TW201805243A - 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

Method and device for treating ammonia-containing discharged water

The invention relates to a method and a device for treating ammonia-containing discharged water, which are used for treating ammonia-containing discharged water discharged from electronics industry factories, chemical factories, and the like, and are recovered as an ammonium solution.

Conventionally, a relatively high ammonia-containing discharge water discharged from an electronics industry factory such as a semiconductor factory, a chemical factory, and a thermal power plant has been performed by, for example, an ammonia stripping method (for example, refer to Patent Document 1) , Evaporation concentration method (for example, refer to Patent Document 2), catalyst wet oxidation method (for example, refer to Patent Document 3), and the like. The discharged water having a relatively low ammonia concentration is treated by, for example, a biological treatment method.

Ammonia stripping method is a treatment method in which ammonia is added to the exhaust water containing ammonia, and after passing through the temperature, it is passed through a diffusing tower filled with a filler and exposed to steam and air to transfer the ammonia in the exhaust water to the gas side . This method is a relatively simple process, but the equipment of the dispersing tower is a large problem. In addition, ammonia that has been transferred to the gas side by heat energy such as heating and steam needs to be further subjected to a high-temperature catalyst oxidation treatment, which has a problem of high treatment cost. In addition, when the catalyst is oxidized, NO _x , N ₂ O, etc. may be generated.

Evaporation and concentration method is a treatment method for heating and evaporating the discharged water containing ammonia, condensing the generated ammonia-containing vapor, and recovering it as ammonia water. This method has the problems of heating energy cost for evaporation, deposition of scale on the heat transfer surface of the evaporator, and the like.

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

In recent years, a gas-liquid separation membrane method has been proposed in which ammonia is removed from discharged water containing ammonia by passing through a hydrophobic porous gas-liquid separation membrane of ammonia without passing through liquid (for example, refer to Patent Document 4). In this method, the ammonia containing the discharged water is made alkaline at a pH of 10 or more, the ammonia in the discharged water is gasified, and the downstream side of the gas-liquid separation membrane is sucked with a vacuum pump to remove ammonia from the containing water. Method for removal of ammonia water. However, an additional ammonium sulfate scrubber is required in this method.

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, ammonia discharged water is adjusted to flow through the outside of the hollow fiber membrane, and a sulfuric acid solution with a pH of 2 or less flows through the inside of the hollow fiber membrane in a countercurrent manner to perform ammonia discharge in the water. Removal and recycling technology. The gasified ammonia comes into contact with sulfuric acid flowing inside the hollow fiber membrane, and is recovered as ammonium sulfate.

The method using a gas-liquid separation membrane is a simple process, and it can economically treat the discharged water containing ammonia, and it can be reused through the ammonium sulfate solution. However, it is caused by the calcium compounds contained in the discharged water containing ammonia. The fouling caused the gas-liquid separation membrane to occlude, and the ammonia removal rate decreased with the passage of processing time. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3987896 [Patent Document 2] Japanese Patent Laid-Open No. 2011-153043 [Patent Document 3] Japanese Patent No. 3272859 [Patent Document 4] Japanese Patent No. 3240694 [Patent Document 5] ] Japanese Patent Laid-Open No. 2013-202475

[Problems to be Solved by the Invention] The present invention aims to suppress the occlusion of a gas-liquid separation membrane due to fouling due to calcium compounds and the like in the treatment of ammonia-containing exhaust water using a gas-liquid separation membrane, and the treatment time elapses. The resulting reduction in ammonia removal rate. [Means for solving problems]

(1) The present invention is a method for treating ammonia-containing discharged water, which is characterized by having the following steps: a Blue's index calculation step to calculate a Blue's index of pH 10 or higher with ammonia-containing discharged water containing calcium; pH adjustment In the step, when the blue index calculated above pH 10 does not reach a predetermined value, the pH of the ammonia-containing discharged water is adjusted to a range of 10 or more until the blue index reaches a pH value of the predetermined value. When the blue index calculated above pH 10 is not less than the predetermined value, the pH is adjusted to 10 or more after adding an antiscalant in the ammonia-containing discharged water; after the ammonia is removed, the ammonia is adjusted from the pH by a gas-liquid separation membrane The ammonia-containing discharged water is removed, and the removed ammonia is contacted with an acid solution to be recovered as an ammonium solution.

(2) In the method for treating ammonia-containing discharged water of (1) above, in the pH adjustment step, it is suitable that the pH of the ammonia-containing discharged water is adjusted to 10 when the calculated Blue index is less than 1.6. The above range is below the pH value of 1.6 when the blue index reaches 1.6. When the blue index calculated above pH 10 is not less than 1.6, it is desirable to adjust the pH to 10 after adding an antiscalant in the ammonia-containing discharged water. the above.

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

(4) The present invention is a device for treating ammonia-containing discharged water, which is characterized by having the following components: a Blue's index calculation unit, which calculates a Blue's index of pH 10 or higher with ammonia-containing discharged water in which calcium is coexisted; pH adjustment The component adjusts the pH of the ammonia-containing discharge water to a pH range of 10 or more to a pH value within 10 when the Blue's index calculated above pH 10 does not reach a predetermined value. When the blue index calculated above pH 10 is not less than a predetermined value, after adding an antiscalant to the discharged water containing ammonia, the pH is adjusted to 10 or more; after the ammonia is removed, the ammonia is adjusted from the pH by a gas-liquid separation membrane The ammonia-containing discharged water is removed, and the removed ammonia is contacted with an acid solution to be recovered as an ammonium solution.

(5) In the above-mentioned (4) treatment device for ammonia-containing discharged water, the pH adjusting member should adjust the pH of the ammonia-containing discharged water to be 10 or more to 10 when the calculated Blue index is less than 1.6. The Dallan index is in the range of pH of 1.6. When the blue index calculated above pH 10 is not less than 1.6, it is suitable to adjust the pH to 10 or more after adding an antiscalant in the ammonia-containing discharged water.

(6) In the apparatus for treating ammonia-containing discharged water as described in (4) or (5) above, the antiscalant preferably contains at least one of an acrylic polymer and a phosphonic acid compound. [Effect of the invention]

According to the present invention, it is possible to prevent generation of scale due to calcium compounds and the like in the treatment of ammonia-containing discharged water using a gas-liquid separation membrane, and to suppress occlusion of the gas-liquid separation membrane and decrease in ammonia removal rate.

An 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.

An outline of an example of the ammonia-containing waste water treatment apparatus according to the embodiment of the present invention is shown in FIG. 1 and its configuration will be described. The ammonia-containing waste water treatment device 1 shown in FIG. 1 includes a raw water tank 10, a pH adjusting device as a pH adjusting member, an ammonia removing device 16 as an ammonia removing member, a circulation tank 18, a sulfuric acid storage tank 20, and acid cleaning. The component acid storage tank 24 and the control device 25. The pH adjusting device includes a scale inhibitor supply device 12, a pH adjusting tank 14, and a pH adjusting agent supply device 22. The antiscalant supply device 12 includes, for example, a antiscalant storage tank and a pump, and is arranged to supply the antiscalant to the discharged water. 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 discharged water.

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

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

The control device 25 includes a processor and a memory, and includes a Lanzi index calculation unit as a functional block. The Lan's index calculation unit calculates the Lan's index of the treated water containing calcium and ammonia containing discharged water at pH 10 or higher. Specifically, the blue concentration at the set pH (10 or more) is calculated using the measured values of the calcium concentration, inorganic carbon concentration, dissolved substance concentration, alkalinity, and discharged water temperature in the above-mentioned discharged water, and the set pH (more than 10). Index. The control device 25 is configured to be capable of inputting, for example, a calcium concentration sensor, an inorganic carbon concentration sensor, (conductivity-converted) a soluble substance concentration meter or a soluble substance concentration meter provided in the raw water tank 10, and an alkalinity. 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 the detected value to the control device 25 as the detected value. In addition, the Blue index may be calculated from the measured calcium concentration and the like, and the calculated value may be input to the control device 25.

The processor of the control device 25 executes each process such as a process of calculating a Lanternite index based on a processing program stored in a program memory, and a process of setting an antiscalant and a pH adjusting agent based on the calculated Lanner index. In this embodiment, the timing of adding the antiscalant and the pH adjusting agent is controlled by the control device 25, and the timing of adding the antiscalant and the pH adjusting agent can also be controlled by an operator or the like based on the calculated blue index.

The method for treating ammonia-containing discharged water and the operation of the ammonia-containing discharged water treatment device 1 according to this embodiment will be described.

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

The calcium concentration, the inorganic carbon concentration, the dissolved substance concentration, the alkalinity, and the temperature of the raw water are detected in the raw water, input to the control device 25, and calculated at pH 10 by using the following formulas (1) to (5) by the blue index calculation unit. The blue index of the above raw water.

Lans index = pH value-pHs + 1.5 x 10 ^-2 (T-25) (1) The pH value in formula (1) is the set pH value, which is set to 10 or more. The pHs in the formula (1) are values obtained from the following formula (2). T in the formula (1) is applicable to the temperature (° C) of the raw water detected by the sensor.

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

[Ca ²⁺ ] = (Ca ²⁺ ) (mg / L) ÷ (40.1 ÷ 2) (3) In the formula (3), (Ca ²⁺ ) (mg / L) is suitable for the calcium measured by the sensor concentration.

[A] (me / L) = (A) (mg / L) ÷ (100 ÷ 2) (4) (A) (mg / L) in formula (4) 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) is applicable to a soluble substance (mg / L) detected by a measuring device or a measuring device (above, the Blue's index calculation step).

With the control device 25, it is possible to determine whether the blue index calculated above pH 10 has not reached a predetermined value. Considering the viewpoint of suppressing the generation of scale in raw water, it is preferable to set a predetermined value, for example, 1.6 or less. In the following description, the predetermined value is set to 1.6.

When the blue index calculated above pH 10 is not less than 1.6, the control device 25 transmits an operation instruction to the antiscalant supply device 12, and the antiscalant is added from the antiscalant supply device 12 through the antiscalant injection pipe 34. To the original water tank 10. In terms of the relationship between the Lans index and pH, the higher the pH, the higher the Lans index. Therefore, when the pH value of the formula (1) is set to, for example, a range of 10, or a range of 10 to 11, when the Blue's index exceeds 1.6, the control device 25 determines that the Blue's index calculated at a pH of 10 or higher at this stage is not less than 1.6, and instructs Adding antiscalant.

The raw water to which the antiscalant is added is supplied to the pH adjustment tank 14 through the raw water supply pipe 32. At this time, the operation instruction is transmitted from the control device 25 to the pH adjusting agent supply device 22, and the pH adjusting agent is added from the pH adjusting agent supply device 22 to the pH adjusting tank 14 through the pH adjusting agent pipe 46 to adjust the pH of the raw water to 10 the above. When the antiscalant is added to the raw water, the pH of the raw water may be at least 10, and there is no particular limitation. In view of suppressing the use amount of the alkaline agent, it is preferable to set the pH around 10.

On the other hand, when the blue index calculated at a pH of 10 or higher does not reach 1.6, raw water (without an antiscalant added) is supplied to the pH adjusting tank 14 through a raw water supply pipe 32. At this time, an operation instruction is transmitted from the control device 25 to the pH adjusting agent supply device 22, and the pH adjusting agent is added from the pH adjusting agent supply device 22 to the pH adjusting tank 14 through the pH adjusting agent pipe 46. The pH of the raw water is adjusted to a range of 10 or more to a pH value at which the Lanin index becomes 1.6 (predetermined value). For example, when the blue index calculated at pH 11 does not reach 1.6 and the pH value of the blue index reaches 1.6 is 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 Laner index becomes 1.6 is obtained from the following formula (6) (above, pH adjustment step). pH = 1.6 + pHs-1.5 × 10 ^-2 (T-25) (6)

By setting the pH of the raw water to be 10 or more, the ammonium ion acid in the raw water is dissociated into ammonia gas, and the ammonia removal rate using the gas-liquid separation membrane in the later stage can be increased. On the other hand, if the pH of the raw water is 10 or higher and the Blue's index is high, the reaction between calcium and carbonic acid in the raw water is high, and scales are generated in a short period of time, so the gas-liquid separation membrane in the later stage is likely to be blocked. Therefore, in this embodiment, when the pH of the raw water is 10 or more and the Blue index is high, an antiscalant is added before the pH of the raw water is adjusted to 10 or more to suppress the generation of scale and to suppress the gas-liquid separation in the later 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 antiscalant is not added to the raw water, it is only adjusted to a pH value range of pH 10 or higher to a value not reaching a Lanin index, and the reduction of the ammonia removal rate with the passage of the treatment time can be suppressed. In addition, since the antiscalant is an organic acid salt, when dissolved in water, the salt concentration increases and the vapor pressure of ammonia decreases. Therefore, if the scale inhibitor is added to water with a low blue index (for example, raw water less than 1.6), that is, water with a relatively low pH and a slightly larger proportion of ammonium ions, the volatilization rate of ammonia will be reduced and the use of The ammonia removal rate of the gas-liquid separation membrane may decrease. In this way, the antiscalant is added only when necessary in accordance with the Blue's index, and a reduction in the ammonia removal rate can be suppressed.

Moreover, by suppressing the occlusion of the membrane as described above, it is possible to reduce the washing frequency of the membrane, and also reduce the cost of the medicine and waste liquid treatment related to the membrane washing.

The pH-adjusted raw water is conveyed 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, ammonia is removed from raw water by a gas-liquid separation membrane 26 that passes through ammonia without passing liquid. The treated water from which ammonia has been removed 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 a 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 piping 44 is supplied to the second liquid chamber 25b from the inlet provided on the other end side of the ammonia removal device 16 through the circulation piping 40, and The ammonia-containing discharged water in the first liquid chamber 25a circulates as a countercurrent. For example, the exhaust water containing ammonia may be circulated on the outside of the hollow fiber membrane (first liquid chamber 25a), and the sulfuric acid solution may be circulated on the inside of the hollow fiber membrane (second liquid chamber 25b). The ammonia that has passed through the gas-liquid separation membrane 26 is in contact with the sulfuric acid solution flowing through the second liquid chamber 25b of the ammonia removal device 16 to produce ammonium sulfate (above, the ammonia removal step).

The produced ammonium sulfate is still dissolved in the sulfuric acid solution, and is conveyed to the circulation tank 18 through the circulation pipe 42 from the outlet of the second liquid chamber 25b provided on one end side of the ammonia removal device 16. The sulfuric acid solution is circulated 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 recycled sulfuric acid solution becomes a predetermined concentration or more, it is discharged from the circulation tank 18 through the recovered ammonium sulfate solution pipe 50 as a recovered ammonium sulfate solution.

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

When oxidants such as hydrogen peroxide are contained in raw water such as discharged water containing calcium and ammonia discharged from electronics factories such as semiconductor factories, the oxidant removal treatment such as injection of reducing agent or activated carbon treatment can be performed before the ammonia removal device 16 Remove the oxidant. This can suppress a reduction in the ammonia removal rate and a deterioration of the gas-liquid separation membrane in the ammonia removal step due to an oxidant such as hydrogen peroxide.

The ammonia concentration 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 to be 25% by mass or more, and to prevent the ammonium sulfate from being easily precipitated, it is preferable to use 900mg / L or more and 2,200mg / L. Concentrations below L work better.

When the ammonia concentration in the raw water is low (for example, when it is less than 900 mg / L), ammonia can be concentrated by a reverse osmosis membrane treatment or the like before the ammonia removal device 16. In order to perform the concentration of ammonium sulfate, the ammonium sulfate solution produced by treating low-concentration ammonia-containing discharged water may be transported from the circulation tank 18 to the original water tank 10 and the like, and the ammonia treatment may be performed again.

If the temperature of the raw water is less than 35 ° C., 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 use a heatable device such as a heat exchanger or a heater to heat the temperature of the raw water to, for example, 35 to 50 ° C. and transport the raw water to the ammonia removal device 16. However, since it is easy to generate scales such as calcium compounds during heating, the heating equipment should preferably be installed in the pH adjusting tank 14 and the pH adjusting water pipe 36 after the scale inhibitor is injected. In consideration of 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 lower. In order to maintain the raw water or adjust the ammonia concentration, the treated water may be recycled to the raw water tank 10 and the like.

The addition position of the antiscalant used in the pH adjustment step may be the raw water tank 10 like the ammonia-containing waste water treatment device 1 shown in FIG. 1, or the ammonia-containing waste water treatment device 3 shown in FIG. 2. The raw water supply pipe 32 is generally used, and although the description in the figure is omitted, the pH adjusting tank 14 may be used. However, when implementing the heating step, considering the viewpoint of suppressing the formation of scale, it is preferable to inject before the heating step. When the antiscalant is added to the raw water tank 10 and the pH adjusting tank 14, it is preferable to use a stirrer or an aeration device for stirring. When adding the antiscalant to the raw water supply pipe, it is preferable to use a line mixer or the like for stirring.

The antiscalant is not particularly limited as long as it can inhibit the generation of scale caused by calcium compounds. Examples include 1-hydroxyethylene-1,1-diphosphonic acid and 2-phosphonic acid butan. Phosphonic acid compounds such as alkane-1,2,4-tricarboxylic acid, ethylenediaminetetramethylenephosphonic acid, nitrogen trimethylphosphonic acid and their salts; orthophosphates, polymeric phosphates, etc. Phosphoric acid-based compounds; Maleic acid-based 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 / nonionic group-containing monomers; terpolymers of (meth) acrylic acid / sulfonic acid / nonionic group-containing monomers, (meth) acrylic acid / acrylamido-alkyl- and Acrylic polymers and the like such as terpolymers of arylsulfonic acid / substituted (meth) acrylamide. Among these, it is preferable to include at least one of a phosphonic acid compound and an acrylic polymer.

Examples of the (meth) acrylic acid constituting the terpolymer include (meth) acrylic acid salts such as methacrylic acid, acrylic acid, and sodium salts thereof. Examples of the acrylamido-alkyl- and / or arylsulfonic acid constituting the terpolymer include 2-acrylamido-2-methylpropanesulfonic acid and a salt thereof. Examples of the substituted (meth) acrylamidoamine constituting the terpolymer include third butylacrylamidonium, third octylacrylamidoamine, and dimethylacrylamidoamine.

The pH adjusting agent used in the pH adjusting step is, for example, a base such as a 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 ion acid 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 considering the membrane, piping material, etc. If it is affected, it should be adjusted to a pH 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 liquid. Examples of the gas-liquid separation membrane 26 include a hydrophobic porous hollow fiber membrane and the like. For example, a hollow fiber membrane having a diameter of about 300 μm, a pore size of about 0.03 μm, and a (average) porosity of about 40 to 50% may be used. With such a gas-liquid separation membrane 26, gaseous ammonia contained in the exhaust water containing calcium and ammonia is removed from the ammonia-containing exhaust water through the gas-liquid separation membrane 26.

It is preferable that an automatic valve is provided in the circulation pipes 40 and 42 connected to the second liquid chamber 25b of the ammonia removing device 16 that circulates the sulfuric acid solution.

It is preferable to inject the sulfuric acid solution from the sulfuric acid storage tank 20 so 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 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 recycled sulfuric acid solution is equal to or higher than a predetermined concentration, for example, 25% by mass or more, the ammonium sulfate solution piping 50 is discharged from the circulation tank 18 as the recovered ammonium sulfate solution.

The concentration of ammonium sulfate in the circulating sulfuric acid solution can be measured using, for example, an ammonium sulfate concentration measuring means such as a hydrometer and a densitometer. Based on the measured ammonium sulfate concentration, the ammonium sulfate concentration may be automatically discharged from the circulation tank 18 through the recovered ammonium sulfate solution piping 50 through the recovered ammonium sulfate solution piping 50 after the ammonium sulfate concentration becomes higher than a predetermined concentration, for example, 25% by mass or more. . Further, it may be provided with equipment 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) in which ammonium sulfate is difficult to precipitate.

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

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

As the acid solution used in the acid washing step, a solution of an acid such as sulfuric acid, hydrochloric acid, or citric acid can be used.

As for the acid cleaning component, an acid storage tank 24 may be additionally provided as shown in the ammonia-containing waste water treatment device 1 shown in FIG. 1, or a sulfuric acid pipe may be provided as shown in the ammonia-containing waste 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 described 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> Treatment of discharged water containing ammonia was performed under the following test conditions. [Test conditions] ・ Use gas-liquid separation membrane: Porous hollow fiber membrane module made of polypropylene ・ Membrane area: 1.4m ²・ Water flow rate: 0.0385m ³ / h ・ Water temperature: 38 ° C In FIG. 1, the heating device is set in the pH adjusting tank 14.

[Raw water quality] Table 1 shows the water quality of the raw water (ammonia-containing discharge water) used.

【Table 1】

[Test method] The blue index of the raw water at pH 10.5 was calculated, and the result was 1.5. The Blue index of the raw water at pH 12.2 was calculated and found to be 3.5. The predetermined value of the Blue's index for judging whether a scale inhibitor is added is set to 1.6. In Example 1, the pH of the raw water was adjusted to 10.5 without adding a scale inhibitor to the raw water, and an ammonia treatment was performed using a gas-liquid separation membrane. In Example 2, after the antiscalant was injected into the raw water, the pH was adjusted to 12.2, and an ammonia treatment was performed using a gas-liquid separation membrane. In the comparative example, without adding an antiscalant to the raw water, the pH of the raw water was adjusted to 12.2, and an ammonia treatment was performed using a gas-liquid separation membrane. The scale inhibitor used in Example 2 includes a terpolymer of acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid / third butylacrylamidine, and 2-phosphonic acid butane-1 , 2,4-tricarboxylic acid.

The ammonia concentration before and after the treatment was measured by JIS K0102 indophenol blue absorption 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 gradually decreased with the passage of water, and it was 44.9% after 19 hours of water passage. The ammonia removal rate in Example 1 was 53.7% even after the passage of water for 110 hours or more, which was approximately the same value as 53.8% at the beginning of the passage of water, and there was almost no decrease in the removal rate. The ammonia removal rate in Example 2 was still 54.5% after 110 hours of water passing, which was about 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's index of pH 10 or higher, the pH is adjusted without adding an antiscalant, and for raw water with a high Blue's index of pH 10 or higher, the pH is adjusted after the addition of an antiscalant to suppress gas. Blockage of the liquid separation membrane and reduction in ammonia removal rate.

In the above test, in order to examine the influence of the blue index of the raw water pH 10 or higher, the blue index was intentionally set to a pH of 1.6 or higher (pH of Example 2 and Comparative Example 12.2). In actual processing, as long as the raw water has the water quality shown in Table 1, the processing based on Example 1 can be performed, for example. In addition, when the water quality of raw water is changed, for example, when the blue index calculated at a pH of 10 or higher is less than 1.6, after adding an antiscalant as in Example 2, the pH is adjusted to 10 or higher and treated.

1. 3‧‧‧ discharge water treatment device containing ammonia
10‧‧‧ original sink
12‧‧‧ Antiscalant supply device
14‧‧‧pH adjusting tank
16‧‧‧Ammonia removal device
18‧‧‧Circulation tank
20‧‧‧Sulfuric acid storage tank
22‧‧‧pH adjusting agent 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‧‧‧ Antiscalant injection pipe
36‧‧‧pH adjusting water pipe
38‧‧‧ treatment water piping
40、42‧‧‧Circular piping
44, 52‧‧‧ Sulfuric acid piping
46‧‧‧pH adjusting agent piping
48‧‧‧Acid plumbing
50‧‧‧ Recovery ammonium sulfate solution piping

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

no

Claims (6)

A method for treating discharged water containing ammonia, which is characterized by having the following steps: a Langelier index calculation step, calculating a Lanke index of pH 10 or higher for ammonia-containing discharged water in which calcium is coexisted; a pH adjustment step, When the blue index calculated above pH 10 does not reach a predetermined value, adjust the pH of the ammonia-containing discharged water to a range of 10 or more to a pH value where the blue index reaches the predetermined value, and at a pH of 10 or more When the calculated Blue index is not up to a predetermined value, after adding a scale inhibitor to the ammonia-containing discharged water, the pH is adjusted to 10 or more. In the ammonia removal step, ammonia is removed from the pH by a gas-liquid separation membrane. The adjusted ammonia-containing discharge water is removed, and the removed ammonia is contacted with the acid solution to be recovered as an ammonium solution. For example, the method for treating ammonia-containing discharged water in item 1 of the scope of the patent application, wherein in the pH adjustment step, when the calculated Lan index is less than 1.6, adjust the pH of the ammonia-containing discharged water to 10 The above range is a range of pH value up to 1.6, and when the blueness index calculated above pH 10 is not less than 1.6, after adding an antiscalant to the ammonia-containing discharged water, the pH is adjusted to 10 or more. . For example, the method for treating discharged water containing ammonia in item 1 or 2 of the patent application scope, wherein the antiscalant contains at least one of an acrylic polymer and a phosphonic acid compound. A treatment device for ammonia-containing discharged water, which is characterized by having the following components: a Lanxian index calculation unit that calculates a Lanxian index of pH 10 or higher for ammonia-containing discharged water in which calcium is coexisted; and a pH adjusting unit at pH 10 When the Lancaine index calculated above does not reach a predetermined value, the pH of the ammonia-containing discharged water is adjusted to be in a range of 10 or more until the Lancaine index reaches a predetermined pH value. When the index does not reach the predetermined value, after adding an antiscalant in the ammonia-containing discharged water, the pH is adjusted to 10 or more; the ammonia removing member adjusts ammonia from the pH-adjusted discharged water containing ammonia through a gas-liquid separation membrane. It is removed and the removed ammonia is contacted with an acid solution to be recovered as an ammonium solution. For example, the treatment device for ammonia-containing discharged water according to item 4 of the scope of the patent application, wherein the pH adjusting member adjusts the pH of the ammonia-containing discharged water to be 10 or more to 10 when the calculated Blue index is less than 1.6. The Darlan index is in a pH range of 1.6. When the Lantern index calculated at a pH of 10 or higher is not lower than 1.6, a scale inhibitor is added to the ammonia-containing discharged water, and then the pH is adjusted to 10 or higher. For example, the treatment device for ammonia-containing discharged water according to item 4 or 5 of the scope of patent application, wherein the antiscalant contains at least one of an acrylic polymer and a phosphonic acid compound.