JP4752351B2 - Method and apparatus for treating fluorine-containing water - Google Patents

Description

  The present invention relates to a method and apparatus for treating fluorine-containing water, and in particular, in two-stage treatment of fluorine-containing water by a calcium fluoride method and a hydroxide coprecipitation method, an efficient treatment is performed with a small amount of chemical use. The present invention relates to a method and apparatus for obtaining high-quality treated water.

  Fluorine-containing wastewater discharged from silicon wafer manufacturing process in semiconductor parts manufacturing, pickling wastewater discharged from stainless steel plate manufacturing process, aluminum surface treatment wastewater, hydrofluoric acid manufacturing wastewater, fertilizer manufacturing wastewater, waste incineration wastewater, etc. Needs to be discharged after fluorine removal treatment to meet the drainage standards. Regarding fluorine-containing wastewater, the development of treatment technology that can further reduce the fluorine concentration of treated water is expected as the wastewater standard was strengthened from 15 mg / L to 8 mg / L in 2001. It is rare.

  Conventionally, a calcium fluoride method and a hydroxide coprecipitation method as advanced treatments are known as methods for treating fluorine-containing water. As shown in FIG. Thereafter, a two-stage treatment method is also known in which advanced treatment is performed by the hydroxide coprecipitation method in the second stage (Non-Patent Document 1). That is, in the calcium fluoride method, the fluorine concentration of the treated water cannot be reduced below the solubility of calcium fluoride, and the waste water standard cannot be satisfied, so such a two-stage treatment is adopted.

  In the calcium fluoride method, after adding a calcium compound to the raw water (fluorine-containing water) from the raw water tank 11 (first reaction tank 12), a neutralizer is added to adjust the pH to around neutral (second reaction) In the tank 13), an insoluble salt of calcium fluoride is produced by the reaction between fluorine and calcium, and a polymer flocculant is added to perform a coagulation treatment (coagulation tank 14), followed by solid-liquid separation (precipitation tank 15). is there. In this method, slaked lime is generally used as the calcium compound, and inexpensive sulfuric acid is usually used as the neutralizing agent, but hydrochloric acid may also be used.

The hydroxide coprecipitation method uses a coprecipitation action when aluminum is precipitated as aluminum hydroxide, and is generally used for advanced treatment. In this method, polyaluminum chloride (PAC) or aluminum sulfate (sulfuric acid band) is added to raw water (the first-stage treated water in FIG. 3) (first reaction tank 16), and then neutralized with a neutralizing agent (first 2 reaction tank 17), a polymer flocculant is added to perform agglomeration treatment (aggregation tank 18), and then solid-liquid separation (precipitation tank 19) is performed. In this method, the pH of the treated water becomes acidic by adding an aluminum compound such as PAC, but the treatment near neutrality can be performed most efficiently, so sodium hydroxide or the like is added as an alkaline agent for neutralization. is doing.
“Pollution Prevention Technology and Regulations” pp. 288-289

  After adding slaked lime to fluorine-containing water, the calcium fluoride method, in which the pH is adjusted to neutral using a neutralizing agent such as sulfuric acid or hydrochloric acid, improves slaked lime in order to improve the treatment water quality by improving the removal of fluorine. When a large amount of is added, the amount of neutralizing agent necessary for neutralization increases, and the chemical cost increases. In addition, when sulfuric acid is used as the neutralizing agent, gypsum is produced by the reaction of slaked lime and sulfuric acid, and the slaked lime added to the fluorine-containing water is not effectively used for fluorine removal. There was also a problem that the amount of generated sludge increased. When the treated water by the calcium fluoride method is further treated by the hydroxide coprecipitation method, by adding an aluminum compound such as PAC, in order to adjust the lowered pH to near neutralization, It is necessary to use a neutralizing agent such as sodium, and there is a problem that the total amount of neutralizing agent used is large as a result of the large amount of neutralizing agent used in the first and second stages.

  The present invention solves the above-mentioned conventional problems, and in the two-stage treatment of fluorine-containing water using the calcium fluoride method and the hydroxide coprecipitation method, the treatment of fluorine-containing water for reducing the amount of neutralizing agent used It is an object to provide a method and apparatus.

The method for treating fluorine-containing water according to the present invention (Claim 1) includes a first fluorine removal step in which a calcium compound flocculant is added to fluorine-containing water and subjected to agglomeration treatment, followed by solid-liquid separation, and the first fluorine Fluorine-containing water having a second fluorine removal step of solid-liquid separation after adding an aluminum compound flocculant to the treated water obtained in the removing step (hereinafter referred to as “first treated water”) In the first fluorine removal step, a calcium compound flocculant is added to the fluorine-containing water to adjust the pH to 10.0 to 13.0, and then sulfuric acid is added as a neutralizing agent . pH of the treated water performs a process such that 8-10, in said second fluorine removal process, 100 to 500 mg / L was added to said first treated water LAC as a aluminum compound-based flocculant And more acid And adjusting the pH6~7 added.

The method for treating fluorine-containing water according to claim 2 is characterized in that, in claim 1, the calcium compound flocculant is slaked lime .

  The method for treating fluorine-containing water according to claim 3 is the method according to claim 1 or 2, wherein the separated sludge obtained in the first fluorine removal step is mixed with the calcium compound flocculant and added to the fluorine-containing water. It is characterized by that.

The apparatus for treating fluorine-containing water according to the present invention (Claim 4) includes a first fluorine removing means for solid-liquid separation after adding a calcium compound flocculant to the fluorine-containing water and subjecting it to aggregation treatment, and the first fluorine Fluorine-containing water having a second fluorine removing means for solid-liquid separation after adding an aluminum compound flocculant to the treated water obtained by the removing means (hereinafter referred to as “first treated water”) in the processing apparatus, in said first fluorine removal means, adding calcium compound-based flocculant to the fluorine containing water and pH10.0~13.0 with, then p H8 ~ by addition of sulfuric acid as a neutralizing agent give 10 first treated water, the added 100 to 500 mg / L the LAC as aluminum compound flocculating agent to said first treated water in the second fluorine removal means, the addition of further acid pH6~7 Adjust to It is characterized in.

The fluorine-containing water treatment apparatus according to claim 5 is characterized in that, in claim 4, the calcium compound flocculant is slaked lime .

  The apparatus for treating fluorine-containing water according to claim 6 is the treatment apparatus according to claim 4 or 5, wherein the separated sludge obtained by the first fluorine removing means is mixed with the calcium compound flocculant and added to the fluorine-containing water. It has the means.

  In the present invention, in the first-stage fluorine removal treatment with the calcium compound-based flocculant, the treatment is performed under conditions such that the pH of the treated water is 8 to 10. Therefore, the pH increased by the addition of the calcium compound-based flocculant is adjusted to pH 7 Compared to the conventional method of returning to neutrality, the amount of neutralizing agent (acid) used is sufficient.

In addition, in the second-stage fluorine removal treatment in which the aluminum compound-based flocculant is added to the treated water obtained by the first-stage fluorine removal treatment to perform aggregation and solid-liquid separation, LAC is used as the aluminum compound-based flocculant. By using this, pH adjustment of the pH-alkaline first treated water can be performed with the aluminum compound-based flocculant itself. That is, in the present invention, LAC can function not only as an aluminum compound-based flocculant but also as a neutralizing agent in the second-stage fluorine removal treatment. For this reason, it is possible to further reduce the amount of acid used as a neutralizing agent for making the treated water of the second stage fluorine removal treatment neutral in pH.

Conventionally, examples of the aluminum compound-based flocculant used in the hydroxide coprecipitation method include PAC and sulfuric acid band, but these chemicals have a high pH, and if the addition amount is the same, the pH of the treated water is adjusted. Lowering effect is low. According to the present invention, the amount of neutralizing agent can be reduced by using LAC as compared to the case of using PAC or the like.

  Therefore, according to the present invention, it is possible to reduce the drug cost by reducing the amount of neutralizing agent used in both the first stage and the second stage.

  In the first stage fluorine removal treatment, the treatment water is treated so that the pH of the treated water is 8.5 to 10, so that the fluorine concentration of the first treated water is compared with the conventional method performed at a neutral pH of 7. However, the fluorine removal efficiency higher than that of the conventional method can be obtained for the following reasons.

  That is, in this first stage fluorine removal treatment, when sulfuric acid is used as a neutralizing agent, as described above, the formation of gypsum and the production of effective calcium due to the formation of an inactive intermediate even below the solubility. Although there was a problem of reduction and increase in the amount of sludge, in the present invention, the amount of neutralizing agent used can be reduced, so it is possible to adjust the pH with the amount of sulfuric acid added without causing such a problem, Problems of consumption and increased sludge are prevented. As a result, the added slaked lime is effectively used for removing fluorine, and the quality of the first treated water is also good. As a result, the quality of the final treated water is also good.

In the present invention, as the aluminum compound-based flocculant, LAC: Liquid Aluminum Chloride produced from electrolytic aluminum waste is used .

  In addition, a part of the separated sludge obtained by the first stage fluorine removal treatment may be mixed with the calcium compound flocculant and added to the fluorine-containing water. In this case, the crystallinity of the sludge is improved. In addition, it is possible to improve the sedimentation property and decrease the water content, to further improve the quality of the treated water and to reduce the amount of generated sludge (claims 3 and 6).

  Hereinafter, embodiments of a method and apparatus for treating fluorine-containing water according to the present invention will be described in detail with reference to the drawings.

  1 and 2 are system diagrams showing an embodiment of a method and apparatus for treating fluorine-containing water according to the present invention. 1 and 2, members having the same functions as those shown in FIG.

  In FIG. 1, raw water (fluorine-containing water) from the raw water tank 11 is introduced into the first reaction tank 12, and after adding the calcium compound-based flocculant in the first reaction tank 12, The pH is adjusted by introducing a neutralizing agent, and an inert salt of calcium fluoride is generated by a reaction between fluorine and calcium. The reaction liquid in the second reaction tank 13 is introduced into a coagulation tank 14 and a polymer coagulant is added for coagulation treatment, followed by solid-liquid separation in the precipitation tank 15.

  In the first fluorine removal treatment, the calcium compound flocculant added to the raw water is not particularly limited, but slaked lime is usually used. However, it is not limited to slaked lime at all, and calcium chloride, calcium carbonate, or the like may be used. These calcium compound type flocculants may be used individually by 1 type, and may use 2 or more types together.

  The addition amount of the calcium compound-based flocculant such as slaked lime is determined by the fluorine concentration in the raw water, and is preferably about 1 to 10 times, particularly about 2 to 5 times the reaction equivalent with respect to the fluorine concentration of the raw water. If the amount of slaked lime added is too small, the fluorine in the raw water cannot be removed sufficiently, and if it is too large, not only slaked lime but also the amount of acid added for subsequent neutralization will increase. In the present invention, since the pH of the treated water is 8 to 10, the amount of acid added as a neutralizing agent can be reduced. For this reason, since there is no problem of wasteful consumption of slaked lime due to gypsum generation or the like when sulfuric acid is used as a neutralizing agent, the fluorine in fluorine-containing water can be added without adding an excessive amount of slaked lime more than the reaction equivalent. It can be removed efficiently.

The solution after adding slaked lime to raw water has a pH of 10.0 to 13. Since it becomes 0 alkaline, then in the second reaction tank 13, an acid as a neutralizing agent is added to this solution to adjust the pH. This pH adjustment is performed so that the treated water (supernatant water) obtained in the precipitation tank 15 has a pH of 8 to 10, preferably 8.5 to 9.5. Generally, since the pH of the first treated water is equal to the adjusted pH of the second reaction tank 13, an acid may be added in the second reaction tank 13 so that the pH is 8-10. Further, the pH of the first treated water is determined from the pH value of the final treated water (pH of about 7), the amount of raw water, the pH of the aluminum compound-based flocculant in the second stage fluorine removal treatment and the amount added, and the neutralizing agent. It can also be obtained by calculation from the type and amount added.

  If the pH of the first treated water is lower than 8, the effect of reducing the amount of neutralizing agent used according to the present invention cannot be sufficiently obtained. If the pH of the first treated water is higher than 10, the neutralizing agent ( A large amount of acid) is required, which is not preferable.

The acid as a neutralizing agent, is sulfuric acid used. After the acid addition, it is preferable to stir the mixture for a predetermined time, for example, about 5 to 20 minutes.

  In the second reaction tank 13, the acid is added to adjust the pH, and after the aggregation treatment for a predetermined time, the polymer flocculant is preferably further added to the aggregation tank 14 for the aggregation treatment. As the polymer flocculant, one or more of polyacrylamide partial hydrolyzate, sodium polyacrylate, polyvinylamidine and the like can be used, and the amount added is the quality of raw water to be treated and the polymer used. Although it varies depending on the flocculant, it is usually about 0.1 to 5 mg / L.

  The coagulation treatment liquid is then subjected to solid-liquid separation to obtain treated water. For this solid-liquid separation, a membrane separator or the like can be used in addition to the precipitation tank 15.

  The treated water of the first stage fluorine removal treatment (the supernatant water of the precipitation tank 15) is then added with an aluminum compound flocculant in the first reaction tank 16 and further neutralized in the second reaction tank 17. After the agent is added and the pH remaining neutral and further remaining fluorine is insolubilized by the coprecipitation action of aluminum hydroxide, the polymer flocculant is added in the agglomeration tank 18 for agglomeration treatment, and then the solid liquid in the precipitation tank 19 To be separated.

In the second fluorine removal treatment, the aluminum compound-based flocculant added to the treated water (first treated water: the supernatant water of the precipitation tank 15) obtained by the first fluorine removal treatment has a pH of 3 or less, particularly pH 2. .5 or less, especially pH1.5 or less, preferably in an aluminum concentration of 6 wt% or less of conditions, pH 3 or less, in particular pH2.5 or less, especially pH1.5 Ru following strongly acidic aluminum-based coagulant der chloride. If this pH value exceeds 3, the neutralization effect due to the addition of this cannot be sufficiently obtained, and the effect of reducing the amount of acid added as a neutralizing agent in the second fluorine removal treatment is sufficient. Can't get to. Also, when the pH exceeds 3, the aluminum ions take a polymer-like form, whereas when the pH is 3 or less, the aluminum ions are dispersed. Dispersed aluminum ions aggregate in a network at the time of addition, so that processing efficiency is improved. Here, the pH of the aluminum compound-based flocculant is a value measured immediately before using the aluminum compound-based flocculant, and in the present invention, at this time, an aluminum concentration of 6% by weight or less indicates pH of 3 or less. It is preferable. In the present invention, “aluminum chloride-based” means that the proportion of aluminum chloride in components other than water is 50% by weight or more.

Aluminum compound flocculating agent used in the present invention are L AC.

  In addition, PAC generally used as an aluminum compound-based flocculant exhibits a pH of 4 to 5 under the condition of an aluminum concentration of 5.3% by weight. On the other hand, LAC has a lower proportion of aluminum hydroxide than PAC, almost 100% is aluminum chloride, and the pH when diluted with water to an aluminum concentration of 5.3% by weight is about 0.00. Since it is strongly acidic with 5, it is effective in the present invention. However, even in the case of PAC, by adding mineral acids such as hydrochloric acid and sulfuric acid and adjusting the aluminum concentration to 6% by weight or less, the pH is 3 or less, particularly 2.5 or less, especially 1.5 or less. Thus, it can be suitably used in the present invention. Alternatively, LAC and PAC may be mixed to form an aluminum compound-based flocculant.

  Such an aluminum compound-based flocculant may be diluted and added for handling. Here, the water used for the preparation of the aqueous solution may be city water, industrial water, or treated water obtained by the treatment according to the present invention, and may be other waste water as described later. It is important to add as an aqueous solution in order to obtain a high neutralizing action.

  If the amount of the aluminum compound-based flocculant is too small, the advanced treatment of fluorine by performing the two-stage fluorine removal treatment cannot be sufficiently performed, and if it is too large, the amount of sludge increases and the pH in the treatment system is increased. Therefore, the addition amount of the aluminum compound-based flocculant is, for example, 100 to 500 mg / L, particularly 200 to 400 mg / L for the first treated water having a pH of 9, for example, generally 50 to It is preferable to be about 500 mg / L.

  The pH after adding the aluminum compound-based flocculant to the first treated water is usually about 5 to 8, although it depends on the pH of the first treated water. Add to adjust pH to pH neutral (pH 6-7).

  As the acid as the neutralizing agent, mineral acids such as hydrochloric acid and sulfuric acid, preferably sulfuric acid is used. However, depending on the pH of the first treated water, the pH of the aluminum compound-based flocculant, and the amount added, it may be necessary to add an alkali such as sodium hydroxide as a neutralizing agent.

  Moreover, in this invention, this neutralizing agent addition can also be made unnecessary by adjusting the pH and addition amount of the aluminum compound type coagulant to be used. That is, the neutralizing agent can be made unnecessary by adding the aluminum compound-based flocculant in such an amount that the pH of the treated water becomes neutral.

  After the addition of the neutralizing agent, it is preferable to agglomerate by stirring for a predetermined time, for example, about 5 to 20 minutes.

  In the second reaction tank 17, the pH is adjusted by adding a neutralizing agent, and after the aggregation treatment for a predetermined time, the polymer flocculant is preferably further added in the aggregation tank 18 for the aggregation treatment. As the polymer flocculant, one or more of polyacrylamide partial hydrolyzate, sodium polyacrylate, polyvinylamidine and the like can be used, and the amount added is the quality of raw water to be treated and the polymer used. Although it varies depending on the flocculant, it is usually about 0.1 to 5 mg / L.

  The coagulation treatment liquid is then subjected to solid-liquid separation to obtain treated water. For this solid-liquid separation, a membrane separator or the like can be used in addition to the precipitation tank 19.

  In the present invention, a part of the separated sludge (a part of the settled sludge in the settling tank 15) obtained in the first-stage fluorine removal treatment is returned to the raw water side, and the crystallinity of the sludge is improved by the seed crystal effect of the returned sludge. Improvement, reduction of moisture content, and improvement of sedimentation can also be achieved. In this case, the return sludge can be mixed with a calcium compound-based flocculant such as slaked lime, and the mixture (hereinafter sometimes referred to as “modified sludge”) can be added to the raw water. The quality of treated water can be improved and the amount of sludge generated can be reduced.

  FIG. 2 is a system diagram showing the case where such sludge is returned. A part of the separated sludge in the sedimentation tank 15 is introduced into the adjustment tank 20, and a calcium compound-based flocculant such as slaked lime is added to the adjustment tank 20. Then, after being mixed with the sludge, the same processing as in FIG. 1 is performed except that it is returned to the first reaction tank 12.

  In this case, if the amount of returned sludge is too small, the above effect due to sludge return cannot be obtained sufficiently, and if too much, the load on the settling tank increases, so the amount of newly generated sludge When the slaked lime and the return sludge are mixed, it is preferable that the pH of the modified sludge is 11 or more.

  The method shown in FIGS. 1 and 2 is an example of an embodiment of the present invention, and the present invention is not limited to the illustrated method unless it exceeds the gist. For example, in FIGS. 1 and 2, an aluminum compound-based flocculant is added to the first reaction tank 16 and a neutralizing agent is added to the second reaction tank 17, but the aluminum compound-based flocculant and the neutralizing agent are the same. It can also be added to the reaction vessel. In this case, the second reaction tank 17 becomes unnecessary. Alternatively, an aluminum compound flocculant and a neutralizing agent may be added to the first reaction tank 16, and a neutralizing agent may be further added in the second reaction tank 17. And as above-mentioned, addition of a neutralizing agent can also be made unnecessary, and the 2nd reaction tank 17 becomes unnecessary in that case. Further, means for adding an acid such as sulfuric acid or hydrochloric acid to the first reaction tank 12 or the pipe between the raw water tank 11 and the first reaction tank 12 in advance is provided, and the amount of slaked lime added to the first reaction tank 12 Can also be controlled by pH. 1 and 2, the settling tanks 15 and 19 discharge the necessary amount of separated sludge to the outside of the system by piping not shown.

  According to the present invention, it is possible to greatly reduce the amount of neutralizing agent used in both the first-stage fluorine removal treatment and the second-stage fluorine removal treatment, and in the first-stage fluorine removal treatment, The consumption of slaked lime is prevented, and high-quality treated water can be obtained by a good coprecipitation effect by an aluminum compound flocculant having a pH of 3 or less, preferably LAC, in the second-stage fluorine removal treatment. Furthermore, the amount of sludge generated can be reduced by reducing the amount of chemical used.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following, the measurement of the fluorine concentration was performed according to JIS K0102 34.1. A polyacrylamide partial hydrolyzate was used as the polymer flocculant.

  In the following Examples and Comparative Examples, processing was performed using electronic industrial wastewater containing 130 mg / L of fluorine as raw water.

Example 1
Raw water was treated according to the method shown in FIG.
After adding 890 mg / L of slaked lime to the raw water, the pH was adjusted to 8.5 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand for precipitation. Thereafter, 200 mg / L of LAC was added to the supernatant water, and the pH was adjusted to 7 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand for precipitation.
While measuring the fluorine concentration and sulfuric acid concentration in the obtained treated water (supernatant water), the amount of generated sludge was examined, and the results are shown in Table 1. In Table 1, the amount of chemicals other than the polymer flocculant is also shown.

Example 2
Raw water was treated according to the method shown in FIG.
For the slaked lime of 890 mg / L with respect to the raw water, the sludge produced in Example 1 is mixed in an amount that is 20 times the amount of sludge to be newly produced to obtain a modified sludge with a pH of 12.8, After this modified sludge was added to the raw water, the pH was adjusted to 8.5 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand for precipitation. Thereafter, 200 mg / L of LAC was added to the supernatant water, and the pH was adjusted to 7 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand for precipitation.
The fluorine and sulfuric acid concentrations of the treated water and the amount of sludge generated were examined, and the results are shown in Table 1 together with the amount of chemical used.

Comparative Example 1
Raw water was treated according to the conventional method shown in FIG.
After adding 890 mg / L of slaked lime to raw water, the pH was adjusted to 7 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand to precipitate. Thereafter, PAC 300 mg / L was added to the supernatant water, and the pH was adjusted to 7 using sodium hydroxide. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand to precipitate.
The fluorine and sulfuric acid concentrations of the treated water and the amount of sludge generated were examined, and the results are shown in Table 1 together with the amount of chemical used.

Comparative Example 2
In Example 1, the treatment was performed in the same manner except that PAC was used instead of LAC.
After adding 890 mg / L of slaked lime to the raw water, the pH was adjusted to 8.5 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand to precipitate. Thereafter, PAC 200 mg / L was added to the supernatant water, and the pH was adjusted to 7 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand to precipitate.
The fluorine and sulfuric acid concentrations of the treated water and the amount of sludge generated were examined, and the results are shown in Table 1 together with the amount of chemical used.

Comparative Example 3
In Comparative Example 2, the treatment was performed in the same manner except that the amount of PAC added was 300 mg / L.
After adding 890 mg / L of slaked lime to the raw water, the pH was adjusted to 8.5 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand to precipitate. Thereafter, PAC 300 mg / L was added to the supernatant water, and the pH was adjusted to 7 using sulfuric acid. After stirring for 30 minutes for aggregation treatment, 1 mg / L of a polymer flocculant was added and allowed to stand to precipitate.
The fluorine and sulfuric acid concentrations of the treated water and the amount of sludge generated were examined, and the results are shown in Table 1 together with the amount of chemical used.

  From Table 1, according to the present invention, it is possible to reduce the amount of chemicals used to obtain an equivalent water quality (6 mg-F / L), with a reduction effect of about 50% for sulfuric acid and about 30% for aluminum compounds. It can be seen that the amount of generated sludge was reduced by 10% or more. In particular, by returning the separated sludge in the first stage fluorine removal treatment and adding it to the raw water, it is possible to reduce the amount of sludge generation by 30% or more to a treated water quality fluorine concentration of 5 mg / L or less.

  Such a method and apparatus for treating fluorine-containing water according to the present invention includes fluorine-containing wastewater discharged from a silicon wafer manufacturing process in semiconductor component manufacturing, pickling wastewater discharged from a stainless steel plate manufacturing process, aluminum surface treatment wastewater, It is effective for the treatment of various fluorine-containing waters such as acid production wastewater, fertilizer production wastewater, and waste incineration wastewater.

It is a systematic diagram which shows embodiment of the processing method and apparatus of the fluorine-containing water of this invention. It is a systematic diagram which shows other embodiment of the processing method and apparatus of the fluorine-containing water of this invention. It is a systematic diagram showing a conventional method.

11 Raw water tank 12, 16 First reaction tank 13, 17 Second reaction tank 14, 18 Coagulation tank 15, 19 Precipitation tank 20 Adjustment tank

Claims (6)

A first fluorine removal step in which a calcium compound flocculant is added to fluorine-containing water and subjected to agglomeration treatment, followed by solid-liquid separation, and treated water obtained in the first fluorine removal step (hereinafter referred to as “first treated water”) In a method for treating fluorine-containing water having a second fluorine removal step in which an aluminum compound-based flocculant is added to and agglomerated and then solid-liquid separated,
In the first fluorine removal step, a calcium compound flocculant is added to the fluorine-containing water to obtain a pH of 10.0 to 13.0, and then sulfuric acid is added as a neutralizing agent to adjust the pH of the first treated water. 8-10 processing performs such that, in said second fluorine removal process is added 100 to 500 mg / L the LAC as a aluminum compound flocculating agent to said first processing water, further adding an acid And adjusting the pH to 6 to 7, a method for treating fluorine-containing water. The method for treating fluorine-containing water according to claim 1, wherein the calcium compound flocculant is slaked lime.   3. The method for treating fluorine-containing water according to claim 1, wherein the separated sludge obtained in the first fluorine removal step is mixed with the calcium compound flocculant and added to the fluorine-containing water. A first fluorine removing means for solid-liquid separation after adding a calcium compound-based flocculant to fluorine-containing water, and treated water obtained by the first fluorine removing means (hereinafter referred to as “first treated water”) In a treatment apparatus for fluorine-containing water having a second fluorine removing means for solid-liquid separation after adding an aluminum compound-based flocculant and aggregating treatment to
In said first fluorine removal means, adding calcium compound-based flocculant to the fluorine containing water and pH10.0~13.0 with, then the first processing of p H8 to 10 by addition of sulfuric acid as a neutralizing agent to obtain an aqueous, that said the LAC as an aluminum compound-based flocculant is added 100 to 500 mg / L with respect to said first treated water in the second fluorine removal means is adjusted to pH6~7 by adding further acid A fluorine-containing water treatment apparatus. The apparatus for treating fluorine-containing water according to claim 4, wherein the calcium compound flocculant is slaked lime.   6. The fluorine-containing water according to claim 4, further comprising means for mixing the separated sludge obtained by the first fluorine removing means with the calcium compound flocculant and adding the mixture to the fluorine-containing water. Processing equipment.

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