JP6718758B2 - Nitrogen-containing wastewater treatment apparatus and treatment method - Google Patents

Description

The present invention relates to a treatment apparatus and a treatment method for nitrogen-containing wastewater.

Ammonia is widely used in semiconductor manufacturing plants for wet cleaning of silicon wafers for semiconductors and semiconductor devices. Nitrogen-containing wastewater containing ammonia discharged from a semiconductor manufacturing factory can be a causative agent of eutrophication in lakes and closed seas, and therefore must be efficiently removed by wastewater treatment facilities in the factory.

As a method for treating ammonia-containing wastewater, for example, a method of performing diffusion treatment in a diffusion tower under alkaline conditions and collecting as high-concentration ammonia water using a condenser, and exhaust gas discharged from the diffusion tower as an ammonia decomposition catalyst A method of oxidizing and decomposing ammonia by contact is known. Further, as a method for treating nitrogen-containing wastewater containing ammonia nitrogen, a biological treatment method using microorganisms is used, and in the nitrification step, ammonia is oxidized to nitrite by ammonia-oxidizing microorganisms, and further nitrite is It is oxidized to nitric acid by a nitrite-oxidizing microorganism, and is detoxified by reducing nitrite and nitric acid to nitrogen gas by a heterotrophic denitrifying microorganism that uses an organic substance as an electron donor in the denitrification process.

On the other hand, a large amount of alcohol such as isopropyl alcohol (IPA) is used in the cleaning and drying process of a semiconductor manufacturing factory. Treatment methods of alcohol-containing wastewater such as IPA-containing wastewater after use differ depending on the concentration of alcohol contained and the amount of other impurities. For example, IPA-containing wastewater having a relatively high IPA concentration and a small amount of impurities can be subjected to concentration treatment using a distillation column and recovered outside the site (recovery of valuables). The low-concentration IPA-containing water that is released by rinsing waste water or from a wafer cleaning device by volatilization and is removed by a detoxification device is treated by a biological treatment method using microorganisms, an accelerated oxidative decomposition method, or the like.

In the treatment of nitrogen-containing wastewater, the method using an ammonia decomposition catalyst has a problem of high running cost.

In addition, in the conventional method using a hydrogen donor in the denitrification process as a biological treatment, the installation space of the device is large, and it is necessary to purchase an organic substance such as methanol as a hydrogen donor and to add a large amount thereof. There is a problem that the value is high (for example, refer to Patent Document 1).

In the treatment of alcohol-containing wastewater, for example, there is a method of concentrating alcohol such as IPA using a distillation column and recovering it outside the site (recovering valuables), but to recover it as valuables, the alcohol is concentrated up to about 85% by weight. Therefore, there is a problem that the installation area of the device is large and the processing cost is high. Further, the distillation column has a problem that it is difficult to control the alcohol concentration on the recovery (concentration) side to be constant in a system in which the alcohol concentration in the water to be treated varies.

Japanese Patent No. 5355314

An object of the present invention is to provide a treatment apparatus and a treatment method for nitrogen-containing wastewater, which can treat both nitrogen-containing wastewater and alcohol-containing wastewater and can reduce the treatment cost.

The present invention provides a biological treatment means for treating nitrogen-containing wastewater using a hydrogen donor ; a reverse osmosis membrane treatment means for concentrating alcohol-containing wastewater, and concentrated water concentrated by the reverse osmosis membrane treatment means. and alcohol, the alcohol concentration means comprises an ultrasonic atomization means for obtaining a treated water; equipped with the alcohol that is concentrated by the alcohol concentration means as the hydrogen donor is used, in the processing apparatus of the nitrogen-containing wastewater is there.

It is preferable that the nitrogen-containing wastewater treatment apparatus further includes a returning means for returning the treated water obtained by the ultrasonic atomizing means to a stage before the reverse osmosis membrane treating means.

In the treatment device for nitrogen-containing wastewater, the nitrogen-containing wastewater is nitrogen-containing wastewater discharged from a semiconductor manufacturing factory, and the alcohol-containing wastewater is preferably alcohol-containing wastewater discharged from the semiconductor manufacturing factory. ..

In the nitrogen-containing wastewater treatment device, it is preferable that the biological treatment means is a biological treatment means using granules in which microorganisms are granulated.

The present invention also provides a biological treatment step of treating nitrogen-containing wastewater using a hydrogen donor ; a reverse osmosis membrane treatment step of concentrating alcohol-containing wastewater, and concentrated water concentrated by the reverse osmosis membrane treatment step. A method for treating nitrogen-containing wastewater, comprising : an alcohol concentration step including a concentrated alcohol and an ultrasonic atomization step for obtaining treated water ; and using the alcohol concentrated by the alcohol concentration step as the hydrogen donor. Is.

It is preferable that the method for treating nitrogen-containing wastewater includes a returning step for returning the treated water obtained by the ultrasonic atomization step to a stage before the reverse osmosis membrane treatment step.

In the method for treating nitrogen-containing wastewater, the nitrogen-containing wastewater is nitrogen-containing wastewater discharged from a semiconductor manufacturing factory, and the alcohol-containing wastewater is preferably alcohol-containing wastewater discharged from the semiconductor manufacturing factory. ..

In the method for treating nitrogen-containing wastewater, the biological treatment step is preferably a biological treatment step using granules in which microorganisms are granulated.

INDUSTRIAL APPLICABILITY The present invention provides a treatment apparatus and a treatment method for nitrogen-containing wastewater, which can treat both nitrogen-containing wastewater and alcohol-containing wastewater and can reduce the treatment cost.

It is a schematic block diagram which shows an example of the processing apparatus of the nitrogen-containing wastewater which concerns on embodiment of this invention. It is a schematic structure figure showing an example of an ultrasonic atomization device as an alcohol concentration device concerning an embodiment of the present invention. It is a schematic block diagram which shows an example of the biological treatment apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the processing apparatus of the nitrogen-containing wastewater which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the processing apparatus of the nitrogen-containing wastewater which concerns on embodiment of this invention.

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

A schematic configuration of an example of a nitrogen-containing wastewater treatment apparatus 1 according to an embodiment of the present invention is shown in FIG. 1, and the configuration will be described.

The nitrogen-containing wastewater treatment apparatus 1 includes an alcohol concentrator 10 as an alcohol concentrating means for concentrating the alcohol-containing wastewater, and a biological treatment apparatus 12 as a biological treatment means for treating the nitrogen-containing wastewater using a hydrogen donor, In the biological treatment device 12, alcohol concentrated by the alcohol concentrator 10 is used as a hydrogen donor.

In the nitrogen-containing wastewater treatment apparatus 1 of FIG. 1, a pipe 14 for supplying alcohol-containing wastewater is connected to the inlet of the alcohol concentrator 10, and a pipe 16 for discharging treated water is connected to the treated water outlet. There is. A pipe 18 for supplying the nitrogen-containing wastewater is connected to the nitrogen-containing wastewater inlet of the biological treatment device 12, and a pipe 20 for discharging the biologically treated water is connected to the outlet. The alcohol concentrate outlet of the alcohol concentrator 10 and the alcohol concentrate inlet of the biological treatment device 12 are connected by a pipe 22.

The method of treating nitrogen-containing wastewater and the operation of the nitrogen-containing wastewater treatment apparatus 1 according to the present embodiment will be described.

Alcohol-containing wastewater containing alcohol is supplied to the alcohol concentrator 10 through the pipe 14, and the alcohol-containing wastewater is concentrated in the alcohol concentrator 10 (alcohol concentration step). The alcohol concentrate containing the concentrated alcohol is supplied to the biological treatment apparatus 12 through the pipe 22. The treated water with reduced alcohol is discharged through the pipe 16.

On the other hand, nitrogen-containing wastewater containing ammonia nitrogen or the like is supplied to the biological treatment device 12 through the pipe 18, and in the biological treatment device 12, alcohol contained in the alcohol concentrated liquid supplied from the alcohol concentration device 10 serves as a hydrogen donor. Used to perform biological treatment of nitrogen-containing wastewater (biological treatment step). The biologically treated water with reduced ammonia nitrogen and the like is discharged through the pipe 20.

Thus, in the step of performing biological (decomposition) treatment using a hydrogen donor on the nitrogen-containing wastewater discharged in any step, the hydrogen donor changes the alcohol-containing wastewater discharged in any step, Alcohol concentrated using an alcohol concentrator. By using the alcohol concentrated by the alcohol concentrator as the hydrogen donor, both the nitrogen-containing wastewater and the alcohol-containing wastewater can be treated, and the treatment cost can be reduced.

The nitrogen-containing wastewater to be treated by the method and apparatus for treating nitrogen-containing wastewater according to the present embodiment may be nitrogen-containing water containing at least one of ammonia nitrogen and nitrate nitrogen, with no particular limitation. However, for example, it is nitrogen-containing wastewater discharged from semiconductor manufacturing factories, liquid crystal manufacturing factories, chemical factories, etc., and ammonia-containing wastewater discharged from the wet cleaning process for semiconductor wafers and semiconductor devices etc. in semiconductor manufacturing factories. Examples include nitrogen-containing wastewater such as wastewater.

The content of at least one of ammonia nitrogen and nitrate nitrogen in the nitrogen-containing wastewater to be treated is, for example, in the range of 10 mg/L to 1,000 mg/L.

In the method and apparatus for treating nitrogen-containing wastewater according to the present embodiment, the alcohol-containing wastewater serving as the supply source of the hydrogen donor may be alcohol-containing water containing alcohol and is not particularly limited. Alcohol-containing wastewater such as isopropyl alcohol (IPA)-containing wastewater discharged from a washing/drying process or the like in a semiconductor manufacturing factory is an alcohol-containing wastewater discharged from a factory, a liquid crystal manufacturing factory, a chemical factory, or the like.

Examples of the alcohol contained in the alcohol-containing wastewater include alcohols having 1 to 3 carbon atoms such as methanol, ethanol, normal propyl alcohol, and isopropyl alcohol (IPA).

As described above, in a semiconductor manufacturing plant, ammonia-containing wastewater is discharged from the wet cleaning process of semiconductor silicon wafers and semiconductor devices, etc., and IPA-containing wastewater is discharged from the cleaning/drying process. When the nitrogen-containing wastewater discharged from the semiconductor manufacturing factory and the alcohol-containing wastewater is alcohol-containing wastewater discharged from the semiconductor manufacturing factory, the nitrogen-containing wastewater treatment method and the processing apparatus according to the present embodiment are preferably applied. can do. For example, the treatment cost can be reduced by using alcohol-containing wastewater discharged from a semiconductor manufacturing factory on the same site as a hydrogen donor for biological treatment.

The content of alcohol in the alcohol-containing wastewater is, for example, in the range of 100 mg/L to 5,000 mg/L.

The alcohol concentration in the alcohol concentrate may be, for example, in the range of 20,000 to less than 600,000 mg/L. When the alcohol concentration in the alcohol concentrate is less than 20,000 mg/L, the supply pump for supplying the hydrogen donor to the biological treatment device 12 becomes large, or when the hydrogen donor is once stored in the intermediate tank. The tank capacity and installation space may increase. Further, as the amount of alcohol supplied increases, the solid-liquid separation tank 46 described later, the capacity of the subsequent storage tank and the pump for supplying the treated water may increase. Further, when the alcohol concentration in the alcohol concentrated solution is concentrated to 600,000 mg/L or more, it may be necessary to make the alcohol concentrating device explosion proof, and the cost may increase.

The alcohol concentrating device 10 as the alcohol concentrating means is not particularly limited as long as it can concentrate alcohol, and is not particularly limited. An ultrasonic atomizing device, a reverse osmosis membrane treatment device, a distillation device, a zeolite membrane treatment device. Etc. It is preferable that the alcohol concentrating device 10 includes an ultrasonic atomizing device in terms of a small installation area, a relatively low treatment cost, and the ability to arbitrarily control the alcohol concentration on the recovery (concentration) side. By using the ultrasonic atomizer, the alcohol in the alcohol concentrate can be stably controlled even if the alcohol concentration of the water containing the alcohol to be treated changes.

The structure of the ultrasonic atomizer is not particularly limited as long as it is a device that can generate mist (fog vapor) from the alcohol-containing wastewater by ultrasonic waves. For example, a liquid phase region in which ultrasonic waves are applied to alcohol-containing wastewater from an ultrasonic wave generator having an ultrasonic vibrator to generate mist and a gas phase region in which the generated mist can be retained in a retrievable state are formed. It is possible to use a device provided with an ultrasonic atomization tank for this purpose (for example, refer to JP-A-2007-118005).

As an example of the configuration of the ultrasonic atomization device, for example, as shown in FIG. 2, an ultrasonic atomization tank 24 as atomization means, a cyclone 26 as gas-liquid separation means, a condenser 28 as cooling and recovery means, and a liquid transfer A configuration including a pump 30 and a blower pump 32 may be mentioned.

For example, an ultrasonic transducer is installed at the bottom of the ultrasonic atomization tank 24 (not shown), and alcohol-containing wastewater is filled in the ultrasonic atomization tank 24 by the liquid feed pump 30 through the pipe 14. When the ultrasonic vibrator is activated, the alcohol-containing wastewater in the ultrasonic atomization tank 24 is atomized to generate mist having a high alcohol-containing concentration (atomization step). A blower pump 32 is provided as an air flow forming means in a pipe 40 that connects the condenser 28 and the upper portion of the ultrasonic atomization tank 24, and the blower pump 32 blows air to generate mist in the upper portion of the ultrasonic atomization tank 24. An air flow path is formed that circulates through the region (not shown), the cyclone 26, and the condenser 28. The mist generated from the alcohol-containing wastewater generated in the ultrasonic atomization tank 24 by this air flow path is supplied to the cyclone 26 through the pipe 34, and gas-liquid separation is performed in the cyclone 26 (gas-liquid separation step). The gas containing the separated mist is supplied to the condenser 28 through the pipe 36, condensed and liquefied in the condenser 28, and recovered as an alcohol concentrate (cooling recovery step). The alcohol concentrate containing the concentrated alcohol is supplied to the biological treatment apparatus 12 through the pipe 22. The residual water remaining in the ultrasonic atomization tank 24 is discharged through the pipe 16 and the separated water separated in the cyclone 26 is discharged through the pipes 38 and 16 as treated water having a low alcohol content.

The frequency of ultrasonic waves, the temperature of the ultrasonic atomization tank, the pressure of the gas phase, and the like are not particularly limited, and can be set according to the type of the alcohol-containing wastewater and its concentration. The frequency of ultrasonic waves can be selected from the range of 15 kHz to 400 MHz, for example.

In order to increase the alcohol concentration in the mist, a multi-stage ultrasonic atomization device in which a plurality of ultrasonic atomization tanks are arranged in series may be used.

In the path from the ultrasonic atomization tank 24 to the condenser 28, in order to prevent the target mist from aggregating, temperature control of devices, pipes, etc. forming the path may be performed as necessary.

In addition to the cyclone, an impactor such as a collision plate may be used as the gas-liquid separating means.

As the cooling recovery means, various condensing devices such as a condenser having a built-in cooling device can be used.

The alcohol concentrate concentrated by the alcohol concentrator 10 may be stored in an intermediate tank or the like, and the amount necessary as a hydrogen donor of the biological treatment device 12 may be sent by a pump or the like. The supply amount of alcohol to the biological treatment device 12 may be managed by a flow meter, a hydrometer, an alcohol concentration meter, or the like.

The biological treatment device 12 as a biological treatment means is not particularly limited in its configuration as long as it is a device capable of decomposing nitrogen-containing wastewater containing ammonia nitrogen and the like by biological treatment using a hydrogen donor. Examples of the biological treatment device 12 include, for example, nitrification means for oxidizing ammonium ions in nitrogen-containing wastewater to nitric acid or nitrous acid by nitrifying bacteria, and a hydrogen donor, and at least one of nitric acid and nitrite among denitrifying bacteria. Examples of the apparatus include a denitrification means for reducing the nitrogen gas to nitrogen gas. In the nitrification means and the denitrification means, a carrier supporting microorganisms may be used, or a granule in which sludge containing microorganisms is self-granulated may be used. The biological treatment device 12 is preferably a granular biological treatment device from the viewpoint of efficient treatment.

As a configuration example of the biological treatment apparatus 12, for example, as shown in FIG. 3, a configuration including a nitrification tank 42 as a nitrification means, a denitrification tank 44 as a denitrification means, and a solid-liquid separation tank 46 as a solid-liquid separation means is provided. Can be mentioned. Nitrification and denitrification may be performed in one tank.

For example, the nitrogen-containing wastewater is supplied to the nitrification tank 42 through the pipe 18, and ammonium ions in the nitrogen-containing wastewater in the nitrification tank 42 under aerobic conditions are converted into nitrite by an ammonia-oxidizing microorganism that is an autotrophic nitrifying bacterium. Oxidation, and nitrite is further oxidized to nitric acid by a nitrite-oxidizing microorganism that is an autotrophic nitrifying bacterium (nitrification process).

The nitrification-treated water that has been nitrification-treated is supplied to the denitrification tank 44 through the pipe 48. On the other hand, the alcohol concentrate is supplied from the alcohol concentration device 10 to the denitrification tank 44 through the pipe 22. In the denitrification tank 44, under anaerobic conditions, alcohol contained in the alcohol concentrate is used as a hydrogen donor, and at least one of nitric acid and nitrous acid is converted into nitrogen gas by a denitrifying microorganism that is a heterotrophic devaginizing bacterium. Reduced (denitrification process).

The denitrification-treated water that has been denitrified is supplied to the solid-liquid separation tank 46 through the pipe 50, and solid-liquid separation is performed in the solid-liquid separation tank 46 (solid-liquid separation step). The biologically treated water separated in the solid-liquid separation step is discharged through the pipe 20. On the other hand, the separated sludge is discharged through the lower pipe 52. At least a part of the sludge is returned to the nitrification tank 42 through the pipe 53.

When the alcohol concentration in the alcohol-containing waste water is low, for example, 100 to less than 5,000 mg/L, the alcohol can be efficiently concentrated by using two or more stages of the alcohol concentration step. For example, the alcohol concentrator 10 includes reverse osmosis membrane treatment means for concentrating alcohol-containing wastewater and ultrasonic atomization means, and concentrates concentrated water by the ultrasonic atomization means from concentrated water concentrated by the reverse osmosis membrane treatment means. It is preferable to obtain the treated alcohol and treated water. When the alcohol concentration in the alcohol-containing wastewater is, for example, 5,000 mg/L or more, the alcohol can be directly concentrated by the ultrasonic atomizing means.

For example, as shown in FIG. 4, a reverse osmosis membrane may be used in the first alcohol concentration step, and ultrasonic atomization may be used in the second alcohol concentration step. The nitrogen-containing wastewater treatment device 3 of FIG. 4 treats the nitrogen-containing wastewater by using a reverse osmosis membrane treatment device 54, an ultrasonic atomization device 56, and a hydrogen donor as alcohol concentration means for concentrating the alcohol-containing wastewater. The biological treatment device 12 is provided as biological treatment means.

In the nitrogen-containing wastewater treatment device 3 in FIG. 4, a pipe 14 for supplying alcohol-containing wastewater is connected to the inlet of the reverse osmosis membrane treatment device 54. The concentrated water outlet of the reverse osmosis membrane treatment device 54 and the inlet of the ultrasonic atomizer 56 are connected by a pipe 60, and the permeated water outlet is connected by a pipe 58. A pipe 16 for discharging treated water is connected to the treated water outlet of the ultrasonic atomizer 56. The pipe 58 is connected to the pipe 16. The upstream side of the connection point of the pipe 16 with the pipe 58 and the pipe 14 are connected by a pipe 62. The pipe 16 and the pipe 62 function as a returning means for returning the treated water obtained by the ultrasonic atomizer 56 to the upstream of the reverse osmosis membrane treatment device 54. A pipe 18 for supplying nitrogen-containing wastewater is connected to a nitrogen-containing wastewater inlet of the biological treatment device 12, and a pipe 20 for discharging biologically-treated water is connected to the outlet thereof. The alcohol concentrate outlet of the ultrasonic atomizer 56 and the alcohol concentrate inlet of the biological treatment device 12 are connected by a pipe 22.

The alcohol-containing wastewater containing alcohol is supplied to the reverse osmosis membrane treatment apparatus 54 through the pipe 14, and the reverse osmosis membrane treatment apparatus 54 performs the reverse osmosis membrane treatment step (reverse osmosis membrane treatment step (first alcohol concentration step)). The concentrated water in which the alcohol is concentrated obtained by the reverse osmosis membrane treatment is supplied to the ultrasonic atomizer 56 through the pipe 60, and the alcohol is further concentrated in the ultrasonic atomizer 56 (the ultrasonic atomization step). (Second alcohol concentration step) (above, alcohol concentration step). The alcohol concentrate containing the concentrated alcohol is supplied to the biological treatment apparatus 12 through the pipe 22. The permeated water obtained by the reverse osmosis membrane treatment is discharged as treated water through the pipe 16 together with the treated water whose alcohol is reduced in the ultrasonic atomizer 56 through the pipe 58.

On the other hand, nitrogen-containing wastewater containing nitrogen is supplied to the biological treatment device 12 through the pipe 18, and in the biological treatment device 12, alcohol contained in the alcohol concentrate supplied from the ultrasonic atomizer 56 is used as a hydrogen donor. Then, biological treatment of the nitrogen-containing wastewater is performed (biological treatment step). The biologically treated water with reduced ammonia nitrogen and the like is discharged through the pipe 20.

Alcohol remains in the residual water remaining in the ultrasonic atomizing tank 24 of the ultrasonic atomizing device 56 after the ultrasonic atomizing process and in the separated water separated in the cyclone 26. For example, when the concentration of alcohol contained in these is equal to or higher than the concentration of the alcohol-containing wastewater flowing into the reverse osmosis membrane treatment device 54, it is returned to the reverse osmosis membrane treatment device 54 through the pipes 62 and 14. Good (return process). By returning to the reverse osmosis membrane treatment device 54, the recovery rate of alcohol can be increased. When the concentration of alcohol contained in these is lower than the concentration of alcohol-containing wastewater flowing into the reverse osmosis membrane treatment apparatus 54, it may be further treated by biological treatment or the like.

The alcohol concentration in the concentrated water obtained by the reverse osmosis membrane treatment in the first alcohol concentration step is higher than the alcohol concentration in the alcohol-containing wastewater of the raw water, and may be, for example, in the range of 1,000 to 40,000 mg/L. If the alcohol concentration in the concentrated water is less than 1,000 mg/L, the device size of the ultrasonic atomizer 56 in the subsequent stage may be large and the treatment cost may be high. Further, when trying to concentrate until the alcohol concentration in the concentrated water exceeds 40,000 mg/L, the alcohol recovery rate in the reverse osmosis membrane treatment device 54 may decrease.

In the reverse osmosis membrane treatment, concentrated water having a desired alcohol concentration may be obtained by providing a plurality of reverse osmosis membranes so that the desired alcohol concentration is reached.

The alcohol concentration in the alcohol concentrated liquid obtained by the ultrasonic atomization treatment in the second alcohol concentration step is higher than the alcohol concentration in the concentrated water obtained by the reverse osmosis membrane treatment, for example, in the range of 20,000 to less than 600,000 mg/L. Good. When the alcohol concentration in the alcohol concentrate is less than 20,000 mg/L, the supply pump for supplying the hydrogen donor to the biological treatment device 12 becomes large, or when the hydrogen donor is once stored in the intermediate tank. The tank capacity and installation space may increase. Further, when the alcohol concentration in the alcohol concentrate is concentrated to 600,000 mg/L or more, it may be necessary to make the ultrasonic atomizing device explosion-proof, and the cost may increase.

When the alcohol concentration in the alcohol-containing wastewater varies (for example, ±20% with respect to the alcohol content in the alcohol-containing wastewater), at least one of the reverse osmosis membrane treatment device 54 and the ultrasonic atomization device 56. A concentration adjusting mechanism may be provided in the preceding stage. As the concentration adjusting mechanism, for example, a plurality of intermediate tanks for respectively storing alcohol-containing wastewater having different alcohol concentrations are provided, and the reverse osmosis membrane treatment device 54 or ultrasonic mist is provided from each intermediate tank so that the set alcohol concentration is obtained. Equipment for supplying the alcohol-containing wastewater by changing the mixing ratio (flow ratio) of the alcohol-containing wastewater supplied to the gasification device 56 may be provided. Further, the concentration may be adjusted by injecting dilution water into the alcohol-containing wastewater.

As described above, preferred forms of the method for treating nitrogen-containing wastewater and the treatment apparatus according to the present embodiment have the following configurations (1) to (5).
(1) As a hydrogen source of a biological treatment process for treating nitrogen-containing wastewater using a hydrogen donor, alcohol such as IPA concentrated in the alcohol concentration step is used from alcohol-containing wastewater such as IPA-containing wastewater.
(2) The alcohol concentration step has two stages.
(3) The first alcohol concentration step is a reverse osmosis membrane treatment.
(4) The second alcohol concentration step is ultrasonic atomization processing.
(5) The treated water of the ultrasonic atomization step is returned to the previous stage of the first alcohol concentration step (reverse osmosis membrane treatment).

Further, when the amount of alcohol in the alcohol-containing wastewater exceeds the required supply amount as a hydrogen donor to the biological treatment device 12, a distillation device and an ultrasonic atomization device may be combined as shown in FIG.

The treatment apparatus 5 for nitrogen-containing wastewater of FIG. 5 is a biological treatment means for treating nitrogen-containing wastewater by using a distillation device 64 and an ultrasonic atomizer 56, and a hydrogen donor as alcohol concentration means for concentrating the alcohol-containing wastewater. And a biological treatment device 12.

In the apparatus 5 for treating wastewater containing nitrogen shown in FIG. 5, a pipe 14 for supplying wastewater containing alcohol is connected to the inlet of the ultrasonic atomizer 56. A pipe 16 for discharging treated water is connected to the treated water outlet of the ultrasonic atomizer 56. The middle of the pipe 14 and the inlet of the distillation apparatus 64 are connected by a pipe 66. A pipe 68 is connected to the recovered alcohol outlet of the distillation apparatus 64, and a pipe 70 connects the recovered water outlet and the pipe 16. A pipe 18 for supplying the nitrogen-containing wastewater is connected to the nitrogen-containing wastewater inlet of the biological treatment device 12, and a pipe 20 for discharging the biologically treated water is connected to the outlet. The alcohol concentrate outlet of the ultrasonic atomizer 56 and the alcohol concentrate inlet of the biological treatment device 12 are connected by a pipe 22.

At least a part of the alcohol-containing waste water containing alcohol is supplied to the ultrasonic atomization device 56 through the pipe 14, and the alcohol is concentrated in the ultrasonic atomization device 56 (ultrasonic atomization step). The alcohol concentrate containing the concentrated alcohol is supplied to the biological treatment apparatus 12 through the pipe 22. The rest of the alcohol-containing wastewater is supplied to the distillation apparatus 64 through the pipes 14 and 66, the distillation processing is performed in the distillation apparatus 64, and the concentrated recovered alcohol and the recovered water are separated (distillation step). The recovered alcohol is discharged through the pipe 68, and the recovered water is discharged through the pipe 16 as the treated water together with the treated water in which the alcohol is reduced in the ultrasonic atomizer 56.

On the other hand, nitrogen-containing wastewater containing nitrogen is supplied to the biological treatment device 12 through the pipe 18, and in the biological treatment device 12, alcohol contained in the alcohol concentrate supplied from the ultrasonic atomizer 56 is used as a hydrogen donor. Then, biological treatment of the nitrogen-containing wastewater is performed (biological treatment step). The biologically treated water with reduced ammonia nitrogen and the like is discharged through the pipe 20.

In the treatment apparatus 5 for nitrogen-containing wastewater in FIG. 5, alcohol-containing wastewater containing a necessary amount of alcohol as a hydrogen donor to the biological treatment apparatus 12 is supplied to the ultrasonic atomizer 56. Other alcohol-containing wastewater can be sent to the distillation device 64, concentrated, and valuablely recovered as recovered alcohol. When the alcohol concentration in the alcohol-containing waste water is low, for example, 100 to less than 5,000 mg/L, the reverse osmosis membrane treatment device 54 is installed in the preceding stage of the ultrasonic atomization device 56 as in FIG. You may.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<Example 1>
Using the ultrasonic atomizer shown in FIG. 2 as the alcohol concentrator 10, the IPA-containing water was concentrated. The IPA concentration of the water to be treated, IPA-containing water, was 1.8% by mass. The water to be treated is sent to the ultrasonic atomization tank 24 by the liquid feed pump 30, and the mist is generated by the ultrasonic vibration (frequency: 2.4 MHz) generated by the ultrasonic vibrator provided inside the ultrasonic atomization tank 24. Let The generated mist was sent to the cyclone 26 in the subsequent stage by the blower pump 32 installed in the ultrasonic atomization tank 24, and gas-liquid separation was performed. The mist having a high IPA concentration separated by the cyclone 26 was further sent to the condenser 28 at the subsequent stage and cooled and recovered as an IPA concentrated liquid. The mist having a high water content obtained in the ultrasonic atomization tank 24 and the cyclone 26 was discharged as treated water. The cooling temperature of the condenser 28 was set to 10°C. The IPA concentration in the IPA concentrated liquid recovered by the above treatment was 8.0% by mass.

The IPA concentration was measured using a gas chromatograph (Model 7820A manufactured by Agilent Technologies, Inc.).

<Example 2>
An examination was performed in the same manner as in Example 1 except that the IPA concentration of the water to be treated in Example 1 was 1.2 mass% and the cooling temperature of the condenser 28 was set to 0°C. The IPA concentration in the IPA concentrated liquid recovered by the above treatment was 8.1% by mass.

<Example 3>
An examination was conducted in the same manner as in Example 1 except that the IPA concentration of the water to be treated in Example 1 was set to 0.9% by mass and the cooling temperature of the condenser 28 was set to −10° C. The IPA concentration in the IPA concentrated liquid recovered by the above treatment was 8.1% by mass.

Thus, the high-concentration IPA concentrated water could be collected by the ultrasonic atomizer of the example. This ultrasonic atomizer is used together with a biological treatment device that treats nitrogen-containing wastewater using a hydrogen donor, and the high-concentration IPA concentrated water obtained by the ultrasonic atomizer is used as a hydrogen donor for the biological treatment device. As a result, the nitrogen-containing wastewater and the alcohol-containing wastewater can be treated together, and the treatment cost can be reduced. Further, by using the ultrasonic atomizer, the IPA concentration in the IPA concentrate can be stably controlled even if the IPA concentration of the water to be treated, IPA-containing water, changes.

1,3,5 treatment device, 10 alcohol concentration device, 12 biological treatment device, 14,16,18,20,22,34,36,38,40,48,50,52,53,58,60,62, 66, 68, 70 Piping, 24 Ultrasonic atomization tank, 26 Cyclone, 28 Condenser, 30 Liquid feed pump, 32 Blower pump, 42 Nitrification tank, 44 Denitrification tank, 46 Solid-liquid separation tank, 54 Reverse osmosis membrane treatment device, 56 Ultrasonic atomizer, 64 distillation device.

Claims (8)

A biological treatment means for treating nitrogen-containing wastewater using a hydrogen donor;
Reverse osmosis membrane treatment means for concentrating alcohol-containing wastewater, and alcohol concentration means including ultrasonic atomization means for obtaining concentrated alcohol and treated water from concentrated water concentrated by the reverse osmosis membrane treatment means. ,
Equipped with
An apparatus for treating nitrogen-containing wastewater, wherein alcohol concentrated by the alcohol concentrating means is used as the hydrogen donor. The apparatus for treating nitrogen-containing wastewater according to claim 1 ,
A treatment device for nitrogen-containing wastewater, comprising return means for returning the treated water obtained by the ultrasonic atomization means to a stage before the reverse osmosis membrane treatment means. A treatment apparatus for nitrogen-containing wastewater according to claim 1 or 2 , wherein
The nitrogen-containing wastewater is nitrogen-containing wastewater discharged from a semiconductor manufacturing plant,
The treatment apparatus for nitrogen-containing wastewater, wherein the alcohol-containing wastewater is alcohol-containing wastewater discharged from the semiconductor manufacturing factory. The nitrogen-containing wastewater treatment device according to any one of claims 1 to 5 ,
A treatment device for nitrogen-containing wastewater, wherein the biological treatment means is a biological treatment means using granules obtained by granulating microorganisms. A biological treatment process for treating nitrogen-containing wastewater using a hydrogen donor;
A reverse osmosis membrane treatment step of concentrating alcohol-containing wastewater, and an alcohol concentration step including an ultrasonic atomization step of obtaining concentrated alcohol and treated water from the concentrated water concentrated by the reverse osmosis membrane treatment step. ,
Including
A method for treating nitrogen-containing wastewater, wherein the alcohol concentrated in the alcohol concentration step is used as the hydrogen donor. The method for treating nitrogen-containing wastewater according to claim 5 ,
A method for treating nitrogen-containing wastewater, comprising a returning step of returning the treated water obtained by the ultrasonic atomization step to a stage before the reverse osmosis membrane treatment step. A method for treating nitrogen-containing wastewater according to claim 5 or 6 , wherein
The nitrogen-containing wastewater is nitrogen-containing wastewater discharged from a semiconductor manufacturing plant,
The method for treating nitrogen-containing wastewater, wherein the alcohol-containing wastewater is alcohol-containing wastewater discharged from the semiconductor manufacturing factory. A method for treating nitrogen-containing wastewater according to any one of claims 8 to 9 ,
A method for treating nitrogen-containing wastewater, wherein the biological treatment step is a biological treatment step using granules obtained by granulating microorganisms.

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