JP6777430B2 - Water treatment equipment - Google Patents

Description

The present invention is, for example, such as ammonia-containing waste water discharged from the manufacturing process of electronic products or its elements, such as semiconductor and liquid crystal, on water treatment MakotoSo location for removing ammonia from the ammonia-containing water.

In the semiconductor manufacturing process and related processes, cleaning is performed using a chemical that is a mixture of ammonia and hydrogen peroxide. After the above cleaning step, cleaning is performed using ultrapure water to remove ammonia remaining on the surface of the product to be cleaned. Therefore, a large amount of wastewater having a low salt concentration and a relatively low concentration of ammonia is discharged. Ammonia is a cause of eutrophication, so it is necessary to treat the wastewater with ammonia. In addition, since a large amount of ultrapure water is required in the cleaning process, it is desirable to collect and reuse the wastewater.

Conventionally, the ammonia stripping method is known as a method for treating ammonia-containing wastewater. In this method, the ammonia-containing wastewater is heated by steam or a heater and dissipated in a dissipating tower. In the case of emission treatment, a high concentration of ammonia is advantageous in terms of treatment cost. Therefore, a method in which ammonia contained in low-concentration ammonia-containing wastewater is adsorbed on a cation exchange resin, then the cation exchange resin is regenerated to obtain a regenerated waste liquid in which ammonia is concentrated, and the regenerated waste liquid is stripped of ammonia to remove ammonia. (Patent Document 1). Ammonia can be oxidatively decomposed and removed by bringing the exhaust gas discharged from the emission tower into contact with the ammonia decomposition catalyst (Patent Document 2).

Special Publication No. 56-042360 JP-A-2003-340440

The cation exchange resin is regenerated with an acid. Therefore, the pH of the regenerated waste liquid is acidic. On the other hand, in ammonia stripping, in order to volatilize ammonia, it is necessary to adjust the pH of the liquid to be dissipated to alkaline and pass water through the dissipating tower. Therefore, when the recycled waste liquid of the cation exchange resin is stripped with ammonia, a large amount of alkali is required for alkalinization.

An object of the present invention is to reduce the amount of alkali added during ammonia stripping in a water treatment method in which ammonia contained in water to be treated is concentrated in a regenerated waste liquid of a cation exchange resin and the regenerated waste liquid is stripped with ammonia. Is to provide a way to do it.

Another object of the present invention is to provide a water treatment apparatus suitable for carrying out this water treatment method.

According to one aspect of the present invention
A water treatment apparatus having a cation exchange resin tower and an anion exchange resin tower for treating water to be treated in which ammonia is dissolved.
A line for supplying an acidic liquid to the cation exchange resin tower and discharging the recycled waste liquid from the cation exchange resin tower.
A line for supplying an alkaline liquid to the anion exchange resin tower and discharging the recycled waste liquid from the anion exchange resin tower.
A mixing device that mixes the regenerated waste liquid discharged from the cation exchange resin tower with the regenerated waste liquid discharged from the anion exchange resin tower to obtain a mixed regenerated waste liquid.
A pH adjustment tank for adding sodium hydroxide to the mixed regeneration waste liquid, and
A dissipative tower for stripping the mixed regenerated waste liquid discharged from the pH adjusting tank, and
Have a,
Provided is a water treatment apparatus in which the ammonia concentration in the water to be treated is 10 mg / L or more and 200 mg / L or less in terms of nitrogen conversion .

According to the present invention, in a water treatment apparatus in which ammonia contained in water to be treated is concentrated in a regenerated waste liquid of a cation exchange resin and the regenerated waste liquid is stripped with ammonia, the amount of alkali added during ammonia stripping is suppressed. Equipment that can be provided is provided.

It is a process flow diagram which shows an example of the water treatment apparatus of this invention. It is a process flow diagram which shows an example of the existing water treatment apparatus to be remodeled. It is a process flow diagram which shows another example of the existing water treatment equipment to be remodeled.

The water treatment method according to the present invention includes an ion exchange step, a recycled waste liquid mixing step, and a stripping step.

[Ion exchange process]
The water to be treated to be treated with water is water in which ammonia is dissolved, for example, ammonia-containing wastewater discharged from an electronic product manufacturing process. Since part of the ammonia dissolved in water becomes ammonium ions, the water to be treated contains ammonium ions.

When the ammonia concentration in the water to be treated is about 10 mg / L or more and 200 mg / L or less, the effect of the present invention is particularly remarkable, which is preferable.

Unless otherwise specified, the "ammonia concentration" in the liquid in the present specification means a concentration including not only free ammonia but also ammonium ions. Unless otherwise specified, when the ammonia concentration in the liquid is expressed in the unit "mg / L", it means the concentration when free ammonia and ammonium ions are converted into nitrogen.

In this step, the water to be treated is passed through a cation exchange resin (a cation exchange resin that adsorbs cations) and an anion exchange resin (an anion exchange resin that adsorbs anions). The order of the treatment with the cation exchange resin and the treatment with the anion exchange resin does not matter. For example, the water to be treated can be passed through a cation exchange resin and then through an anion exchange resin. Alternatively, the water to be treated can be passed through an anion exchange resin and then through a cation exchange resin. A mixed bed of a cation exchange resin and an anion exchange resin can also be used.

When the water to be treated is passed through a cation exchange resin, ammonium ions, cations such as calcium ions and magnesium ions are adsorbed on the cation exchange resin. When the water to be treated is passed through an anion exchange resin, anions such as chloride ion, nitrate ion, nitrite ion and sulfate ion contained in the water to be treated are adsorbed.

Both the cation exchange resin and the anion exchange resin can be appropriately selected from those known in the water treatment field and used. The ion exchange resin includes a gel type, a porous type, and an MR type, and any type of ion exchange resin may be used as the cation exchange resin or the anion exchange resin. The cation exchange resin may be either strongly acidic or weakly acidic, or a combination thereof may be used. The anion exchange resin may be either strongly basic or weakly basic, or a combination thereof may be used.

[Recycled waste liquid mixing process]
In this step, the regenerated waste liquid obtained by regenerating the cation exchange resin and the regenerated waste liquid obtained by regenerating the anion exchange resin are mixed to obtain a mixed regenerated waste liquid.

The cation exchange resin can be regenerated by a known method using an acidic liquid (acid aqueous solution). As the regenerating agent, for example, hydrochloric acid can be used. The reclaimed waste liquid obtained by the reclaiming operation is acidic.

The anion exchange resin can also be regenerated by a known method using an alkaline solution (alkaline aqueous solution). As the regenerating agent, for example, an aqueous sodium hydroxide solution can be used. The reclaimed waste liquid obtained by the reclaiming operation is alkaline.

The cation exchange resin regenerated waste liquid and the anion exchange resin regenerated waste liquid are mixed. By this operation, the cation exchange resin regenerated waste liquid (acidic) is at least partially neutralized by the anion exchange resin regenerated waste liquid (alkaline). As a result, the amount of alkali added during stripping can be reduced or reduced to zero.

[Stripping process]
In this step, ammonia is removed from the mixed regenerated waste liquid by stripping the mixed regenerated waste liquid under alkaline conditions.

When the mixed regenerated waste liquid obtained in the regenerated waste liquid mixing step is alkaline, the mixed regenerated waste liquid can be supplied to the diffusion tower without adjusting the pH. Alternatively, the pH of the mixed regeneration waste liquid can be adjusted (typically increasing the pH) in order to make the mixed regeneration waste liquid alkaline, or to further raise the pH of the mixed regeneration waste liquid even if it is alkaline. .. The pH-adjusted mixed regenerated waste liquid can be supplied to the dissipation tower. Alkali, typically sodium hydroxide, can be added to the mixed reclaimed effluent for pH adjustment.

The pH of the discharge tower inlet liquid (mixed and regenerated waste liquid whose pH is adjusted as necessary) is preferably 9 to 13 from the viewpoint of converting ammonium ions into ammonia and facilitating stripping.

The water temperature of the discharge tower inlet liquid is preferably 40 ° C. or higher and 100 ° C. or lower from the viewpoint of facilitating the volatilization of ammonia gas. Therefore, the mixed and regenerated waste liquid supplied to the diffusion tower can be appropriately heated by a heat exchanger, a heater, or the like.

The ammonia concentration of the discharge tower inlet liquid is preferably 300 mg / L or more from the viewpoint of suppressing the energy required for evaporation. There is no particular upper limit to the ammonia concentration in the discharge tower inlet liquid. However, when the concentration is high, the amount of wastewater is often small, so methods such as off-site disposal may be more cost effective. Therefore, the present invention is particularly suitable when the ammonia concentration of the discharge tower inlet liquid is 10000 mg / L or less.

The ammonia concentration of the treated water (water from which ammonia has been removed) obtained from the scavenging tower is determined from the viewpoint of environmental load such as to meet the discharge standard, or to reduce the nitrogen load if there is treatment in the subsequent stage. , 0 mg / L or more and 100 mg / L or less is preferable.

As the structure of the dissipating tower, a structure known for ammonia stripping can be appropriately adopted, and a shelf tower, a filling tower, or the like can be used as the dissipating tower.

During stripping, steam or air can be blown into the dissipative tower. Alternatively, a heater (reboiler) may be provided at the bottom of the dissipating tower to generate steam without blowing the stripping gas.

A gas containing ammonia gas is obtained from the dissipation tower. This gas may contain water vapor, nitrogen, oxygen and the like, depending on the type of stripping gas.

[Further processing]
Ammonia gas contained in the gas (gas containing ammonia gas) obtained from the emission tower can be converted into nitrogen gas by using an ammonia decomposition catalyst. For this purpose, a catalytic reactor (ammonia catalytic decomposition apparatus) that brings the gas obtained from the dissipation tower into contact with the ammonia decomposition catalyst can be used. As the structure of this catalytic reactor, a structure known in the field of ammonia decomposition can be appropriately adopted, and a fixed layer, a fluidized bed, or the like can be used.

As the ammonia decomposition catalyst, a catalyst known in the field of ammonia decomposition can be used, and in particular, an oxidation catalyst can be used. For example, catalyst active components such as salts or oxides of ruthenium, rhodium, palladium, iridium, platinum, titanium, iron, nickel, cobalt, vanadium, cerium, manganese, etc. on carriers such as titania, silica, alumina, zirconia, zeolite, etc. Can be used as a catalyst supporting the above. The shape of the catalyst is not particularly limited, such as honeycomb, wire mesh, and granular.

[Other processes]
By performing sand filtration or activated carbon treatment as a pretreatment for the treatment with the ion exchange resin, clogging or contamination of the ion exchange resin can be prevented.

[Water treatment equipment]
The water treatment apparatus according to the present invention
Ion exchange resin tower containing cation exchange resin and anion exchange resin,
A mixing device connected to the cation exchange resin regenerated waste liquid outlet and the anion exchange resin regenerated waste liquid outlet of the ion exchange resin tower, and
Includes a divergence tower connected to the outlet of the mixer.

-Ion exchange resin tower The ion exchange resin tower includes a cation exchange resin and an anion exchange resin. The ion exchange resin tower can include a cation exchange resin tower containing a cation exchange resin and an anion exchange resin tower containing an anion exchange resin. In this case, the cation exchange resin tower and the anion exchange resin tower are provided separately, and therefore two or more ion exchange resin towers are used. Alternatively, the ion exchange resin tower can include a mixed bed of a cation exchange resin and an anion exchange resin. In this case, one or more ion exchange resin towers including a mix bed are used.

As the structure of the ion exchange resin tower (cation exchange resin tower, anion exchange resin tower, or ion exchange resin tower provided with a mix bed) itself, those known in the field of water treatment can be appropriately adopted. It is also known that the ion exchange resin tower has an inlet for a regenerating liquid for regenerating the ion exchange resin and an outlet for the regenerated waste liquid after being used for regeneration.

-Mixing device The mixing device is connected to the cation exchange resin regenerated waste liquid outlet and the anion exchange resin regenerated waste liquid outlet of the ion exchange resin tower. In the mixing device, the cation exchange resin regenerated waste liquid outlet and the anion exchange resin regenerated waste liquid are mixed.

When the cation exchange resin tower and the anion exchange resin tower are separately provided, the cation exchange resin regeneration waste liquid outlet of the cation exchange resin tower is connected to the mixing device, and the anion exchange resin regeneration waste liquid outlet of the anion exchange resin tower is provided. Connected to the mixing device.

Similarly, in the case of an apparatus provided with a mix bed, the acid reclaimed waste liquid and the alkaline regenerated waste liquid that are sequentially discharged are mixed by the mixing device.

The mixing device may be a tank or a simple pipe. For example, a tank (or pipe) as a mixing device is provided, a line connecting this tank (or pipe) and the cation exchange resin recycled waste liquid outlet is provided, and this tank (or pipe) and the anion exchange resin recycled waste liquid outlet are connected. A connecting line can be provided. In this tank (or piping), the cation exchange resin regenerated waste liquid outlet and the anion exchange resin regenerated waste liquid can be mixed.

-Dispersion tower The outlet of the mixing device (the outlet for the mixed and regenerated waste liquid) is connected to the dissipating tower, and in particular, is connected to the liquid inlet of the dissipating tower, enabling stripping of the mixed and regenerated waste liquid. Other equipment such as a pH adjustment tank and a heat exchanger can be appropriately provided in the line connecting the outlet of the mixing device and the dissipating tower.

Each line can be configured by appropriately using pipes, valves, pumps and the like.

[Example of water treatment equipment]
FIG. 1 shows a process flow of an example of the water treatment apparatus according to the present invention. In this apparatus, the ion exchange resin tower is composed of a cation exchange resin tower 4 and an anion exchange resin tower 5. Further, the line L16 is used as a mixing device (recycled waste liquid mixing device).

First, an operation in the case of removing ammonium ions from the water to be treated using an ion exchange resin will be described. The water to be treated stored in the drainage tank 1 is sent to the sand filter 2 via the line L1 and then to the activated carbon tower 3 via the line L2. Impurities such as suspended substances are removed from the water to be treated by a sand filter and an activated carbon tower. The water to be treated, which has been pretreated in this way, is sent to the cation exchange resin tower 4 including the cation exchange resin via the line L3. Here cation exchange resin to adsorb ammonium ions (NH ₄ ^+). The liquid treated with the cation exchange resin is sent to the anion exchange resin tower 5 via the line L4. Here anion contained in the water to be treated ^{_{(Cl -, NO 3 -,}} NO 2 -, SO 4 2-) is adsorbed to the anion exchange resin. The liquid treated with the cation exchange resin and the anion exchange resin in this way is high-purity treated water having a reduced ammonium concentration, is discharged from the line L5 to the outside of the water treatment apparatus, and is appropriately reused as recovered water. Or it is released to the outside world.

In order to treat the water to be treated with both the cation exchange resin and the anion exchange resin, the cation exchange resin tower 4 and the anion exchange resin tower 5 can be arranged in series with respect to the flow of the water to be treated. In FIG. 1, the anion exchange resin tower is provided downstream of the cation exchange resin tower, but the cation exchange resin tower may be provided downstream of the anion exchange resin tower. When a mixed bed of a cation exchange resin and an anion exchange resin is used, only one ion exchange resin tower provided with the mix bed can be used instead of the combination of the cation exchange resin tower and the anion exchange resin tower.

Next, the operation when regenerating the ion exchange resin will be described. From the water tank 11 for regeneration, water for regeneration (pure water) is supplied to the cation exchange resin tower 4 and the anion exchange resin tower 5 via the lines L11 and then through the lines L12 and L13, respectively. At this time, hydrochloric acid is added from the line L31 to the regenerating water for the cation exchange resin, and sodium hydroxide is added from the line L32 to the regenerating water for the anion exchange resin. Alternatively, hydrochloric acid and sodium hydroxide may each have a storage tank and a supply line. The regenerated waste liquids from the cation exchange resin column and the anion exchange resin column join the line L16 via the line L14 and the line L15, respectively, and mix with each other here. The mixed regenerated waste liquid is sent from the line L16 to the regenerated waste liquid tank 12. Alternatively, the line L14 and the line L15 may be connected to the recycled waste liquid tank 12, respectively. The mixed regenerated waste liquid is sent from the regenerated waste liquid tank to the pH adjusting tank 13 via the line L17. Here, sodium hydroxide is added to the mixed regenerated waste liquid from the line L33. At this stage, the mixed and regenerated waste liquid is alkaline. This mixed and regenerated waste liquid is supplied to the heat exchanger 14 via the line L18 and heated there. The heated alkaline mixed reclaimed waste liquid is supplied to the dissipation tower 15 via the line 19 and stripped by the steam supplied from the line L34. The gas from the dissipative tower (including ammonia gas removed from the mixed regenerated waste liquid and steam) is discharged from the dissipative tower to the line L20, diluted and adjusted to an appropriate concentration by the air supplied from the line L35, and the line L21 is adjusted. Then, it is sent to the ammonia catalytic decomposition apparatus 16. In the ammonia catalytic decomposition apparatus, ammonia is oxidized and discharged as nitrogen gas (and water) from the line L22 to the outside world. The liquid obtained from the dissipative tower is supplied to the heat exchanger 14 via the line L23, where it is cooled. The cooled liquid obtained on the line L24 is high-purity water (treated water) from which ammonia has been removed, and is appropriately reused or discharged to the outside world.

According to the present invention, the amount of the mixed regenerated waste liquid can be reduced to 1/10 to 1/50 of the amount of water to be treated. Therefore, as compared with the case of directly stripping the water to be treated, the heat energy required for stripping is also reduced to 1/10 to 1/50, which saves energy and reduces the treatment cost. In addition, water treatment can be performed with a smaller facility.

[Modification of existing water treatment equipment]
In order to remove ammonia from the water to be treated in which ammonia is dissolved, a water treatment apparatus including a cation exchange resin tower containing a cation exchange resin may already exist. In this case, it is possible to obtain the above-mentioned excellent water treatment apparatus by modifying the existing water treatment apparatus.

<First modified form: When the existing water treatment device contains a cation resin tower but does not contain an anion exchange resin and does not include a emission tower>
in this case,
An anion exchange resin tower containing an anion exchange resin, arranged in series with the cation resin tower with respect to the flow of water to be treated.
A mixing device connected to the cation exchange resin regeneration waste liquid outlet of the cation exchange resin tower and the anion exchange resin regeneration waste liquid outlet of the anion exchange resin tower, and
A divergence tower connected to the outlet of the mixing device can be provided in addition to the existing water treatment device.

For example, an existing water treatment device can have the process flow shown in FIG. In FIG. 2 (also in FIG. 3), the same devices and lines as those in FIG. 1 are designated by the same reference numerals. The treated water from which ammonia has been removed in the cation exchange resin column 4 is obtained on the line L4. At the time of regeneration of the cation exchange resin, hydrochloric acid (line L31) is added to the regeneration water (line L11) from the regeneration water tank 11, and the hydrochloric acid (line L31) is supplied to the cation exchange resin tower 4 via the line L12. The regenerated waste liquid (line L14) from the regenerated waste liquid outlet of the cation exchange resin tower 4 can be appropriately discarded or sent to another ammonia treatment apparatus such as biological treatment.

By providing the existing water treatment apparatus with equipment or lines shown in FIG. 1 but not shown in FIG. 2, a water treatment apparatus having the process flow shown in FIG. 1 can be obtained. The main equipment to be added is the anion exchange resin column 5, the mixing device (line L16), and the dissipating column 15.

The anion exchange resin tower 5 contains an anion exchange resin. The anion exchange resin column is arranged in series with the cationic resin column with respect to the flow of water to be treated. For example, as shown in FIG. 1, the water to be treated may be treated in the cation exchange resin tower 4 and then in the anion exchange resin tower 5. Alternatively, the water to be treated may be treated in an anion exchange resin column and then in a cation exchange resin column.

The line L16 functioning as a mixing device is connected to the cation exchange resin regeneration waste liquid outlet of the cation exchange resin tower 4 and the anion exchange resin regeneration waste liquid outlet of the anion exchange resin tower 5 via lines L14 and L15, respectively.

The diffuser tower 15 is connected to the outlet of the mixing device (line L16) via the recycled waste liquid tank 12, the line L17, the pH adjusting tank 13, the line L18, the heat exchanger 14, and the line L19.

Therefore, the present invention provides a kit for modifying a water treatment apparatus including a cation exchange resin tower containing a cation exchange resin. This water treatment device modification kit is
An anion exchange resin tower containing an anion exchange resin, arranged in series with the cation resin tower with respect to the flow of water to be treated.
A mixing device connected to the cation exchange resin regeneration waste liquid outlet of the cation exchange resin tower and the anion exchange resin regeneration waste liquid outlet of the anion exchange resin tower, and
Includes a divergence tower connected to the outlet of the mixer.

<Second modification: When the existing water treatment equipment includes not only the cation exchange resin tower but also the dissipation tower, but does not contain the anion exchange resin>
In addition to the cation exchange resin tower, the existing water treatment apparatus may include a dissipative tower connected to the cation exchange resin regenerated waste liquid outlet of the cation exchange resin tower. In that case,
An anion exchange resin tower containing an anion exchange resin, which is arranged in series with the cation resin tower with respect to the flow of water to be treated, and an anion exchange resin tower.
A mixing device connected to the cation exchange resin regenerated waste liquid outlet of the cation exchange resin tower and the anion exchange resin regenerated waste liquid outlet of the anion exchange resin tower, and the outlet of the mixing device is connected to the dissipation tower. A mixing device can be added to the existing water treatment device. As a result, the cation resin recycled waste liquid outlet and the dissipating tower are connected via the mixing device.

For example, an existing water treatment device can have the process flow shown in FIG. The treated water from which ammonia has been removed in the cation exchange resin column 4 is obtained on the line L4. At the time of regeneration of the cation exchange resin, hydrochloric acid (line L31) is added to the regeneration water (line L11) from the regeneration water tank 11, and the hydrochloric acid (line L31) is supplied to the cation exchange resin tower 4 via the line L12. The regenerated waste liquid (line L14) from the regenerated waste liquid outlet of the cation exchange resin tower 4 is sent to the regenerated waste liquid tank 12. In the apparatus shown in FIG. 1, the mixed reclaimed waste liquid is supplied from the reclaimed waste liquid tank 12 to the line L17 and subjected to the subsequent treatment (including stripping). On the other hand, in the apparatus shown in FIG. 3, the recycled waste liquid from the cation exchange resin tower is supplied to the line L17 instead of the mixed recycled waste liquid, and is subjected to the same treatment as in the case of the apparatus of FIG.

By providing the existing water treatment apparatus with equipment and lines shown in FIG. 1 but not shown in FIG. 3, a water treatment apparatus having the process flow shown in FIG. 1 can be obtained. In the existing water treatment apparatus shown in FIG. 3, the cation resin regenerated waste liquid outlet of the cation exchange resin tower 4 and the dissipating tower 15 are the regenerated waste liquid tank 12, the line L17, the pH adjustment tank 13, the line L18, the heat exchanger 14 and the line. It is connected via L19. On the other hand, in the water treatment apparatus shown in FIG. 1, the cationic resin recycled waste liquid outlet and the dissipating tower are connected via a mixing apparatus (line 16) in addition to these devices / lines.

The main equipment to be added is an anion exchange resin tower 5 and a mixing device (line L16).

The anion exchange resin tower 5 contains an anion exchange resin. The anion exchange resin column is arranged in series with the cationic resin column with respect to the flow of water to be treated. For example, as shown in FIG. 1, the water to be treated may be treated in the cation exchange resin tower 4 and then in the anion exchange resin tower 5. Alternatively, the water to be treated may be treated in an anion exchange resin column and then in a cation exchange resin column.

The line L16 functioning as a mixing device is connected to the cation exchange resin regeneration waste liquid outlet of the cation exchange resin tower 4 and the anion exchange resin regeneration waste liquid outlet of the anion exchange resin tower 5 via lines L14 and L15, respectively. Then, the diffusion tower 15 is connected to the outlet of the mixing device (line L16) via the recycled waste liquid tank 12, the line L17, the pH adjusting tank 13, the line L18, the heat exchanger 14, and the line L19.

Therefore, the present invention provides a kit for modifying a water treatment apparatus including a cation exchange resin tower containing a cation exchange resin and a dissipation tower connected to a cation exchange resin regenerated waste liquid outlet of the cation exchange resin tower. .. This water treatment device modification kit is
An anion exchange resin tower containing an anion exchange resin, which is arranged in series with the cation resin tower with respect to the flow of water to be treated, and an anion exchange resin tower.
A mixing device connected to a cation exchange resin regenerated waste liquid outlet of the cation exchange resin tower and an anion exchange resin regenerated waste liquid outlet of the anion exchange resin tower, wherein the outlet of the mixing device is connected to the dissipation tower. Includes mixing device.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

[Example 1]
A process simulation was performed assuming a device having the process flow shown in FIG.

Table 1 summarizes the amount and concentration of water in each process.

The following waters to be treated were assumed.
-Water to be treated: Water adjusted to contain 127 mg / L of Cl ions in addition to 50 mg / L of ammonia (ammonium ion) as NH _4- N (nitrogen equivalent concentration) using NH ₄ Cl.
-Regenerative HCl (L31): Industrial 35% by mass HCl aqueous solution.
-Regeneration NaOH (L32) and Stripping NaOH (L33): Industrial 25% by mass NaOH aqueous solution.
-Regeneration water (L11): pure water.
-Heating steam (L34): 0.5 MPa saturated steam.

The anion tower regeneration waste liquid (L15) contained 7.1 kmol / day of NaOH. At this time, the amount of NaOH (L33) required to adjust the pH of the solution (L17, 50 m ³ / day) obtained by mixing the cation tower regeneration waste liquid with the anion tower regeneration waste liquid is 2 kg / day (100% by mass NaOH conversion) /. Met.

[Comparative Example 1]
The cation tower regeneration waste liquid (L14) was not mixed with the anion tower regeneration waste liquid (L15), and the cation tower regeneration waste liquid was sent to the pH adjustment tank 13 as it was. At this time, NaOH was added from the line L33 so that the pH of the discharge tower inlet liquid (L19) was the same as in Example 1 (pH = 11).

Except for the above, a process simulation was performed in the same manner as in Example 1. The amount of NaOH required to neutralize the liquid (25 m ³ / day) flowing through the line L17 was 287 kg / day (100% by mass NaOH equivalent).

1 Drainage (water to be treated) tank 2 Sand filter 3 Activated carbon tower 4 Cationic exchange resin tower 5 Anion exchange resin tower 11 Regeneration water tank 12 Regeneration waste liquid tank 13 pH adjustment tank 14 Heat exchanger 15 Ammonia dissipative tower 16 Ammonia catalyst decomposition device

Claims (2)

A water treatment apparatus having a cation exchange resin tower and an anion exchange resin tower for treating water to be treated in which ammonia is dissolved.
A line for supplying an acidic liquid to the cation exchange resin tower and discharging the recycled waste liquid from the cation exchange resin tower.
A line for supplying an alkaline liquid to the anion exchange resin tower and discharging the recycled waste liquid from the anion exchange resin tower.
A mixing device that mixes the regenerated waste liquid discharged from the cation exchange resin tower with the regenerated waste liquid discharged from the anion exchange resin tower to obtain a mixed regenerated waste liquid.
A pH adjustment tank for adding sodium hydroxide to the mixed regeneration waste liquid, and
A dissipative tower for stripping the mixed regenerated waste liquid discharged from the pH adjusting tank, and
Have a,
A water treatment apparatus in which the ammonia concentration in the water to be treated is 10 mg / L or more and 200 mg / L or less in terms of nitrogen conversion . The water treatment apparatus according to claim 1, wherein the water to be treated is ammonia-containing wastewater discharged from an electronic product manufacturing process.

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