JP2013063414A - Boron adsorbing apparatus, boron removing system and boron removing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise a boron concentration in a boron-containing eluent eluted from an adsorbent and efficiently remove boron from boron-containing water without condensing the eluent and recover boron in a form of boric acid crystal.SOLUTION: In a container 21 in an absorption column 20, an adsorbent material is manufactured by introducing a glucamine group for adsorbing boron as a functional group to a nonwoven fabric of a polymer material is formed to a band shape and then is wound up to a cylinder. Furthermore, at least one adsorbent module 26 provided with a route changing means for changing a dipping route is inserted in a container 21 so that a shaft center of the adsorbent module 26 may be coaxial with a shaft center of the container to constitute an adsorption column 20. When regenerating, the adsorption column can flow out the eluent containing a high-concentration boric acid reaching the solubility of a boric acid. In a boron removing system, when boron adsorbed in the adsorption column 20 is eluted from the adsorbent module 26, the flowing-out eluent containing the high-concentration boric acid is fractionated and boron is recovered as a boric acid crystal by a cooling crystallization method, and then the eluent is further reutilized.

Description

  The present invention relates to a boron adsorption device, a boron removal system, and a boron removal method for removing boron from boron-containing water.

  Boron is widely used in the fields of plating, glass, medicine, dyes, synthetic fibers and the like, and boron-containing water is discharged from the manufacturing or processing steps in these fields. Further, boron-containing water is also discharged as flue gas desulfurization waste water and waste incinerator waste water at a power plant. On the other hand, it is known that boron may inhibit the growth of animals and plants when present at a certain concentration or more. In Japan, the environmental standard for boron is defined as 1 mg / L or less and the drainage standard is defined as 10 mg / L or less. ing. Therefore, there is a need for a technique for removing and recovering boron from boron-containing water.

  As a conventional boron removal method, a coagulation precipitation method (see Patent Document 1), in which a coagulation precipitate in which boron is taken into a boron-containing water using an aggregating agent such as an aluminum compound and a calcium compound, is generated and separated and removed (see Patent Document 1). Organic solvent extraction method (see Patent Document 2) that extracts and removes boron contained in a mixture of organic solvents, reverse osmosis membrane method (see Patent Document 3) that treats with a reverse osmosis membrane, and boron-containing water as an anion A boron selective adsorption resin method (see Patent Document 4) in which adsorption treatment is performed with an exchange resin (boron selective adsorption resin) is known.

However, the above boron removal method has the following problems.
That is, in the coagulation sedimentation method, it is necessary to use a large amount of chemicals in order to insolubilize boron, and a large amount of sludge is generated, which makes it difficult to treat. Furthermore, since the aggregated precipitate contains a large amount of aluminum compound, calcium compound, etc., boron cannot be recovered and reused. In addition, the organic solvent extraction method is subject to the regulations of the Fire Services Act, and handling is difficult because it is necessary to avoid fire and to be aware of the risk of leakage of the organic solvent itself. is there. In the reverse osmosis membrane method, it is difficult to separate and concentrate boron to a high concentration.

  In addition, in the boron selective adsorption resin method, when recovery and reuse of boron are taken into account, boron-containing water is passed through the boron selective adsorption resin and adsorbed, and then boron is eluted from the boron selective adsorption resin. An acid solution is used to regenerate the boron selective adsorption resin. For this reason, it is necessary to process the acid radical of the eluent. In addition, since the boron concentration of the eluent is low, a concentration step is required to obtain boric acid crystals by the cooling crystallization method. Here, a method is known in which a high-temperature boron-saturated acidic aqueous solution produced by evaporating and concentrating an eluent from which boron is eluted with a mineral acid is crystallized by a cooling crystallization method (see Patent Document 5). However, the apparatus or the process is complicated and a large facility is required, and the initial cost is high, and the running cost for evaporation and concentration is also high.

Regarding the treatment of the acid radical of the eluent, a solution has been achieved by a method of neutralization or an acid radical adsorption treatment with an anion exchange resin (see Patent Document 6).
As for the concentration step, a method of collecting an eluent with a high boron content by introducing a regenerant after draining the residual liquid in the container (see Patent Document 7), the temperature of the mineral acid to 40 to 90 ° C A method of increasing the boron content by increasing the regeneration of the adsorbent resin (see Patent Document 8) has been proposed. However, in any of these methods, since the boron concentration in the eluent is a low value that is considerably lower than the solubility of the boron compound, boric acid crystals cannot be obtained by the cooling crystallization method as it is.

  On the other hand, after boron-containing water is brought into contact with the adsorbent to adsorb boron to the adsorbent, when the adsorbent is regenerated, the boron-saturated acidic aqueous solution is heated and brought into contact with the adsorbent to elute boron from the adsorbent. Attempts have been made to crystallize and separate boric acid by cooling the eluent in a subsequent cooling crystallization step without concentrating the eluent (see Patent Document 9).

  However, the technique described in Patent Document 9 does not provide a means for increasing the boron concentration of the eluent obtained by eluting boron from the adsorbent to near the solubility of the boron compound. Therefore, the boric acid is efficiently crystallized and separated. It has the subject that it is difficult to collect.

Japanese Patent Publication No.58-15193 JP 10-249330 A JP 9-290275 A Japanese Patent Publication No. 2-33292 JP 59-173182 A JP 2001-104807 A Japanese Patent Laid-Open No. 2005-87825 JP 2001-247305 A JP 2004-298738 A

  The present invention has been made in view of such circumstances, and can increase the boron concentration of an eluent containing boron eluted from an adsorbent, and can efficiently form boron from boron-containing water without concentrating the eluent. It is an object of the present invention to provide a boron adsorption apparatus, a boron removal system, and a boron removal method, which can be recovered in the form of boric acid crystals by removing water.

  In order to achieve the above object, a boron adsorption apparatus of the present invention comprises a cylindrical container having a vertical axis, and an adsorbent that is filled in the container and adsorbs boron, The adsorbent has an inlet provided in the upper part for allowing the liquid flowing into the container to flow downward, and an outlet provided in the lower part for allowing the liquid to flow out of the container. An adsorbent module formed by introducing a glucamine group that adsorbs boron as a functional group into a nonwoven fabric made of a polymer material and winding the adsorbent material formed in a strip shape into a column shape is the axis of the adsorbent module Are arranged so as to be coaxial with the axis of the container, and the adsorbent module is configured to change the flow path of the liquid flowing in from the inlet. With change means In addition, by passing boron-containing water through the container, the boron in the boron-containing water is adsorbed to the adsorbent and the treated water in which boron is removed from the boron-containing water is generated. By passing a mineral acid for regeneration through the inside, boron is eluted from the adsorbent adsorbed with boron into the mineral acid, and an eluent containing boron eluted into the mineral acid is generated. It is characterized by.

  In order to achieve the above object, the boron removing system of the present invention includes the boron adsorbing device and the eluent generated in the boron adsorbing device in the order of generation, the first eluent and the second eluent. A fractionation device that is collected in a divided manner, a cooling crystallization device that crystallizes a supersaturated boric acid by cooling the first eluent collected in the fractionation device, and the cooling crystallization device The solid-liquid separation device for separating the eluent containing the boric acid crystals precipitated in step 1 into the residual eluent, which is the eluent excluding the boric acid crystals, and the regeneration used in the boron adsorption device A heating device that heats the mineral acid for heating to 30 to 45 ° C., and the residual eluate after the boric acid crystals are separated and removed in the solid-liquid separation device is the mineral acid for regeneration. It passes through the heating device to the boron adsorption device. After being, the second eluate taken in preparative the content device is returned to the boron adsorber, characterized in that it is reused.

  In order to achieve the above object, the boron removing method of the present invention uses the boron adsorption device to pass boron-containing water through the container, thereby removing boron in the boron-containing water from the adsorbent. And the adsorption step of generating treated water from which boron has been removed from the boron-containing water, and the boron adsorption device, and passing the mineral acid for regeneration into the container, An elution step for eluting boron from the adsorbent adsorbed into the mineral acid and generating an eluent containing boron eluted in the mineral acid, and an eluent generated in the elution step in the order of generation. A fractionation step of collecting the first eluent and the second eluent separately, and cooling the first eluent collected in the fractionation step to crystallize the supersaturated boric acid. Cooling crystal A solid-liquid separation step for separating the eluent containing boric acid crystals precipitated in the cooling crystallization step into boric acid crystals and a residual eluent that is an eluent excluding the boric acid crystals, and the boron A heating step of heating the mineral acid for regeneration used in the adsorption device to 30 to 45 ° C., and a residual eluent after the boric acid crystals are separated and removed in the solid-liquid separation step After being heated as the mineral acid for regeneration and returned to the boron adsorption device, the second eluent collected in the fractionation step is returned to the boron adsorption device and reused. Features.

According to the present invention, the boron concentration of the eluent containing boron eluted from the adsorbent can be increased, and boron can be efficiently removed from the boron-containing water and recovered in the form of boric acid crystals without concentrating the eluent. It becomes possible to do.
As a result, the transpiration energy normally used in the concentration step can be saved, and the boron removal method according to the present invention can also heat the eluent at a low temperature of 30 to 45 ° C. In addition, the amount of energy used for cooling crystallization can be reduced. In addition, by reusing the eluent, the amount of chemical (mineral acid) used can be saved more than before.

It is a figure showing the whole boron removal system composition concerning one embodiment of the present invention. It is a schematic longitudinal cross-sectional view which shows typically the structure of the adsorption tower shown by FIG. It is a figure which shows the adsorbent module shown by FIG. 2, (a) is a schematic enlarged perspective view, (b) is a schematic enlarged front view. It is a figure which shows the relationship between a BV value and the boron concentration of treated water. It is a graph which shows transition of the boric acid concentration of an eluent. It is a graph which shows transition of the boric acid concentration of the eluent about three types of adsorption towers.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
FIG. 1 is a diagram showing an overall configuration of a boron removal system according to an embodiment of the present invention. FIG. 2 is a schematic longitudinal sectional view schematically showing the configuration of the adsorption tower shown in FIG. FIG. 3 is a diagram schematically showing the adsorbent module shown in FIG. 2, in which (a) is a schematic enlarged perspective view, and (b) is a schematic enlarged front view.

  As shown in FIG. 1, the boron removal system 100 is a system that removes boron from raw water (boron-containing water) and collects it in the form of boric acid crystals, an adsorption tower 20 as a boron adsorption device, and a fractionation device 30. A cooling crystallization device 40, a solid-liquid separation device 50, and a heating device 60.

  As shown in FIG. 2, the adsorption tower 20 includes a cylindrical container 21 having a vertical axis and an adsorbent 25 filled in the container 21 and adsorbing boron.

  An adsorbent material 27 (see FIG. 3), which is a material of the adsorbent 25, is created by introducing a glucamine group that adsorbs boron as a functional group into a nonwoven fabric of a polymer material such as polyethylene or polypropylene. The glucamine group is preferably introduced into the nonwoven fabric at a rate of 1.5 to 2.5 mmol / g. This is because if the introduction rate of the glucamine group is smaller than 1.5 mmol / g, the adsorption performance is not sufficient, whereas if it is larger than 2.5 mmol / g, the physical strength of the adsorbent material 27 is lowered. is there.

  The adsorbent 25 is, for example, an adsorbent module 26 formed in a cylindrical shape by winding an adsorbent material 27 (see FIG. 3) formed in a long strip shape with a width of about 300 to 500 mm. One or more cores are inserted into the container 21 so that the core is coaxial with the axis of the container 21.

  The container 21 allows the liquid to flow out of the container 21 and an inlet 22 provided in an upper part for allowing a liquid such as boron-containing water or mineral acid for regeneration to flow downward into the container 21. And an outlet 23 provided in the lower part. The inlet 22 is formed in a lid 21 a that can open and close the upper opening of the container 21, and the outlet 23 is formed in a bottom plate 21 b that closes the lower opening of the container 21. A plurality of inlets 22 and outlets 23 may be provided.

  As shown in FIG. 3, the adsorbent module 26 wraps the adsorbent material 27 in a plurality of layers (for example, 2 to 8 layers) tightly, and then cuts the adsorbent material 27 in the circumferential direction at a plurality of axial positions on the outer peripheral surface. By winding the thread-like member 28 tightly and tightening a plurality of times in the direction in which the outer diameter increases, a cylindrical shape is formed. The axial direction position of the thread-like member 28 is set to a position different from at least one inner thread-like member 28. The thread-like member 28 includes a string-like member. For example, a binding band made of polyolefin can be used.

  Note that the adsorbent module 26 in FIG. 3 is schematically shown for easy understanding, and dimensions such as thickness and outer diameter are drawn differently from actual ones. In addition, the fact that the thread-like member 28 is wound and wrapped around the outer peripheral surface after the adsorbent material 27 is wound in a plurality of layers is configured to be repeated twice for the sake of simplicity in FIG. Is repeated a number of times, an appropriate number of times three or more, depending on the outer diameter of the adsorbent module 26.

  Here, the constricted portion by the thread-like member 28 functions as a path changing means for changing the liquid flow path of the liquid flowing down in the adsorbent module 26. This constricted portion includes a thread-like member 28 and a portion of the adsorbent material 27 that is constricted and compressed by the thread-like member 28. However, the path changing means is not limited to such a configuration. For example, a thread-like member or a piece-like member is mixed inside or on the surface of the adsorbent material 27, or a thread-like member is latticed on the adsorbent material 27. It is also possible to configure the path changing means by weaving in a shape.

  The above-mentioned structure of the adsorbent module 26 is not only adsorption removal of boron, but also by replacing the functional functional group having ion exchange ability or chelate exchange ability introduced into the nonwoven fabric of the adsorption material 27 by graft polymerization, It is possible to adsorb and remove specific ions such as anions, harmful heavy metal ions, fluorine and arsenic, and even organic substances, and at the same time, it can be concentrated by re-elution.

  The packing density of the adsorbent 25 is preferably 170 to 250 g / L. This is because if the packing density is less than 170 g / L, the adsorption performance is not sufficient, while if it is greater than 250 g / L, it is difficult to manufacture even if the adsorbent material 27 is tightly wound. .

  Moreover, it is preferable that the filling height which is the height of the adsorbent 25 with which the container 21 was filled is 1200-6000 mm. This is because if the filling height is lower than 1200 mm, the boron concentration of the eluent from which the boron is eluted from the adsorbent 25 during regeneration with mineral acid is not sufficiently high. On the other hand, if the filling height is higher than 6000 mm, the equipment becomes larger. This is because the cost is increased.

  As shown in FIG. 1, a pipe 1 for flowing raw water (boron-containing water) from a raw water tank 70 and a pipe 2 for flowing regeneration mineral acid are connected above the adsorption tower 20. Has been. In the raw water tank 70, raw water discharged in various facilities, factories, and the like is stored through the piping 4 after impurities are removed by the coarse filter 71.

  Further, below the adsorption tower 20, a pipe 3 for flowing out treated water from which boron has been removed from boron-containing water, and pipes 5 to 7 for flowing out an eluent containing boron eluted in mineral acid, Is connected. That is, the boron-containing water and the mineral acid for regeneration are configured to flow through the adsorption tower 20 in a downward flow. The treated water from the adsorption tower 20 is stored in the treated water tank 75 through the pipe 3.

  The adsorption tower 20 has a function of causing the adsorbent 25 to adsorb boron in the boron-containing water sent through the pipe 1 and generating treated water from which boron has been removed from the boron-containing water. The adsorption tower 20 has a function of eluting boron from the adsorbent 25 on which boron is adsorbed into the mineral acid sent through the pipe 2 and generating an eluent containing boron eluted in the mineral acid. .

  The preparative device 30 collects the eluent generated in the adsorption tower 20 separately in the order of generation into a high concentration eluent as the first eluent and a low concentration eluent as the second eluent ( Sort). In the present embodiment, the low-concentration eluent is further divided into a plurality (here, two) in the order of generation and collected as the first low-concentration eluent and the second low-concentration eluent. Specifically, the fractionation device 30 stores a high-concentration eluent tank 31 that stores a high-concentration eluent that is sent via the pipe 5 and a first low-concentration eluent that is sent via the pipe 6. It has a concentration eluent tank 32 and a second low concentration eluent tank 33 for storing a second low concentration eluent sent via the pipe 7.

  The cooling crystallization apparatus 40 crystallizes supersaturated boric acid by cooling the high-concentration eluent collected in the fractionation apparatus 30. The cooling temperature is, for example, 0 to 6 ° C., and can be easily realized by a normal cooling means. As a cooling method, for example, a method of cooling the outer wall of the cooling crystallizer 40 with a refrigerant, a method of cooling by installing a heat exchanger inside the cooling crystallizer 40, contents outside the cooling crystallizer 40 A method of extracting a part of the water and cooling and circulating it can be used.

  A pipe 8 extending from the high concentration eluent tank 31 of the fractionation device 30 is connected to the cooling crystallization apparatus 40, and the high concentration eluent is supplied to the cooling crystallization apparatus 40 via the pipe 8. The cooling crystallization apparatus 40 is connected to a pipe 11 for allowing an eluent containing boric acid crystals precipitated in the cooling crystallization apparatus 40 to flow out.

  The solid-liquid separation device 50 separates the eluent containing boric acid crystals sent from the cooling crystallizer 40 into boric acid crystals and a residual eluent (elution wastewater) that is an eluent excluding the boric acid crystals. . For solid-liquid separation, various solid-liquid separation means such as a filter and a centrifugal separator can be used alone or in combination.

  An eluent containing boric acid crystals is supplied from the cooling crystallizer 40 to the solid-liquid separator 50 via the pipe 11. The solid-liquid separator 50 is connected to a pipe 12 through which the residual eluent after the boric acid crystals are separated and removed in the solid-liquid separator 50 is flowed out.

  The heating device 60 heats the mineral acid for regeneration that flows into the adsorption tower 20 through the pipe 2. This increases the solubility of boron (boric acid) that is soluble in mineral acid. The temperature of the mineral acid to be heated is preferably 25 to 55 ° C, more preferably 30 to 45 ° C, and further preferably 30 to 40 ° C. If it is larger than the upper limit, the cost for heating increases, the equipment of the heating device 60 increases in size, damage to the adsorbent 25 due to high temperature increases, and treatment of gasified mineral acid is necessary. On the other hand, if the value is smaller than the lower limit, there is a risk that a sufficient difference in solubility from the temperature in the cooling crystallization step cannot be obtained and that elution is insufficient during regeneration. Because it occurs. For example, an electric heater can be used as the heating method. The heating device can also be installed in the high concentration eluent tank 31.

  In the boron removal system 100 of the present embodiment, the pipe 12 through which the residual eluent after the boric acid crystals are separated and removed in the solid-liquid separator 50 is connected to the high-concentration eluent tank 31, so that the high concentration A pipe 13 through which the remaining eluent returned to the eluent tank 31 flows out is connected to the heating device 60. A pipe 9 extending from the first low-concentration eluent tank 32 and a pipe 10 extending from the second low-concentration eluent tank 33 of the sorting device 30 are respectively connected above the adsorption tower 20.

  Further, a pipe 14 for allowing the washing water from the washing water tank 80 to flow is connected to the upper part of the adsorption tower 20, and the washing waste water after washing the adsorption tower 20 flows out to the lower part of the adsorption tower 20. The piping 15 for making it connect is connected. Caustic soda (NaOH) is appropriately added to the washing water in order to return the adsorbent that has become acidic during regeneration to alkaline. The pipe 15 is connected to the raw water tank 70, and the washing waste water is configured to be returned to the raw water tank 70.

  The pipes 1, 2, 9, 10, and 14 are respectively connected to the inlet 22 (see FIG. 2) via, for example, an on-off valve (not shown), and the pipes 3, 5 to 7, and 15 are not shown, for example. It is connected to the outlet 23 (see FIG. 2) through an on-off valve.

Next, a boron removal method using the boron removal system 100 configured as described above will be described.
In the boron removal method according to the present embodiment, boron in the boron-containing water is adsorbed to the adsorbent 25 by passing the boron-containing water through the container 21 using the adsorption tower 20, and boron from the boron-containing water. It has an adsorption process which produces treated water from which water is removed. In addition, the boron removal method uses an adsorption tower 20 to pass a mineral acid for regeneration through the container 21 to elute boron into the mineral acid from the adsorbent 25 on which boron is adsorbed, and And an elution step for producing an eluent containing boron eluted in an acid.

  Further, the boron removal method includes a fractionation step in which the eluent produced in the elution step is collected in the order of production into a high concentration eluent and a low concentration eluent, and a high concentration eluent collected in the fractionation step. The cooling crystallization step of crystallizing the supersaturated boric acid by cooling, and the eluent containing boric acid crystals precipitated in the cooling crystallization step, the eluent from which boric acid crystals and boric acid crystals are removed And a solid-liquid separation step for separating the residual eluent. Further, the boron removing method has a heating step for heating the mineral acid for regeneration used in the adsorption tower 20.

  Then, after the next adsorption step is completed, that is, at the next regeneration of the adsorption tower 20, the residual eluent after the boric acid crystals are separated and removed in the solid-liquid separation step is heated as a mineral acid for regeneration. After returning to the adsorption tower 20, the low concentration eluent collected in the fractionation step is returned to the adsorption tower 20.

Next, each step of the boron removing method will be described in more detail.
The boron-containing water that is subject to purification (boron removal) in the adsorption process is raw water that is discharged in various facilities and factories, and is not particularly limited as long as it is raw water containing boron. Examples of the boron-containing water include wastewater from manufacturing or processing processes in the fields of plating, glass, medicine, dyes, synthetic fibers, and the like, flue gas desulfurization wastewater at power plants, waste incinerator wastewater, and the like. The boron concentration of boron-containing water is, for example, 10 mg / L or more. The boron-containing water is stored in the raw water tank 70 after impurities are removed by passing through the coarse filter 71.

  In the adsorption step, the boron-containing water from the raw water tank 70 flows into the adsorption tower 20 from the pipe 1, and the boron in the boron-containing water is adsorbed by the adsorbent 25 while flowing downward from above the adsorption tower 20. Then, treated water obtained by removing boron from the boron-containing water is generated, flows out from the pipe 3, and is stored in the treated water tank 75. The boron concentration of the purified treated water can be, for example, 1 mg / L or less.

  Here, when the boron-containing water flows downward in the container 21, it flows down in the adsorbent module 26 (see FIG. 3) formed by winding the adsorbent material 27 into a cylindrical shape. At this time, the constricted portion by the thread-like member 28 functions as a path changing unit that changes the flow path of the liquid flowing down in the adsorbent module 26, and boron-containing water is forcibly adsorbed in the adsorbent module 26. The adsorbent module 26 flows down while changing the liquid flow path inside the non-woven fabric of the material 27. Thereby, it is considered that boron in the boron-containing water increases the amount of boron adsorbed on the adsorbent 25 through an increased chance of contacting the functional group (glucamine group) having a boron adsorbing function inside the adsorbent 25.

  Under normal conditions, an adsorption process in which boron-containing water is passed through the adsorption tower 20 to adsorb boron to the adsorbent 25 is continuously performed. And when the adsorption | suction capability of the boron to the adsorbent 25 becomes near a limit and the boron concentration of the treated water after purification becomes larger than a predetermined threshold value (for example, 1 mg / L), the adsorption tower is connected from the pipe 1. The supply of boron-containing water to 20 is stopped, and the adsorption process is temporarily ended.

Next, in order to regenerate the adsorption capacity of the adsorbent 25 of the adsorption tower 20, the mineral acid for regeneration is supplied from the pipe 2 to the adsorption tower 20, and the elution process is started.
In the elution step, while the mineral acid for regeneration flows into the adsorption tower 20 from the pipe 2 and flows from the upper side to the lower side of the adsorption tower 20, boron is eluted from the adsorbent 25 into the mineral acid and also eluted into the mineral acid. The boron-containing eluent is generated and flows out from the pipes 5-7. Here, as the mineral acid for regeneration, for example, an aqueous solution of hydrochloric acid, sulfuric acid, nitric acid or the like is used.

  Here, when the mineral acid for regeneration flows downward in the container 21, it is forced through the non-woven fabric of the adsorbent material 27 within the adsorbent material 27 by the function of the constricted portion by the thread-like member 28. While flowing down, the adsorbent module 26 flows down. Thereby, it is considered that the amount of boron eluted from the adsorbent 25 to the mineral acid increases.

  The eluent generated in the adsorption tower 20 is controlled, for example, by an open / close valve (not shown), so that the high-concentration eluent tank 31, the first low-concentration eluent tank 32, and the second low-concentration tank of the fractionation device 30 are generated. Each is sent separately to the eluent tank 33.

  Next, the eluent is sent from the high-concentration eluent tank 31 through the pipe 8 to the cooling crystallization apparatus 40, and the cooling crystallization process is started. In the cooling crystallization step, the eluent generated in the elution step is cooled to about 5 ° C., for example. Thereby, the solubility of the boron compound (boric acid) in mineral acid falls, and the supersaturated boric acid crystallizes out. The eluent containing boric acid crystals flows out from the pipe 11.

  When the eluent containing boric acid crystals is sent from the cooling crystallizer 40 to the solid-liquid separator 50 via the pipe 11, the solid-liquid separation process is started. In the solid-liquid separation step, the eluent containing boric acid crystals is separated into boric acid crystals and a residual eluent that is an eluent excluding the boric acid crystals. Boric acid crystals are recovered as solids and can be reused as resources in various fields. The residual eluent generated in the solid-liquid separation step is temporarily returned to the high concentration eluent tank 31 via the pipe 12.

  Then, after the next adsorption step is completed, that is, at the next regeneration of the adsorption tower 20, the residual eluent after the boric acid crystals are separated and removed in the solid-liquid separation device 50 is removed from the high concentration eluent tank 31. The first low-concentration eluent and the second low-concentration eluent collected in the preparative device 30 after being returned to the adsorption tower 20 through the heating device 60 as mineral acid for regeneration are the first low-concentration eluent. The tank 32 and the second low-concentration eluent tank 33 are sequentially returned to the adsorption tower 20 respectively.

  In addition, before the residual eluent is heated and returned to the adsorption tower 20, purified water not containing boron heated to the same temperature as the heating temperature in the heating device 60 is passed through the adsorption tower 20. It is preferable. Thereby, it can prevent that the temperature of an eluent falls, and by extension, elution of boron can be promoted and the recovery rate of boron (boric acid) can be stabilized.

  In the residual eluent to be reused, boron that has not been crystallized remains at a high concentration. Therefore, when the adsorption tower 20 is regenerated next time, the boron adsorbed on the adsorbent 25 is eluted and added to the residual eluent, and boron close to the same amount as the boron added to the residual eluent is the cooling crystallization step. In this case, it is precipitated as boric acid crystals, and the boron recovery rate is improved.

  At the time of reuse, the residual eluent sent through the pipe 2 is added with a mineral acid on the way to adjust the concentration of the mineral acid. By adding a new mineral acid to the diluted mineral acid that is the residual eluent, the eluent discharged from the adsorption tower 20 can be used repeatedly any number of times. This is because the functional group that captures boron is a chelate, and has a function of scavenging boron in a neutral / alkaline region while detaching boron in an acidic region.

  In addition, in anticipation of a decrease in concentration when washing water is passed through the adsorption tower 20, the second low-concentration eluent sent through the pipe 10 is adjusted with mineral acid in the middle to adjust the concentration of mineral acid. Is done.

  As described above, in this embodiment, the adsorbent 25 filled in the container 21 of the adsorption tower 20 is formed by introducing a glucamine group that adsorbs boron as a functional group into a nonwoven fabric made of a polymer material, and is formed in a band shape. One or more adsorbent modules 26 formed by winding the adsorbent material 27 into a cylindrical shape are inserted into the container 21 such that the axis of the adsorbent module 26 is coaxial with the axis of the container 21. It is configured. The adsorbent module 26 includes path changing means for changing the flow path of the liquid flowing down through the adsorbent module 26. For example, a constricted portion by the thread-like member 28 constitutes the path changing means.

According to the present embodiment, the adsorbent 25 efficiently removes boron trapped in the adsorbent 25 in the elution step in the elution step as in the adsorption step described in the paragraph [0045]. Thus, the boron concentration in the eluent can be increased, and the boron can be efficiently recovered without removing the boron from the boron-containing water without concentrating the eluent.
As a result, the transpiration energy normally used in the concentration step can be saved, and in the boron removal method of the present embodiment, the eluent can be heated at a low temperature of 30 to 45 ° C. It is possible to reduce the amount of energy used during cooling crystallization. Further, by reusing the eluent, the amount of chemical (mineral acid) used can be saved to 1/3 to 1/2 of the conventional amount.

  Further, in the present embodiment, at the next regeneration of the adsorption tower 20, the residual eluent after the boric acid crystals are separated and removed is heated as a mineral acid for regeneration and returned to the adsorption tower 20. The low-concentration eluent collected in the process is returned to the adsorption tower 20. According to such a configuration, the recovery rate of boron is improved and the eluent can be used repeatedly without being disposed of.

As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to the structure described in the said embodiment, Including suitably combining thru | or selecting the structure described in embodiment, The configuration can be changed as appropriate without departing from the spirit of the invention.
For example, in the above-described embodiment, the container 21 has a cylindrical shape and the adsorbent module 26 inserted into the container 21 has a cylindrical shape. However, the present invention is not limited to this. For example, the container 21 may have another cylindrical shape having a substantially rectangular cross section, and the adsorbent module 26 inserted into the container 21 may have another column shape having a substantially rectangular cross section.

  Next, the effect of this invention is demonstrated using a following example. However, the technical scope of the present invention is not limited to the following examples.

(Experiment 1) Adsorption / regeneration (boron elution) experiment of adsorption tower (1) Adsorption experiment (a) Adsorbent After irradiating a substrate of a polymer material with a low irradiation dose (10 kGy) in an inert gas atmosphere The base material is immersed in a solution adjusted to a concentration of 30 to 50% with a butyl alcohol solvent for 0.5 to 1 minute, and the grafted polymer is subjected to graft polymerization in a reactor in an inert gas atmosphere using the pulled up base material in 2 to 2. An adsorbent material in which methylglucamine groups were introduced at a density of 1.5 to 2.2 mmol / g under conditions of 70 ° C. on a polyethylene and polypropylene nonwoven fabric prepared for 3 hours was prepared.

  The adsorbent material prepared in this way is cut into a strip of width 300mm x length 5000mm, and is tightly wound without gaps while being tightly wrapped with a polyolefin binding band every several layers, and a cylindrical shape with a diameter of 100mm An adsorbent module was created. Note that the width of 300 mm corresponds to the height of the columnar adsorbent module.

(B) Adsorption tower A plurality of the adsorbent modules prepared as described above were inserted into a cylindrical container made of polyvinyl chloride and having an inner diameter of 100 mm to form an adsorbent, thereby creating an adsorption tower. The filling height of the adsorbent filled in the adsorption tower was 2400 mm (height of eight adsorbent modules connected in series).

(C) Experimental method Intermediate treated water after biological treatment of leachable water at an industrial waste disposal site was used as raw water. To this raw water, NaOH at a concentration of 25% is added to raise the pH to 9.5 to 11.5, and the supernatant water on which the aggregated floc is precipitated is adjusted to around pH 8 and at the same time, the boron concentration becomes 100 mg / L. I did it. However, in practice, the boron concentration was 90.6 mg / L. Then, 540 L of the adjusted raw water was passed through the adsorption tower at an SV (Space Velocity) value of about 5.5 (1 / hr) for about 1.9 hours. Here, SV value (1 / hr) = flow rate (L / hr) / adsorbent volume (L).

(D) Experimental Results FIG. 4 is a diagram showing the relationship between the BV value and the boron concentration of treated water.
Boron leaked into the treated water after purification flowing out from the adsorption tower at a concentration of 1 mg / L when the liquid flow rate was 445 L. If this time was taken as breakthrough, the BV (Bed Volume) value at the breakthrough time of the adsorption tower was 23.3. Here, BV value = liquid passing amount (L) / adsorbent volume (L). The amount of adsorbed boron at the time of breakthrough was 39.9 g. Moreover, the total amount of adsorbed boron in the adsorption experiment was 44.8 g. Table 1 shows the results of the boron adsorption performance of the adsorption tower.

(2) Regeneration (boron elution) experiment In this regeneration experiment, the adsorption tower that adsorbs boron in the above-described adsorption experiment was regenerated.

(A) Experimental method First, the adsorption tower was washed and replaced with about 40 L of demineralized water heated to about 30 ° C. The replacement was performed in a downward flow. Thereafter, 1N HCl (1 mol / L HCl aqueous solution) heated to about 30 ° C. was passed downwardly through the adsorption tower. At that time, the flow rate was about 40 L, and the SV value was about 5 (1 / hr).

  Sampling was started after the pH meter confirmed that HCl had come out of the adsorption tower. Sampling was performed every 500 cc in principle. The boron content of the sampled sample was analyzed with an ICP (Inductively coupled plasma) emission spectroscopic analyzer.

(B) Experimental Results FIG. 5 is a graph showing the transition of boric acid concentration in the eluent (regeneration waste liquid).
Here, boron content was converted into boric acid content. The boric acid content was 5.725 times the boron content.

  The eluent having the highest boron concentration (regeneration waste liquid) was a sample collected immediately after the pH dropped rapidly. The boron content at this time was 10900 mg / L, which was 6.24 g / 100 ml in terms of boric acid content. Further, this corresponds to 5.67 (g / 100 g) in terms of weight. This value can be said to have reached the solubility of boric acid at 30 ° C. around 6.23 (g / 100 g).

  Furthermore, when 6 samples showing boric acid concentration of boric acid solubility of 2.98 (g / 100 g) or more at 5 ° C. shown in FIG. 5 are stored in a refrigerator of 5 ° C. or less, a plate-like shape is obtained. Of white transparent boric acid crystals. On the other hand, no boric acid crystals were formed even when other samples having a boric acid concentration of 2.98 (g / 100 g) or less were placed in a refrigerator at 5 ° C. or less.

(C) Conclusion According to this regeneration experiment, when the heated mineral acid (1N HCl) is passed through the adsorption tower that has adsorbed boron in the adsorption experiment, the initial stage of the eluent that flows out is 5 It was concluded that boric acid crystal solids can be easily obtained by refrigeration at ℃ or lower.

(Experiment 2) Adsorption / regeneration (boron elution) experiment when the adsorbent packing height of the adsorption tower is changed (1) Adsorption experiment (a) Adsorbent The adsorbent material and adsorbent module are the same as those in Experiment 1. The same.

(B) Adsorption tower The adsorption tower is substantially the same as Experiment 1 except for the filling height of the adsorbent. Three kinds of adsorbent filling heights were set: 600 mm (two adsorbent modules connected in series), 1200 mm (four adsorbent modules connected in series), and 2400 mm (eight adsorbent modules connected in series). For the filling height of 2400 mm, the data of Experiment 1 is used.

(C) Experimental results Boron leaked into the treated water after purification flowing out from the adsorption tower at a concentration of 1 mg / L in three types of adsorption towers with adsorbent filling heights of 2400 mm, 1200 mm, and 600 mm. , When the liquid flow rates were 445 L, 200 L, and 80 L, respectively. Assuming that this time was broken, the BV values at the time of breakthrough of the adsorption tower were 23.3, 22.3, and 17.0 in the three kinds of adsorption towers, respectively. The amount of adsorbed boron at the time of breakthrough was 39.9 g, 18.5 g, and 7.8 g in the three types of adsorption towers, respectively. Moreover, the total amount of adsorbed boron in the adsorption experiment was 44.8 g, 22.4 g, and 12.8 g, respectively, in the three types of adsorption towers. Table 2 shows the results of boron adsorption performance of three types of adsorption towers with different packing heights.

(2) Regeneration (boron elution) experiment In this regeneration experiment, the adsorbents of the three types of adsorption towers that adsorbed boron in the above-described adsorption experiment were regenerated.

(A) Experimental Method Three types of adsorption towers with the above-mentioned adsorbent packing heights of 2400 mm, 1200 mm, and 600 mm were washed and replaced with about 40 L, 30 L, and 20 L of demineralized water heated to about 30 ° C., respectively. The replacement was performed in a downward flow. Thereafter, 1N HCl (1 mol / L HCl aqueous solution) heated to about 30 ° C. was passed downwardly through the adsorption tower. The liquid flow rates in the three types of adsorption towers were about 40 L, 30 L, and 20 L, respectively, and the SV value was about 5 (1 / hr) for all three types of adsorption towers.

  In all three types of adsorption towers, sampling was started after confirming that HCl came out of the adsorption tower using a pH meter. Sampling was performed every 500 cc in principle. The sampled sample was analyzed for boron content with an ICP emission spectrometer.

(B) Experimental Results FIG. 6 is a graph showing the transition of boric acid concentration in the eluent (regeneration waste liquid) for the three types of adsorption towers. Here, boron content was converted into boric acid content. The boric acid content was 5.725 times the boron content as described above.

  As can be seen from FIG. 6, the peak value (maximum value) of the boric acid concentration tends to decrease as the adsorbent filling height decreases. In the adsorption tower having an adsorbent packing height of 1200 mm, the peak value of boric acid concentration reached the solubility of boric acid at 5.degree. C. of 2.98 (g / 100 g), but the adsorbent filling height was 600 mm. In the adsorption tower, the peak value of the boric acid concentration did not reach the boric acid solubility of 2.98 (g / 100 g) at 5 ° C.

(C) Conclusion According to this regeneration experiment, the boric acid in the eluent (regeneration waste liquid) flowing out of the adsorbent with a filling height of 1200 mm can be easily converted into boric acid crystal solids by refrigeration at 5 ° C or lower. It can be concluded that it is near the limit that can be obtained.

(Experiment 3) Experiment of fractionating eluent, cooling crystallization and solid-liquid separation (1) Objective of experiment In Experiment 1, an eluent with a maximum boron concentration of 10900 mg / L is obtained at an eluent temperature of 30 ° C. I was able to. This value is 6.24 g / 100 ml in terms of boric acid content, and further corresponds to 5.67 (g / 100 g) in terms of weight, and the solubility of boric acid at 30 ° C. is 6.23 ( g / 100 g).
However, the amount of the eluent having a solubility of boric acid of 2.98 (g / 100 g) or more at 5 ° C. is 0.2 in terms of BV value, which is about 20% of the entire eluent (FIG. 5). reference). That is, as shown in FIG. 5, the boron content immediately after the eluent begins to flow out increases, and then tends to decrease rapidly. For this reason, when the eluent is collected and leveled, the boric acid concentration becomes lower than the solubility of boric acid as a whole. Boron exists in the form of boric acid in an acidic aqueous solution. Therefore, if the eluent is treated all at once, boric acid crystals cannot be obtained.
Therefore, out of the eluent produced in the adsorption tower, only the high-concentration eluent with a high boron concentration and high boron concentration is fractionated, and the separated high-concentration eluent is cooled and crystallized / solid-liquid separated, and the boron is separated. An attempt was made to extract acid crystals.

(2) Experimental method The filling height of the adsorbent filled in the adsorption tower was 2400 mm, and boron-containing water was passed through the adsorption tower until the boron content of the treated water reached 1 mg / L or more. After completion of passing the boron-containing water through the adsorption tower, the mineral acid for regeneration was adjusted to 30 ° C. and passed through the adsorption tower. The eluent flowing out from the adsorption tower was collected separately at a predetermined time. That is, a high concentration eluent with a high boron concentration fractionated in the first half and a low concentration eluent with a low boron concentration fractionated in the second half were separated by cooling crystallization and solid-liquid separation. Here, the time of fractionation was the time when the boric acid concentration of the eluent reached the solubility of boric acid at the temperature during cooling crystallization.

(3) Experimental results After cooling and crystallizing the high-concentration eluent at 5 ° C., solid-liquid separation (filtration) yielded 41.2 g of a solid. Assuming that this solid is all boric acid crystals, about 20% of boric acid (39.9 g × 5.725) corresponding to boron adsorbed by the adsorption tower (about 39.9 g, see Experiment 1) Equivalent to.

(Experiment 4) Experiment to increase boron recovery rate (1) Objective of experiment According to Experiment 3, boric acid crystals can be obtained, but about 80% of boron adsorbed by the adsorption tower is in the eluent. Will remain. Therefore, the following method for increasing the recovery rate of boron (boric acid) was tried.

(A) Method of separating eluent, cooling crystallization / solid-liquid separation, and reusing it After passing the boron-containing water through an adsorption tower and completing the adsorption process, 30 to 30 mineral acids for regeneration Adjust the temperature to 45 ° C. and pass through the adsorption tower. When the eluent flowing out from the adsorption tower reaches a pH of 3 or less, the collection of the high concentration eluent is started, and at the same time when the predetermined inflow amount to the adsorption tower flows out from the adsorption tower, the concentration becomes low. Start dispensing the eluent. The fractionation of the low-concentration eluent is stopped when a predetermined inflow amount into the adsorption tower flows out of the adsorption tower, and the washing water is passed through the adsorption tower. The washing water is for extruding the acid remaining in the adsorption tower. Of the fractionated eluent, only the high-concentration eluent is sent to the cooling crystallization / solid-liquid separation step to separate it into boric acid crystals and the residual eluent.
Then, after the next adsorption step is completed, that is, at the next regeneration of the adsorption tower, first, the residual eluent is heated to 30 to 45 ° C. and returned to the adsorption tower, and then the fractionated low concentration elution is performed. The liquid is returned to the adsorption tower at room temperature and reused. Finally, wash water is passed through the adsorption tower.
By repeating such a cycle, crystallization of boron is continuously performed.

(B) Method of increasing the number of divisions in the fractionation of the eluent In order to further increase the boron recovery rate, the eluent is divided into a larger number instead of being divided into a high concentration eluent and a low concentration eluent. Is effective. This is because, by dividing the eluent finely, the concentration difference between the adjacent eluents in the order of generation becomes smaller, so that the adjacent eluents affect each other in the adsorption tower. This is because the amount of density change can be reduced. However, even if the number of divisions is increased too much, the boron recovery rate itself decreases, but the system becomes complicated. Therefore, the division number of the eluent is preferably 3 to 6 and more preferably 3 to 4 in view of efficient operation of the system.

(C) Method of Adding Mineral Acid to Residual Eluent Flowed First in Elution Step Mineral acid used for boron elution is neutralized by the adsorbent in the adsorption tower and consumed for a while. When the mineral acid is consumed, the pH increases and boron is not eluted. Therefore, the eluted boron is not added to the portion where the pH is increased, while the eluent containing boron is diluted by the water held by the adsorbent. For this reason, the pH rises further, and the high concentration boron originally contained in the residual eluent remains in the aqueous solution, so that it is excluded from the sorting target started when the pH becomes, for example, 3 or less. . For this reason, the boron which flows out by washing water will increase. Therefore, by adding mineral acid to the residual eluent that first flows in the elution step, the pH of the aqueous solution is lowered, so that the residual high eluent that is excluded from the sample is reduced, and boron that flows out by the wash water is reduced. Reduce.

(D) Method of Warming Washing Water Before the remaining eluent is warmed and returned to the adsorption tower, warm water containing no boron is passed through the adsorption tower. Thereby, it can prevent that the temperature of an eluent falls, and by extension, elution of boron is promoted and the recovery rate of boron (boric acid) is stabilized.

(2) Experimental method By incorporating all the methods (a) to (d) above, the adsorption of boron by the adsorption tower and the regeneration of the adsorption tower (boron elution) were repeated several times to obtain boron (boric acid). The recovery rate and its reproducibility were observed. Furthermore, the change in the recovery rate of boron due to the change in the heating temperature of the regenerating mineral acid (residual eluent) was observed. The results are shown in Table 3.

When boron is adsorbed, boron that has not been recovered and contained in the wash water discharged during elution in the previous RUN (adsorption and regeneration) flows into the adsorption tower together with the raw water. The adsorption tower used in Experiment 3 was used.
The eluent was fractionated and reused, and the eluent was fractionated in three parts. The ratio of each eluent divided into three was 9: 6: 6, for a total of 21 L. Prior to regeneration of the adsorption tower, purified water having the same temperature as the mineral acid for regeneration (residual eluent) was passed through the adsorption tower. Then, the mineral acid was added so that the mineral acid concentration was approximately doubled with respect to the volume of about 高 used immediately after the start of regeneration in the high-concentration residual eluent.

(3) Experimental results As a result of repeating adsorption and regeneration 10 times as one set, the amount of boric acid adsorbed to the adsorption tower from raw water (boron-containing water) and the amount of boric acid recovered as crystals are: Each of them was 146.5 g (average once) and 136.9 g (average once), and the error between them was within 10%. Here, boron that has not been crystallized remains at a high concentration in the residual eluent that is reused, and the boron adsorbed on the adsorption tower elutes into the residual eluent during the next regeneration of the adsorption tower. It is considered that boron which is added and close to the same amount as boron added to the residual eluent is precipitated as boric acid crystals. On the other hand, the amount of boric acid flowing out as washing wastewater was 30.7 g (average once). Therefore, the recovery rate of boron (boric acid) was 136.9 / (136.9 + 30.7) × 100 = about 82%, which reached a value that could be fully used for practical use.
In addition, when the heating temperature of the mineral acid for regeneration (residual eluent) is changed between 25 to 50 ° C., the recovery amount at an elution temperature lower than 30 ° C. in the recovery amount of boric acid is 30 ° C. or more. There was a clearly less tendency than that at the elution temperature. Therefore, it was considered that the heating temperature is more preferably 30 ° C. or higher.

20 Adsorption tower (boron adsorption device)
21 container 22 inlet 23 outlet 25 adsorbent 26 adsorbent module 28 thread-like member (path changing means)
30 Preparative device 40 Cooling and crystallizing device 50 Solid-liquid separation device 60 Heating device 100 Boron removal system

Claims (11)

A cylindrical container having a vertical axis;
An adsorbent filled in the container and adsorbing boron,
The container has an inlet provided at an upper part for allowing the liquid flowing into the container to flow downward, and an outlet provided at a lower part for allowing the liquid to flow out from the container,
The adsorbent is formed by introducing a glucamine group that adsorbs boron as a functional group into a non-woven fabric of a polymer material, and an adsorbent module formed into a column shape by winding an adsorbent material formed in a strip shape. One or more modules are inserted into the container such that the axis of the module is coaxial with the axis of the container.
The adsorbent module includes path changing means for changing a liquid flow path of the liquid flowing down in the adsorbent module.
By passing boron-containing water into the container, the boron in the boron-containing water is adsorbed to the adsorbent and treated water from which boron is removed from the boron-containing water is generated. By passing a mineral acid for regeneration through, boron is eluted from the adsorbent adsorbed with boron into the mineral acid, and an eluent containing boron eluted into the mineral acid is generated. Boron adsorption device. The adsorbent module repeats a plurality of times in the direction in which the outer diameter increases by winding and binding the thread-like member in the circumferential direction at a plurality of axial positions on the outer peripheral surface after the adsorbent material is wound in a plurality of layers. Is formed into a cylindrical shape,
The axial position of the thread-like member is set to a position different from at least one inner thread-like member, and a constricted portion by the thread-like member constitutes the path changing means. Item 6. The boron adsorption apparatus according to Item 1.   The boron adsorbing device according to claim 1 or 2, wherein the adsorbent filled in the container has a height of 1200 to 6000 mm.   The density | concentration of the adsorbent with which the said container was filled is 170-250 g / L, The boron adsorption | suction apparatus as described in any one of the Claims 1 thru | or 3 characterized by the above-mentioned.   The boron adsorption apparatus according to any one of claims 1 to 4, wherein the introduction ratio of glucamine groups to the nonwoven fabric in the adsorbent material is 1.5 to 2.5 mmol / g. . Boron adsorption device according to any one of claims 1 to 5,
A preparative device for collecting the eluent produced in the boron adsorbing device separately in the order of production into a first eluent and a second eluent;
A cooling crystallizer for crystallizing supersaturated boric acid by cooling the first eluent collected in the fractionator;
A solid-liquid separation device for separating an eluent containing boric acid crystals precipitated in the cooling crystallizer into a residual eluent that is an eluent excluding boric acid crystals and boric acid crystals;
A heating device for heating the mineral acid for regeneration used in the boron adsorption device,
The residual eluate after the boric acid crystals are separated and removed in the solid-liquid separator is returned to the boron adsorber as the mineral acid for regeneration through the heating device, and then collected in the fractionator. The boron removing system is characterized in that the second eluent is returned to the boron adsorption device. The preparative device collects the second eluent in a plurality of generation orders,
7. The boron removal system according to claim 6, wherein the second eluent divided into a plurality is returned to the boron adsorption device in the order of generation.   The residual eluate after the boric acid crystals are separated and removed in the solid-liquid separation device is adjusted with a mineral acid in the middle of being returned to the boron adsorption device to adjust the concentration of the mineral acid. The boron removal system according to claim 6 or 7.   Before the residual eluent after the boric acid crystals are separated and removed in the solid-liquid separator, the heated purified water is passed through the boron adsorber before returning to the boron adsorber via the heating device. The boron removal system according to any one of claims 6 to 8, wherein   The said heating apparatus heats the said mineral acid for reproduction | regeneration used in the said boron adsorption apparatus to 30-45 degreeC, The boron as described in any one of Claim 6 thru | or 9 characterized by the above-mentioned. Removal system. Using the boron adsorption device according to any one of claims 1 to 5, by passing boron-containing water through the container, the boron-containing water is adsorbed by the adsorbent. An adsorption step for producing treated water from which boron is removed from the boron-containing water;
Using the boron adsorber, by passing the mineral acid for regeneration through the container, boron is eluted from the adsorbent on which boron is adsorbed into the mineral acid, and is eluted into the mineral acid. An elution step for producing an eluent containing boron,
A preparative step of collecting the eluent generated in the elution step separately in the order of generation into a first eluent and a second eluent;
A cooling and crystallization step of crystallizing supersaturated boric acid by cooling the first eluent collected in the fractionation step;
A solid-liquid separation step of separating the eluent containing the boric acid crystals precipitated in the cooling crystallization step into boric acid crystals and a residual eluent that is an eluent excluding the boric acid crystals;
A heating step of heating the mineral acid for regeneration used in the boron adsorption device,
The residual eluent after the boric acid crystals are separated and removed in the solid-liquid separation step is heated as the mineral acid for regeneration and returned to the boron adsorption device, and then collected in the fractionation step. A boron removing method, wherein the second eluent is returned to the boron adsorption device.

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