TWI703093B - Processing method and processing device of ammonia-containing discharged water - Google Patents

Abstract

Disclosed is a processing method of ammonia-containing discharged water comprising: a Langelier index calculation step in which Langelier index at a PH value over 10 in ammonia-containing discharged water coexisting with calcium is calculated; a PH value adjustment step wherein, if the Langelier index calculated at a PH value over 10 is under a predetermined value, the PH value of the ammonia-containing discharged water is adjusted from over 10 to a range under a PH value that makes the Langelier index reach the predetermined value; and, otherwise, if the Langelier index calculated at a PH value over 10 is not under a predetermined value, after scale preventive is added to the ammonia-containing discharged water, the PH value is adjusted to over 10; andan ammonia removing step wherein ammonia is removed, by means of gas-liquid separation membrane, from the ammonia-containing discharged water of which the PH value has been adjusted, and the removed ammonia is brought into contact with acid solution and recovered as ammonia solution.

Description

Treatment method and treatment device of discharged water containing ammonia

The present invention relates to a treatment method and treatment device for ammonia-containing discharge water, which processes ammonia-containing discharge water discharged from electronics industry factories, chemical plants, etc., and recovers it in the form of an ammonium solution.

In the past, discharge water with a relatively high ammonia concentration discharged from electronic industry factories such as semiconductor factories, chemical factories, thermal power plants, etc., was performed by, for example, the ammonia stripping method (for example, refer to Patent Document 1) , Evaporation concentration method (for example, refer to Patent Document 2), catalytic wet oxidation method (for example, refer to Patent Document 3), etc. for processing. In addition, the discharged water with a relatively low ammonia concentration is treated by, for example, a biological treatment method.

The ammonia stripping method is a treatment method in which an alkali solution is added to the discharged water containing ammonia, heated, and then passed through a dispersing tower filled with fillers, and exposed to steam and air to transfer the ammonia in the discharged water to the gas side. . This method is a relatively simple treatment, but there is a problem that the equipment of the dispersing tower is large. In addition, the ammonia transferred to the gas side by heat energy such as heating and steam needs to be further subjected to high-temperature catalytic oxidation treatment, which poses a problem of high treatment cost. In addition, when the catalyst is oxidized, NO _x , N ₂ O, etc. may be generated.

The evaporative concentration method is a treatment method in which the discharged water containing ammonia is heated and evaporated, and the generated vapor containing ammonia is condensed, and then recovered in the form of ammonia water. This method has problems such as the cost of heating energy for evaporation and the adhesion of fouling on the heat transfer surface of the evaporator.

The catalytic wet oxidation method is a method of treating discharged water containing ammonia by applying a temperature and pressure of 100 to 370°C in the presence of a catalyst. Due to high temperature and high pressure processing, this method has safety and cost issues.

In recent years, a gas-liquid separation membrane method for removing ammonia from discharged water containing ammonia using a hydrophobic porous gas-liquid separation membrane that passes ammonia without passing liquid has been proposed (for example, refer to Patent Document 4). In this method, the ammonia in the discharged water is made alkaline with a pH of 10 or higher, and the ammonia in the discharged water is gasified, and the downstream side of the gas-liquid separation membrane is sucked by a vacuum pump to remove the ammonia from the A method of removing ammonia from discharged water. However, this method requires an additional ammonium sulfate scrubber.

In addition, it has also been proposed that in the gas-liquid separation membrane method, the sulfuric acid solution is passed through the downstream side of the hydrophobic hollow fiber membrane of the gas-liquid separation membrane and brought into contact with the flow, and recovered as an ammonium sulfate solution Method (for example, refer to Patent Document 5). In this method, the ammonia-containing discharge water adjusted to pH 10 or higher flows through the outside of the hollow fiber membrane, and the sulfuric acid solution with pH 2 or less flows through the inside of the hollow fiber membrane in a counter-current flow to discharge the ammonia in the water. Removal and recycling technology. The gasified ammonia contacts the sulfuric acid flowing inside the hollow fiber membrane and is recovered in the form of ammonium sulfate.

The method of using gas-liquid separation membrane is a simple equipment treatment, and it can economically treat the discharged water containing ammonia, and it can be reused through ammonium sulfate solution, but it is caused by calcium compounds contained in the discharged water containing ammonia. The fouling caused by the occlusion of the gas-liquid separation membrane, the ammonia removal rate decreases as the treatment time passes. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent No. 3987896 [Patent Document 2] Japanese Patent Application Publication No. 2011-153043 [Patent Document 3] Japanese Patent No. 3272859 [Patent Document 4] Japanese Patent No. 3240694 [Patent Document 5 ]JP 2013-202475 Bulletin

[Problem to be Solved by the Invention] The present invention aims to suppress the clogging of the gas-liquid separation membrane due to fouling caused by calcium compounds in the treatment of ammonia-containing discharge water using the gas-liquid separation membrane, and the passage of treatment time And the ammonia removal rate is reduced. [Means to solve the problem]

(1) The present invention is a method for treating discharged water containing ammonia, which is characterized by having the following steps: a Blue's index calculation step to calculate the Blue's index of the discharged water containing ammonia coexisting with calcium at pH 10 or higher; pH adjustment Step, when the Blue's index calculated above pH 10 does not reach a predetermined value, adjust the pH of the discharged water containing ammonia to be above 10 to a range where the Blue's index becomes the predetermined value. When the Blue's index calculated by pH 10 or higher is not below the predetermined value, after adding an anti-scaling agent to the discharged water containing ammonia, adjust the pH to 10 or higher; in the ammonia removal step, the ammonia is adjusted from the pH by a gas-liquid separation membrane The discharged water containing ammonia is removed, and the removed ammonia is contacted with acid solution and recovered in the form of ammonium solution.

(2) In the method for treating ammonia-containing discharged water in (1) above, in the pH adjustment step, it is advisable to adjust the pH of the ammonia-containing discharged water to 10 when the calculated Blue Index does not reach 1.6. Above and below the range where the Blue's index becomes a pH value of 1.6, it is advisable to adjust the pH to 10 after adding an anti-scaling agent to the discharged water containing ammonia when the Blue's index calculated above pH 10 is not less than 1.6. the above.

(3) In the method for treating ammonia-containing discharged water in (1) or (2) above, the antifouling agent preferably contains at least one of an acrylic polymer and a phosphonic acid compound.

(4) The present invention is a treatment device for discharged water containing ammonia, which is characterized by having the following components: a Blue's index calculation means for calculating the Blue's index of the discharged water containing ammonia coexisting with calcium at pH 10 or higher; pH adjustment The component, when the Blue's index calculated above pH 10 does not reach a predetermined value, adjust the pH of the ammonia-containing discharge water to be above 10 to the pH range where the Blue's index becomes the predetermined value. When the Blue's index calculated by pH 10 or higher is not less than the predetermined value, after adding an anti-scaling agent to the discharged water containing ammonia, adjust the pH to 10 or higher; the ammonia removal component uses a gas-liquid separation membrane to adjust the ammonia from the pH The discharged water containing ammonia is removed, and the removed ammonia is contacted with acid solution and recovered in the form of ammonium solution.

(5) In the above-mentioned (4) treatment device for ammonia-containing discharged water, the pH adjustment means should adjust the pH of the ammonia-containing discharged water to be above 10 to not less than 1.6 when the calculated Blue Index is less than 1.6. The Darlene index is within the range of pH value of 1.6. When the Blueness index calculated at pH 10 or higher is not less than 1.6, it is advisable to add an anti-scaling agent to the discharged water containing ammonia and adjust the pH to 10 or higher.

(6) In the above-mentioned (4) or (5), in the ammonia-containing discharge water treatment device, the antifouling agent preferably contains at least one of an acrylic polymer and a phosphonic acid compound. [Effects of Invention]

According to the present invention, it is possible to prevent the generation of fouling caused by calcium compounds in the treatment of ammonia-containing discharge water using the gas-liquid separation membrane, and it is possible to suppress the clogging of the gas-liquid separation membrane and the reduction of the ammonia removal rate.

The embodiment of the present invention will be described. This embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment.

The outline of an example of a treatment device for ammonia-containing discharged water according to an embodiment of the present invention is shown in FIG. 1, and its structure will be described. The ammonia-containing discharge water treatment device 1 shown in FIG. 1 is equipped with: a raw water tank 10, a pH adjustment device as a pH adjustment member, an ammonia removal device 16 as an ammonia removal member, a circulation tank 18, a sulfuric acid storage tank 20, and a pickling Component acid storage tank 24, and control device 25. The pH adjusting device includes an anti-scaling agent supply device 12, a pH adjusting tank 14, and a pH adjusting agent supply device 22. The anti-scaling agent supply device 12 includes, for example, an anti-scaling agent storage tank and a pump, and is configured to supply the anti-scaling agent to the drain water. In addition, the pH adjusting agent supply device 22 includes, for example, a pH adjusting agent storage tank and a pump, and is arranged to supply the pH adjusting agent to the drain water.

The ammonia removal device 16 has a gas-liquid separation membrane 26, and a first liquid chamber 25a and a second liquid chamber 25b partitioned by the gas-liquid separation membrane 26. The gas-liquid separation membrane 26 is a hollow fiber membrane such as a hollow fiber membrane that passes gaseous ammonia without passing liquid. The first liquid chamber 25 a is provided to be adjacent to one surface of the gas-liquid separation membrane 26, and the second liquid chamber 25 b is provided to be adjacent to the other surface of the gas-liquid separation membrane 26. The discharge water containing ammonia is supplied to the first liquid chamber 25a, and the sulfuric acid solution is supplied to the second liquid chamber 25b.

In the discharge water treatment device 1 containing ammonia in FIG. 1, the raw water pipe 30 is connected to the inlet of the raw water tank 10. The outlet of the raw water tank 10 and the inlet of the pH adjustment tank 14 are connected by a raw water supply pipe 32. The outlet of the pH adjustment tank 14 and the inlet of the first liquid chamber 25a provided on one end side of the ammonia removal device 16 are connected by a pH adjustment water pipe 36, and are connected to the first liquid chamber 25a provided on the other end side of the ammonia removal device 16 The outlet is connected with a treated water piping 38. The outlet of the circulation tank 18 and the inlet of the second liquid chamber 25b provided on the other end side of the ammonia removal device 16 are connected by the circulation pipe 40, and the outlet of the second liquid chamber 25b provided on one end side of the ammonia removal device 16 is connected to the circulation The inlet of the tank 18 is connected by a circulation pipe 42. A recovery ammonium sulfate solution pipe 50 is connected to the recovery outlet of the circulation tank 18. The outlet of the sulfuric acid storage tank 20 is connected to the circulation tank 18 via a sulfuric acid pipe 44. The antiscaling agent supply device 12 and the raw water tank 10 are connected by an antiscaling agent injection pipe 34. The pH adjusting agent supply device 22 and the pH adjusting tank 14 are connected by a pH adjusting agent pipe 46. The outlet of the acid storage tank 24 is connected by an acid pipe 48 and a pH adjustment water pipe 36.

The control device 25 includes a processor and a memory, and includes a Blue index calculation unit as a functional block. The Blue's index calculation unit calculates the Blue's index of the discharge water containing calcium and ammonia that is the treatment target at pH 10 or higher. Specifically, using the above-mentioned calcium concentration, inorganic carbon concentration, soluble substance concentration, alkalinity, discharge water temperature detection value, and set pH (10 or more), it is calculated as the blue of the set pH (10 or more) Index. The control device 25 is configured to input, for example, a calcium concentration sensor, an inorganic carbon concentration sensor, a soluble substance concentration meter (converted from conductivity), or a soluble substance concentration meter, and alkalinity provided in the raw water tank 10 Each test value obtained by the tester or alkalinity meter. In addition, an operator or the like may measure the calcium concentration in the discharged water, etc., and input this value into the control device 25 as a detection value. In addition, the Blue's index may be calculated from the measured calcium concentration or the like, and the calculated value may be input to the control device 25.

The processor of the control device 25 executes the processing of calculating the Blue's index based on the processing program stored in the program memory, and the processing of setting the timing of adding the anti-scaling agent and the pH adjuster based on the calculated Blue's index. In this embodiment, the timing of adding the anti-scaling agent and the pH adjusting agent is controlled by the control device 25, and the timing of adding the anti-scaling agent and the pH adjusting agent may also be controlled by the operator or the like based on the calculated Blue's index.

The operation of the ammonia-containing discharged water treatment method and the ammonia-containing discharged water treatment device 1 of the present embodiment will be described.

The discharged water containing ammonia in which calcium coexists is stored in the raw water tank 10 through the raw water pipe 30 as necessary. Hereinafter, the discharged water containing ammonia in which calcium coexists is referred to as raw water.

Detect the calcium concentration, inorganic carbon concentration, soluble substance concentration, alkalinity, and raw water temperature in the raw water, input them to the control device 25, and use the Blue Index calculation unit to calculate pH 10 using the following formulas (1) to (5) The Blue Index of the above raw water.

Blue's index=pH value-pHs+1.5×10 ^-2 (T-25) (1) The pH value in formula (1) is the set pH value, which is set to 10 or more. In addition, pHs in the formula (1) is a value obtained by the following formula (2). The T in formula (1) applies to the temperature (°C) of the raw water detected by the sensor.

pHs=8.313-log[Ca ²⁺ ]-log[A]+S (2) In formula (2), [Ca ²⁺ ] is the amount of calcium ion (me/L), which is calculated by the following formula (3) value. [A] in the formula (2) is the total alkalinity (me/L), which is the value obtained by the following formula (4). S in the formula (2) is the correction value, which is the value obtained by the following formula (5).

[Ca ²⁺ ]=(Ca ²⁺ )(mg/L)÷(40.1÷2) (3) (Ca ²⁺ )(mg/L) in formula (3) applies to the calcium detected by the sensor concentration.

[A](me/L)=(A)(mg/L)÷(100÷2)　　　　(4) (A)(mg/L) in formula (4) is applicable to the tester or measuring device Total alkalinity.

，μ＝2.5×10^-5 ×Sd　　　(5) 式(5)中之Sd適用以測定器或測量器檢測得到的溶解性物質(mg/L)(以上，藍氏指數算出步驟)。【Number 1】 S＝

, Μ=2.5×10 ^-5 ×Sd (5) The Sd in the formula (5) applies to the soluble substance (mg/L) detected by the measuring device or the measuring device (above, the Blue's index calculation step).

With the control device 25, it can be determined whether the Blue's index calculated above pH 10 has not reached a predetermined value. Considering the viewpoint of suppressing the scale of raw water, it is better to set a predetermined value, such as 1.6 or less. Hereinafter, the predetermined value is set to 1.6 for description.

When the Blue's index calculated above pH 10 is not less than 1.6, the control device 25 transmits an operation instruction to the anti-scaling agent supply device 12, and the anti-scaling agent is added from the anti-scaling agent supply device 12 through the anti-scaling agent injection pipe 34 To the original sink 10. In terms of the relationship between the Blue's index and pH, as the pH becomes higher, the Blue's index also becomes higher. Therefore, when the pH value of formula (1) is set to 10, or when the Blue's index exceeds 1.6 when the pH value is in the range of 10 to 11, the control device 25 determines that the Blue's index calculated at pH 10 or higher at this stage is not less than 1.6, and instructs The addition of anti-scaling agent.

The raw water to which the scale inhibitor is added is supplied to the pH adjustment tank 14 through the raw water supply pipe 32. At this time, the control device 25 transmits an operation instruction to the pH adjuster supply device 22, and the pH adjuster is added from the pH adjuster supply device 22 to the pH adjustment tank 14 through the pH adjuster pipe 46 to adjust the pH of the raw water to 10. the above. The pH of the raw water when the scale inhibitor is added to the raw water is not particularly limited as long as the pH is 10 or more. Considering the viewpoint of suppressing the amount of the alkali agent used, the pH is preferably set to around 10.

On the other hand, when the Blue's index calculated at pH 10 or higher is less than 1.6, raw water (without anti-scaling agent) is supplied to the pH adjustment tank 14 through the raw water supply pipe 32. At this time, the control device 25 transmits an operation instruction to the pH adjuster supply device 22, and the pH adjuster is added from the pH adjuster supply device 22 to the pH adjustment tank 14 through the pH adjuster pipe 46. The pH of the raw water is adjusted to be in the range of 10 or more to a pH value that does not reach the blue index of 1.6 (predetermined value). For example, when the Blue's index calculated at pH 11 does not reach 1.6, and the pH of the Blue's index becomes 1.6 to 12.5, the pH of the raw water is adjusted to a range of 10 or more to less than 12.5. The pH value at which the Blue's index becomes 1.6 is calculated by the following formula (6) (above, pH adjustment step). pH=1.6+pHs-1.5×10 ^-2 (T-25) (6)

By making the pH of the raw water 10 or more, the ammonium ion in the raw water is acid-dissociated into ammonia gas, which can increase the ammonia removal rate by the gas-liquid separation membrane in the later stage. On the other hand, if the pH of the raw water is 10 or higher and the Blue's index is high, the calcium in the raw water has a high reactivity with carbonic acid, and fouling occurs in a short time, so the gas-liquid separation membrane in the subsequent stage is likely to be blocked. Therefore, in this embodiment, when the pH of the raw water is 10 or more and the Blue's index is high, the anti-scaling agent is added before the pH of the raw water is adjusted to 10 or more to suppress the generation of scale and prevent the gas-liquid separation in the subsequent stage. Occlusion of the membrane. In addition, when the pH of the raw water is 10 or more and the Blue's index is low, the reactivity of calcium and carbonic acid in the raw water is low, and it takes a long time until the scale is generated. Therefore, even if the anti-scaling agent is not added to the raw water, and only the pH is adjusted to a pH range above 10 to not reach the pH value at which the Blue Index becomes a predetermined value, the reduction in ammonia removal rate that occurs with the passage of treatment time can still be suppressed. In addition, since the scale inhibitor is an organic acid salt, when it is dissolved in water, the salt concentration increases and the ammonia vapor pressure decreases. Therefore, in water with a low Blue index (for example, raw water less than 1.6), that is, if an antiscalant is added to water with a relatively low pH and a slightly higher proportion of ammonium ions, the volatilization rate of ammonia will be reduced. The ammonia removal rate of the gas-liquid separation membrane may decrease. In this way, by adding an anti-scaling agent only when necessary based on the Blue's index, the reduction in ammonia removal rate can be suppressed.

In addition, by suppressing the occlusion of the membrane as described above, the frequency of membrane cleaning can be reduced, and the cost of chemicals and waste liquid treatment related to membrane cleaning can also be reduced.

The pH-adjusted raw water system is sent to the first liquid chamber 25a through the pH-adjusted water pipe 36 from an inlet provided on one end side of the ammonia removal device 16. In the ammonia removal device 16, the ammonia is removed from the raw water by the gas-liquid separation membrane 26 that does not pass through the liquid but passes through the ammonia. The treated water after ammonia removal is discharged from the outlet of the first liquid chamber 25 a provided on the other end side of the ammonia removal device 16 through the treated water pipe 38. On the other hand, the sulfuric acid solution stored from the sulfuric acid storage tank 20 to the circulation tank 18 through the sulfuric acid pipe 44 is supplied to the second liquid chamber 25b from the inlet provided on the other end of the ammonia removal device 16 through the circulation pipe 40, and is combined with The discharge water containing ammonia in the first liquid chamber 25a circulates in a counter-current flow. For example, discharge water containing ammonia may be circulated outside the hollow fiber membrane (first liquid chamber 25a), and a sulfuric acid solution may be circulated inside the hollow fiber membrane (second liquid chamber 25b). The ammonia that has passed through the gas-liquid separation membrane 26 comes into contact with the sulfuric acid solution flowing through the second liquid chamber 25b of the ammonia removal device 16 to generate ammonium sulfate (above, ammonia removal step).

The produced ammonium sulfate is still dissolved in the sulfuric acid solution, and is conveyed to the circulation tank 18 from the outlet of the second liquid chamber 25 b provided at one end of the ammonia removal device 16 through the circulation pipe 42. The sulfuric acid solution circulates through the circulation tank 18, the circulation pipe 40, and the circulation pipe 42 until the ammonium sulfate reaches a predetermined concentration. At this time, the sulfuric acid solution is supplied from the sulfuric acid storage tank 20 to the circulation tank 18 through the sulfuric acid pipe 44, and adjusted so that the pH of the circulating sulfuric acid solution becomes a predetermined value. After the concentration of the ammonium sulfate recovered in the circulating sulfuric acid solution becomes higher than a predetermined concentration, it is discharged from the circulation tank 18 through the recovery ammonium sulfate solution piping 50 in the form of a recovered ammonium sulfate solution.

The raw water to be treated (discharge water containing calcium and ammonia) is discharged water from electronic industry factories such as semiconductor factories, chemical factories, and thermal power plants.

For example, when the discharge water containing calcium and ammonia discharged from semiconductor factories and other electronic industry factories contains oxidants such as hydrogen peroxide in the raw water, it can be treated by reductant injection or activated carbon treatment before the ammonia removal device 16 Remove the oxidant. Thereby, it is possible to suppress the decrease in the ammonia removal rate and the deterioration of the gas-liquid separation membrane in the ammonia removal step due to an oxidizing agent such as hydrogen peroxide.

The concentration of ammonia in the raw water to be treated is not particularly limited. In order to make the concentration of ammonium sulfate in the recovered ammonium sulfate solution 25% by mass or more and become a concentration at which ammonium sulfate is not easy to precipitate, it is preferably 900mg/L or more, 2,200mg/ Concentrations below L work better.

When the ammonia concentration in the raw water is low (for example, when it does not reach 900 mg/L), the ammonia can be concentrated by reverse osmosis membrane treatment or the like before the ammonia removal device 16. In addition, in order to implement the concentration of ammonium sulfate, the ammonium sulfate solution produced by treating the low-concentration ammonia-containing discharged water is sent from the circulation tank 18 back to the original water tank 10 and the like, and the ammonia treatment is performed again.

If the temperature of the raw water is less than 35°C, the ammonia in the raw water is difficult to vaporize, and the ammonia removal rate in the ammonia removal device 16 tends to decrease. Therefore, it is preferable to heat the raw water to a temperature of 35 to 50° C. and send the raw water to the ammonia removal device 16 by using heat-heating equipment such as a heat exchanger and a heater. However, since heating is likely to generate scales such as calcium compounds, the heating equipment should be installed in the pH adjustment tank 14 and the pH adjustment water piping 36 after the anti-scaling agent is injected. In addition, considering the relationship between the temperature of the raw water and the pressure resistance of the membrane, the temperature of the raw water is preferably 50°C or less. In addition, in order to keep the raw water warm or adjust the ammonia concentration, the treated water may be recycled back to the raw water tank 10 and the like.

The addition position of the anti-scaling agent used in the pH adjustment step can be the raw water tank 10 as shown in Fig. 1 for the discharge water treatment device 1 containing ammonia, or the discharge water treatment device 3 containing ammonia as shown in Fig. 2 Generally, it is the raw water supply pipe 32. Although the description in the figure is omitted, it may be the pH adjustment tank 14. However, when the heating step is implemented, considering the viewpoint of inhibiting the formation of fouling, it is better to inject before the heating step. When adding the anti-scaling agent to the raw water tank 10 and the pH adjustment tank 14, it is preferable to use a stirrer, an aeration device, etc., and to add to the raw water supply piping, it is preferable to use a line mixer or the like for mixing.

The anti-scaling agent is not particularly limited as long as it can inhibit the generation of scaling caused by calcium compounds. For example, 1-hydroxyethylene-1,1-diphosphonic acid, 2-phosphonobutanol Phosphonic acids such as alkane-1,2,4-tricarboxylic acid, ethylenediamine tetramethylene phosphonic acid, nitrotrimethyl phosphonic acid and their salts and other phosphonic acid compounds; orthophosphate, polyphosphate, etc. Phosphoric acid compounds; maleic acid compounds such as polymaleic acid and maleic acid copolymers; poly(meth)acrylic acid, maleic acid/(meth)acrylic acid, (meth)acrylic acid/sulfonic acid, (methyl) ) Copolymers of acrylic acid/monomers containing nonionic groups; terpolymers of (meth)acrylic acid/sulfonic acid/monomers containing nonionic groups, (meth)acrylic acid/acrylamide-alkyl- and / Or acrylic polymers such as terpolymers of aryl sulfonic acid/substituted (meth)acrylamide, etc. Among these, it is preferable to include at least one of a phosphonic acid compound and an acrylic polymer.

The (meth)acrylic acid constituting the terpolymer includes, for example, (meth)acrylic acid salts such as methacrylic acid, acrylic acid, and sodium salts thereof. The acrylamide-alkyl- and/or aryl sulfonic acid constituting the terpolymer includes, for example, 2-acrylamide-2-methylpropanesulfonic acid and salts thereof. In addition, the substituted (meth)acrylamide constituting the terpolymer includes, for example, tertiary butylacrylamide, tertiary octylacrylamide, and dimethylacrylamide.

The pH adjusting agent used in the pH adjusting step is, for example, an alkali such as sodium hydroxide solution, or an acid such as hydrochloric acid. Regarding the raw water in the pH adjustment step, in order to dissociate the ammonium ions in the raw water into ammonia gas and increase the ammonia removal rate in the following ammonia removal step, it is only necessary to adjust the pH to 10 or more, but consider the impact of the membrane and piping materials. If affected, it is better to adjust the pH to the range of 10-13. As long as the pH of the raw water is a predetermined value, the pH adjustment step may not be performed.

The gas-liquid separation membrane 26 is not particularly limited as long as it passes gaseous ammonia without passing through liquid. The gas-liquid separation membrane 26 includes, for example, a hydrophobic porous hollow fiber membrane. For example, a hollow fiber membrane with a hollow fiber diameter of about 300 μm, a pore size of about 0.03 μm, and an (average) porosity of about 40 to 50% may be used. With such a gas-liquid separation membrane 26, gaseous ammonia contained in the discharged water containing calcium and ammonia is removed from the discharged water containing ammonia through the gas-liquid separation membrane 26.

It is preferable to equip the circulation pipes 40 and 42 connected to the second liquid chamber 25b of the ammonia removal device 16 for circulating sulfuric acid solution with automatic valves.

It is preferable to inject the sulfuric acid solution from the sulfuric acid storage tank 20 in such a way that the pH of the sulfuric acid solution is maintained at 2 or less. If the pH of the circulating sulfuric acid solution exceeds 2, the ammonia removal rate may decrease.

The sulfuric acid solution added from the sulfuric acid storage tank 20 is preferably as high in concentration as possible. From the viewpoint of operation and the like, the sulfuric acid concentration of the sulfuric acid solution added from the sulfuric acid storage tank 20 is preferably 50% by mass or more.

As described above, after the concentration of the ammonium sulfate recovered in the circulating sulfuric acid solution becomes a predetermined concentration or more, for example, 25% by mass or more, it is discharged from the circulation tank 18 through the recovery ammonium sulfate solution pipe 50 in the form of recovered ammonium sulfate solution.

The concentration of ammonium sulfate in the circulating sulfuric acid solution can be measured with an ammonium sulfate concentration measuring means such as a hydrometer or a densitometer. Based on the measured concentration of ammonium sulfate, when the concentration of ammonium sulfate becomes a predetermined concentration or more, for example, 25% by mass or more, it is automatically discharged from the circulation tank 18 through the recovery ammonium sulfate solution piping 50 in the form of recovered ammonium sulfate solution. . In addition, it is also possible to equip a device that automatically supplies water based on the measured concentration of ammonium sulfate and dilutes it to a concentration (for example, 40% by mass or less) that does not easily precipitate ammonium sulfate.

This embodiment is not limited to the sulfuric acid solution, as long as it is an acid solution such as hydrochloric acid or nitric acid. Considering the high value of industrial and commercial use, it is preferable to use a sulfuric acid solution and recover in the form of ammonium sulfate.

When the gas-liquid separation membrane 26 is contaminated due to fouling, etc., and the ammonia removal rate is reduced, in order to suppress the decrease in the ammonia removal rate, it is better to perform acid cleaning of the gas-liquid separation membrane 26 at a predetermined timing. As shown in FIG. 1, for example, the acid solution is sent from the acid storage tank 24 to the ammonia removal device 16 to the first liquid chamber 25a through the acid piping 48 and the pH adjustment water piping 36 to clean the gas-liquid separation membrane 26 (acid cleaning step).

As the acid solution used in the acid cleaning step, acid solutions such as sulfuric acid, hydrochloric acid, and citric acid can be used.

As for the pickling components, an additional acid storage tank 24 can be installed like the ammonia-containing discharge water treatment device 1 shown in Fig. 1, or a sulfuric acid pipe can be installed like the ammonia-containing discharge water treatment device 3 shown in Fig. 2 52. A part of the sulfuric acid solution sent from the sulfuric acid storage tank 20 to the second liquid chamber 25b of the ammonia removal device 16 is sent to the first liquid chamber 25a. [Example]

Hereinafter, the present invention will be explained more specifically and in detail with examples and comparative examples, but the present invention is not limited to the following examples.

<Examples 1, 2 and comparative examples> The treatment of the discharged water containing ammonia was performed under the following test conditions. [Test conditions] ・Use gas-liquid separation membrane: polypropylene porous hollow fiber membrane module ・Membrane area: 1.4m ²・Water flow rate: 0.0385m ³ /h ・Water temperature: 38℃ <Experimental device> The experimental device such as Figure 1, the heating equipment is set in the pH adjustment tank 14.

[Raw water quality] The water quality of the used raw water (ammonia-containing discharge water) is shown in Table 1.

【Table 1】

[Test method] The Blue's index of the raw water at pH 10.5 was calculated, and the result was 1.5. In addition, the Blue Index of the raw water at pH 12.2 was calculated, and the result was 3.5. The predetermined value of the Blue's index for judging whether to add the anti-scaling agent is set to 1.6. In Example 1, the anti-scaling agent is not added to the raw water and the pH of the raw water is adjusted to 10.5, and ammonia treatment is performed using a gas-liquid separation membrane. In Example 2, after injecting an anti-scaling agent into raw water, the pH was adjusted to 12.2, and ammonia treatment was performed using a gas-liquid separation membrane. In the comparative example, the pH of the raw water was adjusted to 12.2 without adding an anti-scaling agent to the raw water, and ammonia treatment was performed using a gas-liquid separation membrane. The scale inhibitor used in Example 2 includes acrylic acid/2-acrylamide-2-methylpropanesulfonic acid/tertiary butylacrylamide terpolymer, and 2-phosphonobutane-1 ,2,4-Tricarboxylic acid.

The ammonia concentration before and after the treatment was measured by JIS K0102 indophenol blue spectrophotometry, and the ammonia removal rate was calculated.

【Table 2】

In the comparative example, the ammonia removal rate at the beginning of the treatment was 53.4%, and the removal rate slowly decreased with the passage of water passing time, and was 44.9% after 19 hours of passing water. The ammonia removal rate of Example 1 was 53.7% even after more than 110 hours of water passing, which was approximately the same value as 53.8% at the beginning of the water passing, and there was almost no decrease in the removal rate. The ammonia removal rate of Example 2 was still 54.5% after more than 110 hours of water passing, which was approximately the same value as 54.7% at the beginning of water passing, and there was almost no decrease in the removal rate. In other words, it can be said that for raw water with a low Blue Index above pH 10, pH adjustment is performed without adding an antiscalant, and for raw water with a high Blue Index above pH 10, pH adjustment is performed after adding an antiscalant to suppress gas. The occlusion of the liquid separation membrane and the reduction of ammonia removal rate.

In the above test, in order to examine the influence of the Blue's index of raw water with a pH of 10 or higher, the Blue's index was deliberately set to a pH of 1.6 or higher (pH 12.2 in Example 2 and Comparative Example). In actual treatment, as long as it is raw water with the water quality shown in Table 1, the treatment based on Example 1, for example, can be performed. Furthermore, when the water quality of raw water changes, for example, when the Blue's index calculated at pH 10 or higher is not less than 1.6, after adding an anti-scaling agent as in Example 2, it is adjusted to pH 10 or higher and processed.

1,3‧‧‧Discharge water treatment device containing ammonia 10‧‧‧Original water tank 12‧‧‧Anti-scaling agent supply device 14‧‧‧pH adjustment tank 16‧‧‧Ammonia removal device 18‧‧‧Circulation slot 20‧‧‧Sulfuric acid storage tank 22‧‧‧pH adjuster supply device 24‧‧‧acid storage tank 25‧‧‧Control device 25a‧‧‧The first liquid chamber 25b‧‧‧Second liquid chamber 26‧‧‧Gas-liquid separation membrane 30‧‧‧Raw water piping 32‧‧‧Raw water supply piping 34‧‧‧Anti-scaling agent injection pipe 36‧‧‧pH adjustment water piping 38‧‧‧Treatment water piping 40、42‧‧‧Circulating piping 44、52‧‧‧Sulfuric acid piping 46‧‧‧pH adjuster piping 48‧‧‧acid piping 50‧‧‧Piping for recovery of ammonium sulfate solution

Fig. 1 is a schematic configuration diagram showing an example of an ammonia-containing discharge water treatment device according to an embodiment of the present invention. Fig. 2 is a schematic configuration diagram showing another example of the treatment device for ammonia-containing discharged water according to the embodiment of the present invention.

Claims (6)

A treatment method for discharged water containing ammonia, characterized by having the following steps: a Langelier index calculation step, using the following formulas (1)~(5) to calculate the pH of the discharged water containing ammonia containing calcium The above Blue Index; pH adjustment step, when the Blue Index calculated above pH 10 does not reach a predetermined value, adjust the pH of the discharged water containing ammonia to be above 10 until the Blue Index does not reach the predetermined value The range of pH value, when the Blue's index calculated above pH 10 does not reach a predetermined value, after adding a scale inhibitor to the discharged water containing ammonia, adjust the pH to above 10; the ammonia removal step, ammonia from gas-liquid separation by adjusting the pH of the discharged water containing ammonia removal, and ammonia in contact with the acid solution removed and recovered in the form of ammonium hydroxide solution; pH = blue value index s -pHs + 1.5 × 10 ^{- 2} (T-25) (1) In formula (1), the pH value is set to 10 or more, pHs is the value obtained by the following formula (2), and T is the discharged water containing ammonia detected by the sensor Temperature (℃); pHs=8.313-log[Ca ²⁺ ]-log[A]+S (2) In formula (2), [Ca ²⁺ ] is the value calculated by the following formula (3) (me/ L), [A] is the value (me/L) obtained by the following formula (4), and S is the value obtained by the following formula (5); [Ca ²⁺ ]=(Ca ²⁺ )÷(40.1 ÷2) (3) (Ca ²⁺ ) in formula (3) is the calcium concentration (mg/L) detected by the sensor; [A]=(A)÷(100÷2) (4) (4) (A) is the total alkalinity (mg/L) detected by a measuring device or measuring device;

Sd in formula (5) is the concentration of soluble substances (mg/L) detected by a measuring device or measuring device. For example, the treatment method of ammonia-containing discharged water in the scope of patent application, wherein, in the pH adjustment step, when the calculated Blue's index does not reach 1.6, the pH of the ammonia-containing discharged water is adjusted to 10 Above and below the Blue's index into the range of pH 1.6, when the Blue's index calculated above pH 10 is not less than 1.6, after adding an antiscalant to the discharged water containing ammonia, adjust the pH to 10 or more . For example, the method for treating ammonia-containing discharged water according to item 1 or 2 of the scope of patent application, wherein the anti-fouling agent includes at least one of an acrylic polymer and a phosphonic acid compound. A treatment device for discharged water containing ammonia, which is characterized by having the following components: a Blue index calculation component, and the following formulas (1) ~ (5) are used to calculate the value of the discharge water containing ammonia with calcium coexisting at a pH of 10 or higher. Index; pH adjusting means, when the Blue's index calculated above pH 10 does not reach a predetermined value, adjust the pH of the discharged water containing ammonia to be above 10 to the range where the Blue's index becomes the predetermined value of pH , When the Blue's index calculated above pH 10 is not less than the predetermined value, after adding an anti-scaling agent to the discharged water containing ammonia, adjust the pH to above 10; ammonia removal means, the ammonia is removed by the gas-liquid separation membrane It is removed from the discharged water containing ammonia after pH adjustment, and the removed ammonia is contacted with the acid solution to be recovered in the form of ammonium solution; Blue's index=pH value-pHs+1.5×10 ^-2 (T-25) (1 ) In formula (1), the pH value is set to 10 or more, pHs is the value obtained by the following formula (2), and T is the temperature (℃) of the discharged water containing ammonia detected by the sensor; pHs= 8.313-log[Ca ²⁺ ]-log[A]+S (2) In formula (2), [Ca ²⁺ ] is the value (me/L) calculated by the following formula (3), and [A] is The value (me/L) obtained by the following equation (4), S is the value obtained by the following equation (5); [Ca ²⁺ ]=(Ca ²⁺ )÷(40.1÷2) (3) equation ( 3) (Ca ²⁺ ) is the calcium concentration (mg/L) detected by the sensor; [A]=(A)÷(100÷2) (4)(A) in formula (4) It is the total alkalinity (mg/L) detected by the tester or measuring device;

Sd in formula (5) is the concentration of soluble substances (mg/L) detected by a measuring device or measuring device. For example, the treatment device for ammonia-containing discharged water in the fourth item of the scope of patent application, wherein the pH adjusting component adjusts the pH of the ammonia-containing discharged water to be above 10 to no more than 10 when the calculated Blue's index does not reach 1.6 The Darlens index is in the range of pH value of 1.6. When the Blue's index calculated at pH 10 or higher is not less than 1.6, after adding an antiscalant to the discharged water containing ammonia, the pH is adjusted to 10 or higher. For example, the treatment device for ammonia-containing discharged water in the 4th or 5th patent application, wherein the anti-scaling agent contains at least one of an acrylic polymer and a phosphonic acid compound.

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