JPH0783819B2 - Method and apparatus for treating wastewater containing fluoric and hydrogen peroxide and exhaust gas - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for treating fluorine- and hydrogen peroxide-containing wastewater and exhaust gas discharged from a factory for manufacturing electronic parts, electric parts and the like.

[Conventional technology]

In the manufacture of electronic parts and electric parts, fluorine compounds are substances that are indispensable in the surface treatment process such as etching and are widely used. At the same time, hydrogen peroxide is often used for cleaning parts and the like, and particularly in semiconductor manufacturing plants, hydrogen peroxide is often mixed in waste water of fluorine compounds.

There are various kinds of fluorine compounds contained in the wastewater, but in semiconductor manufacturing plants, typical examples are hydrofluoric acid and ammonium fluoride.

Various methods have heretofore been used as methods for removing these fluorine from wastewater.

The main treatment methods are calcium compound addition + precipitation separation method Aluminum compound addition + precipitation separation method Iron salt addition + precipitation separation method Combination of two or more of the above, calcium salt + phosphate + precipitation method Activated alumina Adsorption method There is an adsorption method using activated carbon or bone charcoal.

Among these methods, the coagulation-precipitation method (1) to (4) above is widely adopted as a method for satisfying the fluorine compound content of 15 mg / which is the drainage standard in the Water Pollution Control Law because the maintenance cost is relatively low.

However, as described above, hydrogen peroxide is often mixed in the system for performing the coagulation-sedimentation method at a rate of several tens to several tens of thousands mg / min. Air bubbles are generated from the sludge that once adheres to the flocs and settles in the settling tank, and the flocs re-float and overflow from the settling tank to flow out to the next step. Due to the outflow of flocs, high concentrations of fluoride and SS were sometimes detected in the treated water.

Therefore, in order to remove hydrogen peroxide, an adsorption method using activated carbon and a chemical reaction method by injecting a reducing agent such as sodium bisulfite have been conventionally performed.

FIG. 4 is an explanatory view showing a chemical reaction method by injecting a reducing agent such as sodium bisulfite. Waste water containing fluorine and hydrogen peroxide first flows into the reaction tank 1 to which the reducing agent is added, and the peroxidation is performed there. Decomposes hydrogen. Next, it flows into the reaction tank 2 to which calcium peroxide is added, where calcium fluoride is produced. Further, the calcium fluoride is coagulated in the reaction tank 3 by the polymer coagulant. Then, it flows into the settling tank 4, the sludge is extracted from the bottom, and the treated water is discharged from the upper part. The residence time in the settling tank 4 is generally 3 to 5 hours.

Also, for example, as exhaust gas emitted from a semiconductor factory,
There are acid gases such as hydrofluoric acid, hydrochloric acid, nitric acid, and sulfuric acid, alkali gases such as ammonia gas, organic solvents such as alcohol and developer, poisonous gases such as silane, arsine, and phosphine. It is being processed by a scrubber.

[Problems to be solved by the invention]

However, in the conventional method, the waste water and the exhaust gas are treated separately, which is not desirable because the equipment becomes large.

Also, in the treatment of wastewater, the activated carbon adsorption method has a high running cost, and not only hydrogen peroxide is not selectively adsorbed but a large amount of organic substances, metals, etc. are also adsorbed, resulting in high efficiency. Not good. The reducing agent injection method has a problem that maintenance costs are high, operation management is complicated, and fine flocs are mixed in the treated water, making it difficult to obtain good treated water.

[Object of the Invention]

The present invention has been made to solve the conventional problems, and an object thereof is to remove fluorine and hydrogen peroxide and to treat exhaust gas by a simple means.

[Means for solving problems]

In the method for treating wastewater containing fluorine and hydrogen peroxide and exhaust gas according to the present invention, wastewater containing fluorine and hydrogen peroxide and exhaust gas are introduced into a scrubber provided with an exhaust gas treatment filler in the upper part and a metal catalyst in the lower part. Then, the wastewater is contacted with a metal catalyst to bubble hydrogen peroxide, and a metal salt or a metal compound is added to the dropped wastewater to generate a fluorine compound, which is then discharged from a scrubber and polymer aggregates in a reaction tank. A fluorine compound is added to make flocculant flocs, then it is made to flow with pressurized water from the bottom of the pressure flotation tank to separate the solid liquid, and a part of the treatment liquid is sprayed onto the scrubber exhaust gas treatment filler to generate the exhaust gas. It is configured to pass.

Further, the apparatus for treating wastewater containing fluorine and hydrogen peroxide and the exhaust gas according to the present invention is provided with an exhaust gas treatment filler in the upper portion and a metal catalyst in the lower portion, and fluorine is provided between the exhaust gas treatment filler and the metal catalyst. ， Providing an inflow pipe for introducing hydrogen peroxide-containing wastewater and exhaust gas separately, an absorption liquid spraying pipe on the upper part of the exhaust gas treatment packing, and adding a metal salt or a metal compound to the wastewater dropped below the metal catalyst. A scrubber that forms a waste water storage tank to be reacted, a reaction tank that is connected to this scrubber through a pipe line, and that stirs and mixes a polymer flocculant and waste water, and a reaction tank that is connected at the bottom part through a pipe line. , A pressure flotation tank that separates coagulation flocs by inflowing wastewater together with the pressurized water supplied to the pipeline, a storage tank that stores the treated water derived from the pressure flotation tank, and this storage tank and exhaust gas treatment Absorption on top of packing A spray pipe connected and is formed from the absorption liquid pipe for water of the treated water in the reservoir and the desired neutralizing agent by a pump.

In the present invention, as the metal salt, calcium salt, iron salt and the like are preferable. Further, as the metal compound, a calcium compound, an aluminum compound or the like is suitable.

[Operation of the invention]

In the present invention, wastewater containing fluorine and hydrogen peroxide flows into the pressurized flotation tank together with pressurized water after the aggregate flocs of the fluorine compound are generated by the addition of the metal salt or the metal compound and the polymer flocculant. Therefore, due to the fine bubbles generated by the pressurized water being released to the atmosphere, the bubbles that had mostly adhered to the flocs until then floated up and were removed, and at the same time, part of the hydrogen peroxide dissolved in the wastewater was also removed. Bubbles rise and are removed. Further, since the exhaust gas passes through the exhaust gas treatment filler that sprays the wastewater-treated treatment liquid, harmful substances are absorbed or neutralized by the treatment liquid and are exhausted.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining the process in the present invention.

In the figure, 10 is a scrubber, which is provided with an exhaust gas treatment filler 11 in the upper portion and a metal catalyst 12 in the lower portion, and contains fluorine and hydrogen peroxide between the exhaust gas treatment filler 11 and the metal catalyst 12. A spray pipe 13 connected to a pipe for introducing waste water and a pipe 14 for introducing exhaust gas are separately provided. In addition, a pipe 15 for absorbing liquid is provided on the upper portion of the exhaust gas treatment filler 11, and a metal catalyst
A waste water storage tank 16 for reacting the dripping waste water with a metal salt or a metal compound is formed at the lower part of 12. This wastewater storage tank
The tube 16 is provided with a pipe 17 for introducing stirring air. The scrubber 10 is provided at its upper portion with a discharge port 18 for exhausting exhaust gas. Incidentally, as the material of the metal catalyst 12,
Precious metals are the best, but copper and iron are also possible. The shape may be a cylindrical packing or a net-like one that is installed in the container.

Reference numeral 20 is a reaction tank which is connected to the scrubber 10 through the pipe line 10 to stir and mix the polymer coagulant and the waste water. An agitator 21 is provided inside.

Reference numeral 23 is a pressure flotation tank that is connected to the reaction tank 20 at a bottom portion 24 via a pipe line 22 and separates coagulated flocs by inflowing waste water together with the pressurized water supplied to the pipe line 22. This pressurized flotation tank
In 23, a pipeline 25 for discharging sludge and a pipeline 26 for discharging treated water are separately provided at the upper part.

27 is a storage tank for storing the treated water discharged from the pressurized flotation tank 23. The treated water is discharged from this storage tank 27.

Reference numeral 28 connects this storage tank 27 with the absorption liquid spraying pipe 15 provided on the upper part of the exhaust gas treatment filler 11 and sends the treated water in the storage tank 27 and a desired neutralizing agent by a circulation pump 29. This is the absorption liquid line.

Next, the operation of the present embodiment configured as described above will be described.

Waste water containing fluorine and hydrogen peroxide and exhaust gas are introduced into the scrubber 10 via the spray pipe 13 and the pipe 14, respectively.

Then, when the waste water is sprayed on the metal catalyst 12 by the spray tube 13, hydrogen peroxide in the waste water comes into contact with the metal catalyst 12 to be bubbled. Therefore, oxygen is a scrubber
Ascending within 10, the wastewater drops into the wastewater storage tank 16 below.

In the waste water storage tank 16, desired calcium hydroxide is added and stirring air is supplied through a pipe 17,
Fluorine in the wastewater chemically reacts with calcium hydroxide to produce calcium fluoride.

Next, the wastewater treated in the wastewater storage tank 16 is sent to the reaction tank 20 via the conduit 19. In the reaction tank 20, the polymer flocculant added in a desired amount and the agitator 21 are agitated to agglomerate calcium fluoride to increase flocs.

After that, the wastewater treated in the reaction tank 20 flows in together with the pressurized water from the bottom portion 24 of the pressurized flotation tank 23 through the pipe line 22. At this time, fine bubbles generated when the pressurized water is released to the atmosphere raises and removes the bubbles that have mostly adhered to the flocs until then. At the same time, a part of the hydrogen peroxide dissolved in the raw water is also bubbled by the fine bubbles of the pressurized water, rising and removed.

The residence time of “raw water + pressurized water” in the pressure floating tank 23 is 1 to 3 hours. This is because the pressure levitation tank generally used has a residence time of around 30 minutes.
This is in order to sufficiently generate bubbles of hydrogen peroxide inside.

In order to increase the efficiency of bubble generation, it is effective to inject copper, iron or the like into the reaction tank 20 or mix water containing organic matter in another drainage system.

Here, the copper includes copper sulfate and the like, and the iron includes ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride and the like. The organic waste water includes human waste septic tank treated water, alcohol-containing waste water, fatty acid-containing waste water, and the like.

Thus, the treated water from which the sludge has been removed in the pressure flotation tank 23 is sent to the storage tank 27 via the pipe line 26. Then, from here, it is sent by the pump 29 to the absorbent dispersion pipe 6 in the scrubber 1 through the absorbent conduit 28, and the exhaust gas treating filler 11
Be sprinkled on.

A desired chemical liquid is added to the liquid sprayed from the absorbent spray pipe 15 according to the type of the exhaust gas, but in the present embodiment, since the exhaust gas is hydrofluoric acid, caustic soda is added to adjust the pH to 9 to 9.
It's set to 10.

Therefore, the exhaust gas (hydrofluoric acid) introduced into the scrubber 10 through the pipe 14 is neutralized by the liquid when passing through the exhaust gas treatment filler 11, and is exhausted from the discharge port 18.

Although hydrofluoric acid was used as the exhaust gas in the above embodiment, it may be other acid type, alkali type, organic type, or poison type. In that case, when the exhaust gas is an acid type, a caustic soda is injected, and when the exhaust gas is an alkaline type, hydrochloric acid is injected. If harmful substances are mixed, remove them by adding chemicals suitable for them.

In addition, although SS is almost absent in the absorption liquid circulated through the absorption liquid spray pipe 15, since calcium is dissolved, the pump 29 is continuously operated to prevent deposition of calcium carbonate or the like. Further, since calcium carbonate and the like are deposited also on the exhaust gas treatment filler 11 and the metal catalyst 12 in the scrubber 10, hydrochloric acid is injected into the regular drops to change the calcium carbonate solid matter into calcium chloride liquid. Prevent clogging.

[Effects of the Invention] As described above, according to the present invention, the decomposition process of hydrogen peroxide by a reducing agent is not necessary. Outflow of flocs is extremely small, and good treated water is obtained. Since it is also used as an exhaust gas scrubber, it is advantageous in terms of equipment cost and space. Maintenance cost is reduced because fluorine-containing wastewater is neutralized by the caustic soda solution used for exhaust gas treatment, and the amount of calcium hydroxide to be added can be reduced.
Circulating liquid for exhaust gas treatment is usually 1/5 to 1 of the circulating amount.
/ 10 has the advantage that there is no need to overflow and transfer to the wastewater treatment equipment,

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention, and FIG. 2 is an explanatory view showing a conventional example. 10 …… Scrubber, 11 …… Exhaust gas treatment filler, 12 ……
Metal catalyst, 13,15 ... Spraying pipe, 14 ... Tube, 16 ... Waste water storage tank, 20 ... Reaction tank, 23 ... Pressure flotation tank, 27 ... Storage tank, 28 ... Absorption liquid pipeline , 29 …… Circulation pump.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01D 53/46 53/72 53/77 C02F 1/58 CDG B01D 53/34 120 D 120 A ZAB ( 72) Inventor Yuji Wakabayashi 8-21-1, Ginza, Chuo-ku, Tokyo Incorporated Takenaka Corporation Tokyo Head Office (56) References JP-A-63-20094 (JP, A)

Claims (5)

[Claims] 1. A wastewater containing fluorine and hydrogen peroxide and an exhaust gas,
Introduced into a scrubber with an exhaust gas treatment filler on the top and a metal catalyst on the bottom, contacting the waste water with the metal catalyst to bubble hydrogen peroxide and adding a metal salt or metal compound to the dropping waste water. After the fluorine compound is generated, it is discharged from the scrubber and the polymer flocculant is added in the reaction tank to make the fluorine compound into floc. Then, it is introduced together with pressurized water from the bottom of the pressure flotation tank to separate the solid-liquid. A method for treating wastewater containing fluorine and hydrogen peroxide, and an exhaust gas, wherein the exhaust gas is passed while spraying a part of the treatment liquid on a scrubber filler for exhaust gas treatment. 2. The method for treating waste gas containing fluorine and hydrogen peroxide and exhaust gas according to claim 1, wherein the metal salt is calcium salt, iron salt or the like. 3. The method for treating wastewater containing fluorine and hydrogen peroxide and exhaust gas according to claim 1, wherein the metal compound is a calcium compound, an aluminum compound or the like. 4. Exhaust gas is acid-based gas such as hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, alkali-based gas such as ammonia gas, alcohol,
The method for treating fluorine-containing and hydrogen peroxide-containing wastewater and exhaust gas according to claim 1, which is an organic type such as a developing solution and a toxic type such as silane, arsine and phosphine. 5. An inflow for providing an exhaust gas treatment filler on the upper portion and a metal catalyst on the lower portion, and separately introducing waste water containing fluorine and hydrogen peroxide and exhaust gas between the exhaust gas treatment filler and the metal catalyst. A scrubber provided with a pipe, a pipe for spraying the absorbing liquid on the upper part of the exhaust gas treatment filler, and a wastewater storage tank for reacting the metal salt or the metal compound with the wastewater added to the bottom of the metal catalyst, and the scrubber and the pipe. A reaction tank that is connected via a channel to stir and mix the polymer flocculant and the waste water, and this reaction tank is connected at the bottom via a pipeline, and the waste water is introduced together with the pressurized water supplied to the pipeline and aggregated. The pressure flotation tank that separates the flocs, the storage tank that stores the treated water derived from this pressure flotation tank, and this storage tank and the absorption liquid spray pipe provided above the exhaust gas treatment filler are connected. Then, the treated water in the storage tank is pumped. Fluorine, characterized in that it is composed of the absorption liquid pipe for water and the desired neutralizing agent, the hydrogen peroxide-containing wastewater and exhaust gas processing apparatus.