JPH1177065A - Treatment method of ammonium adipate waste liquid - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To efficiently remove adipic acid ions and ammonium ions from waste liquid containing ammonium adipate generated during chemical conversion treatment of aluminum material, etc., to provide a safe wastewater and to increase adipic acid. Provide a method that can be recovered in purity. SOLUTION: A waste liquid containing ammonium adipate is made weakly alkaline by adding a calcium source such as slaked lime and heated to simultaneously carry out crystallization and deammonification of calcium adipate, and a dense slurry of crystallized calcium adipate. By adding sulfuric acid or hydrochloric acid to
Organic compounds (COD) and ammonia nitrogen in wastewater can be reduced simply and easily. Further, adipic acid can be recovered with high purity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a waste liquid containing ammonium adipate generated during a chemical conversion treatment or the like in a method for producing an aluminum electrode foil for an electrolytic capacitor, for example.

[0002]

2. Description of the Related Art Conventionally, a method for treating adipic acid waste liquid is disclosed in Japanese Patent Application Laid-Open Nos. 1-224092 and 54-11-11.
Methods described in JP-A-5314 and JP-A-51-32513 are exemplified. In each of these methods, an adipic acid waste liquid is added with an inorganic salt in an acidic state or concentrated to crystallize adipic acid.However, it can be said that the recovery rate of adipic acid is still sufficient. No further improvement was desired. Furthermore, no consideration has been given to an effective treatment of a waste liquid containing ammonium adipate composed of a component having high solubility.

Next, generation of waste liquid containing ammonium adipate from the chemical conversion treatment in the method for producing an aluminum electrode foil for an electrolytic capacitor will be described in detail.
In an aluminum electrolytic capacitor characterized by small size and large capacity, an aluminum foil is subjected to a so-called etching treatment to increase the effective surface area, and then subjected to a chemical treatment to form an insulating aluminum oxide film on the surface. In this chemical conversion treatment,
In the past, a borate-based electrolytic solution (chemical conversion solution) was used, but an ammonium adipate chemical conversion bath was proposed in order to improve characteristics such as withstand voltage, dielectric constant, and insulation properties (German Patent 19).
No. 36267, JP-A-49-81240, etc.). Further, by using it in combination with a chemical conversion treatment using a phosphoric acid-based bath, a higher-performance electrode foil can be obtained (JP-A-52-923).
No. 60), currently, a two-stage chemical conversion treatment using an ammonium adipate chemical conversion bath and a phosphoric acid chemical conversion bath is widely performed.

[0004] In these chemical conversion treatments, impurities accumulate in the chemical conversion bath due to the dissolution of electrochemical reaction products and aluminum materials, and if the chemical conversion treatment is continued as it is, the physical and electrochemical performance of the aluminum electrode foil is reduced. After a predetermined amount of the aluminum material, the chemical conversion treatment is performed in place of a new chemical conversion bath. And the aging chemical bath becomes waste liquid. That is, a waste liquid containing ammonium adipate is generated from this chemical conversion treatment. Further, a phosphoric acid waste liquid is also generated from this chemical conversion treatment. Power is usually supplied in a wet manner to protect the surface, but a waste liquid containing a medium concentration of ammonium adipate is also generated from this power supply device for the same reason.

[0005]

Among the above waste liquids, the phosphoric acid waste liquid is insolubilized as calcium phosphate by adding a generally well-known calcium compound (such as calcium hydroxide), and the calcium phosphate is solidified. 2. Description of the Related Art A wide variety of methods have been widely used in which liquids are separated and collected, used as useful resources, and used as safe wastewater.

However, the waste liquid containing ammonium adipate is composed of an organic acid component having high water solubility and an ammonia component.
The adipic acid treatment method disclosed in, for example, Japanese Patent No. 4092 cannot be effectively applied. In addition, as a chemical method, a method of separating an ammonium gas by heating an ammonium salt waste liquid to make it alkaline with sodium hydroxide and separating ammonia gas by heating and a method of separating an organic acid under acidity by a mineral acid are also known. A waste liquid containing ammonium adipate has a problem in that adipic acid is not easily separated after removing ammonia. That is, adipic acid has a moderate solubility among organic acids, and even at a normal temperature, even if the pH is lowered to about 2, 20 to 30 g / l is dissolved (COD 3000 to 4
000 ppm), and it is not easy to reduce the solubility to several g / l by ordinary industrial cooling. Therefore, in this chemical method, a large amount of adipic acid remains in the remaining mother liquor after the separation of crystallization adipic acid, and cannot be discharged as wastewater. It is necessary to join the untreated waste liquid and circulate it.

However, since salt is generated by adding sodium hydroxide or a mineral acid, the salt concentration increases at an accelerated rate by the above-mentioned circulating treatment, and sometimes becomes higher than adipic acid. For this reason, there is a problem that other salts are crystallized together with the crystallization of adipic acid in the above-mentioned treatment step, and it is difficult to convert the salts into useful resources.

As described above, there is no definitive method for treating a waste liquid containing ammonium adipate. Partial treatments such as a microorganism treatment method and an ion exchange method, and environmental problems can be avoided by dilution with a large amount of water. That is the fact. Moreover, in the microorganism treatment method, since ammonia must be removed in advance, a huge amount of aeration equipment is required, and there are problems such as sludge treatment. Further, even if the separation of ammonia and the separation of adipic acid are performed by using an ion exchange resin, a secondary problem occurs in the treatment of the eluent and the regenerating solution, and the economic burden is not easy.

An object of the present invention is to provide an effective treatment method capable of almost recovering an adipic acid component and an ammonia component from a waste liquid containing ammonium adipate composed of a component having high water solubility. Another object of the present invention is to provide a treatment method capable of recovering adipic acid with high purity.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies on a method for effectively treating a waste liquid containing ammonium adipate, and as a result, typically using calcium hydroxide, a simple process using adipic acid A method for treating a waste liquid containing ammonium to effectively remove an adipic acid component and an ammonia component and to make it a useful resource has been found.

In other words, the method for treating ammonium adipate waste liquid according to the present invention comprises adding a calcium source which reacts with the ammonium adipate to produce calcium adipate to a waste liquid containing ammonium adipate, makes the calcium adipate weakly alkaline, and heats it. The generated ammonia gas is separated out of the reaction solution, the waste liquid containing calcium adipate crystallized in the reaction liquid is subjected to sedimentation treatment, and the supernatant is separated from the remaining dense portion (usually ammonium adipate waste liquid). Sulfuric acid is added to the concentrated solution having a concentration of adipic acid which is 2 to 3 times that of the concentrated solution), and the generated calcium sulfate is separated by solid-liquid separation and collected. The remaining solution is cooled to crystallize adipic acid,
It is characterized in that it is subjected to solid-liquid separation to recover adipic acid. According to the present invention, the waste liquid containing ammonium adipate is an organic acid salt having relatively high water solubility and solid-liquid separation is difficult. However, the calcium source is added to the waste liquid, and the waste liquid is made weakly alkaline and heated. By doing so, it is possible to crystallize calcium adipate having a relatively low solubility and a negative change in solubility due to a temperature rise in the waste liquid after the addition of the calcium source. At the same time, since the waste liquid after the addition of the calcium source is weakly alkaline and heated, ammonia easily becomes gaseous and is separated out of the waste liquid at a high rate. Then, the waste liquid is settled and the supernatant liquid is separated. The remaining portion of the crystallized calcium adipate (concentrated slurry) is added with sulfuric acid to make it weakly acidic. Calcium sulfate having a small amount and free adipic acid in a dissolved state are formed. Therefore, the precipitated calcium sulfate is subjected to solid-liquid separation to leave an adipic acid solution. When this solution is cooled, adipic acid is easily crystallized, so that high-purity adipic acid can be separated and recovered at a higher rate than in the waste liquid. The invention of claim 2 of the present application is characterized in that, in the invention of claim 1, the solid-liquid separation of the calcium sulfate is performed while maintaining the temperature of the solution at 60 ° C. or higher. By maintaining the temperature at this temperature, adipic acid is almost in a dissolved state. Therefore, by solid-liquid separation of precipitated calcium sulfate, adipic acid and calcium sulfate can be almost completely separated.

According to a third aspect of the present invention, there is provided a method according to the first aspect, wherein hydrochloric acid is added in place of the sulfuric acid according to the first aspect of the invention to dissolve the crystallized calcium adipate, and the solution is cooled to crystallize adipic acid. Is separated into solid and liquid to recover adipic acid. Thereby, the same function and effect as the first aspect of the invention can be obtained.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the supernatant is returned to the upstream, combined with the untreated waste ammonium adipate, and circulated. It is characterized by the following. According to the present invention, the supernatant of the treated wastewater is circulated together with the untreated wastewater without being drained as it is, so that the separation and recovery of adipic ion can be further increased.
Furthermore, since the supernatant contains only a very small amount of unnecessary salts, the wastewater is concentrated as a pretreatment by an economical reverse osmosis treatment (hereinafter referred to as an RO treatment). It is possible. In the supernatant alone, calcium adipate is crystallized immediately during the concentration treatment, which makes operation difficult.Therefore, in the present invention, the calcium adipate is particularly combined with the untreated ammonium adipate waste liquid to relatively reduce the proportion of calcium adipate,
One of the points is to concentrate the combined liquid to a concentration suitable for processing while maintaining the solubility within the solubility.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the calcium source is calcium hydroxide. Calcium hydroxide itself functions as both the calcium source and the alkalizing agent, so that it can be completed with one type of additive as compared to the case where separate agents are used for the calcium source and the alkalizing agent. it can. In addition, it is easy to control and control the amount of addition. Further, calcium hydroxide is economical because it is easy to obtain and handle.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the waste liquid containing ammonium adipate is subjected to a concentration treatment of ammonium adipate before adding a calcium source. Is what you do. According to this invention, the crystallization rate of calcium adipate is increased by the concentration treatment, and the calcium adipate can be separated and recovered at a higher recovery rate.

The invention of claim 7 of the present application is characterized in that, in the invention of claim 6, ammonium adipate is concentrated to 60 g / l or more. By concentrating to such an extent, separation and recovery at a high recovery rate can be performed reliably and easily.

[0017] The invention of claim 8 of the present application is characterized in that, in any of the inventions of claims 1 to 7, the separation of the ammonia gas and the crystallization of calcium adipate are performed in a temperature range of 70 ° C to 100 ° C. It is assumed that. Since calcium adipate has the property that the change in solubility due to temperature rise is negative, by performing the crystallization in a temperature range of 70 ° C to 100 ° C, the crystallization rate can be kept high, and after crystallization, Can be prevented from being redissolved. If the temperature is kept at this temperature for about 1 to 5 hours, most of calcium adipate is crystallized.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the pH of the solution is adjusted to 4 or less by adding the sulfuric acid or hydrochloric acid. Thereby, the decomposition reaction of calcium adipate can be almost completed.

The invention described in claim 10 of the present application is the invention according to claims 1 to 9
In any of the described inventions, the crystallization and recovery of adipic acid are performed by cooling the solution to 5 to 20 ° C. Since the solubility of adipic acid is approximately 15 g / l at 20 ° C., most of adipic acid can be recovered as white crystals by cooling to 20 ° C. or less. Although the recovery efficiency becomes better as the temperature becomes lower, excessive cooling imposes a heavy burden on the refrigeration equipment and causes inconvenience in operation due to local crystallization. 1
Around 0 ° C. is appropriate.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Waste liquids to be treated in the present invention are all waste liquids containing ammonium adipate from various sources. Hereinafter, adipic acid generated in the process of manufacturing aluminum electrode foil for electrolytic capacitors will be described. A waste liquid containing ammonium will be described as an example. Among the waste liquids containing ammonium adipate generated by the chemical conversion treatment, except for dilute waste liquids (usually COD of 4 ppm or less) such as finishing cleaning liquids of, for example, COD of 10 ppm or less, which can be flowed to the drainage system as they are, high concentration aging chemical baths and chemical formation. It treats waste liquid from medium facilities such as waste liquid from ancillary equipment such as a power supply tank in the process and intermediate cleaning liquid. Usually, the main chemical liquid is ammonium adipate 20 to 130 g / l, especially 50 to 110 g / l.
A g / l concentration is widely used, and waste liquid having a concentration of 6 to 15 g / l is generated from the incidental equipment and the intermediate cleaning liquid.

In the present invention, in order to efficiently crystallize ammonium adipate having a solubility of several hundred g / l as calcium adipate having a relatively low solubility to remove adipate ions from the waste liquid, A concentrated ammonium adipate waste liquid is desirable. In particular, the amount of ammonium adipate is at least 60 g / l, preferably 80 g / l.
If it is 1 or more, separation and recovery at a high recovery rate can be performed reliably and easily. The concentration method may be any known method, but the present invention mainly focuses on the RO treatment method. According to the RO treatment method, ammonium adipate can be easily reduced to about 110.
It can be concentrated to about g / l. However, since the RO treatment method is affected by the total amount of solutes, it is desirable that salts other than adipate be as small as possible. In the present invention, since there is no unnecessary increase in salts due to the addition of sodium hydroxide or the like as described later, the concentration by the RO treatment method can be effectively used.

The calcium source is not particularly limited as long as it can crystallize calcium adipate under weak alkalinity. Calcium hydroxide itself is used for both the calcium source and the alkalizing agent. In order to work, the two roles can be fulfilled by one type of additive. In addition, it is easy to control and control the amount of addition. Furthermore, it is inexpensive because ordinary industrial calcium hydroxide can be used. It is preferable that calcium hydroxide is uniformly dispersed and added to the waste liquid, and is added in advance as lime milk in order to carry out the reaction efficiently. The higher the concentration of milk of lime, the smaller the amount of liquid phase and the higher the recovery rate of calcium adipate, which is desirable. However, if the concentration is excessive, the supply pipe is likely to be clogged during continuous use. Therefore, the concentration is preferably 30% by weight or less, and practically 10 to 15% by weight.

As the reaction milk base, industrial water is usually used. However, as described above, the amount of liquid phase increases and the concentration of adipate ions decreases accordingly, and the amount of leaked adipate after recovery of calcium adipate increases. Since the yield is reduced, the precipitated calcium adipate is subjected to a sedimentation treatment, and a portion of the supernatant is treated with calcium hydroxide and refluxed as lime milk, whereby the recovery rate is further improved.

Calcium adipate has the lowest solubility among adipates, and details of its solubility in a saturated solution of calcium hydroxide are not clear. However, according to experiments conducted by the present inventors, it is roughly shown in Table 1. Value. From this Table 1, it is considered that the transformation point between the monohydrate and the anhydrous salt in the aqueous solution is approximately 85 to 95 ° C.

[0025]

[Table 1]

Therefore, in order to efficiently collect adipate ions, it is desirable that the higher the temperature, the lower the solubility. However, practically, the solubility depends on the scale of the apparatus, the total amount of wastewater, and the presence or absence of post-treatment of the wastewater after the treatment according to the present invention. It is determined. Generally, 9
It is advantageous to set the range of the equilibrium solubility at 5 ° C. or higher to reduce the concentration of dissolved calcium adipate, but it is necessary to note that a large amount of heat energy is required. Practically, monohydrate crystallization occurs at 70 to 90 ° C., a part of water is taken out as crystallization water, and the amount of residual solution is reduced. As a result, the total amount of leaked adipate ions is reduced. It is often advantageous as a treatment.

The calcium hydroxide treatment of ammonium adipate can be carried out by any of a batch method and a continuous method, but it is intended to prevent variations in the amount of generated ammonia and the properties (sedimentation and filterability) of the produced calcium adipate. Continuous processing is desirable for the temperature stability of the whole system. This is because calcium adipate may be re-dissolved due to a temperature drop and the recovery rate may be reduced. The heating method is
In addition to the method using steam or electric heat, any known method such as an indirect heating method using waste heat from another process, a direct heating method such as blowing in high-temperature air for ammonia carrier, or a method using these methods may be used.

The aging for release of ammonia gas and crystallization of calcium adipate is carried out at a predetermined temperature (70 ° C. to 10 ° C.).
0 ° C.), but in a batch mode 1-4
In the case of a single-tank treatment, a residence time of 2 to 5 hours is almost sufficient for practical use. Since the solution during aging is weakly alkaline and in a heated state, ammonia is easily gasified and separated, but the ammonia concentration in the exhaust gas is at least below the explosion limit, preferably 4 to 10% by volume (dry basis). ) Must be managed. Specifically, if industrial air, preferably heated air, is blown into the bottom of the treatment tank, 95% or more of ammonia can be easily recovered during the aging time.

The suspension of calcium adipate after completion of the training is immediately subjected to a sedimentation treatment. Since the change in solubility of calcium adipate is negative with respect to temperature, it is necessary to avoid the temperature drop after aging as much as possible. Re-dissolves as the temperature decreases, increasing COD in the wastewater,
Care should be taken to keep the temperature and complete separation as much as possible. The temperature should be kept below 15 ° C, preferably below 10 ° C. Practically, immediately after completion of ripening, it is led to a continuous settling tank having a sufficient heat retaining zone to perform settling treatment. At this time, the calcium adipate crystallized under heating has an extremely good sedimentation property, and has a residence time of 1 to 3 hours in a normal vertical continuous sedimentation tank, and has a clarified supernatant and a solid concentration of 200 g / l or more. A dense part can be obtained.

The supernatant was calcium adipate 15-1.
In addition to 7 g / l, it contains a small amount of ammonia and free calcium hydroxide, is combined with untreated ammonium adipate waste liquid, concentrated and circulated. The concentration is increased to a predetermined concentration (60 g / l or more in terms of ammonium adipate). However, since the crystallization of calcium adipate occurs during the concentration of the supernatant alone, it is mixed with the untreated ammonium adipate waste liquid as described above. Then, concentration is performed by relatively lowering the concentration of calcium adipate to prevent the crystallization. Also, a small amount of free calcium hydroxide in the supernatant, when mixed with untreated ammonium adipate waste liquid, reacts with ammonium adipate to produce calcium adipate and ammonia. Unlike the case of concentration, Ca (OH) ₂ and other insoluble calcium compounds are not generated, so that concentration can be performed smoothly.

When the ammonia concentration becomes high and there is an inconvenience in the operation of concentration or in the environment, the pH of the supernatant is adjusted to pH with an acid before mixing with the ammonium adipate waste liquid.
It is good to adjust. As the acid, a mineral acid such as hydrochloric acid or sulfuric acid may be used, but in the present invention, a part of adipic acid obtained in the final step may be used. Usually, pH adjustment is not required if calcium adipate crystallization is performed at 70 ° C. or more and the ammonia removal rate is 95% or more.

The concentrated hot slurry of crystallized calcium adipate contains crystallized calcium adipate, dissolved calcium adipate and a small amount of free alkali. Sulfuric acid (or hydrochloric acid) in an equivalent amount or a trace amount of these
To produce calcium sulfate (calcium chloride) and free adipic acid by a metathesis reaction. This reaction is PH
Beginning at 6 and ending at PH4, practically 3.5 to 3.5
4.0 is the end point.

As a result of the reaction, when sulfuric acid is added, most of the generated calcium sulfate is precipitated as dihydrate, while free adipic acid is approximately 140 g / l or more. In the present invention, in order to separate calcium sulfate in a dissolved state of adipic acid, the temperature of the solution is prevented from lowering, and usually 60 ° C.
Do not fall below. On the other hand, when hydrochloric acid is added, the generated calcium chloride is dissolved because of its high solubility.

The remaining solution from which the calcium sulfate was separated was
Since it mainly contains adipic acid and contains only a small amount of other salts, it is practically cooled to 5 to 20 ° C., particularly around 10 ° C., to thereby crystallize and recover adipic acid of relatively high purity. be able to. On the other hand, in the case of calcium chloride, even if adipic acid is crystallized by cooling, it remains dissolved, so that only adipic acid can be similarly crystallized and recovered.

The adipate ion in the filtrate recovered by solid-liquid separation of the crystallized adipic acid is about 1/10 to 1/20 of the initial ammonium adipate waste liquid. This filtrate is used as a dispersion medium for making lime milk as required,
The residual liquid is sent to the collective drainage system of the electrode foil chemical conversion treatment, and can be safely discharged after the neutralization treatment. If there is dilute wastewater from another process, it can be safely released together with the wastewater from the other process after pH adjustment in practical use.

Further, a phosphoric acid waste liquid generated in the aluminum electrode foil manufacturing process as diluting water (JP-A-51-8780)
U.S. Pat. No. 6,086,098) has the advantage that the COD in the wastewater is further reduced to 1/2 to 2/3 by the effect of collecting the adipate ions by the calcium phosphate sludge in addition to the dilution effect.

As described above, according to the present invention, ammonia and adipic acid can be recovered from a waste liquid containing ammonium adipate to provide a sufficiently safe wastewater. You may use a process together. These treatments do not contain ammonia or other harmful substances in the treatment, and most of them are treated, so that sufficient effects can be obtained with very small-scale facilities.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it is a matter of course that the device and method of each unit operation are not limited thereto. FIG.
BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows the method of treating the waste liquid containing ammonium adipate with calcium hydroxide which is the basic of this invention. Low and medium concentrations (hereinafter refer to those with a concentration of 0.06 to 60 g / l) and high concentrations (hereinafter refer to those with a concentration of 60 g / l or more) excluding a dilute waste liquid with a COD of 10 ppm or less that can be directly discharged. The waste liquid containing ammonium adipate is temporarily stored in the waste liquid storage tank 1 in order to make the concentration as uniform as possible.
It is summarized in 2. The capacity of the storage tanks 1 and 2 is determined by the number of source devices, the generation cycle, and the concentration fluctuation state. The amount of the high concentration waste liquid is generally smaller than the amount of the low concentration medium waste liquid. Like the two types of storage tanks 1, 2
If a predetermined ratio is provided and each of them is extracted from each of them, the size can be reduced.

The waste liquid continuously withdrawn from the storage tanks 1 and 2 is sent to a mixing tank 7 where it merges with a supernatant liquid returned from a sedimentation tank 5 to be described later. R
Ammonium adipate is 80 to 100 by the O device 3
g / l, preferably to 100 g / l. As described above, when the supernatant is refluxed, it is not separately concentrated, but is once mixed with the waste liquid before the treatment, and then subjected to RO treatment, whereby the unnecessary insolubles are smoothly concentrated without crystallization. Often it is possible.

The concentrated ammonium adipate waste liquid is continuously guided to a calcium adipate tank (hereinafter referred to as an azical tank) 4 provided with a stirring device (not shown) using a steam jacket and rotary blades. On the other hand, calcium hydroxide (e.g., industrial slaked lime No. 1) is emulsified with industrial water or a part of the supernatant, and 10 to 1
5% by weight of lime milk. The lime milk is continuously added to the azical tank 4, and the pH in the tank 4 is adjusted to 10.5-12.
0 (however, the measured value at normal temperature after cooling the sample), and the liquid temperature is maintained at 70 to 90 ° C. The residence time of the reaction solution in the azical tank 4 is appropriately 1 to 10 hours, and the tank capacity, temperature, PH conditions and the like are selected so as to be preferably 3 to 4 hours. During this time, air, preferably heated air at 100 to 300 ° C. (for example, air utilizing the exhaust heat generated during the combustion processing of the recovered ammonia) is supplied from the lower part of the tank 4 to 4 to 6% by volume of ammonia generated from the liquid. (Dry base).

By this calcium hydroxide treatment, 95% or more of the ammonia is separated and recovered outside the waste liquid system, and white crystals of calcium adipate monohydrate crystallize in the tank 4, and the calcium adipate in the liquid phase is removed. The concentration is 14-16 g / l
(13.7 to 15.7 g in terms of ammonium adipate
/ L) On the other hand, the residual ammonia concentration in the liquid phase is 2.0 g
/ L or less.

The suspension containing the crystallized calcium adipate overflowed or extracted from the appropriate position is immediately sent to a continuous vertical sedimentation tank 5 where it is subjected to a sedimentation treatment for 1 to 3 hours. . During this time, in order to prevent re-dissolution of the crystallized calcium adipate due to a decrease in the temperature of the waste liquid, the waste liquid is kept warm by a heat retaining zone (not shown) provided in the sedimentation tank 5, and at least 70 ° C. or more, preferably 75 ° C. To do. The sedimentation process separates the supernatant into a dense part. The supernatant is returned to the mixing tank 7 and circulated. The solid concentration 200 extracted from the lower part of the settling tank 5
Sulfuric acid is added to the dense portion of ~ 300 g / l, and calcium sulfate is crystallized in a warm state while free adipic acid is dissolved in the solution. In the present invention, the calcium adipate treatment is carried out at 70 ° C. or higher, usually at 80 to 90 ° C., and the dense slurry is obtained at 65 to 75 ° C. through the sedimentation treatment by the heat-preserving sedimentation layer 5, and the heat of reaction due to the addition of sulfuric acid is also reduced. Because there is
After the reaction, the temperature is 60 ° C. or higher. If attention is paid to keeping the temperature of the neutralization tank 8, there is no particular need for heating. The sulfuric acid used is
In consideration of the efficiency of the subsequent adipic acid crystallization, a high concentration is desirable in order to suppress an increase in volume.
It is preferable to use 60% sulfuric acid.

A known method can be used for solid-liquid separation of calcium sulfate. However, in order to maintain the equipment (reduce the adhesion of calcium sulfate) and to use calcium sulfate as a useful resource, it is easy to wash and maintain filtration. It is preferable to use the device 9. When washing, the washing water is combined with the filtrate without particular separation.

The remaining solution from which calcium sulfate was recovered was
It is led to the crystallization tank 10 with a stirring device having a water cooling jacket and stirring blades, where adipic acid crystallization treatment is performed. When cooled to 10 ° C, the retention time is 4 to
After 8 hours, the concentration of adipic acid in the solution becomes 10 g / l.

The crystallized adipic acid crystal is rich in separability and is a simple filtration device 11 (eg, a basket type filtration device or a suction filtration device).
And the attached liquid component can be reduced to 10% or less, and particularly to 4 to 7% by combined use of air blowing with a suction filtration device.

The wastewater after the separation of adipic acid is greatly reduced in both volume and adipic acid ion concentration as compared with the initial adipic acid waste liquid, so that it is subjected to a lump neutralization treatment together with the wastewater from the other process and discharged safely. You.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Quantitative numerical values in the examples are obtained by converting experimental results on a scale of 1/10 to 1/20 to actual scales in order to easily understand the effects.

[0048] (Example 1) has a configuration as shown in FIG. 1, January (24 × 30 hours) per about 120 m ³ aging chemical bath containing ammonium adipate 75 g / l, about 8
about 510 m ³ and 0.03 g
g / l of the waste liquid of the dilute cleaning liquid in the chemical conversion step using ammonium adipate in the production of the electrode foil to generate about 2000 m ³ , the dilute cleaning liquid is discharged to the drainage system as it is,
89 m ^{3 of} supernatant liquid (calcium adipate 15.
0g / l, Ca (OH) 2 0.3g / l, NH 3 1.9g
/ L) in a mixing tank 7, ammonium adipate 18.1 g / l, calcium adipate 1.9 g / l,
A mixed solution containing 0.25 g / l of NH ₃ was 719 m ³ .

Subsequently, the mixture was subjected to RO treatment to obtain a concentrated solution 1 containing 85.9 g / l of ammonium adipate, 9.3 g / l of calcium adipate, and 1.2 g / l of NH _3.
50.6 m ³ were obtained. Of the dehydrated amount of about 568 m ³ , the leaked adipic acid is about 0.1 g / l in terms of ammonium adipate.
(60 kg).

The concentrated liquid is introduced into an agital tank 4 (with an internal volume of about 1 m ³ ) provided with a heating jacket and a rotary blade type stirring device together with 32.8 m ^{3 of} 15% lime milk, and is subjected to continuous treatment. The azical tank 4 always keeps 85 ° C. and the liquid amount (slurry amount) 0.9 m ³ , and the residence time is nominally equivalent to 3 hours with respect to the inflow amount. The tank 4
Air heated to 150 ° C. was blown from the bottom at a rate of 81 Nm ³ / hour, and 2457 kg of ammonia was blown from the top.
(94.7% in terms of treated waste liquid) was collected outside the system at a concentration of 5% by volume with respect to air, accompanied by steam.

The 150 m ³ of the slurry after the crystallization of calcium adipate monohydrate was subsequently sedimented continuously for 3 hours in a sedimentation tank 5 with a heat insulating zone of 0.7 mdia, and 89 m ^{3 of} the supernatant was obtained. Dense slurry 61m ³ (solid concentration 2
25 g / l), and the supernatant is refluxed to the mixed layer 7 for circulation treatment as it is.

The dense slurry was introduced into a neutralization tank 8 equipped with the above-mentioned jacket and a rotary blade type stirring device, and kept at 50 ° C.
The pH was adjusted to 4.0 by adding 11.9 t of Baume sulfuric acid.
After an average residence time of 2 hours at 65 ° C., the crystallized calcium sulfate was filtered with a filter 9 using a 5 atm filter press.
After washing with water of m ^3, the mixture was air-pressed to obtain 17.6 t of calcium sulfate dihydrate containing 30% of attached moisture.

165 g / l of adipic acid, (NH ₄ ) ₂ SO
₄ Filtration solution containing 6.1 g / l and 2 g / l of CaSO ₄ 63.
8 m ³ was led to a crystallization tank 10 equipped with a water cooling jacket and a rotary blade type stirring device, where it was cooled to 10 ° C. to crystallize adipic acid. The suspension containing the crystallized adipic acid, which had been subjected to the crystallization treatment for 6 hours, was subjected to solid-liquid separation by the suction filtration device 11 to recover adipic acid. The recovered adipic acid was 10.6 tons containing 6% of attached moisture (adipic acid 94.0%, (N
H ₄ ) ₂ SO _{4 (} 0.04%, CaSO ₄ 0.01%).

The composition of 58 m ³ of the filtrate (waste water) was 10 g / l of adipic acid, 6.6 g / l of (NH ₄ ) ₂ SO ₄ and CaS
O ₄ 2.2 g / l and which was, which is collectively wastewater treatment with other process waste water, CO in the total wastewater 12000 m ³
D was 8 ppm and ammoniacal nitrogen was 9 ppm.

(Embodiment 2) In this embodiment, as shown in FIG. 2, hydrochloric acid is added in place of sulfuric acid of Embodiment 1. In this case, the generated calcium chloride has high solubility and is soluble, so that the step of filtering calcium sulfate in the case of adding sulfuric acid is eliminated. Calcium chloride is contained in the filtrate after crystallization of adipic acid in the final step and is subjected to wastewater treatment. Others are basically the same.

The step of adding hydrochloric acid to the dense slurry of crystallized calcium adipate will be described in detail. To explain, 15.7 t of 35% hydrochloric acid is added to neutralization tank 8 to dissolve calcium adipate (PH 4.0). , Adipic acid 146g /
1, CaCl ₂ 111 g / l, NH ₄ Cl 4.3 g / l
After the solution was adjusted to 72.5 m ³ , the solution was guided to the crystallization tank 10 equipped with a water-cooled jacket, cooled to 10 ° C., and continuously stirred for 4 hours while stirring.

The slurry after adipic acid crystallization was subjected to a solid-liquid separation treatment in a continuous suction filtration device 11 to recover 10.6 t of adipic acid containing 6% of attached moisture. Filtrate (waste water) is 6
It was 6.7 m ³ . The composition of the recovered adipic acid was 93.5% of adipic acid in a wet state, 0.03% of NH ₄ Cl,
CaCl ₂ was 0.7%.

66.7 m ³ of waste water is adipic acid 10 g /
l, 4.6 g / l of NH ₄ Cl, 119 g / l of CaCl ₂
When this was discharged into the collective drainage system, the COD at a total wastewater amount of 12000 m ³ was 8.6 ppm, and the ammonia nitrogen was 9 ppm.

[0059]

According to the method of the present invention, the waste liquid containing ammonium adipate is added to a calcium source such as slaked lime, made weakly alkaline, and heated to simultaneously carry out crystallization and deammonification of calcium adipate. By adding sulfuric acid or hydrochloric acid to the dense slurry of the crystallized calcium adipate, the organic compounds (COD) and ammonia nitrogen in the wastewater can be easily and easily reduced. Further, adipic acid can be recovered with high purity.

[Brief description of the drawings]

FIG. 1 is a basic schematic configuration diagram of a method for treating a waste liquid containing ammonium adipate of the present invention.

FIG. 2 is a basic schematic configuration diagram of a method for treating a waste liquid containing ammonium adipate according to another example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Storage tank 2 Storage tank 3 RO treatment 4 Azical tank 5 Sedimentation tank 7 Mixing tank 8 Neutralization tank 9 Filtration device 10 Crystallization tank 11 Filtration device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B01D 9/02 608 B01D 9/02 608B 610 610Z 615 615Z 618 618Z 625 625E 625A C07C 51/43 C07C 51/43 55/14 55 / 14 (72) Inventor Noboru Sugiyama 1-34-1 Kambara-cho, Kambara-cho, Anbara-gun, Shizuoka Prefecture Inside Nippon Light Metal Co., Ltd. Group Technology Center (72) Inventor Yasushi Egami 1-34-1, Kambara, Kambara-cho, Anbara-gun, Shizuoka Japan Light Metal Corporation Group Technology Center

Claims (10)

[Claims] 1. A wastewater containing ammonium adipate is added with a calcium source which reacts with said ammonium adipate to form calcium adipate, is made weakly alkaline, and is heated. Separated, the waste liquid containing calcium adipate crystallized in the reaction solution was subjected to sedimentation treatment, sulfuric acid was added to the remaining dense part where the supernatant was separated, and the generated calcium sulfate was collected by solid-liquid separation and recovered. Thereafter, the remaining solution is cooled to crystallize adipic acid, and this is separated into solid and liquid to recover adipic acid. 2. The method for treating ammonium adipate waste liquid according to claim 1, wherein the solid-liquid separation of the calcium sulfate is performed while maintaining the temperature of the solution at 60 ° C. or higher. 3. A wastewater containing ammonium adipate is added with a calcium source which reacts with said ammonium adipate to form calcium adipate, and is made weakly alkaline and heated, and the ammonia gas generated is discharged outside the reaction solution. Separated, the waste liquid containing calcium adipate crystallized in the reaction solution is subjected to sedimentation treatment, hydrochloric acid is added to the remaining dense part where the supernatant is separated, the crystallized substance is dissolved, and the solution is cooled. A crystallizing adipic acid, followed by solid-liquid separation to recover adipic acid. 4. The ammonium adipate waste liquid according to claim 1, wherein the supernatant liquid is returned upstream, combined with the untreated ammonium adipate waste liquid and circulated. Processing method. 5. The method for treating an ammonium adipate waste liquid according to claim 1, wherein the calcium source is calcium hydroxide. 6. The method according to claim 1, wherein the waste liquid containing ammonium adipate is subjected to concentration treatment of ammonium adipate before adding a calcium source. 7. The method for treating ammonium adipate waste liquid according to claim 6, wherein the ammonium adipate is concentrated to 60 g / l or more. 8. The method for treating an ammonium adipate waste liquid according to claim 1, wherein the separation of the ammonium gas and the crystallization of calcium adipate are performed in a temperature range of 70 ° C. to 100 ° C. . 9. The method according to claim 1, wherein the pH of the solution is adjusted to 4 or less by adding the sulfuric acid or hydrochloric acid. 10. The method for treating ammonium adipate waste liquid according to claim 1, wherein the crystallization and recovery of adipic acid are performed by cooling the solution to 5 to 20 ° C.