated water (water quality of the ultrafiltration membrane permeated water).

<Comparative example 1>
A filtration test using an ultrafiltration membrane (hollow fiber membrane, membrane material: polyvinylidene fluoride) was performed using the processing apparatus shown in FIG. The water to be treated was supplied to an internal pressure type ultrafiltration membrane (UF membrane, see Table 1), and the filtration treatment was performed by a cross-flow method. The amount of circulating water was adjusted so that the linear velocity of the cross flow was 2 m / s. Filtration was performed at a pressure of 100 kPa, and when a stable flux was measured, the flux was not stable and dropped to 5 LMH or less, so the test was stopped. Table 2 shows the water to be treated and the quality of the treated water (water quality of the ultrafiltration membrane permeated water).

The fractional molecular weight of the ultrafiltration membrane was confirmed by measuring the inhibition rate using several types of marker molecules having different molecular weights and confirming from the molecular weight of the marker molecule having an inhibition rate of 90% or more (fractional molecular weight reference URL:). http://chemeng.in.coocan.jp/memb/m_mb4.html). The TOC was measured using a combustion type TOC measuring device (TOC-V manufactured by Shimadzu Corporation). The carrageenan concentration (mg / L) was measured from the concentration of high molecular weight organic matter using a TOC component separation measuring device (manufactured by DOC Labor, LC-OCD). The stable flux was determined by passing water to be treated through the membrane and confirming the flux in which the flux decrease per hour was 10% or less.

<Examples 1 to 6 and Comparative Examples 1 to 3>
Hereinafter, the same test was repeated by changing the film material, the cross-flow linear velocity, and the molecular weight cut-off. The experimental conditions are summarized in Table 3, and the results are summarized in Tables 4 to 6.

From these test results, the conditions under which the TOC component can be reduced and stable operation can be performed are considered as follows.
Membrane material: Polysulfone or polyacrylic nitrile Fractional molecular weight: preferably less than 50,000 Da, more preferably more than 4,000 Da and less than 50,000 Da, more preferably 6,000 Da or more and 13,000 Da or less. Is more preferable.
Cross-flow linear velocity: preferably 0.5 or more (considering the strength of the membrane and the economic efficiency of increasing the pump capacity).

[Reverse osmosis membrane water flow test]
<Examples 7 and 8, Comparative Examples 4 and 5>
FIG. 3 shows a schematic configuration of the device used in the reverse osmosis membrane water flow test. As the water to be treated for the reverse osmosis membrane, the ultrafiltration untreated water (Comparative Example 4), the treated water of Example 1 (ultrafiltration membrane permeated water) (Example 7), and the treated water of Example 5 above. (Example 8), the treated water of Comparative Example 3 (Comparative Example 5) was used.

The water to be treated was passed through a reverse osmosis membrane (manufactured by Organo Corporation, OFR-625), and the degree of flux reduction after 24 hours was confirmed. The results are shown in Table 7.

In Comparative Examples 4 and 5, the flux is significantly reduced, and it cannot be said that stable water flow is possible. On the other hand, in Examples 7 and 8 in which the TOC is reduced, the decrease in flux is suppressed, and the reduction of the TOC component in the ultrafiltration membrane treatment in the previous stage of the reverse osmosis membrane is for stable operation of the reverse osmosis membrane. It can be said that it is important.

In order to confirm that potassium chloride was concentrated by the reverse osmosis membrane treatment, water quality analysis of the reverse osmosis membrane concentrated water was performed using an ion chromatograph device (manufactured by Shimadzu Corporation, HIC-SP type). The results of water quality analysis are shown in Table 8.

It was confirmed that a potassium chloride concentration of 1.5% by weight or more is desirable for the recovered reverse osmosis membrane concentrated water, and that the TOC component can be reduced and potassium chloride can be recovered by the method of the example.

As described above, by the method of the example, it was possible to carry out the membrane treatment for reducing the TOC component of the thickening polysaccharide-containing water while suppressing fouling. In addition, reduction of TOC component and recovery of inorganic salts such as potassium chloride could be achieved.

1,3 Treatment equipment, 10 Water tanks to be treated, 12 Ultrafiltration membrane treatment equipment, 14 Ultrafiltration membrane permeation tanks, 16 Reverse osmosis membrane treatment equipment, 18, 20, 22 Pumps, 24 Water pipes to be treated, 26 Treatment Water supply pipe, 28 ultrafiltration membrane permeable water pipe, 30 ultrafiltration membrane permeable water supply pipe, 32 reverse osmosis membrane permeable water pipe, 34 reverse osmosis membrane concentrated water pipe, 36 reverse osmosis water pipe, 38 ultrafiltration membrane Concentrated water piping, 40 discharge piping, 50 equipment, 52 reverse osmosis membrane concentrated water return piping.

Claims (8)

Ultrafiltration membrane treatment step in which water to be treated, which is a dehydration solution containing gelled thickening polysaccharide and inorganic salt, discharged from the production process of thickening polysaccharide is passed through the ultrafiltration membrane by a cross-flow method. When,
A reverse osmosis membrane treatment step in which the ultrafiltration membrane permeated water obtained in the ultrafiltration membrane treatment step is passed through the reverse osmosis membrane.
Including
The membrane material of the ultrafiltration membrane is polysulfone or polyacrylic nitrile.
A method for treating thickening polysaccharide-containing water, which comprises recovering the reverse osmosis membrane concentrated water obtained in the reverse osmosis membrane treatment step and reusing it in the manufacturing step of the thickening polysaccharide. .. The method for treating thickening polysaccharide-containing water according to claim 1.
A method for treating thickening polysaccharide-containing water, wherein the ultrafiltration membrane has a molecular weight cut off of less than 50,000 Da. The method for treating thickening polysaccharide-containing water according to claim 1 or 2.
A method for treating thickening polysaccharide-containing water, which comprises a cross-flow linear velocity of 0.5 m / s or more when passing water through the ultrafiltration membrane. The method for treating thickening polysaccharide-containing water according to any one of claims 1 to 3.
The content of the thickening polysaccharide in the water to be treated is in the range of 50 mg / L to 100 mg / L as TOC (total organic carbon amount) , and the content of the inorganic salt is 0.2% by weight to 1 by weight. A method for treating thickening polysaccharide-containing water, which comprises a range of 0.0% by weight. Ultrafiltration membrane treatment means for passing water to be treated, which is a dehydration solution containing gelled thickening polysaccharide and inorganic salt, discharged from the manufacturing process of the thickening polysaccharide through the ultrafiltration membrane by a cross-flow method. When,
A reverse osmosis membrane treatment means for passing the ultrafiltration membrane permeated water obtained by the ultrafiltration membrane treatment means through the reverse osmosis membrane is provided.
The membrane material of the ultrafiltration membrane is polysulfone or polyacrylic nitrile.
A treatment apparatus for thickening polysaccharide-containing water, which comprises recovering reverse osmosis membrane concentrated water obtained by the reverse osmosis membrane treatment means and reusing it in the process for producing the thickening polysaccharide. .. The thickening polysaccharide-containing water treatment apparatus according to claim 5.
A device for treating thickening polysaccharide-containing water, characterized in that the fractional molecular weight of the ultrafiltration membrane is less than 50,000 Da. The thickening polysaccharide-containing water treatment apparatus according to claim 5 or 6.
A thickening polysaccharide-containing water treatment apparatus, characterized in that the cross-flow linear velocity when passing water through the ultrafiltration membrane is 0.5 m / s or more. The thickening polysaccharide-containing water treatment apparatus according to any one of claims 5 to 7.
The content of the thickening polysaccharide in the water to be treated is in the range of 50 mg / L to 100 mg / L as TOC (total organic carbon amount) , and the content of the inorganic salt is 0.2% by weight to 1 by weight. A thickening polysaccharide-containing water treatment apparatus, characterized in that it is in the range of 0.0% by weight.

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