JP7089345B2 - Water treatment method and water treatment equipment - Google Patents

Description

The present invention relates to a water treatment method and a water treatment apparatus, and more particularly to a water treatment method and a water treatment apparatus for removing fluorine and boron from water to be treated containing fluorine and boron.

Fluorine and boron are contained in high concentrations in wastewater in the glass manufacturing industry and the plating industry. The wastewater standard values for fluorine and boron are severely restricted by environment-related laws such as the Sewerage Law or the Water Pollution Control Law. Therefore, it is necessary to reduce the concentration of the wastewater containing fluorine and boron by adding chemicals as appropriate to coagulate and insolubilize the fluorine and boron in the wastewater and discharge the wastewater.

However, in the wastewater in which fluorine and boron coexist, there is a problem that fluorine and boron are combined in an acidic region to generate persistent borofluoric acid, which cannot be removed by ordinary agglutination insolubilization. Conventionally, as a technique for removing boronic acid in wastewater, aluminum sulfate or polyaluminum chloride is added to wastewater containing borofluoric acid to decompose boron chloride, and a calcium compound is added to the decomposition product to add fluorine in wastewater. And the method of producing boron as a solid substance is the mainstream (see, for example, Patent Documents 1 and 2). Further, as a method for treating wastewater containing fluorine, which is not wastewater containing fluorine and boron, a method of adding activated alumina powder as an adsorbent to the wastewater is known (see, for example, Patent Document 3).

Japanese Unexamined Patent Publication No. 2009-23365 (published on October 15, 2009) Japanese Unexamined Patent Publication No. 2016-163857 (published on September 8, 2016) Japanese Unexamined Patent Publication No. 2002-86160 (published on March 26, 2002)

However, the conventional method for treating water to be treated containing fluorine and boron as described above is not sufficient in terms of excellent treatment efficiency, sludge generation amount, and treatment cost. In the method of adding aluminum sulfate (also referred to as liquid van) described in Patent Document 1, a large amount of sludge is generated by the reaction between the decomposition product and the calcium compound, and the treatment efficiency is not sufficient. .. The method of adding polyaluminum chloride (also referred to as PAC from Poly Aluminum Chloride) described in Patent Document 2 (PAC method) has a problem in terms of cost.

The present invention has been made in view of the above problems, and an object thereof is to obtain fluorine from water to be treated containing fluorine and boron, which has excellent treatment efficiency, reduces sludge generation amount, and can suppress treatment cost. And to realize a water treatment method and a water treatment apparatus for removing boron.

One embodiment of the present invention has the following configuration.
[1] A water treatment method for removing fluorine and boron from water to be treated containing fluorine and boron, in which the water to be treated is passed through a column filled with alumina in an acidic state. A water treatment method comprising, and an immobilization step of bringing the water to be treated and the immobilizing agent into contact after the column liquid passing step.
[2] The water treatment method according to [1], wherein the alumina is activated alumina.
[3] The water treatment method according to [1] or [2], wherein the column is further filled with a rectifying accelerator.
[4] The invention according to any one of [1] to [3], which comprises a retention step of retaining water to be treated that has passed through the column between the column liquid passing step and the immobilization step. Water treatment method.
[5] A water treatment device for removing fluorine and boron from water to be treated containing fluorine and boron, in which a column filled with alumina and water to be treated that has passed through the column are brought into contact with a fixing agent. A water treatment device, including an immobilization unit for.
[6] The water treatment apparatus according to [5], wherein the alumina is activated alumina.
[7] The water treatment apparatus according to [5] or [6], wherein the column is further filled with a rectifying accelerator.
[8] The water treatment apparatus according to any one of [5] to [7], further including a retention portion for retaining the water to be treated that has passed through the column.
[9] Three or more of the columns are provided, and the plurality of columns are connected to each other so that the water to be treated is not passed through at least one column during the operation of the water treatment device. The water treatment apparatus according to any one of [5] to [8] to which the water treatment apparatus is connected.

According to the water treatment method according to the embodiment of the present invention, fluorine and boron are removed from the water to be treated containing fluorine and boron, which has excellent treatment efficiency, reduces sludge generation amount, and can suppress treatment cost. It has the effect that a water treatment method and a water treatment device can be realized.

It is a figure which shows typically the apparatus used in the Example of this invention. It is a figure which shows typically the water treatment apparatus which concerns on one Embodiment of this invention. It is a figure which shows typically the water treatment apparatus which concerns on one Embodiment of this invention. It is a figure which shows typically the water treatment apparatus which concerns on one Embodiment of this invention. It is a figure which shows typically the water treatment apparatus which concerns on one Embodiment of this invention.

An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope of the claims, and the technical means disclosed in the different embodiments may be appropriately combined. The obtained embodiments are also included in the technical scope of the present invention. Unless otherwise specified in the present specification, "A to B" representing a numerical range means "A or more and B or less".

[1. Water treatment method]
The water treatment method according to the embodiment of the present invention is a water treatment method for removing fluorine and boron from the water to be treated containing fluorine and boron, and the water to be treated is filled with alumina in an acidic state. It includes a column liquid passing step of passing liquid through the column and an immobilization step of bringing the water to be treated into contact with the immobilizing agent after the column liquid passing step.

In one embodiment of the present invention, the treated water containing fluorine and boron, which is the target of water treatment, includes groundwater, hot spring water, swamp lake water, seawater, factory wastewater, mine wastewater, river water and the like containing fluorine and boron. It should be. According to the water treatment method according to the embodiment of the present invention, fluorine and boron can be removed with high efficiency from wastewater of a glass manufacturing factory and a plating factory containing particularly high concentrations of fluorine and boron.

The fluorine contained in the water to be treated may be present in any form in the water to be treated. Therefore, fluorine may exist as an ion or may exist as a fluorine compound in a state of being bonded to another element. The content of fluorine in the water to be treated is not particularly limited, but the fluorine atom is preferably 0.01% by weight to 30% by weight, preferably 0.05% by weight or more, based on the weight of the water to be treated. It is more preferably 20% by weight, further preferably 0.1% by weight to 10% by weight, and particularly preferably 0.2% by weight to 4% by weight.

Boron contained in the water to be treated may also be present in the water to be treated in any form. Therefore, boron may exist as an ion or may exist as a boron compound in a state of being bonded to another element. The content of boron in the water to be treated is not particularly limited, but the boron atom is preferably 0.0012% by weight to 3.6% by weight, preferably 0.006% by weight, based on the weight of the water to be treated. It is more preferably% to 2.4% by weight, further preferably 0.012% by weight to 1.2% by weight, and particularly preferably 0.024% by weight to 0.48% by weight.

Especially in the acidic region, in the water to be treated in which fluorine and boron coexist, fluorine and boron are combined to form persistent borofluoric acid (HBF ₄ ), which produces borofluoride ions (BF _4- ⁾ . It exists in form.

According to the configuration of the present embodiment, the water treatment method according to the embodiment of the present invention has the following advantages (1) to (4).
(1) Compared with the conventional method of adding aluminum sulfate, an aluminum sulfate storage tank, a liquid feeding facility for aluminum sulfate, and a large decomposition tank for reacting aluminum sulfate with the water to be treated (in the water to be treated). It is necessary to add aluminum sulfate containing twice the amount of aluminum that reacts with the total fluorine contained in the water to be treated and mix it, and the decomposition tank becomes large depending on the amount of water to be treated at one time. Will be) becomes unnecessary.
(2) The amount of precipitate (sludge) generated in the immobilization step is small. In the prior art, a large amount of a precipitate derived from aluminum sulfate (calcium sulfate, aluminum hydroxide, etc.) is produced. On the other hand, the water treatment method according to the embodiment of the present invention does not produce sulfate. In addition, aluminum is gradually eluted in the column to form borofluoric acid (HBF ₄ ) or borofluoride ion (BF _4- ⁾ (hereinafter, borofluoric acid (HBF ₄ ) or borofluoride ion (BF _4- ⁾ in the present specification). Is referred to as "boric acid"), so that the amount of aluminum used is small, and therefore the amount of sludge such as aluminum hydroxide produced in the immobilization step is also small.
(3) Since a column is used, it can be packaged by a cartridge method, which increases versatility. In particular, it is advantageous for introduction to glass manufacturing factories in countries where it is difficult to procure aluminum sulfate.
(4) Since alumina, which is scheduled to be discarded, can be used, resource utilization and cost reduction can be realized.

[1-1. Column liquid passing process]
The water treatment method according to the embodiment of the present invention includes a column liquid passing step of passing the water to be treated to a column filled with alumina in an acidic state.

In this step, the water to be treated is passed through the column in an acidic state. If the water to be treated is acidic, the alumina filled in the column dissolves in the contacted water to be treated, and aluminum ions elute on the surface of the alumina. The eluted aluminum ions react with bofoic acid to produce aluminum fluoride. That is, borofluoric acid is decomposed.

Further, since the reaction between alumina and the acid is an exothermic reaction, the generated heat further promotes the reaction between the aluminum ion and the borofluoric acid, in other words, the decomposition reaction of the borofluoric acid.

Therefore, even when the water to be treated contains borofluoric acid, it is possible to decompose the borofluoric acid by passing the water to be treated through a column filled with alumina in an acidic state. After decomposition, boron becomes boric acid. On the other hand, some of the fluorine becomes hydrogen fluoride, and the other becomes aluminum fluoride. The generated boric acid, aluminum fluoride, and hydrogen fluoride are discharged into the water to be treated after passing through the column.

In this step, "acidic" means that the pH may be less than 7, but from the viewpoint that a suitable amount of aluminum ions can be eluted from alumina, it is more preferably less than 5, still more preferably less than 4.5, and further. It is preferably less than 4. The pH may be less than 3 or less than 2. Further, the water to be treated is not particularly limited as long as it is in an acidic state, and may be hydrogen ions derived from hydrochloric acid, sulfuric acid, nitric acid or the like. The lower limit of pH is not particularly limited, but is larger than 0.

In this step, the water to be treated may be passed through the column in an acidic state. Therefore, when the water to be treated is originally acidic, the water to be treated may be passed through the column as it is. When the water to be treated is not acidic or when it is desired to increase the acidity, the water treatment method according to the embodiment of the present invention has an acidic pH or a predetermined acidity before the column liquid passing step. It may include a pH adjusting step for adjusting to. The pH adjustment step can be performed by adding an acid such as hydrochloric acid, sulfuric acid, and nitric acid to the water to be treated.

The alumina filled in the column is not particularly limited, and examples thereof include alumina, activated alumina, and alumina hydroxide (alumina hydrate). Of these, activated alumina is more preferable from the viewpoint of being able to efficiently decompose borofluoric acid. Examples of the active alumina include active alumina, NKHD-24HD, NKHD-46HD, NKHD-24, NKHD-46, NKHO-24, HD-13, FD-24, KHS-46, KHA-46, KHA-24, KHO-46, KHO-24, KHO-12, KHD-46, KHD-24, KCG-30, KCG-1525W, KC-501, A-11, AC-11, AC-12R (Sumitomo Chemical Co., Ltd.); Active Alumina, NSA20-3 × 6, NSA20-5 × 8, NSA20-7 × 12, NST-5, NST-7, NST-3, NST-3H, NA-3 (Nikki Universal Co., Ltd.); Active Alumina, D-201 (3x6), D-201 (5x8), D-201 (7x12), A-201-4 (7x12), A204-8 (7x12), AZ-300 (7 × 14), CG-731 (5 × 8) (Union Showa Co., Ltd.); Aluminum oxide 60 active type basic activity I (0.063-0.200 mm), Aluminum oxide 90 active type neutral activity I (0.063-0.200 mm), aluminum oxide 90 active type acidic activity I (0.063-0.200 mm), aluminum oxide 90 active type basic activity I (0.063-0.200 mm), Aluminum oxide 150 basic (Merck Co., Ltd.) or the like can be used. Alternatively, as the activated alumina, activated alumina generated as waste in the production of activated alumina, aluminum refining, alumina catalyst and the like can also be used.

The shape of the alumina is not particularly limited as long as it is in the form of particles, and may be spherical, elliptical, amorphous or crushed.

The average particle size of the alumina is preferably 5 mm or less, more preferably 1 mm to 4 mm in a dry state. When the average particle size of the alumina is 1 mm or more, it is preferable from the viewpoint that clogging of the column is unlikely to occur. Further, when the average particle size of the alumina is 5 mm or less, the liquid flow through the column becomes more uniform (in other words, the uneven flow of the liquid through the column can be prevented), which is preferable.

In the present specification, unless otherwise specified, the average particle size means a value determined by the following method. First, a sample is taken from several places of the set of particles to be a sample. Each sample was observed with a microscope, and for a total of 100 or more particles in the sample collected from several locations, the major axis diameter of one target particle, that is, the largest dimension of the particle shape. Measure the dimensions in the larger direction of. Of the 100 or more measured values, the average of 60% of the measured values excluding the upper and lower 20% is defined as the average particle size in the present invention.

In this step, the flow rate at which the water to be treated is passed through the column is not particularly limited, and the optimum flow rate may be appropriately determined, but SV = 0.4 to 5, more preferably. Pass the liquid at SV = 1 to 4. Here, the SV is a unit indicating how many times the resin volume is passed per hour. When SV = 0.4 or more, the drift when passing the column liquid can be reduced, which is preferable. Further, when SV = 5 or less, overflow due to an increase in liquid passage resistance at the time of column liquid passage can be prevented, which is preferable.

Further, in this step, the direction in which the water to be treated is passed through the column is not particularly limited, and may be a downward flow or an upward flow.

The column may be a column filled with alumina, but in the water treatment method according to the embodiment of the present invention, a rectifying accelerator may be further filled in addition to alumina. As the particle size of alumina becomes smaller due to the reaction between the acid and alumina, the liquid permeability of the water to be treated may decrease when the liquid is passed for a long time. By using a column filled with a rectifying accelerator in addition to alumina, it is possible to prevent such deterioration of the liquid permeability of the water to be treated.

The rectification promoting material is not particularly limited as long as it is a material that is inert to acidic water to be treated, and examples thereof include resins, fluorine-resistant metals, and fluorine-resistant rubbers, among which resins are used. Is more preferable. The resin is not limited to this, and for example, polyethylene resin, polypropylene resin, acrylic resin and the like can be preferably used. The shape of the rectifying accelerator is not particularly limited, and examples thereof include a particle shape, a bead shape, a fibrous shape, and a tubular shape. Above all, the rectifying accelerator is more preferably resin beads. When the rectifying accelerator is a bead, its particle size is not particularly limited, but it is preferably larger than the diameter of the liquid feeding tube.

The rectifying accelerator may be filled in the column in a state of being uniformly mixed with alumina, or the rectifying accelerator and alumina may be alternately filled in layers. Above all, from the viewpoint of preventing deterioration of the liquid permeability of the water to be treated, it is more preferable that the rectifying accelerator and alumina are alternately filled in layers. Further, the number of layers to be laminated is not particularly limited, but it is more preferable that the rectifying accelerator and alumina having multiple layers, for example, two to three layers each, are alternately filled in layers. The order of the layers in the case of filling in layers is not particularly limited, and the number of layers of the rectifying accelerator and the number of layers of alumina may be the same or different. Laminating so that at least one of the inlet side and the outlet side of the column, more preferably both the inlet side and the outlet side of the column, is filled with the rectifying accelerator reduces the liquid permeability of the water to be treated. More preferable from the viewpoint of prevention. The column 1 schematically shown in FIG. 1 is filled with two layers of the rectifying accelerator 3 in a layered manner so as to sandwich the one layer of alumina 2, and promotes rectification on both the inlet side and the outlet side of the column 1. This is an example in which the material 3 is filled.

[1-2. Immobilization process]
The water treatment method according to the embodiment of the present invention includes an immobilization step of bringing the water to be treated and the immobilizing agent into contact with each other after the column liquid passing step.

In this step, by reacting the water to be treated after passing through the column with an immobilizing agent, fluorine and boron contained in the water to be treated can be precipitated as an insoluble compound. By separating the precipitated insoluble compound, fluorine and boron can be removed from the water to be treated.

The immobilizing agent is not particularly limited, but is preferably a calcium compound or a mixture containing a calcium compound, which is basic when dissolved because it can neutralize the water to be treated and is inexpensive. Examples of the calcium compound or the mixture of calcium compounds include calcium hydroxide, a mixture of calcium carbonate and sodium hydroxide, and a mixture of calcium carbonate and sodium carbonate. Above all, the fixing agent is more preferably calcium hydroxide.

The method of contacting the water to be treated with the immobilizing agent is not particularly limited, but for example, the water to be treated is introduced into the immobilization tank (immobilization portion) and the immobilizing agent is added. Examples thereof include a method of contacting after or while adding. The immobilization tank may be equipped with a stirring device in order to efficiently react the immobilizing agent with the water to be treated.

FIG. 2 schematically shows water treatment methods according to various embodiments of the present invention. In FIG. 2, in the embodiment in which the water to be treated from the water storage tank 5 to be treated is sent by the route shown by the solid line A, the water to be treated after passing through the column 1 in the column liquid passing step is directly immobilized. The liquid is sent to the tank (immobilization portion) 7 and brought into contact with the immobilizing agent. The embodiment shown by the solid line A can be suitably used when the concentrations of fluorine and boron in the water to be treated are relatively low.

In the water treatment method according to the embodiment of the present invention, aluminum sulfate (liquid van) and / or aluminum chloride (PAC) is further added after the column liquid passing step and before the dehydration step described later, for example, in the immobilization step. It may be added. When added, it is possible to reduce the amount of sludge generated in the immobilization step, and it is also possible to promote the immobilization of fluorine.

[1-3. Retention process]
The water treatment method according to the embodiment of the present invention may include a retention step of retaining the water to be treated that has passed through the column between the column liquid passing step and the immobilization step.

In the column liquid passing step, depending on the content of fluorine and boron in the water to be treated, the acidity of the water to be treated, SV, etc., it is the aluminum ion eluted from alumina and does not react with the fluorine ion or borofluoric acid. , Excess aluminum ions may be contained in the water to be treated after passing through the column. In such a case, as shown by the dotted line B in FIG. 2, the water to be treated discharged from the column 1 is transferred to, for example, a column after the column liquid passing step and before the immobilization step. It is retained in the directly connected retention tank (retention section) 6. As a result, when the bohic acid is not sufficiently decomposed in the column 1, it is possible to give time for sufficiently decomposing the bohic acid in the retention tank 6. Therefore, surplus aluminum ions can be used for decomposition of borofluoric acid without waste, and the amount of alumina used can be reduced. Further, by reducing the amount of aluminum ions sent to the immobilization step, for example, sludge generated by the reaction between calcium hydroxide and aluminum ions can be reduced. The retention tank 6 may be provided with a stirring device in order to efficiently proceed with the decomposition reaction of borofluoric acid.

"When the borofluoric acid is not sufficiently decomposed" means that the borofluoric acid is decomposed by the aluminum ion even though the alumina filled in the column is dissolved by the acid and the aluminum ion is generated. As soon as the liquid passes through the column (faster than all of the aluminum ions produced are used to break down borofluoric acid).

For example, the time that the liquid stayed in the column was sufficient for the formation of aluminum ions, but not enough for the decomposition of borosilicate into boron and fluorine ions. In that case, "when not disassembled" occurs.

Further, in FIG. 2, in the retention step, the water to be treated discharged from the column 1 is retained in the retention tank 6, but the water to be treated discharged from the column 1 is filled with, for example, the rectification accelerator. It may be retained in the column.

In the water treatment method according to another embodiment of the present invention, as shown by the alternate long and short dash line C in FIG. 2, a part of the water to be treated from the water storage tank 5 to be treated is in an acidic state of alumina 2. The water to be treated is allowed to pass through the column 1 filled with the water, and the water to be treated discharged from the column 1 is retained in the retention tank (retention portion) 6, and then brought into contact with the fixing agent, and the remaining one of the water to be treated is contacted. As for the portion, the liquid is directly sent to the retention tank 6 without passing the liquid through the column 1 filled with the alumina 2. According to such an embodiment, in the embodiment shown by the dotted line B described above, even when the surplus aluminum ions are discharged from the retention tank 6 to the immobilization tank (immobilization portion) 7, the retention tank 6 still has surplus aluminum ions. The surplus aluminum ions present can be used to decompose the bohic acid in the water to be treated that has not passed through the column 1. Therefore, the amount of alumina 2 used can be reduced. Further, by reducing the amount of aluminum ions sent to the immobilization step, for example, sludge generated by the reaction between calcium hydroxide and aluminum ions can be reduced.

The embodiment in which the water to be treated is sent by the route shown by the solid line A in FIG. 2, the embodiment in which the water to be treated is sent by the route shown by the solid line B, and the water to be treated by the route shown by the solid line C. Which of the embodiments to send the liquid is selected depends on the content of fluorine and boron in the water to be treated in the water storage tank 5 to be treated, the acidity of the water to be treated, the SV of the column 1 filled with alumina 2, and the like. Can be decided. It is also possible to monitor the concentration of aluminum ions at the outlet of the column 1 and the outlet of the retention tank 6 and switch which embodiment the water treatment is performed according to the measured concentration.

[1-4. Dehydration process]
The water treatment method according to the embodiment of the present invention may have a dehydration step after the immobilization step. The dehydration step is a step of separating the insoluble compound precipitated in the immobilization step from the water to be treated. The dehydration step can be performed by filtration using a belt press filter, a filter press, a vacuum dehydrator or the like.

[2. Water treatment equipment]
The water treatment apparatus according to the embodiment of the present invention is a water treatment apparatus that removes fluorine and boron from the water to be treated containing fluorine and boron, and is a water treatment apparatus that has passed through a column filled with alumina and the column to be treated. Includes an immobilization section for contacting water with the immobilizing agent.

A water treatment apparatus according to a preferred embodiment of the present invention includes a column filled with alumina and an immobilization unit connected to the downstream side of the column.

In the water treatment apparatus according to the embodiment of the present invention, the water to be treated containing fluorine and boron, the column filled with alumina, and the immobilizing agent are described in [1. Since it is as described in [Water treatment method], the description thereof is omitted here.

The immobilization portion for contacting the water to be treated that has passed through the column with the immobilizing agent is the water to be treated that has passed through the column (in other words, the water to be treated discharged from the column) and the immobilization portion. It is not particularly limited as long as it is a container capable of reacting with an agent and precipitating or immobilizing fluorine and boron contained in the water to be treated as an insoluble compound. Therefore, for example, the above-mentioned immobilization tank may be used as the immobilization unit, or a column filled with the immobilization agent may be used as the immobilization unit.

In the water treatment apparatus according to the embodiment of the present invention, the immobilization portion is connected to the downstream side of the column. Here, the immobilization unit may include a supply unit for supplying the immobilizing agent. As a result, the immobilizing agent can be added to the water to be treated that has been sent to the immobilization portion. The supply unit may have any configuration as long as it can supply the immobilizing agent, and a conventionally known configuration can be appropriately selected.

Further, the column may be a column in which a rectifying accelerator is further filled in addition to alumina. The rectifying accelerator used in the present embodiment is also described in [1. Since it is as described in [Water treatment method], the description thereof is omitted here.

The water treatment apparatus according to the embodiment of the present invention may be configured to send the water to be treated from the water storage tank 5 to be treated by the route shown by the solid line A shown in FIG. 2, for example. In such a case, the water treatment apparatus includes a column 1 filled with alumina 2, a liquid feeding line in which the upstream side is connected to the column 1 and the water to be treated that has passed through the column 1 flows, and the liquid feeding line. It includes an immobilization tank (immobilization unit) 7 connected to the downstream side.

The liquid feeding line may include a liquid feeding pipe, a circulation pump, and the like, and as the liquid feeding pipe, the circulation pump, and the like, a well-known liquid feeding pipe, a circulation pump, and the like can be used.

Further, the water treatment apparatus according to the embodiment of the present invention may further include a retention portion for retaining the water to be treated that has passed through the column. The water treatment apparatus according to the embodiment of the present invention includes a column filled with alumina and an immobilization portion connected to the downstream side of the column, which is downstream of the column and is the immobilization portion. A retention portion for retaining the water to be treated discharged from the column may be connected upstream.

The retaining portion for retaining the water to be treated discharged from the column is particularly limited as long as it is a container in which the water to be treated discharged from the column can be retained in order to further promote the decomposition reaction of borofluoric acid. However, it may be, for example, the above-mentioned retention tank, a column filled with a rectifying accelerator, or the like.

The retention portion is downstream of the column and is connected to the upstream of the immobilization portion, and the water to be treated after the decomposition reaction of borofluoric acid is promoted in the retention portion is transferred to the immobilization portion. The liquid is sent and fixed in the immobilization part.

The water treatment apparatus according to the embodiment of the present invention including such a retention portion is configured to, for example, send the water to be treated from the water storage tank 5 to be treated by the route shown by the dotted line B shown in FIG. It may have been done. In such a case, the water treatment apparatus includes a column 1 filled with alumina 2, a liquid feeding line in which the upstream side is connected to the column 1 and the water to be treated that has passed through the column 1 flows, and the liquid feeding line. A retention tank (retention portion) 6 connected to the downstream side, a liquid feeding line in which the upstream side is connected to the retention tank 6 and the water to be treated discharged from the retention tank 6 flows, and a liquid feeding line. It includes an immobilization tank (immobilization portion) 7 connected to the downstream side. With such a configuration, surplus aluminum ions can be used for decomposition of borofluoric acid without waste, so that the amount of alumina used can be reduced. Further, since the amount of aluminum ions sent to the immobilization step can be reduced, sludge generated by the reaction with calcium hydroxide can be reduced, for example. The retention tank 6 may be provided with a stirring device in order to efficiently proceed with the decomposition reaction of borofluoric acid. Further, instead of the retention tank 6 shown in FIG. 2, the retention tank 6 may be retained in a column filled with the rectifying accelerator. The column filled with the rectifying accelerator can also promote the decomposition reaction of boodi acid, and the column has the advantage that it is easier to replace and handle than the case of a tank. be. Here, the rectifying accelerator to be filled in the column as the retention portion is described in the above [1. It is the same as the rectifying accelerator described in [Water treatment method].

The water treatment apparatus according to another embodiment of the present invention including the retention portion is such that the water to be treated from the water storage tank 5 to be treated is sent by, for example, the route shown by the alternate long and short dash line C shown in FIG. It may be configured in. In such a case, the water treatment apparatus connects the liquid feeding line through which the water to be treated is distributed to the column 1 filled with alumina, the column 1 filled with alumina, and the upstream side to the column 1 and the column 1 is connected. A liquid feeding line through which the water to be treated passes through the above, a stagnant tank (retaining portion) 6 connected to the downstream side of the liquid feeding line, and an upstream side connected to the stagnant tank 6 and from the stagnant tank 6. The liquid feed line through which the discharged water to be treated flows, the immobilization tank (immobilization unit) 7 connected to the downstream side of the liquid feed line, and the column 1 filled with the alumina 2 to be treated. It includes a line that branches upstream of the column 1 from the flowing liquid feeding line and feeds the water to be treated to the retention tank 6. With such a configuration, even when the surplus aluminum ions from the retention tank 6 are discharged to the immobilization tank 7, the surplus aluminum ions existing in the retention tank 6 are used and do not pass through the column 1. It can decompose bohic acid in the water to be treated. Therefore, the amount of alumina 2 used can be reduced. Further, since the amount of aluminum ions sent to the immobilization step can be reduced, sludge generated by the reaction with calcium hydroxide can be reduced, for example.

Further, the water treatment apparatus according to another embodiment of the present invention includes a column 1 filled with alumina 2 and an immobilization tank (immobilization unit) connected to the downstream side of the column 1 shown in FIG. ) 7 is included, and a retention tank (retention portion) 6 for retaining the water to be treated discharged from the column 1 is connected to the downstream of the column 1 and upstream of the immobilization tank 7. Further, it includes all the liquid feeding lines shown in FIG. 2, and the configuration of the liquid feeding line can be switched between the following A to C.
A: Liquid feeding line connected to the column 1 on the upstream side and to the immobilization tank 7 on the downstream side: A liquid feeding line connected to the column 1 on the upstream side and to the retention tank 6 on the downstream side, and Liquid feeding line C connected to the retention tank 6 on the upstream side and to the immobilization tank 7 on the downstream side: the liquid feeding line connected to the column 1 on the upstream side, the liquid feeding line connected to the retention tank 6 on the downstream side, and the upstream side The liquid feeding line whose downstream side is connected to the immobilized tank 7 and the liquid feeding line which distributes the water to be treated to the column 1 are branched upstream of the column 1 and connected to the staying tank 6. The line that has been.

The liquid feed line is switched by the content of fluorine and boron in the water to be treated, the acidity of the water to be treated, the SV of the column 1 filled with alumina 2, and the concentration of aluminum ions in the water to be treated discharged from the column 1. , And the deterioration of the packing (alumina 2, etc.) of the column 1 is appropriately performed. Further, the water treatment device according to the present embodiment may be provided with an aluminum ion monitoring device at the outlet of the column 1 and the outlet of the retention tank 6. The aluminum ion monitoring device can monitor the concentration of aluminum ions, and can switch which liquid feeding line configuration is used for water treatment according to the measured concentration. For example, if aluminum ions are not detected at the outlet of column 1, the configuration of A may be switched to be selected. If aluminum ions are detected at the outlet of the column 1 but no aluminum ions are detected at the outlet of the retention tank 6, the configuration of B may be selected. Alternatively, if aluminum ions are detected at both the outlet of the column 1 and the outlet of the retention tank 6, the configuration of C may be selected. The liquid feeding line can be switched by a valve or the like (not shown). Further, the switching of the liquid feeding line may be performed by the control unit that automatically switches the liquid feeding line based on the data measured by the aluminum ion monitoring device. In such a case, as the aluminum ion monitoring device, an aluminum ion continuous monitoring device that continuously monitors the aluminum ion concentration may be used. The aluminum ion monitoring device is not particularly limited, and conventionally known ones can be appropriately used. For example, an aluminum ion concentration analyzer AL-4000S manufactured by JMS Co., Ltd. may be used. Can be done.

The water treatment apparatus according to the embodiment of the present invention may have at least the above-mentioned configuration, but may also have a pH adjusting unit upstream of the column, if necessary. , A solid-liquid separation device for solid-liquid separation of the mixture of the immobilization portion may be provided downstream of the immobilization portion.

Further, in the embodiment shown in FIG. 2, one column is used as the column 1, but in the water treatment apparatus according to another embodiment of the present invention, two or more columns are used as the column 1. May be used. Two or more columns may be connected in series or in parallel. For example, as the column 1, two or more columns connected in series, more preferably two columns connected in series can be preferably used. When two or more columns are used, when the decomposition failure of borofluoric acid occurs in one column due to an increase in the concentration of borofluoric acid in the column or a drift in the column due to a poor filling of alumina or the like. Even if it is present, the decomposition of borofluoric acid can be surely performed in other columns.

Further, in the water treatment apparatus according to another embodiment of the present invention, in addition to the column, a column filled with at least one spare alumina is arranged so as to be connectable, and the column used is the same. When the removal capacity is reduced, the connection of the column having the reduced removal capacity is cut off, and the connection can be switched so that the spare column is used. According to this embodiment, continuous operation is possible without stopping the water treatment.

Alternatively, the water treatment apparatus according to another embodiment of the present invention includes three or more of the columns, and the plurality of columns are connected to each other, and at least one column is operated during the operation of the water treatment apparatus. The columns may be connected to each other so that the water to be treated does not pass through.

FIG. 3 is a diagram schematically showing an example of a water treatment device according to the present embodiment. In the water treatment apparatus shown in FIG. 3, two columns 1 connected in series are used as the column 1, and in addition to the two columns 1, a column 1 filled with one spare alumina 2 can be connected. When the removal capacity of the upstream column 1 of the two columns 1 used is reduced, the connection of the upstream column 1 with the reduced removal capacity is cut off. Of the two columns 1, the connection can be switched so that the downstream column 1 and the spare column 1 are used, and the same switching is continuously performed between the three columns 1. As you can see, the connection can be switched.

More specifically, in the water treatment apparatus shown in FIG. 3, three columns 1 are provided as columns 1 filled with alumina 2, and two of the columns 1, that is, columns A, B, and B, are provided. And C tower, and either C tower and A tower are connected as two columns 1 connected in series, and an aluminum ion monitoring device 8 is provided at the outlet of each column 1. Has been done. According to such an embodiment, the operation is first performed in a state where the tower A and the tower B are connected so as to be used (the route (i) in FIG. 3), and the aluminum ion monitoring device at the exit of the tower A is used. When a decrease in the concentration of aluminum ions is detected by 8, the connection of the A tower is cut off, and the connection is switched so that the B tower and the C tower are used (path (ii) in FIG. 3). .. While the connection is cut off, the tower A is washed and newly filled with alumina 2. Similarly, when the aluminum ion monitoring device 8 at the exit of the B tower detects a decrease in the concentration of aluminum ions, the connection of the B tower is cut off and the connection is switched so that the C tower and the A tower are used. (Route (iii) in FIG. 3). While the connection is cut off, the B tower is washed and newly filled with alumina 2. The retention tank (retention portion) 6 is connected to the downstream of the two columns 1, and the immobilization tank (immobilization portion) 7 is connected to the downstream of the retention tank 6. The water treatment device shown in FIG. 3 has a configuration including the above-mentioned column 1, the retention tank 6, and the immobilization tank 7, but the immobilization tank 7 is directly downstream of the two columns. May be connected. The liquid feeding line can be switched by a valve or the like (not shown). Further, the switching of the liquid feeding line may be performed by the control unit that automatically switches the liquid feeding line based on the data measured by the aluminum ion monitoring device 8. In such a case, as the aluminum ion monitoring device 8, an aluminum ion continuous monitoring device that continuously monitors the aluminum ion concentration may be used.

FIG. 4 is a diagram schematically showing a modified example of the water treatment apparatus according to the present embodiment. In the water treatment apparatus shown in FIG. 4, a column filled with the rectifying accelerator is provided as the retention portion 6.

As described above, the decrease in the removal ability of the column can be detected, for example, by detecting the decrease in the concentration of aluminum ions at the outlet of the column. Alternatively, the decrease in the removal ability of the column can also be detected by visually confirming that the amount of alumina in the column has decreased.

The decrease in the removal ability of the column can also be determined by detecting the fluorine ions contained in the water to be treated after passing through the column. As the amount of alumina in the column decreases, the amount of aluminum ions produced by the dissolution of alumina also decreases, and the amount of borofluoric acid decomposed accordingly also decreases. If the amount of borofluoric acid decomposed decreases, the amount of boron trifluoride produced decreases, and therefore the amount of fluorine ions decreases. Therefore, the degree of destruction of the column can be determined by detecting the fluorine ions contained in the water to be treated after passing through the column.

Further, the water treatment apparatus according to another embodiment of the present invention is in contact with a storage tank containing water to be treated containing fluorine and boron, a column filled with alumina, and the water to be treated and an immobilizing agent that have passed through the column. The water to be treated may be circulated between the storage tank and the column filled with alumina, including an immobilization portion for allowing the water to be treated. An example of the water treatment apparatus is shown in FIG.

As shown in FIG. 5, in the water treatment apparatus according to the embodiment, a liquid feeding line is connected to the storage tank 9 on the upstream side and to the column 1 on the downstream side (a line for feeding the liquid to be treated from the storage tank 9 to the column 1). ) And a route (a solid line) including a liquid feeding line (a line in which the water to be treated that has passed through the column 1 is sent to the storage tank 9 again) connected to the column 1 on the upstream side and to the storage tank 9 on the downstream side (shown by a solid line). The route (i)) and both the upstream side and the downstream side are connected to the storage tank 9, and a liquid feeding line (indicated by a dotted line) that takes out the water to be treated from the storage tank 9 and sends the liquid to the storage tank 9 again. Includes a liquid feeding line that feeds the water to be treated to the immobilization tank (immobilization portion) 7.

With this configuration, the water to be treated is sent from the storage tank 9 to the column 1, and the water to be treated that has passed through the column 1 is returned to the storage tank 9 again and circulates between the storage tank 9 and the column 1. ing. At this time, in the column liquid passing step, the excess aluminum ions that are the aluminum ions eluted from the alumina 2 and have not reacted with the fluorine ions or the boric acid are contained in the water to be treated after passing through the column 1. In addition, the acidity of the water to be treated, SV, etc. are selected. As a result, when the water to be treated passes through the column 1, a part of the boric acid is decomposed, and at the same time, aluminum ions are eluted from the alumina 2 by the acid in the water to be treated. The eluted aluminum ions are supplied to the storage tank 9, and the borofluoric acid is also decomposed in the storage tank 9. That is, in the water treatment apparatus according to the present embodiment, the storage tank 9 is a storage tank for waste liquid and at the same time fulfills the function of the above-mentioned retention tank (retention portion), and the water to be treated that has passed through the column 1 in the storage tank 9. A retention step is performed to retain the water. For example, a pump is used to circulate the water to be treated. Then, the water to be treated is agitated in the storage tank 9 by the circulating flow of the water to be treated in the route (i).

Further, the water to be treated is stirred in the storage tank 9 by circulating the water to be treated by the route (ii) shown by the dotted line in FIG. Here, for example, a pump is connected to the liquid feeding line for taking out the water to be treated from the storage tank 9 and feeding the liquid to the storage tank 9 again in order to obtain the stirring effect of the water to be treated in the storage tank 9. By using the route (i) and the route (ii) in combination, the optimum supply of aluminum ions can be ensured and the water to be treated in the storage tank 9 can be agitated. Further, since the temperature of the water to be treated can be raised by the heat generated from the pump, the reaction can be promoted. Any pump may be used as the pump, but from the viewpoint of the stirring effect, a circulation pump such as a centrifugal pump can be preferably used.

The column 1 may be filled with a rectifying accelerator in addition to the alumina 2.

In the embodiment shown in FIG. 5, the water to be treated in the storage tank 9 is stirred by circulating the water to be treated by a pump, but in another embodiment, the storage tank 9 is provided with a stirring device for stirring. It may be done by the device.

In the embodiment shown in FIG. 5, two routes are shown as a liquid feeding line for feeding the water to be treated to the immobilization tank 7. One is a route between the column 1 and the storage tank 9 that branches from the route (i) before passing through the column 1 and sends the water to be treated to the immobilization tank 7. This is a route between the column 1 and the storage tank 9 that branches from the route (i) after passing through the column 1 and sends the water to be treated that has passed through the column 1 to the immobilization tank 7. These two routes are usually closed by a valve or the like, and one or both of the valves are opened as appropriate, and the water to be treated is sent to the immobilization tank 7. The opening time is determined by the concentration of borofluoric acid in the water to be treated and the like. In the embodiment shown in FIG. 5, the liquid feeding line for feeding the water to be treated to the immobilization tank 7 is branched from the route (i), but is not limited to this, and is not limited to the route (ii). It may be branched and configured.

According to the water treatment apparatus according to the present embodiment, the retention tank (retention portion) 6 as shown in FIGS. 2 to 4 is unnecessary, and two or more columns as shown in FIGS. 3 and 4 are not required. 1 is unnecessary. Therefore, the system of the entire equipment becomes simple, and there is an advantage that the time and cost required for maintaining the equipment can be reduced and the installation area of the equipment can be reduced.

Further, since it is a closed method of circulation between the storage tank 9 and the column 1, the water to be treated is supplied to the next immobilization step after confirming whether or not the borofluoric acid has been treated, so that the borofluoric acid is not decomposed. The risk of outflow can be reduced.

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 these Examples.

(A) Model drainage (water to be treated)
The model drainage was prepared as follows.
(1) 114.4 mL of a 48 wt% hydrogen fluoride solution (density 1.15 g / mL) was added to 3 L of 20 wt% hydrochloric acid.
(2) 57 g of boric acid was added to the solution obtained in (1) above, and the mixture was thoroughly stirred and dissolved.
(3) To the solution obtained in (2) above, 20 wt% hydrochloric acid was added to make a total volume of 5 L, and the mixture was stirred and mixed.

Table 1 shows the pH in the model effluent and the concentrations of fluorine and boron.

In the table, "TF" represents the total amount of fluorine, "F-" represents the amount of fluorine present as a fluorine ion, ^and "BF4 _- F" represents the amount of fluorine present as borofluoric acid. "B" represents the total amount of boron. In Examples and Comparative Examples, the total fluorine amount is measured by the JIS K 0102-34.1 absorptiometry method, and the amount of fluorine (F- ⁾ present as fluorine ions is measured by the ion chromatograph method. The amount of boron (B) was measured using JIS K 0102-47.1 methylene blue absorptiometry.

(B) Actual drainage (water to be treated)
The effluent generated in the glass manufacturing industry was used. Table 2 shows the pH in the actual drainage solution and the concentrations of fluorine and boron.

(C) Alumina In Examples 1 to 4, activated alumina (referred to as waste activated alumina) generated as waste in the production of activated alumina was used as alumina. The average particle size of the waste activated alumina was 1 mm to 6 mm, and the density was 0.862 g / mL.

In Comparative Examples 1 to 3 and Example 5, activated alumina (manufactured by Sumitomo Chemical Co., Ltd., NKHD-24HD, particle size: 2 to 4 mm, density: 0.806 g / mL) was used as alumina.

(D) Rectification accelerator In Examples 3 and 4, resin beads (round beads manufactured by Daiso Sangyo Co., Ltd., density 0.556 g / mL) were used as the rectification accelerator.

[Example 1]
The model effluent was treated using a small scale column filled with activated alumina.

100 mL of waste activated alumina was filled in a 200 mL resin graduated cylinder, and pure water was filled up to the holding liquid level. Then, the model drainage was started to be supplied to the column using the same apparatus as that shown in FIG. The flow rate of the model drainage to the column was 100 mL / h (SV = 1), and the model drainage was passed through the column for 5 hours. From 5 hours to 1 hour after the start of supply to the column (in other words, the start of liquid flow), 100 mL of the effluent from the column was collected and used as a sample for analysis.

The amount of fluorine (F ⁻ ) and the total amount of boron (B) present as fluorine ions in the effluent (100 mL) were measured. In addition, by subtracting the amount of fluorine (F- ⁾ present as fluorine ions in the effluent from the total amount of fluorine in the model effluent, the amount of fluorine (BF4 _- F) present as borofluoric acid in the effluent is calculated. (Concentration (converted value)). By subtracting BF ₄ -F (concentration (converted value)) in the effluent from BF ₄ -F in the model effluent, the reduced concentration of BF ₄ -F in the model effluent due to column flow (calculation) Value) was calculated. The value calculated by (decreased concentration / concentration of BF ₄ -F in the model drainage) × 100 was taken as the decomposition rate of borofluoric acid (calculated value). The results are shown in Table 3. As shown in Table 3, it was confirmed that 83% of the borofluoric acid in the water to be treated was decomposed by passing through the column.

[Example 2]
The actual effluent was treated using a small scale column filled with activated alumina.

100 mL of waste activated alumina was filled in a 200 mL resin graduated cylinder, and pure water was filled up to the holding liquid level. After that, the supply of the actual drainage liquid to the column was started using the same equipment as that shown in FIG. The flow rate of the actual drainage to the column was 100 mL / h (SV = 1), and the actual drainage was allowed to pass through the column for 5 hours. From 5 hours to 1 hour after the start of supply to the column, 100 mL of the effluent from the column was collected and used as a sample for analysis.

In the same manner as in Example 1, the amount of fluorine (F ⁻ ) and the total amount of boron (B) present as fluorine ions in the effluent (100 mL) were measured, and the amount of fluorine (BF) present as borofluoric acid in the effluent was measured. ₄ -F) (concentration (converted value)), the reduced concentration of boronic acid in the actual drainage (calculated value), and the decomposition rate of boronic acid (calculated value) were determined. The results are shown in Table 4. As shown in Table 4, it was confirmed that 85% of the borofluoric acid in the water to be treated was decomposed by passing through the column.

[Example 3]
In addition to activated alumina, a small-scale column filled with resin beads as a rectification accelerator was used to treat the model effluent.

Instead of 100 mL of waste activated alumina, 42 mL of waste activated alumina and 20 g of resin beads were filled in the column. As a filling mode, in FIG. 1, the three layers of alumina and the resin beads are made of 200 mL of resin so that the waste activated alumina and the resin beads are layered in two layers from above the column. A measuring cylinder was filled with pure water up to the holding liquid surface, and an apparatus having the same configuration as shown in FIG. 1 except for the column was manufactured. After that, the supply of the model drainage to the column was started using the device. The flow rate of the model drainage to the column was 100 mL / h (SV = 2.4, excluding the volume of the resin beads), and the model drainage was passed through the column for 5 hours. From 5 hours to 1 hour after the start of supply to the column, 100 mL of the effluent from the column was collected and used as a sample for analysis.

In the same manner as in Example 1, the amount of fluorine (F ⁻ ) and the total amount of boron (B) present as fluorine ions in the effluent (100 mL) were measured, and the amount of fluorine (BF) present as borofluoric acid in the effluent was measured. ₄ -F) (concentration (converted value)), the reduced concentration of boronic acid in the model drainage (calculated value), and the decomposition rate of boronic acid (calculated value) were determined. The results are shown in Table 5. As shown in Table 5, it was confirmed that 83% of the borofluoric acid in the water to be treated was decomposed by passing through the column. Further, as compared with Example 1, even when the flow rate of the model drainage (SV = 2.4) is 2.4 times faster than the flow rate of Example 1 (SV = 1). It can be seen that the borofluoric acid was suitably decomposed.

[Example 4]
In addition to activated alumina, a small-scale column filled with resin beads as a rectification accelerator was used to treat the actual effluent.

Instead of 100 mL of waste activated alumina, 50 mL of waste activated alumina and 50 g of resin beads are filled in a 200 mL resin graduated cylinder in the order of resin beads, waste activated alumina, and resin beads from above the column, and the holding liquid level. The apparatus as shown in FIG. 1 was manufactured by filling it with pure water. Then, using the apparatus shown in FIG. 1, the supply of the actual drainage liquid to the column was started. The flow rate of the actual drainage liquid to the column was 100 mL / h (SV = 2, excluding the volume of the resin beads), and the actual drainage liquid was passed through the column for 5 hours. From 5 hours to 1 hour after the start of supply to the column, 100 mL of the effluent from the column was collected and used as a sample for analysis.

In the same manner as in Example 1, the amount of fluorine (F ⁻ ) and the total amount of boron (B) present as fluorine ions in the effluent (100 mL) were measured, and the amount of fluorine (BF) present as borofluoric acid in the effluent was measured. ₄ -F) (concentration (converted value)), the reduced concentration of boronic acid in the actual drainage (calculated value), and the decomposition rate of boronic acid (calculated value) were determined. The results are shown in Table 6. As shown in Table 6, it was confirmed that 85% of the borofluoric acid in the water to be treated was decomposed by passing through the column. Further, as compared with Example 2, even when the liquid passing speed (SV = 2) of the actual drainage is twice as fast as the liquid passing speed (SV = 1) of Example 2, it is suitable for hoof. It can be seen that the acid has been decomposed.

(Comparative Example 1)
To 300 mL of the actual drainage liquid, 1.5 mL of activated alumina, which is an amount required for the decomposition of borofluoric acid contained in the actual drainage liquid and the reaction with fluorine, was added, and the mixture was stirred and mixed. After stirring for 3 days, activated alumina was not completely dissolved. Then, 90 mL of a 15% calcium hydroxide solution was added as an immobilizing agent to adjust the pH to 10, and immobilization was performed. Then, the solution containing sludge was filtered and the filtrate was analyzed.

Table 7 shows the amount of sludge generated, the concentration of TF and BF ₄ ^- F (calculated value) in the solution before filtration (during mixing), and the concentration of FF and TF in the filtrate (analysis). Value), as well as the reduced concentration (TF removal rate) of bohic acid in the actual drainage.

In the table, MLSS refers to suspended solids.

(Comparative Example 2)
To 300 mL of the actual effluent, 3.0 mL of activated alumina, which is twice the amount required for the decomposition of borofluoric acid contained in the actual effluent and the reaction with fluorine, was added, and 15% as an immobilizing agent. The actual drainage was treated in the same manner as in Comparative Example 1 except that 104.8 mL of the calcium hydroxide solution was used. The results are shown in Table 7.

(Comparative Example 3)
To 300 mL of the actual effluent, 5.5 mL of activated alumina, which is four times the amount required for the decomposition of borofluoric acid contained in the actual effluent and the reaction with fluorine, was added, and 15% as an immobilizing agent. The actual drainage was treated in the same manner as in Comparative Example 1 except that 123 mL of the calcium hydroxide solution was used. The results are shown in Table 7.

From Table 7, in Comparative Examples 1 to 3 in which activated alumina was added to the actual drainage liquid, the sludge generation amount (kg-sludge) was generated even though the TF removal rate (%) was as low as 4, 15 and 34, respectively. It can be seen that the amount of / m3 drainage) is as ^high as 41.1, 59.5, 85.5 on a dry basis and 308.6, 413.8, 525.7 on a wet basis, respectively. The following causes (1) to (3) can be considered as the causes of the large amount of sludge generated. (1) By adding activated alumina to the actual drainage liquid, a large amount of aluminum ions were generated. (2) Most of the aluminum ions generated by (1) above were not used for the decomposition of borofluoric acid. (3) According to the above (2), a large amount of aluminum ions and calcium hydroxide reacted to generate a large amount of aluminum hydroxide. In (1) above, it can be seen from the comparison between the amount of activated alumina added and the amount of activated alumina that did not dissolve after stirring for 3 days, that 90% or more of the added activated alumina was dissolved. Further, the above (2) can be seen from the fact that the TF removal rate is low.

(Comparative Example 4)
Mix 50 mL of real effluent, 50 mL and 100 mL of water, and add 12.7 mL of aluminum sulfate solution to the mixture, which is twice the theoretical amount required for the decomposition of borofluoric acid contained in the actual effluent and the reaction with fluorine. (Liquid aluminum sulfate (trade name) manufactured by Sumitomo Chemical Co., Ltd.) was added, and the mixture was stirred and reacted at room temperature (measured value: 21 ° C.) for 1 hour. Then, 39.8 mL of a 15% calcium hydroxide solution was added as an immobilizing agent to adjust the pH to 9.43 or 9.42, and immobilization was performed. Then, the solution containing sludge was filtered and the filtrate was analyzed.

Table 8 shows the amount of sludge generated, the concentration of TF in the solution before filtration (calculated value), the concentration of F- ^and TF in the filtrate (analytical value), and the actual drainage. The decrease concentration (TF removal rate) of borofluoric acid is shown. In Comparative Example 4, the same experiment 2 was performed twice, and the experiment No. 4 was performed respectively. It is described as 1 and 2.

* 1: g-ds / mL-drainage (ds represents dry base)
* 2: g-ws / mL-drainage (ws represents wet base)
[Example 5]
The actual effluent was treated using a small scale column filled with activated alumina.

62 mL of waste activated alumina was filled in a 200 mL resin graduated cylinder, and pure water was filled up to the holding liquid level. After that, the supply of the actual drainage liquid to the column was started using the same equipment as that shown in FIG. The flow rate of the actual drainage to the column was 100 mL / h (SV = 1.6), and the actual drainage was allowed to pass through the column for 24 hours. From 24 hours to 2 hours after the start of supply to the column, 200 mL of the effluent from the column was collected, and 100 mL of it was used as a sample for analysis.

In the same manner as in Example 1, the amount of fluorine (F ⁻ ) and the total amount of boron (B) present as fluorine ions in the effluent (100 mL) were measured, and the amount of fluorine (BF) present as borofluoric acid in the effluent was measured. ₄ -F) (concentration (converted value)), the reduced concentration of boronic acid in the actual drainage (calculated value), and the decomposition rate of boronic acid (calculated value) were determined. The results are shown in Table 9.

Further, in another device, the actual drainage liquid was passed through the column for 24 hours by the same method as described above. From 24 hours to 2 hours after the start of supply to the column, 200 mL of the effluent from the column was collected, and 100 mL of it was used as a sample to be used in the immobilization step. In the immobilization step, 22 mL of a 15% calcium hydroxide solution was added as an immobilizing agent to adjust the pH to 10.05, and immobilization was performed. After that, the amount of sludge was measured. The results are shown in Table 9.

From Table 9, it can be seen that in Example 5, 85% of the boric acid in the actual drainage was decomposed by passing through the column. On the other hand, in Comparative Examples 1 to 3 shown in Table 7, the TF removal rate is remarkably low. Comparing the sludge generation amount of Comparative Example 3 (TF removal rate 34%) having the highest TF removal rate among Comparative Examples 1 to 3 with the sludge generation amount of Example 5, Example 5 has a difference. It can be seen that the sludge generation amount is lower than 61.4 kg-sludge / m3 ^- drainage, despite the high decomposition rate.

According to the present invention, it is possible to realize a water treatment method for water to be treated containing fluorine and boron, which is excellent in treatment efficiency, reduces sludge generation amount, and can suppress treatment cost, and thus is in the field of water treatment. In particular, it is very useful for wastewater treatment in technical fields in which fluorine and boron are contained in wastewater, such as the glass industry field and the plating industry field.

1 Column 2 Alumina 3 Rectification accelerator 4 Treated water storage tank 5 Treated water storage tank 6 Retention part (retention tank)
7 Immobilization part (immobilization tank)
8 Aluminum ion monitoring device 9 Storage tank

Claims (11)

A water treatment method for removing fluorine and boron from water to be treated containing fluorine and boron.
A column liquid passing step in which the water to be treated is passed through a column filled with alumina in an acidic state of less than pH 2 , and an immobilization step in which the water to be treated and the immobilizing agent are brought into contact with each other after the column passing step. , Including
The water to be treated contains borofluoric acid and contains
The water treatment method , wherein the immobilizing agent is a calcium compound or a mixture containing a calcium compound . The water treatment method according to claim 1, wherein the alumina is activated alumina. The water treatment method according to claim 1 or 2, wherein the column is further filled with a rectifying accelerator. The water treatment method according to claim 3, wherein the column is filled with the rectifying accelerator and the alumina in alternating layers. Between the column liquid passing step and the immobilization step,
The water treatment method according to any one of claims 1 to 4, which comprises a retention step of retaining the water to be treated that has passed through the column. A water treatment device that removes fluorine and boron from water to be treated containing fluorine and boron.
Includes a column filled with alumina and an immobilization section for contacting the water to be treated that has passed through the column with the immobilizing agent.
The water to be treated contains borofluoric acid and contains
An pH adjusting unit for adjusting the pH to less than 2 is provided upstream of the column.
The immobilizing agent is a calcium compound or a mixture containing a calcium compound, which is a water treatment apparatus. The water treatment apparatus according to claim 6, wherein the alumina is activated alumina. The water treatment apparatus according to claim 6 or 7, wherein the column is further filled with a rectifying accelerator. The water treatment apparatus according to claim 8, wherein the column is filled with the rectifying accelerator and the alumina in alternating layers. The water treatment apparatus according to any one of claims 6 to 9, further comprising a retention portion for retaining the water to be treated that has passed through the column. With three or more of the columns
The plurality of columns are connected to each other and
The water treatment device according to any one of claims 6 to 10, wherein the columns are connected to each other so that the water to be treated is not passed through at least one column during the operation of the water treatment device.

Images