JP6045966B2 - Fluorine-containing wastewater treatment method and fluorine-containing wastewater treatment equipment - Google Patents

Description

  The present invention relates to a method for treating fluorine-containing wastewater containing fluoride ions and borofluoride ions and a treatment apparatus for fluorine-containing wastewater.

  As a method for treating wastewater containing fluoride ions and borofluoride ions, there is a method in which an aluminum compound is added to decompose the borofluoride ions, and then a calcium compound is added to form a sparingly soluble fluoride, followed by solid-liquid separation. (For example, refer to Patent Documents 1 and 2). However, in order to obtain treated water quality that can satisfy the discharge standard by this method, it is necessary to add a large amount of an aluminum compound, which is disadvantageous in terms of cost.

  In order to reduce the amount of aluminum compound added, for example, as in Patent Document 3, the sludge containing aluminum generated in the subsequent solid-liquid separation is circulated, and the fluorine in the sludge and the unreacted aluminum are reused. There is also a method of reducing the amount of aluminum compound added. However, in this method, in order to obtain a treated water quality that can satisfy the discharge standard, it is necessary to heat the waste water to 50 to 80 ° C., which requires energy costs.

  Further, as another method for reducing the amount of aluminum compound added, for example, as disclosed in Patent Document 4, a pH of 7 or more generated after adding sodium hydroxide to sludge containing aluminum generated in the subsequent solid-liquid separation, preferably There is also a method in which a suspension having a pH of 9 or more is subjected to solid-liquid separation and water-soluble aluminum contained in the obtained aqueous solution is reused. However, as a result of investigations by the present inventors, it has been found that this method does not sufficiently regenerate aluminum with respect to wastewater containing borofluoride ions, and the aluminum compound cannot be effectively reduced.

  Thus, as a method for treating wastewater containing fluoride ions and borofluoride ions, in order to obtain treated water that can satisfy the discharge standard, a large amount of aluminum compound is added or energy is added to heat. It was necessary and was not cost effective and energy efficient.

Japanese Examined Patent Publication No. 54-018064 Japanese Patent No. 36356643 Japanese Patent No. 4954131 Japanese Patent No. 2564252

  An object of the present invention is to provide a fluorine-containing wastewater treatment method and treatment apparatus that can reduce the amount of aluminum compound added and efficiently treat wastewater containing fluoride ions and borofluoride ions. .

The present invention further includes a first solidification step in which a calcium compound is added to wastewater containing fluoride ions and borofluoride ions to solidify the fluoride ions, and the reaction liquid obtained in the first solidification step Addition of aluminum compound to agglomeration step for agglomeration, first solid-liquid separation step for solid-liquid separation of sludge generated in the agglomeration step, and addition of aluminum compound to the separated water obtained in the first solid-liquid separation step A decomposition step of decomposing the borofluoride ions, a second solidification step of solidifying the fluoride ions by adding a calcium compound to the decomposition treated water containing the fluoride ions generated in the decomposition step, and a second solid-liquid separation step of solid-liquid separation of the formed sludge in the second solidification process, to reproduce the sludge by adding at least a portion acids sludge was subjected to solid-liquid separation at the second solid-liquid separation process And raw step, and returning step for returning the reproduction sludge the reproduction as in the aggregation step and the decomposition Engineering is a processing method of a fluorine-containing waste water containing.

  In the method for treating fluorine-containing wastewater, the reaction pH in the sludge regeneration in the regeneration step is preferably 4 or less.

Moreover, this invention adds the calcium compound to the waste_water | drain containing a fluoride ion and a borofluoride ion, and solidifies the said fluoride ion, The reaction liquid obtained at the said 1st solidification process Aggregating means for further adding and aggregating an aluminum compound, a first solid-liquid separating means for solid-liquid separation of the sludge produced in the aggregating step, and an aluminum compound in the separated water obtained by the first solid-liquid separating means A decomposition means for decomposing the borofluoride ions, a second solidification means for adding calcium compounds to the decomposition treated water containing the fluoride ions generated by the decomposition means, and solidifying the fluoride ions; a second solid-liquid separation means, the sludge by adding at least a portion acids sludge was subjected to solid-liquid separation at the second solid-liquid separation means again to solid-liquid separation of the formed sludge in the second solid means Reproducing means for a processing unit of a fluorine-containing waste water and a returning means for returning the reproduction sludge the reproduction to said aggregation means and the degradation hand stage.

  In the fluorine-containing wastewater treatment apparatus, the reaction pH in the sludge regeneration of the regeneration means is preferably 4 or less.

  In the present invention, the recycled sludge is returned to at least one of the aggregating means and the decomposing means, so that the amount of aluminum compound added can be reduced and wastewater containing fluoride ions and borofluoride ions can be treated efficiently. A treatment method and treatment apparatus for fluorine-containing wastewater can be provided.

It is a schematic block diagram which shows an example of the processing apparatus of the fluorine-containing waste_water | drain which concerns on embodiment of this invention.

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

  An outline of an example of a fluorine-containing wastewater treatment apparatus according to an embodiment of the present invention is shown in FIG. The waste water treatment apparatus 1 includes a first solidification tank 10 as a first solidification means, a coagulation tank 12 as a coagulation means, a first precipitation tank 14 as a first solid-liquid separation means, and a decomposition as a decomposition means. A tank 16, a second solidification tank 18 as a second solidification means, a second precipitation tank 20 as a second solid-liquid separation means, and a regeneration tank 22 as a regeneration means are provided.

  In the wastewater treatment apparatus 1 of FIG. 1, a raw water pipe 24 is connected to the inlet of the first solidification tank 10, and the outlet of the first solidification tank 10 and the inlet of the coagulation tank 12 are connected by the first solidification treatment water pipe 26. The outlet of the coagulation tank 12 and the inlet of the first sedimentation tank 14 are connected by a coagulation treatment water pipe 28, and the upper outlet of the first sedimentation tank 14 and the inlet of the decomposition tank 16 are connected by a separation water pipe 30, The outlet of the tank 16 and the inlet of the second solidification tank 18 are connected by a cracked water pipe 32, and the outlet of the second solidification tank 18 and the inlet of the second sedimentation tank 20 are connected by a second solidified water pipe 34. The treated water pipe 36 is connected to the upper outlet of the second sedimentation tank 20, the lower outlet of the second sedimentation tank 20 and the inlet of the regeneration tank 22 are connected by a sludge pipe 38, and the lower outlet of the regeneration tank 22 is agglomerated. The tank 12 and the decomposition tank 16 are used as return means. They are connected to each other by a feed pipe 40. In the first solidification tank 10, the agglomeration tank 12, the decomposition tank 16, the second solidification tank 18, and the regeneration tank 22, stirring devices 42, 44, 46, 48, and 50 having stirring blades as stirring means are installed. May be.

  An operation of the fluorine-containing wastewater treatment method and wastewater treatment apparatus 1 according to the present embodiment will be described.

Fluorine-containing wastewater containing fluoride ions (F ⁻ ) and borofluoride ions (BF ⁴⁻ ), which are raw water, is sent to the first solidification tank 10 through the raw water pipe 24, and in the first solidification tank 10, calcium compounds Is added, and fluoride ions contained in the fluorine-containing waste water are solidified to produce calcium fluoride (CaF ₂ ) (first solidification step). In the first solidification tank 10, the contents may be stirred by the stirring device 42.

  The 1st solidification process water which is the reaction liquid obtained at the 1st solidification process is sent to the aggregation tank 12 through the 1st solidification process water piping 26, and an aluminum compound is further added in the aggregation tank 12, and aggregation is carried out. Reaction is performed (aggregation step). In the aggregation tank 12, the contents may be stirred by the stirring device 44.

  The agglomerated water containing sludge generated in the agglomeration process is sent to the first sedimentation tank 14 through the agglomeration-treated water pipe 28 and is solid-liquid separated by sedimentation separation in the first sedimentation tank 14 (first solid-liquid separation). Process). The solid-liquid separated sludge is discharged from the lower outlet of the first settling tank 14.

  On the other hand, the separated and separated water is fed from the upper outlet of the first sedimentation tank 14 to the decomposition tank 16 through the separation water pipe 30, and an aluminum compound is added to the decomposition tank 16 and the borofluoride contained in the separated water. Ions are decomposed into boron ions and fluoride ions (decomposition step). In the decomposition tank 16, the contents may be stirred by the stirring device 46.

The decomposition treated water containing fluoride ions generated in the decomposition step is sent to the second solidification tank 18 through the decomposition treatment water pipe 32, and the calcium compound is added in the second solidification tank 18, and the fluoride ions are solidified. To produce sludge containing calcium fluoride (CaF ₂ ) (second solidification step). In the second solidification tank 18, the contents may be stirred by the stirring device 48.

  The 2nd solidification process water containing the sludge produced | generated at the 2nd solidification process is sent to the 2nd sedimentation tank 20 through the 2nd solidification process water piping 34, and is solid-liquid by sedimentation separation etc. in the 2nd precipitation tank 20. Separated (second solid-liquid separation step). The treated water subjected to the solid-liquid separation is discharged from the upper outlet of the second sedimentation tank 20 through the treated water pipe 36.

  On the other hand, at least a part of the solid-liquid separated sludge is sent to the regeneration tank 22 through the sludge pipe 38, and acid is added in the regeneration tank 22 to regenerate the sludge (regeneration process). In the regeneration tank 22, the contents may be stirred by the stirring device 50.

  The regenerated sludge regenerated in the regenerating process is returned to at least one of the aggregation tank 12 and the decomposition tank 16 through the return pipe 40 (returning process).

  In treating wastewater containing borofluoride ions, a sludge circulation regeneration process is effective in order to reduce the amount of aluminum compound added. Conventionally, as described above, a method for recycling sludge has been proposed in which an alkali such as sodium hydroxide is added to adjust the pH to 9 or more, aluminum is dissolved, the suspension is solid-liquid separated, and the supernatant is reused. It was. However, this method requires a new settling tank in order to separate the suspension into solid and liquid, which is disadvantageous in terms of cost.

  As a result of studies by the present inventors, it has been clarified that when sludge is regenerated at a pH of 9 or more, the sludge regeneration efficiency is remarkably reduced. As this cause, it is conceivable that calcium aluminate is generated at pH 9 or more, and aluminum is solidified and removed by solid-liquid separation.

  In addition, when the sludge regenerated at pH 9 or higher is circulated without solid-liquid separation, the solidified calcium aluminate adsorbs boron, so that it is considered that boron concentration occurs in the process. Concentrated boron inhibits the decomposition of borofluoride ions, so the fluorine concentration of the treated water is considered to increase.

  Therefore, in the method for treating fluorine-containing wastewater according to this embodiment, acid is used for sludge regeneration. By regenerating sludge with acid, it is possible to effectively regenerate aluminum, which can greatly reduce the amount of aluminum added and achieve water quality that meets discharge standards without heating. it can. Regenerated sludge regenerated with acid has a high ability to decompose borofluoride ions and adsorb fluorine, and therefore, it is considered that the effect of reducing aluminum compounds is higher than returning sludge that has not been regenerated.

  In the method for treating fluorine-containing wastewater according to the present embodiment, the regenerated sludge containing regenerated boron is also returned to the preceding fluorine treatment (aggregation step) together with the decomposition (decomposition step) of borofluoride ions. According to this method, in addition to the effect of reducing the amount of aluminum compound added, it has been found that the flocs coagulation in the coagulation step is greatly improved and the leakage of fine particles in the first sedimentation tank 14 is extremely reduced. . The reason for this is not clear, but it is thought that when boron in the regenerated sludge coexists in the agglomeration tank 12 in the previous stage, boron and calcium or aluminum react to generate high-density floc. As a result, the fluorine concentration in the agglomerated water in the agglomeration treatment is reduced, and the fluoride ion concentration that inhibits the decomposition of borofluoride ions in the subsequent stage is reduced. Therefore, the amount of aluminum used for the decomposition of borofluoride ions is reduced. It is thought that it can be greatly reduced.

  The concentration of fluoride ions in the fluorine-containing wastewater to be treated is not particularly limited. For example, the concentration is 100 mg / L to 100,000 mg / L, and the concentration of borofluoride ions is not particularly limited. For example, it is the range of 10 mg / L-10000 mg / L.

  Examples of the calcium compound used in the first solidification step include calcium salts such as calcium hydroxide, calcium carbonate, and calcium chloride, and calcium hydroxide is preferable from the viewpoint of cost.

  The addition amount of the calcium compound in the first solidification step is, for example, in the range of 0.5 mol to 0.7 mol with respect to 1 mol of fluoride ions in the fluorine-containing wastewater to be treated. If the addition amount of the calcium compound is less than 0.5 mol with respect to 1 mol of fluoride ions, the fluorine concentration in the first solidified treated water may become high due to the small amount of calcium compound added. Exceeding the mole may be disadvantageous in cost.

  Although the reaction temperature in a 1st solidification process does not have a restriction | limiting in particular, For example, it is the range of 10 to 30 degreeC.

  The reaction pH in the first solidification step is preferably in the range of 7-9. When the reaction pH of the first solidification step is less than 7, the solidified calcium fluoride may be redissolved, and when it exceeds 9, the cost may be disadvantageous.

  Examples of the aluminum compound used in the aggregation step include aluminum salts such as polyaluminum chloride (PAC), aluminum chloride, and aluminum sulfate.

  The addition amount of the aluminum compound in the aggregation step is, for example, in the range of 100 to 1000 mg / L. If the added amount of the aluminum compound is less than 100 mg / L, the aggregation may be poor, and if it exceeds 1000 mg / L, the cost may be disadvantageous.

  Although there is no restriction | limiting in particular in the reaction temperature in an aggregation process, For example, it is the range of 10 to 30 degreeC.

  The reaction pH in the aggregation step is preferably in the range of 6-8. If the reaction pH in the aggregation process is less than 6 and exceeds 8, the aggregation failure may occur.

  The separation method in the first solid-liquid separation step is not particularly limited, and examples thereof include sedimentation separation by natural sedimentation, pressurized flotation, membrane separation, and the like, and sedimentation separation is preferable from the viewpoint of cost.

  Examples of the aluminum compound used in the decomposition step include aluminum salts such as polyaluminum chloride (PAC), aluminum chloride, and aluminum sulfate.

  The addition amount of the aluminum compound in the decomposition step is, for example, in the range of 3 mol to 10 mol as aluminum with respect to 1 mol of borofluoride ions in the separated water. When the addition amount of the aluminum compound is less than 3 mol per mol of the borofluoride ion, the decomposition rate may be remarkably reduced, and when it exceeds 10 mol, the cost may be disadvantageous.

  Although the reaction temperature in a decomposition process does not have a restriction | limiting in particular, For example, it is the range of 10 to 30 degreeC. If the reaction temperature is less than 10 ° C, the decomposition rate may be remarkably reduced, and if it exceeds 30 ° C, heating is required, which may be disadvantageous in terms of cost.

  The reaction pH in the decomposition step is preferably in the range of 2 to 4. To reduce the reaction pH in the decomposition step to less than 2, a large amount of acid is required, which may be disadvantageous in cost. When it exceeds 4, the borofluoride ion may hardly be decomposed at room temperature.

  The decomposition step may include a first decomposition step for reacting at pH 2 or lower and a second decomposition step for further reacting the first decomposition treated water obtained in the first decomposition step at pH 2 to 4. By making the borofluoride ion decomposition tank multistage and reacting at pH 2 or lower first, then reacting at pH 2-4, the discharge standard can be satisfied within a reaction time of, for example, several hours without any particular heating. It becomes easier to obtain treated water quality. The concentration of borofluoride ions can be effectively reduced rather than simply reacting under a certain condition of pH 5 or lower.

  Examples of the calcium compound used in the second solidification step include calcium salts such as calcium hydroxide, calcium carbonate, and calcium chloride, and calcium hydroxide is preferable from the viewpoint of cost.

  The amount of calcium compound added in the second solidification step is, for example, in the range of 2 mol to 2.5 mol with respect to 1 mol of borofluoride ions in the separated water. When the amount of calcium compound added is less than 2 moles per mole of borofluoride ions, fluorine may not be solidified sufficiently, and when it exceeds 2.5 moles, the cost may be disadvantageous. There is.

  Although the reaction temperature in a 2nd solidification process does not have a restriction | limiting in particular, For example, it is the range of 10 to 30 degreeC.

  The reaction pH in the second solidification step is preferably in the range of 7-9. If the reaction pH of the second solidification step is less than 7, the solidification reaction may be inhibited. If it exceeds 9, the cost may be disadvantageous.

  The separation method in the second solid-liquid separation step is not particularly limited, and examples thereof include sedimentation separation by natural sedimentation, pressurized flotation, membrane separation and the like, and sedimentation separation is preferable from the viewpoint of cost.

  Although there is no restriction | limiting in particular as an acid used for reproduction | regeneration of sludge in a reproduction | regeneration process, it is preferable that it is at least 1 of hydrochloric acid, a sulfuric acid, and nitric acid, and hydrochloric acid is more preferable from viewpoints, such as reactivity.

  The reaction pH in the regeneration of sludge in the regeneration step is preferably 4 or less, and more preferably 2 or less. Usually, since the pH of the decomposition step is acidic, the amount of acid added can be reduced as compared with the case where sludge is regenerated with alkali. If the reaction pH in the regeneration of sludge in the regeneration process exceeds 4, aluminum may not be sufficiently regenerated.

  Although the reaction temperature in a reproduction | regeneration process does not have a restriction | limiting in particular, For example, it is the range of 10 to 30 degreeC. If the reaction temperature is less than 10 ° C, the regeneration rate may be slow, and if it exceeds 30 ° C, heating may be required, which may be disadvantageous in terms of cost.

  The regenerated sludge to be returned to the coagulation step is preferably regenerated and returned, for example, from 5 to 50 mass% of the solid-liquid separated sludge. Moreover, it is preferable that the regenerated sludge to be returned to the decomposition step is regenerated and returned, for example, from 5 to 50% by mass of the sludge separated into solid and liquid.

  In order to further reduce the amount of aluminum compound added and more efficiently treat wastewater containing borofluoride ions, it is preferable to return the regenerated sludge to both the agglomeration step and the decomposition step in the return step.

  Further, the regenerated sludge may be returned to the second solidification step. By returning the regenerated sludge to the second solidification step, the aluminum concentration in the second solidification step is increased and the ability to adsorb fluorine is increased, so that it becomes easier to obtain treated water having a fluorine concentration that satisfies the discharge standard.

  The fluorine-containing wastewater treatment method and treatment apparatus according to the present embodiment includes, for example, fluorine-containing wastewater containing fluoride ions and borofluoride ions discharged from flue gas desulfurization equipment, and fluorine-containing wastewater discharged from a glass etching step. It can be suitably applied to such processing.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Examples 1 and 2, Reference Examples 1 to 6 , Comparative Examples 1 to 5>
Using the processing apparatus shown in FIG. 1, experiments were conducted under the following conditions using borofluoride ions: 160 mg / L, fluoride ions: 1500 mg / L, and pH 2 glass etching wastewater as raw water.

[Experimental conditions]
(1) First solidification step Calcium compound to be added: calcium hydroxide (Ca (OH) ₂ )
Amount of calcium compound added: 3700 mg / L
Reaction pH 9, Ca agent: Ca (OH) ₂ , 3700 mg / L
Reaction temperature: 20 ° C
Reaction time: 10 minutes (2) Aggregation step Aluminum compound to be added: 10% polyaluminum chloride (PAC) aqueous solution Addition amount of aluminum compound: as shown in Table 1 Reaction pH 7
Reaction temperature: 20 ° C
Reaction time: 10 minutes (3) First solid-liquid separation step Solid-liquid separation method: sedimentation separation pH 7
(4) Decomposition step Aluminum compound to be added: 10% polyaluminum chloride (PAC) aqueous solution Addition amount of aluminum compound: as shown in Table 1 Reaction pH 2
Reaction temperature: 20 ° C
Reaction time: 2 hours (5) Second solidification step Calcium compound to be added: Calcium hydroxide (Ca (OH) ₂ )
Amount of calcium compound added: 1300 mg / L
Reaction pH 9
Reaction temperature: 20 ° C
Reaction time: 10 minutes (6) Second solid-liquid separation step Solid-liquid separation method: Sedimentation separation pH 7
(7) Regeneration process (Comparative Example 1 is not regenerated or returned)
Regenerant to be added: acid (hydrochloric acid, Examples 1 and 2, Reference Examples 1 to 6 ), alkali (sodium hydroxide, Comparative Examples 2 and 3) or no addition (Comparative Examples 4 and 5)
Reaction pH: as shown in Table 1 Reaction temperature: 20 ° C
Reaction time: 10 minutes (8) Return process Return amount: As shown in Table 1

For Examples 1 and 2, Reference Examples 1 to 6 , and Comparative Examples 1 to 5, the total fluorine concentration (total F) of the obtained treated water was measured using a total fluorine measuring device (Auto Analyzer III, manufactured by BRAN + LUEBBE). The results are shown in Table 1. The total fluorine concentration of the treated water is the total value of fluorine of borofluoride ions and fluorine of fluoride ions.

-In Reference Example 1, 30% by mass of sludge generated in the second solid-liquid separation step was regenerated at pH 4 by acid addition and returned to the aggregation step, so that the total F of separated water was greatly reduced. Therefore, the total treated water F became 8 mg / L or less of the discharge standard value.
-In Reference Example 2, 30% by mass of sludge generated in the second solid-liquid separation process is regenerated at pH 4 by acid addition and returned to the decomposition process, so that the amount of PAC added in the decomposition process is reduced, and treated water Total F became 8 mg / L or less of the discharge standard value.
In Reference Example 3, 30% by mass of sludge generated in the second solid-liquid separation process was regenerated at pH 2 by acid addition and returned to the aggregation process, so that the total F of separated water was greatly reduced. Therefore, the total treated water F became 8 mg / L or less of the discharge standard value.
-In Reference Example 4, 30% by mass of sludge generated in the second solid-liquid separation process is regenerated at pH 2 by acid addition and returned to the decomposition process, so that the amount of PAC added in the decomposition process is reduced, and treated water Total F became 8 mg / L or less of the discharge standard value.
-In Example 1 , sludge generated in the second solid-liquid separation step is regenerated at pH 2 by acid addition, and is returned to both the aggregation step and the decomposition step by 5% by mass, thereby being added in the aggregation step and the decomposition step. The amount of PAC could be reduced.
In Example 2 , sludge generated in the second solid-liquid separation process is regenerated at pH 2 by acid addition, and is added to both the aggregation process and the decomposition process by 30% by mass, so that it is added in the aggregation process and the decomposition process. The amount of PAC could be greatly reduced.
In Reference Example 5 , 30% by mass of sludge generated in the second solid-liquid separation process was regenerated at pH 5 by acid addition and returned to the aggregation process. Although the total F of treated water was lower than that of Comparative Example 1, it did not become 8 mg / L or less, which is the discharge standard value.
In Reference Example 6 , 30% by mass of sludge generated in the second solid-liquid separation step was regenerated at pH 5 by acid addition and returned to the decomposition step. Although the total F of treated water was lower than that of Comparative Example 1, it did not become 8 mg / L or less, which is the discharge standard value.

In Comparative Example 1, since the sludge generated in the second solid-liquid separation process was not returned, the total treated water F was a high value of 32 mg / L.
In Comparative Example 2, 30% by mass of sludge generated in the second solid-liquid separation process was regenerated at pH 10 by alkali addition and returned to the coagulation process, but the effect was low and the total F of treated water was as high as 22 mg / L Met.
In Comparative Example 3, 30% by mass of sludge generated in the second solid-liquid separation step was regenerated at pH 10 by alkali addition and returned to the decomposition step, but the effect was low, and the total F of treated water was 8 mg / L or less did not become.
In Comparative Example 4, 30% by mass of the mud generated in the second solid-liquid separation step was returned to the aggregation step without being regenerated, but the effect was low, and the total treated water F was as high as 28 mg / L.
In Comparative Example 5, 30% by mass of the sludge generated in the second solid-liquid separation step was returned to the decomposition step without being regenerated, but the effect was weak and the total treated water F did not become 8 mg / L or less.

  DESCRIPTION OF SYMBOLS 1 Waste water treatment apparatus, 10 1st solidification tank, 12 Coagulation tank, 14 1st sedimentation tank, 16 Decomposition tank, 18 2nd solidification tank, 20 2nd sedimentation tank, 22 Regeneration tank, 24 Raw water piping, 26 1st Solidified treated water pipe, 28 Aggregated treated water pipe, 30 Separated water pipe, 32 Decomposed treated water pipe, 34 Second solidified treated water pipe, 36 Treated water pipe, 38 Sludge pipe, 40 Return pipe, 42, 44, 46 , 48, 50 Stirrer.

Claims (4)

A first solidification step of adding a calcium compound to waste water containing fluoride ions and borofluoride ions, and solidifying the fluoride ions;
An agglomeration step in which an aluminum compound is further added to the reaction liquid obtained in the first solidification step to agglomerate;
A first solid-liquid separation step for solid-liquid separation of the sludge generated in the aggregation step;
A decomposition step of adding an aluminum compound to the separated water obtained in the first solid-liquid separation step and decomposing the borofluoride ions;
A second solidification step of adding a calcium compound to the decomposition-treated water containing fluoride ions generated in the decomposition step, and solidifying the fluoride ions;
A second solid-liquid separation step for solid-liquid separation of the sludge generated in the second solidification step;
A regeneration step of regenerating sludge by adding an acid to at least a part of the sludge solid-liquid separated in the second solid-liquid separation step ;
A returning step of returning the playback sludge the reproduction as in the aggregation step and the decomposition Engineering,
A method for treating fluorine-containing wastewater, comprising: It is a processing method of the fluorine content drainage according to claim 1,
A method for treating fluorine-containing wastewater, wherein a reaction pH in sludge regeneration in the regeneration step is 4 or less. A first solidifying means for adding a calcium compound to waste water containing fluoride ions and borofluoride ions, and solidifying the fluoride ions;
An aggregating means for further adding an aluminum compound to the reaction liquid obtained in the first solidification step to agglomerate;
First solid-liquid separation means for solid-liquid separation of the sludge generated in the aggregation step;
A decomposition means for adding an aluminum compound to the separated water obtained by the first solid-liquid separation means and decomposing the borofluoride ions;
A second solidifying means for solidifying the fluoride ions by adding a calcium compound to the decomposition treated water containing fluoride ions generated by the decomposition means;
Second solid-liquid separation means for solid-liquid separation of the sludge produced by the second solidification means;
A regeneration means for regenerating sludge by adding acid to at least a part of the sludge solid-liquid separated by the second solid-liquid separation means ;
And returning means for returning the reproduction sludge the reproduction to said aggregation means and the degradation hand stage,
An apparatus for treating fluorine-containing wastewater, comprising: The fluorine-containing wastewater treatment apparatus according to claim 3 ,
A treatment apparatus for fluorine-containing wastewater, wherein a reaction pH in sludge regeneration of the regeneration means is 4 or less.

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