JP5347664B2 - Method and apparatus for treating fluorine-containing wastewater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for treating fluorine-containing waste water which are capable of efficiently treating fluorine-containing waste water including hydrofluoric acid and ammonium fluoride such as BHF waste water in a narrow installation space and has high practicality even for the fluorine-containing waste water of a large flux and for the fluorine-containing waste water of a large flux fluctuation, too. <P>SOLUTION: Fluorine-containing waste water including hydrofluoric acid and ammonium fluoride is adjusted so as to fall into the range of pH 10 to 13 and is concentrated by vaporization, whereby ammonia is removed from separate distilled water that is separated and fluorine is removed from concentrated water. By concentrating the fluorine-containing waste water including hydrofluoric acid and ammonium fluoride in a condition of pH 10 to 13 by vaporization, ammonia is easily separated from a fluoride to the separate distilled water side and is concentrated to provide distilled water of high ammonia concentration and small flux and, therefore, ammonia in the separate vaporized water can be easily treated according to the normal method. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a treatment method and a treatment apparatus for fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride discharged from a manufacturing process of electronic products such as semiconductors and liquid crystals or elements thereof.

  Wet etching agent called buffered hydrofluoric acid (BHF) containing ammonium fluoride and hydrofluoric acid is used in semiconductor manufacturing processes and related processes, various metal materials, single crystal materials, and surface treatment processes such as optical materials. Yes. For this reason, wastewater containing a large amount of ammonium fluoride and hydrofluoric acid (BHF wastewater) is discharged from these surface treatment steps.

  However, since hydrofluoric acid is highly corrosive, damages the pipe fistula, and fluorine inhibits the biological treatment function at the final treatment plant, it is necessary to remove the fluorine in the BHF waste water. Moreover, since ammonium ion becomes a source of eutrophication in a closed water area, it is necessary to remove ammonium ion in BHF waste water.

  Conventionally, as a method for treating fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride, calcium compounds such as calcium hydroxide and calcium chloride are added to fluorine-containing wastewater to precipitate fluorine ions as insoluble calcium fluoride. After removal, the ammonium ion contained in the water has been treated by a biological nitrification denitrification method. However, the biological nitrification denitrification method requires a large-capacity nitrification reaction tank and a denitrification tank, and a large amount of biological sludge is generated due to the biological treatment. For this reason, the processing method and apparatus of the ammonium fluoride containing waste water which can be processed with a small apparatus and have little generation amount of sludge were calculated | required.

  In order to solve this problem, Patent Document 1 discloses that ammonium fluoride-containing wastewater is treated with a stripping tower under alkaline conditions, and the exhaust gas discharged from the stripping tower is brought into contact with an ammonia decomposition catalyst. A method has been proposed in which calcium salt is added to water after oxidative decomposition and removal of ammonia and ammonia is removed, and fluorine contained in the water is removed as calcium fluoride. In this method, for example, as shown in FIG. 3, ammonium fluoride-containing wastewater is sent to a pH adjustment tank 12 equipped with a pH meter 11, adjusted to a predetermined alkaline condition by adding an alkali agent, and pH adjusted water is supplied. After the heat is exchanged with the effluent water of the diffusion tower 15 by the heat exchanger 14 by the pump 13 to recover the residual heat, the heat is supplied to the liquid distributor 16 at the top of the diffusion tower 15. The lower part of the stripping tower 15 is supplied with air as a carrier gas and steam for heating, and is brought into contact with the flowing down drainage and countercurrent. The treated water from which ammonia has been transferred to the gas phase is removed by a pump 17 from the bottom of the tower, and is sent to the fluorine treatment process via the heat exchanger 14. The exhaust gas flowing out from the top of the stripping tower 15 is brought into contact with the ammonia decomposition catalyst in the catalytic reactor 18 to oxidize and decompose the contained ammonia and release it as a harmless processing gas.

  According to this method, it is said that fluorine can be treated after removing ammonia nitrogen in the ammonium fluoride-containing wastewater effectively using a small-scale apparatus without generating biological sludge. .

  However, in the case where a large amount of fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride is discharged, the efficiency of the stripping treatment described in Patent Document 1 is poor and practicality is low. Originally, BHF wastewater has a high concentration and a small flow rate. Normally, BHF wastewater is mixed with a low concentration and high flow hydrofluoric acid wastewater on the upstream side. And it becomes a large flow rate. For such BHF wastewater treatment, the method described in Patent Document 1 is less practical.

  In Patent Document 2, there is a method of adding caustic soda to the fluorine-containing wastewater so that the pH of the concentrated water is 6 to 8.5 and evaporating and concentrating it in order to reduce the amount of fluorine-containing wastewater. Proposed. However, if this method is applied to fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride, ammonia will be concentrated on the concentrated water side together with fluoride, so ammoniacal nitrogen cannot be removed prior to fluorine treatment. .

Japanese Patent No. 3912157 Japanese Patent No. 3284260

  The present invention solves the above-mentioned conventional problems, and can treat fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride, such as BHF wastewater, with high efficiency in a small installation space. An object is to provide a highly practical method and apparatus for containing wastewater and fluorine-containing wastewater having a large flow rate fluctuation.

  The method for treating fluorine-containing wastewater according to the present invention (Claim 1) is a method for treating fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride, wherein the fluorine-containing wastewater is adjusted to pH 10-13 and evaporated and concentrated. And an ammonia removal step of removing ammonia from the separated distilled water separated in the evaporation and concentration step.

  The method for treating fluorine-containing wastewater according to claim 2 is the method according to claim 1, wherein the ammonia removal step is a diffusion step in which the separated distilled water is diffused to obtain a gas containing ammonia, and the ammonia-containing gas from the diffusion step. And a decomposition step of bringing the ammonia into contact with an ammonia decomposition catalyst.

  A method for treating fluorine-containing wastewater according to a third aspect of the present invention is the method according to the first or second aspect, further comprising a fluorine removal step of removing fluorine from the separated concentrated water separated in the evaporation concentration step.

  A method for treating fluorine-containing wastewater according to claim 4 is characterized in that, in any one of claims 1 to 3, separation concentrated water having a fluorine concentration of 1.6 wt% or less is obtained in the evaporation concentration step. .

  The apparatus for treating fluorine-containing wastewater according to the present invention (Claim 5) is an apparatus for treating fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride, and adjusting the fluorine-containing wastewater to pH 10 to 13 for evaporation and concentration. And ammonia removal means for removing ammonia from the separated distilled water separated by the evaporation and concentration means.

  The apparatus for treating fluorine-containing wastewater according to claim 6 is the ammonia decomposition method according to claim 5, wherein the ammonia removing means introduces a stripping tower for stripping the separated distilled water and an ammonia-containing gas from the stripping tower. And a catalytic reaction tower packed with a catalyst.

  According to a seventh aspect of the present invention, there is provided a fluorine-containing wastewater treatment apparatus according to the fifth or sixth aspect, further comprising fluorine removal means for removing fluorine from the separated concentrated water separated by the evaporation and concentration means.

  The apparatus for treating fluorine-containing wastewater according to claim 8 is characterized in that, in any one of claims 5 to 7, the concentrated evaporation means obtains separated concentrated water having a fluorine concentration of 1.6% by weight or less. .

  According to the present invention, a fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride is evaporated and concentrated under the conditions of pH 10 to 13, whereby ammonia is easily separated and concentrated on the distilled water side from the fluoride, and high ammonia. Since distilled water having a concentration and a small flow rate can be obtained, ammonia in the separated distilled water can be easily treated according to a conventional method. For this reason, even in a fluorine-containing wastewater having a large flow rate or a fluorine-containing wastewater having a large flow fluctuation, it is possible to easily separate ammonia and treat ammonia in the fluorine-containing wastewater by applying evaporation concentration. Further, the separated concentrated water containing fluorine from which ammonia has been separated can be easily treated in accordance with a normal treatment method for fluorine-containing waste water.

  In the present invention, ammonia in the separated distilled water can be efficiently decomposed and removed by stripping the separated distilled water to obtain a gas containing ammonia, and bringing the ammonia-containing gas into contact with an ammonia decomposition catalyst ( Claims 2 and 6).

  Further, it is preferable to further remove fluorine from the separated concentrated water obtained by distillation concentration of fluorine-containing wastewater, and this fluorine removal treatment separates and removes fluorine in the separated concentrated water as calcium fluoride according to a conventional method. Therefore, it can be carried out easily and efficiently (claims 3 and 7).

  In addition, in the evaporation concentration, if the fluorine concentration in the separated concentrated water is excessively high, the solubility of the fluoride will be exceeded, and the fluoride will precipitate in the concentration device, the efficiency of the device will decrease, and stable operation will not be possible, It is preferable to carry out evaporation and concentration under conditions such that separated concentrated water having a fluorine concentration of 1.6% by weight or less can be obtained by diluting with water as necessary (Claims 4 and 8).

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

Embodiments of a method and apparatus for treating fluorine-containing wastewater according to the present invention will be described in detail below with reference to the drawings.
1 and 2 are system diagrams showing an embodiment of a treatment method and treatment apparatus for fluorine-containing waste water according to the present invention. In FIGS. 4 is a catalytic reaction tower, 5 is a calcium carbonate packed tower, and 6 is an ammonia distillation tower.

<Fluorine-containing wastewater>
The fluorine-containing wastewater to be treated in the present invention is water containing hydrofluoric acid and ammonium fluoride, and there is no particular limitation. However, when treating a large amount of fluorine-containing wastewater, evaporative concentration is adopted. Since the effects of the present invention are effectively exhibited, the present invention is suitable for the treatment of a large amount of fluorine-containing wastewater or fluorine-containing wastewater having a large flow rate fluctuation. Examples of such fluorine-containing wastewater include wastewater obtained by mixing the above-described BHF wastewater with etching wastewater using other etching agents, quartz tube cleaning wastewater, and the like.

Typical examples of the water quality and flow rate of the fluorine-containing wastewater to be treated in the present invention include the following, but are not limited to such water quality and flow rate.
Fluorine-containing wastewater concentration: 1 to 200 g / L
NH ₃ —N concentration: 0.9 to 150 g / L
pH: 1-4
Flow rate: 1-30 m ³ / hr

<PH adjustment and dilution>
In the present invention, the fluorine-containing wastewater as described above is first adjusted to pH 10 to 13 and evaporated and concentrated.

  Usually, since the fluorine-containing waste water to be treated in the present invention has a pH of about 1 to 4 as described above, an alkaline agent is used for this pH adjustment. In this pH adjustment, as shown in FIGS. 1 and 2, a pH adjusting tank 1 having a pH meter 1A may be provided, and an alkali agent may be added and controlled by a chemical injection pump 1B linked to the pH meter 1A. An alkali agent may be added directly to the transfer pipe.

  There is no restriction | limiting in particular as an alkaline agent used for pH adjustment, Sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate etc. can be used. These are usually added to fluorine-containing wastewater as an aqueous solution of about 5 to 10% by weight.

In the present invention, the pH of the fluorine-containing wastewater is adjusted to 10 to 13, preferably 11 to 12, by adding an alkaline agent. That is, by making the pH alkaline, the equilibrium reaction represented by the following formula shifts to the right side and it is easy to evaporate ammonia from the fluorine-containing wastewater, but if this pH is too low, in the next evaporation concentration step, Ammonia cannot be concentrated to the separated distilled water side. By adjusting the pH to 10 or more according to the present invention, ammonia can be efficiently concentrated in separated distilled water separated by evaporation and concentration.
NH ₄ ⁺ OH ⁻ ＮＨ NH ₃ + H ₂ O

  However, even if the pH is excessively high, there is no difference in the evaporative concentration effect of ammonia, and the addition amount of the alkaline agent is increased, which is uneconomical. Therefore, the upper limit of the adjusted pH is set to 13 or less.

  In addition, if the fluorine concentration of the fluorine-containing wastewater is high and the concentration is further increased by evaporation concentration, fluoride such as sodium fluoride is deposited in the evaporation concentration device, which reduces the efficiency of the device and ensures stable operation. Can not continue. Therefore, prior to evaporative concentration, the diluted concentrated water obtained by evaporative concentration is fed to the evaporative concentration device by adding diluted water to the fluorine-containing waste water so that the fluorine concentration does not precipitate as fluoride. It is preferable to adjust the fluorine concentration of water.

  In FIGS. 1 and 2, for adjustment of the fluorine concentration, dilution water is supplied to the pH adjustment tank 1 by a pump 2 </ b> B interlocked with a fluorine concentration meter 2 </ b> A provided in a separation concentrated water transfer pipe from the evaporation concentration device 2. However, the fluorine concentration meter 2A integrates the concentration ratio in the evaporative concentration apparatus 2 to transfer the pH adjusted water from the pH adjustment tank 1 or the pH adjustment tank 1 to the evaporative concentration apparatus 2. You may provide in piping. The fluorine-containing waste water may be diluted continuously or batchwise.

  As the dilution water, industrial water, treated water according to the present invention, or the like can be used.

  Such a fluorine-containing wastewater dilution control means is required when the flow rate and composition of the fluorine-containing wastewater fluctuate, but if these are constant, a preset amount of dilution water can be added. good. In addition, when the concentration of fluorine in separated concentrated water obtained by evaporation concentration is not higher than 1.6% by weight, or when diluted with water added as an aqueous solution of an alkaline agent for pH adjustment, When the fluorine concentration is 1.6% by weight or less, this dilution is unnecessary.

<Evaporation concentration>
The fluorine-containing wastewater that has been adjusted for pH and further diluted with water as needed is introduced into the evaporating and concentrating device 2 and evaporatively concentrated by distillation according to a conventional method.
By this evaporation and concentration, the ammonia in the fluorine-containing wastewater is concentrated and separated on the separated distilled water side, and the fluorine is separated into the separated and concentrated water.

  In the present invention, fluorine-containing wastewater having the following water quality and flow rate is converted into, for example, separated distilled water and separated concentrated water having the following water quality and flow rate by evaporating and concentrating under high alkaline conditions of pH 10-13. Can be separated.

<Ammonia removal of separated distilled water>
The method for removing ammonia from the separated distilled water obtained by evaporation and concentration is not particularly limited, but as shown in FIG. The ammonia-containing gas obtained from No. 3 may be introduced into a catalytic reaction column 4 packed with an ammonia decomposition catalyst to decompose ammonia, and separated distilled water is introduced into the ammonia distillation column 6 as shown in FIG. Then, ammonia distillation may be performed. The ammonia removal treatment by the stripping tower 3 and the catalytic reaction tower 4 shown in FIG. 1 can be performed in the same manner as the conventional method shown in FIG.

  When the separated distilled water is diffused in the stripping tower 3, the stripping tower to be used is not particularly limited. For example, a liquid dispersion type such as a packed tower, a spray tower, a cyclone scrubber, a venturi scrubber, a fluidized bed stripping tower, a wet wall tower Examples include a diffusion tower, and a gas dispersion type diffusion tower such as a plate tower and a bubble tower.

  The diffusion treatment in the diffusion tower 3 is preferably performed under heating since the ammonia removal rate can be increased and treated water having a low ammonia concentration can be obtained. The degree of heating is preferably 40 to 100 ° C, particularly preferably 60 to 90 ° C.

  There is no restriction | limiting in particular in the heating method in the stripping tower 3, For example, a vapor | steam may be supplied and heated in the stripping tower 3, and a stripping tower may be heated with a heat medium. When the stripping treatment is performed in the stripping tower 3 under heating, the effluent water from the stripping tower 3 is high temperature, so heat exchange is performed between the separated distilled water supplied to the stripping tower 3 and the effluent water from the stripping tower 3. Preferably, the thermal energy is recovered.

  If the operating conditions are adjusted in the stripping treatment in the stripping tower 3, ammonia in the separated distilled water is transferred to the exhaust gas by 95% or more, but treated water having a low ammonia concentration is obtained. Is processed.

  The ammonia-containing exhaust gas discharged from the stripping tower 3 is then introduced into the catalytic reaction tower 4 and oxidatively decomposed by an ammonia decomposition catalyst filled in the tower.

  The catalyst reaction tower 4 is not particularly limited, and for example, either a fixed bed catalyst reaction tower or a fluidized bed catalyst reaction tower can be used.

  Also, the ammonia decomposition catalyst to be used is not particularly limited. For example, on a carrier such as titania, silica, alumina, zirconia, zeolite, ruthenium, rhodium, palladium, iridium, platinum, iron, nickel, cobalt, titanium, vanadium, etc. Alternatively, a catalyst on which a catalytically active component such as a salt or oxide thereof is supported can be mentioned.

The contact between the ammonia-containing exhaust gas and the ammonia decomposition catalyst in the catalytic reaction tower 4 is preferably performed at 250 to 500 ° C, more preferably 350 to 450 ° C. By bringing the ammonia-containing exhaust gas into contact with the ammonia decomposition catalyst at such a temperature, ammonia can be oxidatively decomposed into harmless nitrogen and water by the reaction shown by the following formula, with an ammonia concentration of 30 ppm (volume ratio) or less, NOx A processing gas having a concentration of 10 ppm (volume ratio) or less can be obtained.
4NH ₃ + 3O ₂ → 2N ₂ + 6H ₂ O

On the other hand, as shown in FIG. 2, when the separated distilled water is distilled in the ammonia distillation column 6, NH ₃ − is obtained by performing ammonia distillation using the packed distillation column 6 at a temperature of about 92 to 99 ° C. It can be separated by distillation into ammonia water having an N concentration of about 20 to 25% and treated water having an NH ₃ —N concentration of 100 mg / L or less, and the treated water treats the remaining NH ₃ -N in a diluted waste water treatment system. .

  In any case, according to the present invention, the fluorine-containing waste water is evaporated and concentrated under a high alkaline condition to obtain a separated flow of distilled water having a concentrated ammonia concentration. By performing the ammonia removal treatment, it is possible to efficiently decompose or recover ammonia.

<Fluorine removal of separated concentrated water>
The separated concentrated water obtained by the evaporative concentration apparatus 2 is water in which ammonia in the fluorine-containing wastewater is removed and the flow rate is reduced to concentrate fluorine. In the present invention, this separated concentrated water is preferably used. The fluorine is removed.

  There is no particular limitation on the method for removing fluorine from the separated concentrated water. For example, calcium compounds such as calcium hydroxide and calcium chloride are added to the separated concentrated water to precipitate hardly soluble calcium fluoride, which is then separated into solid and liquid. As shown in FIGS. 1 and 2, it is possible to adopt a method in which the separated concentrated water is passed through the calcium carbonate packed tower 5 to generate calcium fluoride. After solid-liquid separation using fluorine as calcium fluoride, it is also possible to add aluminum compounds such as aluminum sulfate and polyaluminum chloride to separate into solid and liquid. The remaining fluorine can also be adsorbed and removed by contacting with the adsorbent.

  The amount of the calcium compound added to the separated concentrated water is preferably 0.5 to 3 mol, more preferably 1 to 2.5 mol based on 1 mol of fluorine ions in the separated concentrated water. After adding the calcium compound to the separated concentrated water, the pH is preferably adjusted to 6 to 11, and more preferably adjusted to 6.5 to 10. It is preferable to add the calcium compound, adjust the pH, and precipitate the calcium fluoride so that the water is transferred to a coagulation tank and a coagulant is added to aggregate the calcium fluoride precipitate.

  When the separated concentrated water is passed through the calcium carbonate packed tower 5 to remove fluorine, the calcium carbonate packed tower is not particularly limited, but for example, a calcium carbonate packed tower described in JP-A-6-154768. Can be used.

When the separated concentrated water is passed through such a calcium carbonate packed tower, the fluorine in the separated concentrated water reacts with the calcium carbonate particles in the calcium carbonate packed tower and is fixed to the calcium carbonate particles as calcium fluoride and removed. Treated water having a low fluorine concentration is obtained as the effluent of the calcium packed tower.
The calcium carbonate particles fixed with fluorine in the separated concentrated water are appropriately extracted from the calcium carbonate packed tower to recover calcium fluoride.

  When a fluorine adsorbent is used to remove residual fluorine, the fluorine adsorbent adsorbs metal ions that form complex compounds with fluorine ions such as cerium, hafnium, titanium, zirconium, iron, aluminum, and lanthanide. Fluorine adsorption resins, adsorbents such as activated carbon, activated alumina, hydrous titanium oxide, zeolite, and magnesia can be used.

  In the present invention, in the process of removing the fluorine of the separated concentrated water, only the separated concentrated water may be supplied to the fluorine removing step, and the separated concentrated water contains another hydrofluoric acid discharged from another process. It may be treated by mixing with fluorine-containing wastewater such as wastewater.

  By such a fluorine removal treatment, treated water having a fluorine concentration of preferably 8 mg / L or less can be obtained, and this treated water is usually discharged into sewers and rivers.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

[Example 1]
The fluorine-containing waste water having the following water quality and flow rate was treated by the procedure shown in FIG.

<Fluorine-containing wastewater quality and flow rate>
F concentration: 8,900 mg / L
NH ₃ -N concentration: 10,000mg / L
pH: 3.5
Flow rate: 2.4 m ³ / hr

  First, in the pH adjustment tank 1, 10% by weight sodium hydroxide aqueous solution is added to fluorine-containing wastewater to adjust the pH to 12, and the pH adjusted water is evaporated and concentrated by the evaporating and concentrating device 2 to separate the distilled water having the following water quality and flow rate. Separated concentrated water was obtained.

<Separated distilled water / water quality / flow rate>
F concentration: 2 mg / L
NH ₃ —N concentration: 22,000 mg / L
pH: 12
Flow rate: 1.0 m ³ / hr
<Separated concentrated water / water quality / flow rate>
F concentration: 15,000 mg / L
NH ₃ -N concentration: 70 mg / L
pH: 10.9
Flow rate: 1.6 m ³ / hr

The obtained separated distilled water was introduced from the top of the diffusion tower (φ450 mm × H3000 mm, manufactured by SUS316) 3 and heated to 45 ° C., and aerated by blowing air of 20 m ³ / min as a carrier gas. An ammonia-containing exhaust gas having an ammonia concentration of 1.9% was obtained. The ammonia-containing exhaust gas was diluted twice in the air, heated to 400 ° C. and introduced into the catalytic reaction tower 4 filled with a titania catalyst at a flow rate of 40 m ³ / min to decompose ammonia.
As a result, a treatment gas having an ammonia concentration of 30 ppm and an NO _x concentration of 10 ppm was obtained from the catalytic reaction tower 4.
The treated water after the aeration treatment in the diffusion tower 3 has a pH of 11.1 and an NH ₄ —N concentration of 150 mg / L, and this water was treated with the remaining NH ₃ —N in a diluted waste water treatment system.
On the other hand, the separated concentrated water is passed through a calcium carbonate packed tower 5 filled with calcium carbonate having an average particle size of 0.32 mm, with a water flow rate SV2h ⁻¹ , circulation LV 20 m / h, and 3 towers in series to remove fluorine. The process to do.
As a result, treated water having a fluorine concentration of 150 mg / L could be obtained.

  From the above results, it can be seen that according to the present invention, ammonia can be separated and concentrated efficiently from fluorine-containing wastewater, and fluorine in concentrated water after separation of ammonia can also be efficiently treated.

[Comparative Example 1]
In Example 1, after evaporating and concentrating, after adding sodium hydroxide aqueous solution to fluorine-containing wastewater and adjusting to pH 12, it processed similarly except having introduce | transduced directly into the stripping tower.
As a result, due to the increase in water flow rate of the stripping tower, sufficient stripping treatment cannot be performed, the ammonia concentration of the exhaust gas from the stripping tower is 1.5%, and the treated water has a pH of 11.5, NH ₄ -N. The concentration was 1250 mg / L.

  In this comparative example, the treatment efficiency in the stripping tower is poor because it treats a large amount of fluorine-containing wastewater, and in order to obtain sufficient efficiency equivalent to that of Example 1, a plurality of stripping towers are arranged in parallel or in multiple stages. It was necessary to install.

DESCRIPTION OF SYMBOLS 1 pH adjustment tank 2 Evaporative concentration apparatus 3 Stripping tower 4 Catalytic reaction tower 5 Calcium carbonate packed tower 6 Ammonia distillation tower

Claims (8)

In a method for treating fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride,
An evaporative concentration step of adjusting the fluorine-containing wastewater to pH 10 to 13 and evaporating and concentrating;
A method for treating fluorine-containing wastewater, comprising an ammonia removal step of removing ammonia from the separated distilled water separated in the evaporation concentration step.   2. The ammonia removal step according to claim 1, wherein the ammonia removal step includes a diffusion step of releasing the separated distilled water to obtain a gas containing ammonia, and a decomposition step of bringing the ammonia-containing gas from the diffusion step into contact with an ammonia decomposition catalyst. A method for treating fluorine-containing wastewater.   The method for treating fluorine-containing wastewater according to claim 1 or 2, further comprising a fluorine removing step of removing fluorine from the separated concentrated water separated in the evaporation and concentration step.   4. The method for treating fluorine-containing wastewater according to any one of claims 1 to 3, wherein separated concentrated water having a fluorine concentration of 1.6% by weight or less is obtained in the evaporation concentration step. In an apparatus for treating fluorine-containing wastewater containing hydrofluoric acid and ammonium fluoride,
Evaporative concentration means for adjusting the fluorine-containing wastewater to pH 10-13 and evaporating and concentrating;
An apparatus for treating fluorine-containing wastewater, comprising ammonia removing means for removing ammonia from the separated distilled water separated by the evaporation and concentration means.   6. The ammonia removing means according to claim 5, comprising a stripping tower for stripping the separated distilled water, and a catalytic reaction tower filled with an ammonia decomposition catalyst into which ammonia-containing gas from the stripping tower is introduced. An apparatus for treating fluorine-containing wastewater.   7. The apparatus for treating fluorine-containing wastewater according to claim 5, further comprising fluorine removing means for removing fluorine from the separated concentrated water separated by the evaporation and concentration means.   The apparatus for treating fluorine-containing wastewater according to any one of claims 5 to 7, wherein the concentrated evaporation means obtains separated concentrated water having a fluorine concentration of 1.6% by weight or less.

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