TW201808820A - Water treatment method and apparatus, method of modifying water treatment apparatus, and kit for modifying water treatment apparatus - Google Patents

Abstract

The invention enables the treatment of ammonia in water containing a low concentration of ammonia, with minimal energy consumption and without the discharge of ammonium sulfate. The invention provides a water treatment method including: (a) a step of adding an alkali to a water to be treated containing dissolved ammonia, thereby converting the ammonium ions to ammonia; (b) a step of supplying the liquid obtained in step (a) to the supply side of a gas-liquid separation membrane, and supplying a sulfuric acid aqueous solution to the permeate side, thereby causing ammonia gas to permeate the gas-liquid separation membrane and the permeated ammonia gas to be absorbed by the sulfuric acid aqueous solution, and obtaining an ammonium sulfate aqueous solution from the permeate side and a treated water from the supply side; (c) a step of diluting the ammonium sulfate aqueous solution obtained in step (b) with a diluent; and (d) a step of obtaining a treated water from the diluted ammonium sulfate aqueous solution obtained in step (c) by stripping the solution under alkaline conditions. Also provided is an apparatus suitable for carrying out this method. The invention also provides a method and a kit for modifying a water treatment apparatus to obtain this apparatus.

Description

Water treatment method, water treatment device, water treatment device reconstruction method, and water treatment device reconstruction kit

The present invention relates to a water treatment method and a water treatment device for removing ammonia from water containing ammonia, and the water containing ammonia is, for example, ammonia-containing wastewater discharged from the manufacturing process of electronic products such as semiconductors and liquid crystals, or the components thereof. .

In the semiconductor manufacturing step or a related step, cleaning is performed by using a medicine in which ammonia and hydrogen peroxide are mixed. After the above cleaning step, ultrapure water is used for cleaning to remove ammonia remaining on the surface of the product to be cleaned. Therefore, a large amount of drainage with low salt concentration and low ammonia concentration will be discharged. Ammonia is considered to be the cause of superior oxidation, so ammonia treatment in wastewater is necessary.

As a conventional method for treating wastewater containing ammonia, an ammonia stripping method is known. In this method, the waste water containing ammonia is heated with steam, a heater, or the like, and is subjected to a desorption treatment in a desorption tower. The exhaust gas discharged from the desorption tower can be removed by oxidizing and decomposing ammonia by bringing it into contact with an ammonia decomposition catalyst (Patent Document 1).

In addition, as another method for treating ammonia drainage, a method of performing deamination gas treatment by heating a wastewater containing ammonia and passing through a gas-liquid separation membrane module that allows gas to pass through but liquid does not pass is known (Patent Document 2) ). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2003-340440 [Patent Document 2] Japanese Patent Laid-Open No. 6-39367

[Problems to be Solved by the Invention] When a wastewater containing a low concentration of ammonia is treated by an ammonia stripping method, a large amount of water needs to be evaporated. Therefore, the energy consumption is large and the device is huge, so such a treatment is not practical.

According to the method using a gas-liquid separation membrane, ammonia gas can be obtained even from drainage containing a low concentration of ammonia. Ammonia gas can be absorbed into sulfuric acid and converted into ammonium phosphonate. However, at this time, in order to process the generated high-concentration ammonium rhenate solution or the solidified ammonium rhenate as industrial waste, considerable costs will be incurred. Or some people consider using the gas stripping method in high-concentration ammonium rhenate solution. At this time, in order to convert ammonium ions in the solution into ammonia, a base such as sodium hydroxide must be added to the solution. However, at this time, it is thought that crystals of sodium sulfate having a low solubility will precipitate, and gas stripping will become difficult.

An object of the present invention is to provide a water treatment method and a water treatment device capable of treating ammonia in water containing a low concentration of ammonia with low energy consumption without discharging ammonium osmate.

Another object of the present invention is to provide a water treatment device reconstruction method and a water treatment device reconstruction kit for obtaining the water treatment device. [Means for solving problems]

According to one aspect of the present invention, there is provided a water treatment method including the following steps: a) converting ammonium ions into ammonia by adding a base to treated water in which ammonia is dissolved; b) by The liquid in step a is supplied to the supply side of the gas-liquid separation membrane, while the sulfuric acid aqueous solution is supplied to the permeate side of the gas-liquid separation membrane, so that the ammonia gas passes through the gas-liquid separation membrane, and the sulfuric acid aqueous solution absorbs the ammonia gas that has passed through, An ammonium phosphonate aqueous solution is obtained on the side, and a treated water having a reduced ammonia concentration is obtained from the supply side; c) the ammonium phosphonate aqueous solution obtained from step b is diluted with dilution water; and d) the diluted phosphonium acid obtained from step c is diluted The ammonium aqueous solution is stripped under alkaline conditions, and the treated water having a reduced ammonia concentration is obtained from the diluted ammonium gallate solution.

According to another aspect of the present invention, a water treatment device is provided, including the following components: an alkali adding device for adding alkali to the water to be treated in which ammonia is dissolved; a gas-liquid membrane separation device; a desorption tower; a first pipeline, The outlet of the alkali adding device is connected to the inlet of the flow path of the gas-liquid membrane separation device; the sulfuric acid solution supply device supplies the sulfuric acid solution to the inlet of the permeate side flow path of the gas-liquid membrane separation device; the second line connects the gas and liquid The permeate-side flow path outlet of the membrane separation device is connected to the liquid inlet of the desorption tower; the dilution water addition device is installed in the middle of the aforementioned second pipeline.

According to still another aspect of the present invention, a method for reforming a water treatment device is provided. The water treatment device includes: an alkali adding device for adding alkali to the treated water in which ammonia is dissolved; a gas-liquid membrane separation device; and a first tube The outlet of the alkali adding device is connected to the inlet of the flow path of the gas-liquid membrane separation device; and the sulfuric acid aqueous solution supply device supplies the sulfuric acid aqueous solution to the inlet of the flow-side flow path of the gas-liquid membrane separation device; The transformation method includes the steps of installing the following components in the aforementioned water treatment device; a desorption tower; a second pipeline connecting the outlet of the permeate side flow path of the gas-liquid membrane separation device to the liquid inlet of the desorption tower; and a dilution water adding device configured at On the way to the second pipeline.

According to another aspect of the present invention, there is provided a water treatment device retrofit kit for retrofitting a water treatment device kit including the following components: an alkali adding device for adding alkali to the treated water in which ammonia is dissolved; Liquid membrane separation device; the first line connects the outlet of the alkali adding device to the inlet of the supply side flow path of the gas-liquid membrane separation device; and the sulfuric acid aqueous solution supply device supplies the sulfuric acid aqueous solution to the permeate side flow of the gas-liquid membrane separation device The water treatment device retrofit kit includes: a desorption tower; a second pipeline connecting the outlet of the gas-liquid membrane separation device through the side of the flow path to the liquid inlet of the desorption tower; and a dilution water adding device arranged in the aforementioned first 2 On the way to the pipeline. [Effect of Invention]

According to the present invention, it is possible to provide a water treatment method and a water treatment device capable of treating ammonia in water containing low concentration of ammonia with low energy consumption without discharging ammonium osmate.

According to the present invention, there is provided a method for reforming a water treatment device for obtaining the water treatment device, and a kit for modifying a water treatment device.

The inventors have repeatedly researched in order to solve the above-mentioned problems and found that: a gas-liquid separation cartridge is used to generate ammonium gallate and obtain an ammonium gallate aqueous solution, and then the ammonium gallate aqueous solution is diluted with water and subjected to alkaline conditions. The following method of desorption treatment in the desorption tower is effective to solve the problem, and even complete the present invention.

According to the present invention, the wastewater containing ammonia can be treated in a small device with low energy, and can be treated without generating waste such as sludge.

Here, the solubility (in atmospheric pressure (0.101 MPa)) of ammonium phosphonate or ammonium sulfate (NH ₄ ) ₂ SO ₄ and sodium sulfate Na ₂ SO ₄ to water is shown in Table 1. It should be noted that sodium sulfate is less soluble in water than ammonium gallate.

【Table 1】

The water treatment method related to the present invention includes steps a to d.

[Step a] The water to be treated is water in which ammonia is dissolved, for example, ammonia-containing wastewater discharged from an electronic product manufacturing process. A part of ammonia dissolved in water will change into ammonium ions, so the treated water contains ammonium ions.

The ammonia concentration in the treated water should be from 500mg / L to 5000mg / L. If it is 500 mg / L or more, the membrane area of the gas-liquid separation membrane necessary for processing becomes large, and it is easy to prevent the cost advantage from being reduced compared with biological treatment. When the concentration is 5000 mg / L or less, the effect of the present invention is particularly significant compared with a case where direct stripping is performed without passing through a gas-liquid separation membrane.

In addition, in this specification, unless otherwise stated, "ammonia concentration" in a liquid means not only free ammonia but also the concentration of ammonium ions. In addition, unless otherwise stated, when the ammonia concentration in a liquid is expressed in the unit "mg / L", it means the concentration when free ammonia and ammonium ions are converted into nitrogen.

In step a, ammonium ions are converted into ammonia by adding an alkali to the water to be treated. Also, even if _{^{"NH 4 + + OH - → NH}} 3 + H 2 O " for the reaction. It is sufficient to convert part of the ammonium ions in the treated water into ammonia. As the base, for example, an alkali metal salt can be used, and in particular, sodium hydroxide can be used.

In order to sufficiently convert ammonium ions into ammonia, the pH of the water to be treated (the liquid obtained from step a) after the addition of the alkali is preferably 9 or more.

[Step b] In this step, the liquid obtained from step a (the treated water after the alkali is added) is supplied to the supply side of the gas-liquid separation membrane, and the sulfuric acid aqueous solution is supplied to the permeate side of the gas-liquid separation membrane. Thereby, the ammonia gas in the treated water will pass through the gas-liquid separation membrane, and the ammonia gas that has passed through will be absorbed by the sulfuric acid aqueous solution. Ammonium sulfate (2NH ₃ + H ₂ SO ₄ → (NH ₄ ) ₂ SO ₄ ) is formed in the sulfuric acid aqueous solution that has absorbed ammonia gas. Therefore, an aqueous solution of ammonium phosphonate can be obtained from the permeate side of the gas-liquid separation membrane. Further, from the supply side of the gas-liquid separation membrane, treated water having a reduced ammonia concentration can be obtained.

As the gas-liquid separation membrane, a known gas-liquid separation membrane capable of performing deammonia gas treatment can be used, and for example, a hydrophobic porous membrane can be used. Gas-liquid separation membranes of hollow fiber membrane type, spiral membrane type or flat membrane type can be used.

In the case of a hollow fiber membrane, for example, a membrane having a diameter of about 300 μm, a pore diameter of about 0.03 μm, and a (average) porosity of about 40 to 50% is preferred.

It is advantageous that the sulfuric acid aqueous solution supplied to the gas-liquid separation membrane has a high sulfuric acid concentration. The reason is that the concentration of the produced ammonium osmate becomes high, and a small sulfuric acid storage tank can be used, etc., which is excellent from the viewpoint of operation. The higher the concentration of the generated ammonium gallate, the smaller the amount of the ammonium gallate solution discharged from the permeate side of the gas-liquid separation membrane. When carrying out post-treatment such as ammonium gallate recovery or gas stripping, a small amount of this discharge is advantageous in terms of cost. Specifically, the concentration of the sulfuric acid aqueous solution supplied to the gas-liquid separation membrane is preferably 50% by mass or more. For example, an approximately 96-98% by mass sulfuric acid aqueous solution that can be easily obtained in the form of "concentrated sulfuric acid" in industry can be supplied to a gas-liquid separation membrane.

The aqueous sulfuric acid solution supplied to the gas-liquid separation membrane may contain ammonium phosphonate.

In order to vaporize ammonia to improve the efficiency of permeating the gas-liquid separation membrane, and to reduce the ammonia concentration of the treated water discharged from the supply side of the gas-liquid separation membrane, the water temperature during gas-liquid separation should preferably be 20 to 50 ° C. Before supplying the treated water after the alkali is added to the gas-liquid separation membrane, it is preferable to increase the processing efficiency by using a heater (for example, an electric heater) or a heat exchanger in advance to increase the processing efficiency.

When the treated water contains suspended matter, it should be removed through a filter, screen, etc. before being supplied to the gas-liquid separation membrane.

[Step c] This step is to dilute the ammonium oxalate aqueous solution obtained in step b with dilution water. Can be used as dilution water: pure water, industrial water, tap water, filtered water, etc. Also, in step c, one or both of the treated water obtained from step b and the treated water obtained from step d may be used as the dilution water.

Considering the viewpoint of suppressing the occurrence of scale in the water treatment device, it is preferable that the dilution water is water that does not contain high-concentration calcium, magnesium, and other substances that cause scale. For example, water with a total hardness of 200 mg-CaCO ₃ / L or less, preferably 20 mg-CaCO ₃ / L or less can be used. The same applies to treated water.

In step d, the diluted ammonium rhenate solution is processed under alkaline conditions, but at this time, there is a possibility that an alkali salt (for example, sodium sulfate) is precipitated from the ammonium rhenate solution. In order to prevent the precipitation of the alkali salt in step d, the ammonium phosphonate aqueous solution is diluted in step c.

Therefore, in step c, the ammonium phosphonate aqueous solution is diluted in advance so that the concentration of the alkali salt (for example, the concentration of sodium sulfate becomes the concentration below the solubility shown in Table 1) is not precipitated in step d. The amount of the dilution water sufficient to prevent precipitation in step d can be estimated in advance, and the amount of dilution water is quantitatively injected in step c. Alternatively, the concentration of sulfate ions in the ammonium rhenate aqueous solution discharged from step b may be measured by a meter, and the dilution water may be injected in step c so that the value becomes less than the solubility. Or, if the correspondence between the conductivity of the aqueous solution of ammonium osmium acid and the sulfate ion concentration is grasped in advance using preliminary experiments, etc., the conductivity may be used instead of the sulfate ion concentration to determine the injection amount of the dilution water.

In step d, when sodium hydroxide is added to the diluted ammonium rhenate aqueous solution in order to achieve alkaline conditions, the ammonium rhenate aqueous solution may be diluted in advance in step c to make the The concentration of Na ₂ SO _{4 is} less than the solubility (see Table 1), preferably 30% by mass or less, and more preferably 16% by mass or less.

[Step d] This step is a step of stripping the diluted ammonium gallate aqueous solution (diluted ammonium gallate aqueous solution) obtained from step c under alkaline conditions. As a result, ammonia was removed from the dilute ammonium phosphonate aqueous solution. From the desorption column, a gas containing ammonia gas and treated water having a reduced ammonia concentration can be obtained.

In step d, in order to achieve an alkaline condition, that is, to convert a dilute ammonium phosphonate aqueous solution to alkaline, it is desirable in terms of cost to add sodium hydroxide to the dilute ammonium phosphonate aqueous solution. In order to convert most of the ammonium ions in the wastewater into ammonia gas to reduce the ammonia concentration in the treated water, the pH of the diluted ammonium osmate aqueous solution for stripping should be 9 ~ 13.

As described above, the concentration of ammonium osmate in the liquid (the diluted aqueous solution of ammonium osmate that has been alkalized) is preferably 30% by mass or less, and more preferably 16% by mass or less from the viewpoint of preventing salt precipitation.

At the temperature of the liquid at the inlet of the desorption tower where the stripping is carried out (the diluted aqueous ammonium osmate solution), in order to increase the proportion of ammonia volatilization, it is preferably 40 ° C to 100 ° C.

From the ammonia concentration of the treated water (water with reduced ammonia concentration) obtained from the desorption tower, it is considered to be 0 mg / L or more and 100 mg / L or more in order to comply with the load on the environment such as the discharge limit value or to reduce the nitrogen load on the post-treatment. L or less.

When stripping, steam or air can be blown into the desorption tower. Alternatively, instead of blowing in the stripping gas, a heater (reboiler) may be provided at the bottom of the desorption tower to generate steam.

A gas containing ammonia gas can be obtained from the desorption tower. This gas may contain water vapor, nitrogen, oxygen, etc. depending on the type of stripping gas.

[Further processing] The ammonia gas contained in the gas (gas containing ammonia gas) obtained from the desorption tower can be converted into nitrogen gas using an ammonia decomposition catalyst. For this purpose, a catalyst reactor (ammonia catalyst decomposition device) that contacts the gas obtained from the desorption tower with the ammonia decomposition catalyst can be used. As for the structure of this catalyst reactor, a structure known in the field of ammonia decomposition can be suitably used, and a fixed layer, a fluidized layer, or the like can be used.

As the ammonia decomposition catalyst, a catalyst known in the ammonia decomposition field can be used, and in particular, an oxidation catalyst can be used. For example, a catalyst active ingredient such as a salt or an oxide of ruthenium, rhodium, palladium, iridium, platinum, titanium, iron, nickel, cobalt, vanadium, cerium, manganese or the like can be supported on titanium oxide, silicon dioxide, Catalyst made of alumina, zirconia, zeolite, etc. The shape of the catalyst is not particularly limited, such as honeycomb shape, metal mesh type, and granular shape.

[Water Treatment Device] The water treatment device related to the present invention includes the following components: an alkali adding device that adds alkali to the water to be treated in which ammonia is dissolved; a gas-liquid membrane separation device; a desorption tower; a first line that adds an alkali adding device The outlet is connected to the inlet on the supply side of the gas-liquid membrane separation device; the sulfuric acid solution supply device supplies the sulfuric acid solution to the inlet on the permeate side of the gas-liquid film separation device; the second line connects the gas-liquid film separation device The outlet through the side flow path is connected to the liquid inlet of the desorption tower; and the dilution water adding device is installed in the middle of the aforementioned second pipeline.

･ Alkali addition device If the alkali addition device is a device that can add alkali (typically, sodium hydroxide) to the water to be treated, it can be used appropriately, and a structure known in the field of water treatment can be appropriately used. For example, a pH adjustment tank provided with a component to which sodium hydroxide is introduced can be used as an alkali addition device. The treated water to which alkali has been added is discharged from the outlet of the alkali adding device.

･ Gas-liquid membrane separation device The gas-liquid membrane separation device is a separation device containing a gas-liquid separation membrane. As the structure of the gas-liquid membrane separation device, a structure known in the field of water treatment can be appropriately adopted. The gas-liquid membrane separation device has a supply-side flow path and a permeate-side flow path with a gas-liquid separation membrane interposed therebetween. The first line connecting the outlet of the alkali addition device to the inlet of the supply side flow path of the gas-liquid membrane separation device is used to supply the treated water obtained by adding alkali to the supply side flow path as a fluid to be subjected to separation. . Ammonia passes through the gas-liquid separation membrane and moves to the permeate-side flow path.

The sulfuric acid aqueous solution is supplied to the permeate-side flow path by a sulfuric acid solution supply device that supplies a sulfuric acid aqueous solution to the inlet of the permeate-side flow path of the gas-liquid membrane separation device. The ammonia that has passed through the membrane is absorbed by the sulfuric acid aqueous solution to generate an aqueous ammonium phosphonate solution, and the aqueous ammonium phosphonate solution is discharged from the permeate-side flow path.

･ Sulfuric acid aqueous solution supply device As the sulfuric acid aqueous solution supply device, a device capable of supplying a sulfuric acid aqueous solution to a permeate-side flow path can be appropriately used. For example, a water (also an ammonium osmate aqueous solution) supply pipe may be connected to the inlet of the permeate side flow path, and a pipe for adding sulfuric acid (especially concentrated sulfuric acid) to water flowing in the water supply pipe may be provided.

･ Desorption tower As the structure of the desorption tower, a structure known in ammonia stripping can be suitably used. As for the desorption tower, a layered tower, a packed tower, or the like can be used.

An ammonium gallate solution is supplied to the desorption tower through a second line connecting the outlet of the permeate side flow path of the gas-liquid membrane separation device to the liquid inlet of the desorption tower (the supply port of the liquid to be stripped). A dilution water adding device is provided in the middle of the pipeline.

･ Dilution water addition device As a dilution water addition device, it can be properly used in the middle of the second pipeline (between the gas-liquid membrane separation device through the side flow channel exit and the desorption tower). The dilution water can be added to the second pipeline. Device in flowing ammonium osmate solution. For example, the dilution water supply line can be connected to the second line.

The water treatment device may include a pipeline connecting the outlet of the supply side flow path of the gas-liquid membrane separation device or the liquid outlet of the desorption tower to the dilution water addition device. Thereby, the treated water obtained from the gas-liquid membrane separation device or the treated water obtained from the desorption tower can be used as the dilution water.

Each pipeline can be configured using piping, valves, pumps, and the like as appropriate.

[Example of Water Treatment Device] The processing flow of an example of the water treatment device related to the present invention is shown in FIG. 1.

The water to be treated stored in the drainage tank 1 is sent to the pH adjusting tank (for water to be treated) 2 through the pipe L1. Here, alkali (NaOH) is added to the water to be treated from the line L31. The treated water added with the alkali is sent to the filter 3 through the line L2. Here, suspended matter is removed from the water to be treated. The liquid that has passed the filter is sent to the heat exchanger 4 through the line L3 for heating. The heated liquid is sent to a heater (electric heater) 5 through a line L4 for further heating. The further heated liquid is supplied to the supply-side flow path 6 a of the gas-liquid membrane separation device 6 through the line L5. Here, the ammonia gas contained in the liquid supplied from the line L5 passes through the gas-liquid separation membrane 6c and moves to the permeate-side flow path 6b. Therefore, the ammonia gas concentration in the liquid supplied from the pipe L5 is reduced, and the treated water having the reduced ammonia concentration is discharged from the supply-side flow path 6a. The treated water is sent to the heat exchanger 4 via the line L6, and is cooled there. Cooled (heat-recovered) treated water is available in line L7. The treated water is appropriately reused or discharged to the outside world.

The sulfuric acid aqueous solution is supplied from the line L11 to the permeate-side flow path 6 b of the gas-liquid membrane separation device 6. The ammonia gas that has passed through the gas-liquid separation membrane 6c will be absorbed by the sulfuric acid aqueous solution in the permeate-side flow path 6b to generate an ammonium phosphonate aqueous solution, and then discharged to the pipeline L12. The ammonium phosphonate aqueous solution is sent from the line L12 to the circulation tank 7. An aqueous solution of ammonium gallate is sent from the circulation tank 7 to the filter 8 through the line L13, and suspended matter is removed there. The ammonium gallate aqueous solution from which the suspended matter has been removed is discharged from the filter 8 to the pipeline L14, mixed with sulfuric acid supplied from the pipeline L32, and then supplied from the pipeline L11 as an aqueous sulfuric acid solution (containing ammonium gallate from the pipeline L14) To the transmission-side flow path 6b. Closed loop is formed by pipelines L11, L12, L13, L14. Here, if the pipeline L21 is closed by a suitable valve (not shown), the ammonium osmate aqueous solution will be slowly accumulated in the circulation tank 7. After the circulation tank 7 has accumulated more than a certain amount of an aqueous solution of ammonium gallate, the valve of the pipeline L21 is opened, and the aqueous solution of ammonium gallate is sent from the circulation tank 7 to the ammonium sulfate aqueous solution tank 9 through the pipeline L21. Here, dilution water is added from the line L22, and the diluted ammonium phosphonate aqueous solution is sent to the pH adjusting tank (for the ammonium phosphonate aqueous solution) 10 via the line L23. Here, the base (NaOH) is added from the line L33 to the aqueous ammonium oxalate solution, and the pH of the aqueous ammonium oxalate solution becomes alkaline. The alkaline ammonium phosphonate aqueous solution is supplied to the heat exchanger 11 through a line L24, and is heated there. The heated alkaline ammonium phosphonate aqueous solution is supplied to the desorption tower 12 through the line L25, and is stripped by the steam supplied from the line L34. The gas (including ammonia and steam removed from the ammonium phosphonate solution) is discharged from the desorption tower to the line L26, diluted with the air supplied from the line L35 to a suitable concentration, and sent to the ammonia catalyst decomposition device through the line L27. 13. In the ammonia catalyst decomposition device, ammonia is oxidized and discharged from the pipeline L28 to the outside in the form of nitrogen (and moisture). The liquid obtained from the desorption tower is sent to the heat exchanger 11 via the line L29 and is cooled there. The high-purity water (processed water) obtained by removing ammonia from the cooled liquid system obtained in the pipeline L30 is appropriately reused or discharged to the outside.

When the line L7 or the line L30 is connected to the line L22, the treated water obtained from the gas-liquid separation membrane supply-side flow path 6a or the treated water obtained from the desorption tower can be used as the dilution water.

According to the present invention, the amount of the dilute ammonium phosphonate solution can be 1/10 to 1/300 with respect to the amount of water to be treated. Therefore, compared with the case where the treated water is directly stripped, the heat energy required for stripping also becomes 1/10 to 1/300, which saves energy and reduces treatment costs.

Moreover, compared with the case where ammonium osmate is solidified and processed, it is easier to convey and transport by operating in the state of an ammonium osmate solution. Therefore, the steps until the aqueous ammonium phosphonate solution is obtained (the steps up to step b), and the steps for treating the aqueous ammonium phosphonate solution (the steps subsequent to step c) can also be performed at locations remote from each other. For example, the ammonium osmate aqueous solution (obtained from the permeate side of the gas-liquid separation membrane in step b) is recovered from a plurality of locations and concentrated in a single location, and then a one-time ammonia stripping (processing after step c) is performed there. For easy and efficient. The reason is that the desorption tower can be continuously and efficiently operated by processing a large amount of an aqueous ammonium phosphonate solution at the same place.

[Reconstruction of Existing Water Treatment Equipment] There may be a water treatment equipment in which ammonia is removed from the treated water in which ammonia is dissolved using a gas-liquid separation membrane. At this time, the aforementioned excellent water treatment device can be obtained by modifying the existing water treatment device.

The existing device includes an alkali adding device that adds alkali to the treated water in which ammonia is dissolved; a gas-liquid membrane separation device; and a first line that connects the outlet of the alkali adding device to the supply-side flow path of the gas-liquid membrane separation device. An inlet; and a sulfuric acid aqueous solution supply device for supplying a sulfuric acid aqueous solution to a permeate-side flow path inlet of the gas-liquid membrane separation device. The existing water treatment device is provided with: a desorption tower; a second pipeline, which connects the transmission side outlet of the gas-liquid membrane separation device to the liquid inlet of the desorption tower; and a dilution water adding device, which is arranged in the aforementioned second During the pipeline, the water treatment device can be modified.

The existing water treatment device may include, for example, a portion (devices 1 to 8, pipes L1 to L7, L11 to L14, L31, and L32) located upstream of the pipeline L21 shown in FIG. 1. In this existing water treatment device, if an aqueous solution of ammonium gallate is accumulated in the circulation tank 7, the aqueous solution of ammonium gallate can be taken out from the circulation tank 7, and the ammonium gallate should be solidified according to need, and then treated as industrial waste. The existing water treatment device can be provided with a pipeline L21 as shown in FIG. 1 and a portion downstream of the pipeline L21 (devices 9-13, pipelines L21-L30, L33-L35). The water treatment device thus modified has a processing flow as shown in FIG. 1 and is suitable for implementing the aforementioned water treatment method.

Therefore, the present invention provides a kit for retrofitting a water treatment device including the following components: an alkali adding device for adding alkali to the water to be treated in which ammonia is dissolved; a gas-liquid membrane separation device; and a first pipeline for adding alkali The outlet of the device is connected to the supply-side flow path inlet of the gas-liquid membrane separation device; and the sulfuric acid aqueous solution supply device supplies the sulfuric acid aqueous solution to the permeate-side flow path inlet of the gas-liquid membrane separation device. This kit includes: a desorption tower; a second pipeline that connects the permeate side flow path outlet of the gas-liquid membrane separation device to the liquid inlet of the desorption tower; and a dilution water adding device arranged in the middle of the aforementioned second pipeline. [Example]

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

A simulation process is performed on a device having the processing flow shown in FIG. 1.

The results are summarized in Table 2. The amount of water to be treated (line L1) is 100m ³ / day, but the water to be treated using the gas-liquid separation reduces 3.6m ³ / day to the volume, in order to prevent the precipitation of sodium sulfate is added dilution water 5.0m ³ As a result, the amount of the stripping solution was 8.6 m ³ / day. That is, the amount of liquid at the inlet of the desorption tower is about 1/12 (= 8.6 / 100) with respect to the amount of water to be treated. Therefore, it is considered that, compared with the case where the treated water is directly stripped, according to the present invention, the heat energy required for the stripping also becomes about 1/12.

【Table 2】 * 1: Concentration expressed by converting ammonia (free ammonia and ammonium ions) into nitrogen. * 2: The volume flow rate is converted to 0 ° C and atmospheric pressure (0.101 MPa).

The following substances are assumed for NaOH and the like. ･ NaOH (pipes L31, L33): 25% by mass NaOH aqueous solution for industrial use. ･ H ₂ SO ₄ (pipe L32): 98% by mass H ₂ SO ₄ aqueous solution for industrial use. ･ Water vapor (pipe L34): 0.5MPa saturated water vapor.

1‧‧‧Drain (treated water) tank
2‧‧‧pH adjusting tank
3‧‧‧ filter
4‧‧‧ heat exchanger
5‧‧‧ heater
6‧‧‧Gas-liquid membrane separation device
Supply side flow path of 6a‧‧‧ gas-liquid membrane separation device
6b‧‧‧Gas-liquid membrane separation device's permeate side flow path
6c‧‧‧Gas-liquid separation membrane
7‧‧‧ ammonium sulfate aqueous solution circulation tank
8‧‧‧ Filter
9‧‧‧ ammonium sulfate solution tank
10‧‧‧pH adjusting tank
11‧‧‧ heat exchanger
12‧‧‧ ammonia desorption tower
13‧‧‧Ammonia catalyst decomposition device
L1 ~ L7, L11 ~ 14, L21 ~ 35‧‧‧pipe

[Fig. 1] A processing flowchart showing an example of the water treatment device of the present invention.

1‧‧‧Drain (treated water) tank

2‧‧‧pH adjusting tank

3‧‧‧ filter

4‧‧‧ heat exchanger

5‧‧‧ heater

6‧‧‧Gas-liquid membrane separation device

Supply side flow path of 6a‧‧‧ gas-liquid membrane separation device

6b‧‧‧Gas-liquid membrane separation device's permeate side flow path

6c‧‧‧Gas-liquid separation membrane

7‧‧‧ ammonium sulfate aqueous solution circulation tank

8‧‧‧ Filter

9‧‧‧ ammonium sulfate solution tank

10‧‧‧pH adjusting tank

11‧‧‧ heat exchanger

12‧‧‧ ammonia desorption tower

13‧‧‧Ammonia catalyst decomposition device

L1 ~ L7, L11 ~ 14, L21 ~ 35‧‧‧pipe

Claims (7)

A water treatment method comprising the steps of: a) converting ammonium ions into ammonia by adding a base to treated water in which ammonia is dissolved; b) by supplying a liquid obtained in step a to a gas-liquid separation membrane On the supply side, the sulfuric acid aqueous solution is simultaneously supplied to the permeation side of the gas-liquid separation membrane, so that ammonia gas permeates the gas-liquid separation membrane, and the sulfuric acid aqueous solution absorbs the permeated ammonia gas. Treated water with reduced ammonia concentration; c) diluting the ammonium oxalate aqueous solution obtained from step b with diluted water; and d) stripping the diluted ammonium phosphonate aqueous solution obtained from step c under alkaline conditions (Stripping), and treated water having a reduced ammonia concentration is obtained from a dilute aqueous ammonium gallate solution. For example, the water treatment method in the scope of application for patent No. 1 is to use one or both of the treated water obtained in step b and the treated water obtained in step d as the dilution water in step c. For example, the water treatment method according to item 1 or 2 of the patent application scope, wherein the ammonia concentration in the treated water is 500 mg / L or more and 5000 mg / L or less in terms of nitrogen. A water treatment device includes the following components: an alkali adding device that adds alkali to the treated water in which ammonia is dissolved; a gas-liquid membrane separation device; a desorption tower; a first pipeline that connects the outlet of the alkali adding device to Supply side flow path inlet of gas-liquid membrane separation device; Sulfuric acid aqueous solution supply device, which supplies sulfuric acid aqueous solution to the permeate side flow path inlet of the gas-liquid membrane separation device; second line, permeate side flow path of the gas-liquid membrane separation device The outlet is connected to the liquid inlet of the desorption tower; the dilution water adding device is set in the middle of the second pipeline. For example, the water treatment device of the scope of application for patent No. 4 includes a pipeline connecting the outlet of the supply side flow path of the gas-liquid membrane separation device or the liquid outlet of the desorption tower to the dilution water addition device. A method for reforming a water treatment device. The water treatment device includes: an alkali adding device for adding alkali to the water to be treated in which ammonia is dissolved; a gas-liquid membrane separation device; and a first pipeline connecting the outlet of the alkali adding device to the gas. Supply side flow path inlet of liquid film separation device; and sulfuric acid aqueous solution supply device to supply sulfuric acid aqueous solution to permeate side flow path inlet of gas-liquid film separation device; The method for reforming the water treatment device includes setting the following components in the water treatment device Steps: desorption tower; second pipeline, connecting the outlet of the gas-liquid membrane separation device through the side of the flow path to the liquid inlet of the desorption tower; and dilution water adding device, arranged in the middle of the second pipeline. A water treatment device retrofit kit is used to retrofit a water treatment device comprising the following components: an alkali adding device that adds alkali to the water to be treated in which ammonia is dissolved; a gas-liquid membrane separation device; The outlet of the alkali adding device is connected to the supply-side flow path inlet of the gas-liquid membrane separation device; and the sulfuric acid aqueous solution supply device supplies the sulfuric acid aqueous solution to the permeate-side flow path inlet of the gas-liquid membrane separation device; the water treatment device reconstruction kit includes : Desorption tower; second pipeline, which connects the outlet of the permeate side flow path of the gas-liquid membrane separation device to the liquid inlet of the desorption tower; and dilution water adding device, which is arranged in the middle of the second pipeline.