KR20060051767A - Treating method of drainage containing fluorine - Google Patents

Abstract

Add the agent containing calcium salt to the treated wastewater, adjust the pH to 4-12, add the first step of separating the formed precipitate, and add the drug containing alkali carbonate to the water after the first step It adjusts pH to 9-12, and consists of the 2nd process which isolate | separates the produced | generated deposit, and the deposit produced in the 2nd process is conveyed for pH control of a 1st process. As a result, the wastewater containing fluorine can be treated stably with respect to fluctuations in the load on the processing apparatus, and the amount of waste generated can be minimized.

Fluorine-containing drainage, treatment method, alkali carbonate

Description

Fluorine-containing wastewater treatment method {TREATING METHOD OF DRAINAGE CONTAINING FLUORINE}

1 is a graph showing the test results of Examples 1 to 5 and Comparative Examples 1 to 3 of the present invention.

2 is a graph showing test results of Examples 6 to 10 and Comparative Examples 4 to 6 of the present invention.

The present invention relates to a method for treating wastewater containing fluorine.

Examples of the wastewater containing fluorine include etching in a semiconductor manufacturing process of the electronic industry, substrate washing drainage, factory drainage such as pickling and electrolytic refining of aluminum in the manufacturing process of stainless steel, and drainage of a coal-fired power plant. Drainage may contain heavy metals. Conventionally, as a method of treating wastewater containing fluorine and heavy metals, a method of performing coagulation precipitation treatment by adding calcium salt to treated water to make fluorine calcium fluoride, insolubilizing heavy metals, and the like.

However, in the flocculation sedimentation treatment method, it is difficult to stably reduce the concentration of fluorine in the treated water to below the drainage standard value, and since the drainage standard implemented in July 2001 has a fluorine concentration of 8 mg / L or less, As said general treatment method, it was extremely difficult to satisfy the drainage criterion.

In order to satisfy the above drainage standard, a two-stage flocculation precipitation treatment method in which an aluminum salt or the like is further added to water that has been treated by the above-described general treatment method to reduce the fluorine concentration (for example, Japanese Patent No. 2912237). However, in the above treatment method, a large amount of aluminum salt or the like must be added to reduce the fluorine concentration, and since a good dehydration flock is not produced, dehydration and solid-liquid separation are difficult. There was a problem that a large amount of waste was generated.

In addition, the water obtained by the above general treatment method is passed through a tower filled with a fluorine adsorbent to adsorb and remove fluorine (for example, Japanese Patent Application Laid-Open No. 10-113672 and Japanese Patent Application Laid-Open). Although the reduction of fluorine concentration can be expected with this method, the treatment system becomes complicated, such as the regeneration of the adsorbent after the adsorbent breaks through. Moreover, the operating margin with respect to the change of the load to a processing apparatus, such as a change of drainage amount, is comparatively small.

Furthermore, there is also a method in which a compound containing a rare earth element is added to the treated water obtained by the above general treatment method to form an insoluble precipitate, thereby removing fluorine (for example, Japanese Patent Laid-Open No. 2002-1313). Reference). Since fluoride of rare earth elements is poorly soluble, removal of fluorine is expected, but there is a problem in dehydration of the produced precipitates, a large load on the filtration device, and loss of economy due to an increase in running cost.

This invention is made | formed in view of the above circumstances, The objective is that the wastewater containing fluorine can be processed to the criteria which satisfy | fills the drainage standard, and is stable also about the fluctuation | variation of the load to a processing apparatus. It is possible to provide a method for treating wastewater containing fluorine, which can minimize the amount of waste generated.

In order to achieve the above object, in the treatment method of fluorine-containing wastewater according to the present invention, after adding a chemical liquid contained in the form of calcium ions to the treated wastewater containing fluorine, at least one alkali carbonate solution is added to the pH. To 9 to 12, characterized in that to separate the resulting precipitate.

According to the present invention, the chemical liquid contained in the form of calcium ions is selected from the group of drugs containing calcium components.

According to the present invention, the at least one alkali carbonate solution is selected from the group of sodium carbonate, potassium carbonate, lithium carbonate and mixtures thereof.

Moreover, according to this invention, fluorine ion is adsorb | sucked and occluded by carbonation reaction in the said alkaline carbonate solution and the calcium ion liquid contained in the said to-be-processed wastewater.

Moreover, according to this invention, the production | generation rate of calcium carbonate produced by the said carbonation reaction is 90%, It is characterized by the above-mentioned.

Moreover, the processing method of the fluorine-containing wastewater by this invention is the 1st process of adding the chemical | medical agent containing a calcium salt in the wastewater to be processed, adjusting pH to 4-9, and solid-liquid separation of the produced deposit, and said agent The second step of adjusting the pH to 9-12 by separating the low concentration fluorine ions contained in the treated water after the solid-liquid separation in one step by adding a drug containing at least one alkali carbonate, and separating the resulting precipitate It is characterized by.

According to the present invention, the precipitate separated in the second step is recycled as a neutralizing agent for pH adjustment of the first step.

According to the present invention, first, a drug containing calcium salt is added to the wastewater to be treated, and the pH of the wastewater to be treated is adjusted to 4 to 12, preferably 9 to 10. As a chemical | medical agent to add, what added sodium hydroxide etc. to a calcium salt solution or slurry or solid, such as calcium hydroxide, calcium chloride, calcium carbonate, or these salts as needed is required. Here, since the amount of calcium required to generate calcium fluoride may be added to the amount of fluorine in the wastewater to be treated and adjusted to an appropriate pH, the amount of the chemical agent to be added is not limited to the above. The drainage after pH adjustment includes precipitates such as calcium fluoride, but the precipitate is solid-liquid separated by a thickener, solid-liquid separator, or the like, and the solution is transferred to the second process as water which has been treated in the first process. do.

Next, in the 2nd process, the chemical | medical agent containing sodium carbonate is added to the water processed by the 1st process, and pH is adjusted to 9-12, Preferably it is 10-11. Here, mainly, the calcium ion dissolved in the water which completed the process of the 1st process precipitates as calcium carbonate according to following Formula.

Ca ^{2 +} + Na ₂ CO _3- > CaCO ₃ ↓ + 2Na ⁺

As a chemical | medical agent to add, what added sodium hydroxide etc. to the sodium carbonate solution or the sodium carbonate solution is preferable. Here, a carbonate root necessary for precipitating calcium ions contained in the treated water as potassium carbonate is added, and the pH value in the treated water may be adjusted to a pH range where the solubility product of calcium carbonate is minimized. The agent to add is not limited to said thing. By this operation, calcium ions in the treated water precipitate as calcium carbonate, fluorine in the treated water is adsorbed to the precipitate, and the fluorine concentration in the treated water is stably reduced below the drainage standard. If the pH value is less than 9, the calcium carbonate production rate is low, so the adsorption of fluorine becomes insufficient, and if it exceeds 12, the alkalinity becomes excessively strong, and once the calcium carbonate produced is redissolved, the fluorine adsorbed once is poor. not.

In this way, the calcium carbonate produced in the water to be treated has a high fluorine ion adsorption capacity and high reaction activity. In addition, the coprecipitation effect of attracting and precipitating particulate calcium fluoride is precipitated. As a result, it is important to produce calcium carbonate in the treatment process step to enable high efficiency fluorine removal. In other words, the adsorption or occlusion in the present invention means that the fluorine ions in the treated water are adsorbed and fixed with calcium carbonate upon the production of calcium carbonate by the physical or chemical action of the fluorine ions. If the production rate of calcium carbonate is less than 90%, the adsorption performance of fluorine is low, which is not good.

The precipitate containing calcium carbonate produced by the above operation as a main component has both good sedimentability and dehydration, and can be easily solid-liquid separated from the treated water. The solution from which the precipitate is separated is water which has been defluorinated and neutralized with a chemical such as hydrochloric acid or sulfuric acid and then drained.

On the other hand, the separated precipitate contains calcium carbonate as a main component and a small amount of fluorine is adsorbed. Therefore, in this deposit, calcium exists in excess of the amount of calcium required to produce calcium fluoride with respect to the amount of fluorine in a deposit. When this deposit is returned to a 1st process, this excess calcium can be effectively recycled in order to produce a neutralizing agent or calcium fluoride. Moreover, by conveying a deposit, the amount of calcium newly thrown in a 1st process can be reduced.

That is, since only a small amount of calcium ions are present in the treated water, as a result, the amount of calcium added for the series of treatments is to be spent as almost all calcium fluoride. The generation of excessive precipitation for fluorine in the wastewater to be treated is suppressed, and the amount of waste generated can be minimized.

Moreover, according to this invention, it is possible to respond flexibly to the fluctuation | variation of the fluorine load (product of a fluorine concentration and a discharge amount) of waste water to be processed. For example, in the first step, when the fluorine load is lowered, since most of the required amount of calcium is supplied by the calcium carbonate returned from the second step, the amount of calcium newly added to adjust to a predetermined pH is Less. When the fluorine load increases, the calcium carbonate conveyed from the second step alone is insufficient in the amount of calcium supplied, so that the amount of calcium newly introduced to adjust to a predetermined pH increases.

In the second step, since the reaction shown in the above reaction formula is the main reaction, the pH of the water to be treated hardly changes while a precipitate of calcium carbonate is produced. When the necessary carbonate root is supplied to calcium in the water to be treated, and the formation of the precipitate is completed, sodium carbonate becomes excessive and the pH rises. Therefore, if the pH of the water to be treated is controlled to a predetermined value, the required amount of sodium carbonate is supplied autonomously.

As is clear from the above description, according to the fluorine-containing wastewater treatment method of the present invention, a high-quality treated wastewater from which fluorine is highly removed can be obtained.

Hereinafter, although an Example demonstrates this invention more concretely, compared with a comparative example, this invention is not limited to these Examples.

Comparative Examples 1-3 and Inventive Examples 1-5

A 1 L aqueous solution of pH 4 containing fluorine concentration 15 mg / L and calcium concentration 1000 mg / L (0.025 mol / L calcium chloride solution) was used as a sample. The pH was adjusted to 6-12 with 10 wt% sodium carbonate solution, and it stirred for 10 minutes, and the produced calcium carbonate was filtered and the fluorine concentration in the filtrate and the produced | generated amount of calcium carbonate were analyzed. In other words, the water temperature is 21 ~ 24 ℃. The results are shown in Table 1 and FIG. 1.

Under the treatment conditions in which the pH was maintained in the range of 9 to 12, the fluorine concentration in the filtrate was 8 mg / L or less (drainage standard), and it was confirmed that the fluorine removal enhancement process was possible.

TABLE 1

No Adjustable pH Fluoride Concentration in Filtrate (mg / L) CaCo ₃ production rate (%) Comparative Example 1 6.1 15.2 0 Comparative Example 2 7.1 14.9 8 Comparative Example 3 8 12 20 Example 1 8.9 7.1 94 Example 2 9.4 5.4 98 Example 3 10.2 3.9 99.8 Example 4 10.9 3.5 99.8 Example 5 12 5.8 89

Comparative Examples 4-6 and Inventive Examples 6-10

A 1 L aqueous solution of pH 4 containing fluorine concentration 15 mg / L and calcium concentration 4000 mg / L (0.10 mol / L calcium chloride solution) was used as a sample. The pH was adjusted to 6-12 with 10 wt% sodium carbonate solution, and it stirred for 10 minutes, and the produced calcium carbonate was filtered and the fluorine concentration in the filtrate and the produced | generated amount of calcium carbonate were analyzed. That is, water temperature is 21-25 degreeC. The results are shown in Table 2 and FIG.

Under the treatment conditions in which the pH was maintained in the range of 8 to 12, the concentration of fluorine in the filtrate was 8 mg / L or less (drainage standard), and it was found that the fluorine removal efficiency was improved when the amount of precipitated calcium carbonate increased. have.

TABLE 2

No Adjustable pH Fluoride Concentration in Filtrate (mg / L) CaCo ₃ production rate (%) Comparative Example 4 6 14.9 0 Comparative Example 5 7 15.2 0 Comparative Example 6 8 7.4 44 Example 6 9.1 4.8 94 Example 7 9.8 2 99.8 Example 8 10.5 0.8 99.8 Example 9 10.8 0.5 99.8 Example 10 12 2.4 94

Inventive Example 11

1 L of the to-be-processed water of 10 mg / L of fluorine concentrations was extract | collected to the polyethylene beaker. Next, 0.5 mL of 4 mol / L calcium chloride solution was added to this, pH was adjusted to 11 with 10 wt% sodium carbonate solution, stirring, and stirring for 10 minutes, fluorine ion was made to adsorb | suck to the produced calcium carbonate. Then, after solid-liquid separation by filtration operation, the fluorine ion concentration in a filtrate was measured with the ion chromatography analyzer. The fluorine concentration was 7.3 mg / L.

Inventive Example 12

1 L of water to be treated having a fluorine concentration of 10 mg / L was collected in a polyethylene beaker. Next, 1 mL of 4 mol / L calcium chloride solution was added to this, pH was adjusted to 11 with 10 wt% sodium carbonate solution, stirring, and stirring for 10 minutes, fluorine ion was made to adsorb | suck to the produced calcium carbonate. Then, after solid-liquid separation by filtration operation, the fluorine ion concentration in a filtrate was measured with the ion chromatography analyzer. The fluorine concentration was 6.5 mg / L.

Inventive Example 13

1 L of water to be treated having a fluorine concentration of 10 mg / L was collected in a polyethylene beaker. Next, 5 mL of a 4 mol / L calcium chloride solution was added to this, pH was adjusted to 11 with 10 wt% sodium carbonate solution, stirring, and stirring for 10 minutes, fluorine ion was made to adsorb | suck to the produced calcium carbonate. Then, after solid-liquid separation by filtration operation, the fluorine ion concentration in a filtrate was measured with the ion chromatography analyzer. The fluorine concentration was 3.6 mg / L.

Inventive Example 14

1 L of water to be treated having a fluorine concentration of 10 mg / L was collected in a polyethylene beaker. Next, 25 mL of 4 mol / L calcium chloride solution was added to this, pH was adjusted to 11 with 10 wt% sodium carbonate solution, stirring, and stirring for 10 minutes, fluorine ion was made to adsorb | suck to the produced calcium carbonate. Then, after solid-liquid separation by filtration operation, the fluorine ion concentration in a filtrate was measured with the ion chromatography analyzer. The fluorine concentration was 0.35 mg / L.

Inventive Example 15

1 L of water to be treated having a fluorine concentration of 10 mg / L was collected in a polyethylene beaker. Next, 50 mL of a 4 mol / L calcium chloride solution was added to this, pH was adjusted to 11 with 10 wt% sodium carbonate solution, stirring for 10 minutes, and fluorine ion was made to adsorb | suck to the produced calcium carbonate. Then, after solid-liquid separation by filtration operation, the fluorine ion concentration in a filtrate was measured with the ion chromatography analyzer. The fluorine concentration was 0.45 mg / L.

Inventive Example 16

1 L of water to be treated having a fluorine concentration of 10 mg / L was collected in a polyethylene beaker. Next, 100 mL of 4 mol / L calcium chloride solution was added to this, pH was adjusted to 11 with 10 wt% sodium carbonate solution, stirring, and stirring for 10 minutes, fluorine ion was made to adsorb | suck to the produced calcium carbonate. Then, after solid-liquid separation by filtration operation, the fluorine ion concentration in a filtrate was measured with the ion chromatography analyzer. The fluorine concentration was 0.75 mg / L.

Inventive Example 17

1 L of water to be treated having a fluorine concentration of 10 mg / L was collected in a polyethylene beaker. Next, 250 mL of 4 mol / L calcium chloride solution was added to this, pH was adjusted to 11 with 10 wt% sodium carbonate solution, stirring, and stirring for 10 minutes, fluorine ion was made to adsorb | suck to the produced calcium carbonate. Then, after solid-liquid separation by filtration operation, the fluorine ion concentration in a filtrate was measured with the ion chromatography analyzer. The fluorine concentration was less than 0.1 mg / L (below the lower limit of determination).

Inventive Example 18

100 ml of superfluoric acid-containing wastewater (fluorine concentration: 50 g / L, acetic acid concentration: 170 g / L) was placed in a beaker, and 67 ml of a mixture of a 25 wt% sodium hydroxide solution and a 25 wt% calcium hydroxide slurry was added to adjust the pH to 10. After stirring vigorously for 5 minutes and stirring for 3.5 hours slowly, it filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 10.4 mg / L.

Furthermore, 50 ml of the obtained filtrate was put into the beaker, the 5 wt% sodium carbonate solution was added, and pH was adjusted to 10.8. After stirring this vigorously for 30 minutes, the produced calcium carbonate was filtered using the filter. The fluorine concentration in the obtained filtrate was less than 1.0 mg / L.

Inventive Example 19

100 ml of superfluoric acid-containing wastewater (fluorine concentration: 6.6 g / L, acetic acid concentration: 22 g / L) was placed in a beaker, and 9 ml of a mixture of 25 wt% sodium hydroxide solution and 25 wt% calcium hydroxide slurry was added to adjust the pH to 10. . After stirring vigorously for 5 minutes and stirring for 3.5 hours slowly, it filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 10 mg / L.

Furthermore, 50 ml of the obtained filtrate was put into the beaker, the 5 wt% sodium carbonate solution was added, and pH was adjusted to 11.0. After stirring this vigorously for 30 minutes, the produced calcium carbonate was filtered using the filter. The fluorine concentration in the obtained filtrate was less than 4 mg / L.

Inventive Example 20

100 ml of superfluoric acid-containing wastewater (fluorine concentration: 0.22 g / L, acetic acid concentration: 3.3 g / L) was placed in a beaker, and 2.5 ml of a mixture of a 5 wt% sodium hydroxide solution and a 25 wt% calcium hydroxide slurry was added. Adjusted. After stirring vigorously for 5 minutes and stirring for 3.5 hours slowly, it filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 15 mg / L.

Further, 50 ml of the filtrate obtained was placed in a beaker, and a 5 wt% sodium carbonate solution was added to adjust the pH to 10.9. After stirring this vigorously for 30 minutes, the produced calcium carbonate slurry was filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was less than 5 mg / L.

Inventive Example 21

100 ml of superfluoric acid-containing wastewater (fluorine concentration: 0.22 g / L, acetic acid concentration: 3.3 g / L) was placed in a beaker, and 2.5 ml of a mixture of the calcium carbonate slurry obtained in Example 13 of the present invention was added to pH 10. Adjusted. After stirring vigorously for 5 minutes and stirring for 3.5 hours slowly, it filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 11 mg / L.

Furthermore, 50 ml of the obtained filtrate was put into the beaker, the 5 wt% sodium carbonate solution was added, and pH was adjusted to 10.9. After stirring this vigorously for 30 minutes, the produced calcium carbonate slurry was filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 5 mg / L.

Inventive Example 22

100 ml of superfluoric acid-containing wastewater (fluorine concentration: 0.22 g / L, acetic acid concentration: 3.3 g / L) was placed in a beaker, and 0.1 ml of a mixture of a 5 wt% sodium hydroxide solution and a 25 wt% calcium hydroxide slurry was added. Adjusted. After stirring vigorously for 5 minutes and stirring for 3.5 hours slowly, it filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 20 mg / L.

Furthermore, 50 ml of the obtained filtrate was put into the beaker, the 35 wt% hydrochloric acid solution and the 5 wt% sodium carbonate solution were added, and pH was adjusted to 9. After stirring this vigorously for 30 minutes, the produced calcium carbonate was filtered using the filter. The fluorine concentration in the obtained filtrate was 3 mg / L.

Inventive Example 23

100 ml of superfluoric acid-containing wastewater (fluorine concentration: 0.22 g / L, acetic acid concentration: 3.3 g / L) was placed in a beaker, and 1.0 ml of a mixture of a 5 wt% sodium hydroxide solution and a 25 wt% calcium hydroxide slurry was added. Adjusted. After stirring vigorously for 5 minutes and stirring for 3.5 hours slowly, it filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 20 mg / L.

Furthermore, 50 ml of the obtained filtrate was put in the beaker, the thing which mixed 5 wt% sodium carbonate solution and 25 wt% sodium hydroxide solution was added, and pH was adjusted to 9. After stirring this vigorously for 30 minutes, the produced calcium carbonate was filtered using the filter. The fluorine concentration in the obtained filtrate was 6 mg / L.

Inventive Example 24

100 ml of superfluoric acid-containing wastewater (fluorine concentration: 0.22 g / L, acetic acid concentration: 3.3 g / L) was placed in a beaker, and 3.0 ml of a mixture of a 5 wt% sodium hydroxide solution and a 25 wt% calcium hydroxide slurry was added. Adjusted. After stirring vigorously for 5 minutes and stirring for 3.5 hours slowly, it filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 15 mg / L.

Furthermore, 50 ml of the obtained filtrate was put into the beaker, the 35 wt% hydrochloric acid solution and the 5 wt% sodium carbonate solution were added, and pH was adjusted to 9. After stirring this vigorously for 30 minutes, the produced calcium carbonate was filtered using the filter. The fluorine concentration in the obtained filtrate was 7 mg / L.

Inventive Example 25

100 ml of superfluoric acid-containing wastewater (fluorine concentration: 0.22 g / L, acetic acid concentration: 3.3 g / L) was placed in a beaker, and 3.0 ml of a mixture of a 5 wt% sodium hydroxide solution and a 25 wt% calcium hydroxide slurry was added. Adjusted. After stirring vigorously for 5 minutes and stirring for 3.5 hours slowly, it filtered using 5A filter paper. The fluorine concentration in the obtained filtrate was 15 mg / L.

Furthermore, 50 ml of the obtained filtrate was put in the beaker, the 5 wt% sodium carbonate solution (adjusting the sodium hydroxide containing sodium hydroxide solution) was added, and pH was adjusted to 12. After stirring this vigorously for 30 minutes, the produced calcium carbonate was filtered using the filter. The fluorine concentration in the obtained filtrate was 5 mg / L.

Next, the comparative example corresponding to Examples 11-17 of this invention is demonstrated.

Comparative Example 7

1 L of water to be treated having a fluorine concentration of 10 mg / L was collected in a polyethylene beaker. Next, 50 g of particulate calcium carbonate was added thereto, and the pH was adjusted to 11 with 2.5 wt% sodium hydroxide solution, followed by stirring for 30 minutes. Then, after solid-liquid separation by the filtration operation, the fluorine ion concentration in the filtrate was measured with the ion chromatography analyzer. The fluorine concentration was 10.1 mg / L.

Comparative Example 8

1 L of water to be treated having a fluorine concentration of 10 mg / L was collected in a polyethylene beaker. Next, after adjusting pH to 11 with the 10 wt% calcium hydroxide slurry, 25 g of granular calcium carbonate was further added, and it stirred for 30 minutes. Then, after solid-liquid separation by the filtration operation, the fluorine ion concentration in the filtrate was measured with the ion chromatography analyzer. The fluorine concentration was 9.4 mg / L.

As can be seen from the above description, in the method according to the present invention, it is possible to adsorb and fix fluorine to the produced carbonate particles by using a carbonation reaction in a liquid by calcium ions and carbonate ions in the water to be treated, and excellent fluorine. The removal process can be realized. However, simply contacting fluorine ions in a liquid with a solid form such as calcium carbonate or calcium hydroxide in the form of particles or powders, as can be clearly seen from the comparative example, can not expect good fluorine removal.

As can be seen from the above description, according to the present invention, the wastewater containing fluorine can be treated to a level that satisfies the drainage criterion, and stable treatment is possible against fluctuations in the load on the processing apparatus and the amount of waste generated. It is possible to provide a treatment method for fluorine-containing wastewater which can minimize the

Claims (7)

After adding a chemical liquid containing calcium ions to the treated wastewater containing fluorine, at least one alkali carbonate solution is added to adjust the pH to 9 to 12, and the resulting precipitate is separated. Method of treatment of containing drainage. The method of claim 1, The chemical liquid contained in the form of calcium ions is selected from the group of drugs containing a calcium component. The method of claim 1, At least one alkali carbonate solution is selected from the group of sodium carbonate, potassium carbonate, lithium carbonate and mixtures thereof. The method of claim 1, A method for treating fluorine-containing wastewater, wherein fluorine ions are adsorbed and occluded by a carbonation reaction in a solution of the alkaline carbonate solution and calcium ions contained in the wastewater to be treated. The method of claim 4, wherein A method for treating fluorine-containing wastewater, wherein the rate of generation of calcium carbonate produced by the carbonation reaction is 90%. In the method for treating wastewater containing fluorine, the first step of adding a chemical agent containing calcium salt to the wastewater to be treated to adjust the pH to 4 to 9 and separating the resulting precipitate into solid-liquid separation; And a second step of adjusting the low concentration fluorine ions contained in the treated water after solid-liquid separation to pH 9-12 by adding a chemical agent containing at least one alkali carbonate, and separating the produced precipitate. Method of treating fluorine-containing drainage. The method of claim 6, A method for treating fluorine-containing wastewater, wherein the precipitate separated in the second step is reused as a neutralizing agent for pH adjustment of the first step.

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