JP2016087172A - Urea-containing liquid treatment method, treatment liquid, and urea-containing liquid treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method for a urea-containing liquid capable of highly efficiently removing urea from the urea-containing liquid, and preventing urea-derived ammonia from remaining.SOLUTION: The urea-containing liquid treatment method includes: a first adsorption step of bringing a strongly acidic cation exchange resin into contact with an untreated urea-containing liquid such that the urea contained in the urea-containing liquid is adsorbed in the strongly acidic cation exchange resin, the strongly acidic cation exchange resin having an average pore diameter of 1 to 90 nm and a specific surface area of 10 m/gdry to 800 m/gdry; and a second adsorption step of bringing the strongly acidic cation exchange resin into contact with a treatment intermediate liquid, which has passed through the first adsorption step, such that the urea contained in the treatment intermediate liquid is adsorbed in the strongly acidic cation exchange resin.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a urea-containing liquid processing method, a processing liquid, and a urea-containing liquid processing apparatus.

  Conventionally, a processing method for removing urea from a liquid containing urea has been studied. For example, in a dialysate used for artificial dialysis, urea removed from the blood of a subject who has undergone a dialysis treatment is transferred to the dialysate, so that the used dialysate contains certain urea. Several techniques for removing urea from the used dialysate have been proposed.

  For example, Patent Document 1 below discloses a urea adsorbent (hereinafter also referred to as Cited Invention 1) made of a polymer containing a specific polyoxyalkylene glycol derivative as a constituent component. According to Example 1 of the same document 1, it is described that when the cited invention 1 was put into 50 ml of an aqueous solution of 100 mg urea / dl and treated, the urea concentration decreased to 60 mg urea / dl.

Patent Document 2 below discloses a wearable artificial kidney dialysis system having a urea removal layer (hereinafter also referred to as Cited Invention 2).
Cited invention 2 is a layer for removing urea contained in the peritoneal dialysis solution, and it is described in paragraph [0012] of the same document that it contains a constituent that can pass urea but repels cations. . The paragraph [0034] in the same document lists a plurality of modes that the cited invention 2 can take. Specifically, as one embodiment (hereinafter referred to as the first embodiment), Cited Invention 2 comprises an ion exchange resin such as a strong acid cation exchange resin and a basic anion exchange resin for removing urea or a dual characteristic resin. It is mentioned. Further, as a different aspect of the cited invention 2 (hereinafter referred to as a second aspect), an aspect composed of a ureolytic enzyme and an ion exchange resin or an inorganic adsorbent is mentioned.

JP-A-62-33539 Special table 2010-536473 gazette

  The used dialysate is generally discarded as a waste liquid. On the other hand, there has been a desire to facilitate the disposal of the used dialysate by reducing the urea concentration before disposal. Furthermore, there has been a demand for substantially removing urea from the used dialysate and reusing it as a dialysate.

  However, although various studies have been made to remove urea in the liquid as exemplified in Patent Document 1 or 2, the spent dialysate can be easily discarded or removed so as to be reusable. No technology has yet been proposed that can remove urea at a high rate. Therefore, the used dialysate has been generally discarded without being reused.

  For example, as described above, prior art 1 only discloses the result of removing about 40% of urea contained in 50 ml of an aqueous solution of 100 mg urea / dl, and shows a removal rate far from the viewpoint of reuse. There are only.

  In addition, a plurality of specific examples of strong acid cation exchange resins and basic anion exchange resins used in Cited Invention 2 relating to the first aspect of Prior Art 2 are listed in Patent Document 2, but known ion exchange resins It is only listed, and no urea removal rate is shown. That is, the first aspect only describes that urea is adsorbed and removed by an ion exchange resin within a conventionally known range, and further improvement is required from the viewpoint of highly efficient urea removal.

  Further, the second aspect of the prior art 2 is a conventional method in which urea in a liquid is hydrolyzed into ammonia with a urea degrading enzyme (urease), and the ammonia is captured with an ammonia scavenger, resulting in a decrease in urea content. It is based on a known method. However, when such a known method is applied to a used dialysate, there are the following problems. That is, it is a well-known knowledge that ammonia is essentially unnecessary for the human body. Therefore, when there is a possibility that untreated ammonia remains in the treated dialysate, there is a problem in reusing the treated dialysate.

  The second aspect of Prior Art 2 uses a material that selectively passes urea without receiving cations such as calcium, decomposes the passed urea into ammonia, and captures the ammonia. Thus, since it is necessary to pass urea through a special material that does not accept cations such as calcium, urea that has not passed through remains in the used dialysate, and as a result, it is shown in the table of paragraph 2 [0086] of the cited document. As can be seen, the reduction rate of urea is as low as less than 40%.

  The above-mentioned problems in removing urea from used dialysate are the same as for urea-containing liquids other than used dialysate because the urea removal rate is low and ammonia may remain in the treated liquid. It was a problem.

  The present invention has been made in view of the above problems. That is, the present invention provides a urea-containing liquid processing method and a urea-containing liquid processing apparatus capable of removing urea from a urea-containing liquid with high efficiency and avoiding remaining ammonia derived from urea. In addition, the present invention provides a treatment liquid in which urea is removed from the urea-containing liquid with high efficiency and the remaining ammonia derived from urea is avoided.

The urea-containing liquid treatment method according to the first aspect of the present invention is a urea-containing liquid treatment method in which urea is adsorbed and separated on a strong acid cation exchange resin, and the strong acid cation exchange resin has an average pore diameter. 1 nm or more and 90 nm or less, a specific surface area of 10 m ² / gdry or more and 800 m ² / gdry or less, and the strong acid cation exchange resin and the untreated urea-containing liquid are brought into contact with each other and contained in the urea-containing liquid. A first adsorption step for adsorbing urea on the strong acid cation exchange resin, and the urea contained in the treatment intermediate solution by contacting the strong acid cation exchange resin with the treatment intermediate solution after the first adsorption step. And a second adsorption step for adsorbing the strongly acidic cation exchange resin, wherein the second adsorption step is performed n times (where n is an integer of 1 or more).

  The treatment liquid according to the second aspect of the present invention is obtained by carrying out the urea-containing liquid treatment method of the present invention.

The urea-containing liquid processing apparatus according to the third aspect of the present invention is a processing apparatus for urea-containing liquid that is separated by adsorbing urea to a strongly acidic cation exchange resin, and has an average pore diameter of 1 nm or more and 90 nm or less. A first treatment tank in which the strongly acidic cation exchange resin having a surface area of 10 m ² / gdry or more and 800 m ² / gdry or less is contained, and an untreated urea-containing liquid is fed;
A second processing tank in which the strongly acidic cation exchange resin is accommodated and a processing intermediate liquid that has passed through the first processing tank is supplied, and the number of the second processing tanks is n (where n is It is an integer of 1 or more.

  According to the urea-containing liquid processing method and the urea-containing liquid processing apparatus of the present invention, it is possible to remove urea from the urea-containing liquid with high efficiency. In the present invention, urea itself is adsorbed with a strongly acidic cation exchange resin without hydrolyzing urea into ammonia, so that urea-derived ammonia does not remain in the liquid after treatment.

It is a graph which shows the adsorption isotherm of the strongly acidic cation exchange resin used for this invention. It is the schematic of the urea containing liquid processing apparatus used for 2nd embodiment of this invention. It is the schematic of the urea containing liquid processing apparatus used for 3rd embodiment of this invention.

  The present inventor has worked diligently to make it possible to remove urea to such an extent that the urea-containing liquid including the used dialysate can be reused or the waste liquid treatment of the urea-containing liquid can be made easier. . In order to achieve the problem of reusing the urea-containing liquid or facilitating waste liquid treatment, it is necessary to achieve a dramatic improvement with respect to the urea removal rate shown in the prior arts 1 and 2. There is also a demand that ammonia derived from urea does not substantially remain in the treated liquid. Therefore, the present inventor has studied in detail various materials that can be adsorbed without hydrolyzing urea into ammonia. Specifically, the urea adsorption test described below was conducted. As a result, it was found that urea can be adsorbed and removed from the urea-containing liquid with a significantly high adsorption rate by using a material having very limited conditions. A typical example in this study is shown in Table 1.

(Urea adsorption test)
That is, 10 g of a plurality of adsorbents (adsorbents 1 to 8 in the table) were prepared, and each was accommodated in a conical stoppered Erlenmeyer flask having a capacity of 200 ml.
Commercially available urea was added to pure water to prepare a urea-containing liquid having a urea concentration of 360 mg / l, and 50 ml of the urea-containing liquid was added to the conical flask with a stopper.
As described above, a stirrer was put into the conical stoppered Erlenmeyer flask to which the adsorbent and the urea-containing liquid were added, and the mixture was stirred for 3 hours at 500 rpm at room temperature to perform the adsorption treatment. Centrifugation was performed after stirring, and then the adsorbent and the liquid were separated by filtration with a 50 μm filter, and the filtrate (treatment liquid) was used as a test liquid for nitrogen determination. The determination of nitrogen and the analysis of urea concentration were performed by the same method as the Kjeldahl method and the ion chromatography method described in (Evaluation) of the examples described later.

Table 1 shows the average pore diameter (nm), specific surface area (m ² / g), amount of adsorbent used (g), stirring time (treatment time (treatment time (treatment time ( hr)), urea concentration of urea-containing liquid (pre-treatment urea concentration (mg / l)), urea concentration of treatment liquid (urea concentration after treatment (mg / l)), urea removed from urea-containing liquid by adsorption treatment The urea removal rate (urea removal rate (%)) and the urea adsorption amount (mg / g) for the adsorbent used were shown. Moreover, the thing whose urea removal rate (%) was 50% or more was evaluated as (circle), and the thing which was less than 50% was evaluated as x. The adsorbents 1 and 2 used were dried, the adsorbents 3 to 8 were hydrated, and the dry weight of the strongly acidic cation exchange resin contained in the adsorbents 1 to 8 was 10 g. Adjusted as follows. Table 1 shows the weights of the adsorbents 1 and 2 which are dried products and the adsorbents 3 to 8 which are hydrous materials.

  As shown in Table 1, in this study, among various ion exchange resins, strongly acidic cation exchange resins having an average pore diameter and specific surface area within a predetermined range are significantly higher in urea removal than other adsorbents. It was found to show a rate. Accordingly, the present inventor has further studied to achieve a very high removal rate using a strongly acidic cation exchange resin having an average pore diameter and specific surface area within a predetermined range, and has completed the present invention. Below, the urea containing liquid processing method concerning 1st embodiment of this invention is demonstrated in detail.

<First embodiment>
The urea-containing liquid treatment method according to the first embodiment (hereinafter also referred to as the present treatment method) is a urea-containing liquid treatment method in which urea is adsorbed and separated on a strongly acidic cation exchange resin, and the average pore diameter is 1 nm. A strongly acidic cation exchange resin having a surface area of 90 nm or less and a specific surface area of 10 m ² / gdry to 800 m ² / gdry is used.
The urea-containing liquid processing method according to the present embodiment includes a first adsorption step and a second adsorption step.
The first adsorption step is a step of bringing the strong acid cation exchange resin and the untreated urea-containing liquid into contact with each other to adsorb urea contained in the urea-containing liquid onto the strong acid cation exchange resin.
The second adsorption step is a step in which the strong acid cation exchange resin is brought into contact with the treatment intermediate solution that has passed through the first adsorption step to adsorb urea contained in the treatment intermediate solution onto the strong acid cation exchange resin. The two adsorption steps are performed n times (where n is an integer of 1 or more).

The reason why a significantly high urea removal rate is shown by using a strongly acidic cation exchange resin having an average pore diameter and a specific surface area within a predetermined range is not clear. However, the present inventor speculates that the adsorption of urea is drastically improved by using a strongly acidic cation exchange resin having an appropriate porous structure.
In this treatment method, an extremely high urea removal rate can be realized by using the optimum strongly acidic cation exchange resin and repeating the adsorption step a plurality of times. Very high means, for example, that the urea removal rate is 50% or more, preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, particularly 94% or more, ideally substantially 98%. That's it. The urea removal rate is the urea reduction rate (%) converted from the urea concentration of the treated liquid treated by the present treatment method with respect to the urea concentration of the urea-containing liquid provided for the present treatment method.

  In this treatment method, urea is adsorbed on the strongly acidic cation exchange resin without hydrolysis of ammonia into ammonia as described above, so that urea-derived ammonia does not remain in the treatment liquid.

The strong acid cation exchange resin used in this treatment method can be appropriately selected from known strong acid cation exchange resins within a range having a predetermined range of average pore diameter and specific surface area. For example, the strongly acidic cation exchange resin has a sulfonic acid group proton type (—SO ₃ H), a sulfonic acid group sodium type (—SO ₃ Na), and a carboxylic acid group calcium type (—COOCa) as an exchange group. Those are preferred. According to these exchange groups, protons (H), sodium (Na) or calcium (Ca) in the exchange group are exchanged with urea, or protons (H), sodium (Na) or calcium (Ca in the exchange group are exchanged. This is because urea is smoothly adsorbed when nitrogen contained in urea is bound to).
The base structure of the strongly acidic cation exchange resin used in the present invention is not particularly limited, and examples thereof include base structures such as styrene, methacryl, acrylic, Teflon, and pyridine.
The strongly acidic cation exchange resin used in this treatment method is a so-called porous ion exchange resin.

The strongly acidic cation exchange resin used in this treatment method has an average pore diameter of 1 nm or more and 90 nm or less. When the average pore diameter is 1 nm or more, it seems that an appropriate porosity for adsorption of urea is provided. Moreover, when the average pore diameter is 90 nm or less, it seems that a sufficient surface area is easily obtained for adsorption of urea.
The strongly acidic cation exchange resin used in this treatment method has a specific surface area of 10 m ² / gdry to 800 m ² / gdry. When the specific surface area is 10 m ² / gdry or more, it is considered that an adsorption surface for adsorbing urea is sufficiently provided. Moreover, when the specific surface area is 800 m ² / gdry or less, it is possible to prevent the porous structure of the strongly acidic cation exchange resin from being refined to the extent that the adsorption of urea is inhibited.
From the above viewpoint, the lower limit of the average pore diameter is more preferably 5 nm or more, further preferably 10 nm or more, and particularly preferably 15 nm or more. Further, the upper limit of the average pore diameter is more preferably 80 nm or less, further preferably 60 nm or less, and particularly preferably 40 nm or less.
From the above viewpoint, the lower limit of the specific surface area is more preferably 10 m ² / g or more, further preferably 20 m ² / g or more, and particularly preferably 30 m ² / g or more.

  The measurement method of the average pore diameter and specific surface area of the strongly acidic cation exchange resin is not particularly limited and can be appropriately measured by a known method. For example, an adsorption isotherm is determined by a gas adsorption method, Each can be calculated from the adsorption isotherm.

The urea-containing liquid used in this treatment method means a liquid material containing at least urea. Either a liquid substance containing only urea as a contained substance (solute) or a liquid substance containing urea and any other substance as a contained substance (solute) may be used.
Examples of the urea-containing material include, but are not limited to, waste liquids from factories and laboratories, used artificial dialysates, and the like.

  The urea concentration of the urea-containing liquid used for this treatment method is not particularly limited. For example, in one of the preferred embodiments of this treatment method, the urea concentration of the urea-containing liquid used in the first adsorption step is 1200 mg / L or less.

  According to this treatment method, even with a urea-containing liquid having a very low urea concentration (low-concentration urea-containing liquid), an extremely high urea removal rate can be realized. Therefore, according to this aspect, it is possible to provide a treatment liquid in which the amount of remaining urea is extremely small and waste liquid treatment is easy or reusable. According to this treatment method, even if the urea concentration of the urea-containing liquid used in the first adsorption step is 800 mg / L or less, particularly 400 mg / L or less, it is possible to achieve an extremely high urea removal rate. .

The present inventor has prepared an adsorption isotherm indicating a relation of adsorption of urea to the strongly acidic cation exchange resin used in the present treatment method with respect to the low concentration urea-containing liquid. More specifically, using a strongly acidic cation exchange resin (adsorbent 1 shown in Table 1) showing an average pore diameter and specific surface area within a predetermined range specified in the present processing method, measurements 1 to 3 are performed as follows. went.
Measurement 1 was carried out in the same manner as the urea adsorption test described above, except that the amount of the strongly acidic cation exchange resin was 20 g.
Measurement 2 was carried out with the same contents as the experimental section of the adsorbent 1 shown in Table 1.
Measurement 3 includes the above-described urea adsorption test except that the amount of urea to be contained was increased and the urea concentration of the urea-containing liquid (pretreatment urea concentration (mg / l)) was set to 1007 (mg / l). A similar method was performed.
Then, in the measurements 1 to 3, the urea adsorption test was performed to obtain the post-treatment urea concentration (mg / l) and the urea adsorption amount (mg / g) per unit weight was calculated. The results are shown in Table 2. In addition, the vertical axis plots the results of measurements 1 to 3 with the amount of urea adsorbed on the adsorbent per unit weight (mg / g) and the horizontal axis the urea concentration after treatment as the urea equilibrium concentration (mg / l). Was used to determine the adsorption isotherm. The adsorption isotherm is shown in FIG. The determination of nitrogen and the analysis of urea concentration were carried out by the same methods as the Kjeldahl method and the ion chromatography method described in (Evaluation) of the examples described later. Measurements 1 to 3 confirmed in advance that the urea concentration reached a sufficient equilibrium when the treatment time was 3 hours.

  From FIG. 1, it was confirmed that the adsorption isotherm indicated by the low-concentration urea-containing liquid and the strongly acidic cation exchange resin used in this treatment method is shown by a straight line. As a result, it was confirmed that when the urea is adsorbed and removed from the low-concentration urea-containing liquid by this treatment method, the adsorption amount can be obtained by calculation in advance, so that the removal treatment can be easily managed. In addition, from the results of Measurement 2 and Measurement 3 in this study, it was shown that the urea removal rate was constant even when the urea concentration in the urea-containing liquid increased or decreased for a certain strongly acidic cation exchange resin. As a result, when the low-concentration urea-containing liquid is processed in the present processing method, the urea adsorption amount in the first adsorption step and the second adsorption step can be calculated in advance, and the design of the treatment process is easy. It was confirmed that there was.

As described above, since this treatment method is effective as a method for removing urea from a low-concentration urea-containing solution, it is preferable to select a used artificial dialysis solution as the urea-containing solution in this treatment method. .
About 20 g to 32 g of urea is excluded from subjects who have received dialysis treatment of adults weighing 50 to 80 kg in one day of artificial dialysis, and the dialysate used is about 100 L to 150 L. Accordingly, the spent dialysate contains urea at a concentration of about 133 mg / l to about 320 mg / l. Such a concentration is a concentration level contained in the low concentration urea-containing liquid described above. In other words, the urea contained in the used dialysate can be removed by this treatment method to an extent that it can be easily discarded and reused.

Next, the first adsorption process and the second adsorption process in this processing method will be described. This treatment method has a feature that an extremely high urea removal rate can be achieved by repeating the adsorption step a plurality of times.
The amount of urea removed increases by increasing the amount of adsorbent used in one adsorption step with respect to a predetermined amount of urea-containing liquid. This is apparent from, for example, the results of measurement 1 and measurement 2 described above (see Table 2). However, as a result of various studies, the present inventor can increase the amount of urea removed by repeating the adsorption step a plurality of times, rather than increasing the amount of adsorbent used in one adsorption step. I found.

The first adsorption step in this treatment method is a step of bringing the strong acid cation exchange resin into contact with an untreated urea-containing liquid to adsorb urea contained in the urea-containing liquid onto the strong acid cation exchange resin. . Here, the untreated urea-containing liquid means a urea-containing liquid before being treated in the first adsorption step or the second adsorption step in the present treatment method.
Contacting the strong acid cation exchange resin with the urea-containing liquid means that the exchange groups of the strong acid cation exchange resin are mixed together so that urea contained in the urea-containing liquid can be adsorbed. .

In this treatment method, for example, in the first adsorption step, the strongly acidic cation exchange resin and the urea-containing liquid are preferably brought into contact until the urea concentration in the urea-containing liquid reaches substantially equilibrium.
The adsorption rate of the secondary adsorption step can be increased by adsorbing urea to the strongly acidic cation exchange resin until the urea equilibrium concentration is reached in the first adsorption step.
Here, equilibrium means a state in which the amount of urea adsorbed to the strong acid cation exchange resin and the amount of urea adsorbed on the strong acid cation exchange resin are separated from the liquid phase. In the present invention, “substantially equilibrated” means a state in which the urea concentration in the urea-containing liquid does not substantially decrease or is sufficiently low even when the first adsorption step is continued.

The second adsorption step in this treatment method includes a strongly acidic cation exchange resin having an average pore diameter and specific surface area within a predetermined range and the treatment intermediate solution that has undergone the first adsorption step, and is included in the treatment intermediate solution. This is a step of adsorbing urea on the strongly acidic cation exchange resin. The second adsorption step is performed n times (where n is an integer of 1 or more). For example, the second adsorption step may be performed once or repeated twice or more.
By repeating the contact step between the urea-containing liquid (or the treatment intermediate liquid) and the strongly acidic cation exchange resin, it is possible to reliably remove a trace amount of urea in the liquid, resulting in extremely high-efficiency urea. Make removal possible.

  Between the first adsorption step and the second adsorption step, or between the second adsorption steps repeated a plurality of times, any step can be appropriately performed without departing from the gist of the present invention. For example, after the completion of the first adsorption step, a centrifugation step or a filtration separation step for separating the urea-containing liquid and the strong acid cation exchange resin may be appropriately performed. The treated intermediate solution obtained by separation from the strongly acidic cation exchange resin is allowed to the subsequent second adsorption step.

The strongly acidic cation exchange resin used in each of the first adsorption step and the second adsorption step may be the same or the same type of resin, or may be a different type of resin. The same resin means a resin having the same chemical composition, average pore diameter and specific surface area of the strongly acidic cation exchange resin. The same kind of resin means a resin in which any one or all of the chemical composition, the average pore diameter, and the specific surface area are different, but the exchange groups are the same. Different resins mean resins having different chemical compositions, average pore diameters, specific surface areas, and exchange groups.
Further, the strong acid cation exchange resins used in the first adsorption step and the second adsorption step may be composed of only the same strong acid cation exchange resin, or the same or different strong acid cation exchange resins. May be composed of a mixture of

For example, the strong acid cation exchange resin used in the first adsorption step and the strong acid cation exchange resin used in the second adsorption step contain the same resin, and are used in the first adsorption step. The total amount of strongly acidic cation exchange resin used in the second adsorption step can be made smaller than the total amount.
Here, for example, the strongly acidic cation exchange resin used in the first adsorption step and the strong acid cation exchange resin used in the second adsorption step may be substantially the same resin.

  Since the treatment intermediate solution supplied to the second adsorption step has a lower urea concentration than the untreated urea-containing solution provided to the first adsorption step, the adsorbent used in the second adsorption step Even if the amount is reduced compared to the first adsorption step, a sufficiently high urea removal rate can be shown.

  As described above, by implementing this treatment method, a urea removal rate that is dramatically higher than the urea removal rate in the prior art has been achieved, and a treatment liquid having a very low urea residual amount can be provided. it can.

That is, the treatment liquid obtained by carrying out the treatment method described above is the second invention.
According to the second aspect of the present invention, urea is removed at an extremely high removal rate with respect to an untreated urea-containing liquid, so that it can be reused without being discarded or used as a liquid in a different application. .
For example, when the untreated urea-containing liquid is a used dialysate, the process liquid according to the second aspect of the present invention can be used again as a dialysate. Of course, adjustment of the concentration of active ingredients necessary for dialysis in order to obtain an optimal dialysis solution may be performed on the treatment solution.

  Also, from the viewpoint of disposal, the treatment liquid has an extremely small amount of urea and does not contain urea-derived ammonia, thus facilitating the disposal work and having an advantage as a waste liquid.

  Therefore, as a modification of the present processing method, it can be used as a method for discarding the urea-containing liquid by further including a discarding step for discarding the processing liquid obtained in the second adsorption step.

<Second embodiment>
Next, the batch type urea-containing liquid treatment method of the present invention will be described as a second embodiment of the present invention. In the description of the second embodiment, the urea-containing liquid processing apparatus 100 will be described as an example using FIG. 2 as appropriate. FIG. 2 is a schematic view of the urea-containing liquid processing apparatus 100 used in the second embodiment of the present invention. For the basic matters of the urea-containing liquid treatment method according to the second embodiment, the description items of the treatment method described in the first embodiment are referred to as appropriate.

  In the urea-containing liquid processing method according to the second embodiment, the first adsorption step and the second adsorption step have a plurality of processes including a liquid supply process, a contact process, a separation process, and a discharge process, and the plurality of processes Is carried out by a batch type process in which one cycle is performed. The liquid supply process is a process of supplying the urea-containing liquid or the processing intermediate liquid to the strongly acidic cation exchange resin. The contact process is a process of bringing the urea-containing liquid or the process intermediate liquid supplied by the liquid supply process into contact with the strongly acidic cation exchange resin. The separation treatment is a treatment for separating the urea-containing liquid or the treatment intermediate liquid and the strongly acidic cation exchange resin that are in contact with each other by contact treatment. The discharge process is a process of discharging the urea-containing liquid or the process intermediate liquid separated by the separation process.

  By performing the first adsorption step and the second adsorption step including the predetermined treatment by batch processing, it is easy to manage the adsorption conditions in each adsorption step to be constant. For example, by performing batch processing on the first adsorption step and the second adsorption step, it is easy to manage the urea concentration equilibrium of the urea-containing liquid (processing intermediate solution) in each adsorption step.

  In the present processing method according to the second embodiment, the processing intermediate liquid is not transferred between the first adsorption step and the second adsorption step while the first adsorption step is performed. After completion of the adsorption process in the first adsorption process, the process intermediate liquid discharged from the first adsorption process is brought into contact with a new strong acidic cation exchange resin to perform the second adsorption process. However, in the present embodiment, the batch type treatment means that a small amount of the processing intermediate liquid that does not affect the treatment of the first adsorption step and the second adsorption step is transferred to the second adsorption step during the first adsorption step. It doesn't exclude everything that you do.

  Hereinafter, the processing method according to the second embodiment will be further described using the urea-containing liquid processing apparatus 100 shown in FIG. A urea-containing liquid processing apparatus 100 shown in FIG. 2 is an example of a urea-containing liquid processing apparatus (hereinafter also referred to as the present processing apparatus) according to the third aspect of the present invention.

The urea-containing liquid processing apparatus 100 is a urea-containing liquid processing apparatus that adsorbs urea to a strongly acidic cation exchange resin and separates it. The urea-containing liquid processing apparatus 100 includes a first processing tank 10 and a second processing tank 20. The first treatment tank 10 contains a strongly acidic cation exchange resin 30 having an average pore diameter of 1 nm or more and 90 nm or less and a specific surface area of 10 m ² / gdry or more and 800 m ² / gdry or less, and untreated urea. It is the processing tank in which the containing liquid 110 is supplied. The second processing tank 20 is a processing tank in which the strongly acidic cation exchange resin 40 is accommodated and a processing intermediate liquid (not shown) discharged from the first processing tank 10 is supplied. In the urea-containing liquid processing apparatus 100, n second processing tanks 20 (where n is an integer of 1 or more) are provided. In the present embodiment, specifically, there is one second processing tank 20.

  According to the urea containing liquid processing apparatus 100, since the 1st processing tank 10 and the 2nd processing tank 20 are provided, the processing method of this invention can be implemented. The first treatment tank 10 and the second treatment tank 20 contain the strong acid cation exchange resin 30 and the strong acid cation exchange resin 40, respectively, and are supplied with an untreated urea-containing liquid or a treatment intermediate liquid. Maintenance is easy because of this simple configuration.

  Hereinafter, the urea-containing liquid processing apparatus 100 will be described in more detail. The urea-containing liquid processing apparatus 100 has a stock solution tank 112 on the upstream side of the first processing tank 10. An untreated urea-containing liquid 110 is stored in the stock solution tank 112. The urea-containing liquid 110 stored in the stock solution tank 112 is supplied by the water supply pump 114 and supplied to the first treatment tank 10 through the water supply pipe 116 from the liquid supply port 12 provided in the first treatment tank 10. A strong acid cation exchange resin 30 is accommodated in the first treatment tank 10, and the urea-containing liquid 110 supplied from the liquid supply port 12 is supplied to the strong acid cation exchange resin 30. . Thereby, the liquid supply process in this processing method is performed. In the liquid supply process, the strong acid cation exchange resin 30 may be accommodated after the urea-containing liquid 110 is supplied to the first treatment tank 10. In this specification, the urea-containing liquid processing apparatus 100 may be described with the stock solution tank 112 side as an upstream side and the processed liquid tank 128 side as a downstream side.

  After the liquid supply process, a contact process is performed. That is, in the first treatment tank 10, the urea-containing liquid 110 and the strong acid cation exchange resin 30 are brought into contact so that the urea-containing liquid 110 can be adsorbed to the exchange groups in the strong acid cation exchange resin 30.

  The contact treatment is, for example, one of a stirring and mixing treatment, a fixed bed treatment, a moving bed treatment, or a fluidized bed treatment. Specifically, the first treatment tank 10 and the second treatment tank 20 of the urea-containing liquid treatment apparatus 100 are stirring and mixing tanks that perform a stirring and mixing process as a contact process.

  The stirring and mixing process is a process of stirring the strongly acidic cation exchange resin 30 and the urea-containing liquid 110 accommodated in the first processing tank 10 for a predetermined time. The first treatment tank 10 in the urea-containing liquid treatment apparatus 100 has a stirring and mixing unit for performing a stirring and mixing process. Specifically, stirring blades 18 extending from the top plate 117 toward the inside are provided as stirring and mixing means. The stirring blade 18 is rotated to stir and mix the urea-containing liquid 110 supplied to the first treatment tank 10 and the strong acid cation exchange resin 30 to perform a stirring and mixing process. By the stirring and mixing process, the urea-containing liquid 110 is efficiently brought into contact with the strongly acidic cation exchange resin 30 having an average pore diameter and specific surface area within a predetermined range in a short time, thereby making urea highly acidic cation highly efficient. It can be adsorbed on the exchange resin 30. The 2nd processing tank 20 similarly has the stirring blade 18, and the stirring mixing process mentioned above is implemented.

  The stirring and mixing conditions can be appropriately determined in consideration of the urea concentration of the strong acid cation exchange resin 30 and the urea-containing liquid 110 used. For example, the stirring condition in which the urea concentration of the urea-containing liquid 110 reaches equilibrium may be confirmed in advance, and the stirring and mixing process may be performed under the stirring condition. Alternatively, a urea concentration measuring device for observing the urea concentration may be provided in the first treatment tank 10 and the stirring and mixing may be terminated by confirming that the urea concentration has reached equilibrium. The stirring speed of the stirring and mixing means is not particularly limited, but can be about 50 to 2000 revolutions / minute.

In the urea-containing liquid processing apparatus 100, the stirring and mixing process may be appropriately replaced with a fixed bed type process, a moving bed type process, or a fluidized bed type process. That is, the first treatment tank 10 and / or the second treatment tank 20 which are stirring and mixing tanks may be appropriately replaced with a fixed bed tank, a moving bed tank or a fluidized bed tank (not shown).
In the fixed bed tank, the storage position of the strong acid cation exchange resin 30 accommodated in the first treatment tank 10 is substantially fixed to the first treatment tank 10, and the fixed strong acid cation exchange resin 30 is fixed. On the other hand, the urea-containing liquid 110 is passed. Here, “substantially fixed” includes that at least a part of the strong acid cation exchange resin 30 undergoes some positional fluctuation by contacting the urea-containing liquid 110 passing therethrough.
In the moving bed type tank, the strong acid cation exchange resin 30 in contact with the urea-containing liquid 110 in the first treatment tank 10 is continuously extracted from the first treatment tank 10 and a new strong acid cation exchange resin 30 is continuously added. The first processing tank 10 is filled with a structure.
The fluidized bed tank has a configuration in which the urea-containing liquid 110 is supplied upward in the first processing tank 10 and the strongly acidic cation exchange resin 30 accommodated in the first processing tank 10 is caused to flow inside. Fluidized bed processing can increase the contact rate between a solid and a fluid.

  After the contact process described above is completed, a separation process is performed, and then a discharge process is performed. In the urea-containing liquid processing apparatus 100, a discharge port 14 is provided in the lower part of the first processing tank 10. The outlet 14 allows the urea-containing liquid 110 to pass therethrough without passing through the strong acid cation exchange resin 30. Thereby, the separation process for separating the urea-containing liquid 110 and the strong acid cation exchange resin 30 and the discharge process for discharging the urea-containing liquid 110 from the first treatment tank 10 are performed simultaneously.

  The urea-containing liquid processing apparatus 100 has a water supply pipe 122 that continues from the first processing tank 10 to the second processing tank 20. An opening / closing valve 118 capable of opening and closing the flow path of the water supply pipe 122 is provided at an intermediate portion from the discharge port 14 of the water supply pipe 122. When the first adsorption step is being performed in the first treatment tank 10, the on-off valve 118 is closed, and when the first adsorption step is completed and the processing intermediate liquid moves to the second adsorption step, the on-off valve 118. Is released. Thereby, batch processing is performed in the urea-containing liquid processing apparatus 100.

The processing intermediate liquid discharged from the discharge port 14 is supplied from the liquid supply port 12 to the second processing tank 20 through the water supply pipe 122. The strongly acidic cation exchange resin 40 is accommodated in the second treatment tank 20, and the second adsorption process is performed in the same manner as the first adsorption process performed in the first treatment tank 10. In the present embodiment, the second treatment tank 20 is also provided with a stirring and mixing means (stirring blade 18) for performing the stirring and mixing process. However, the urea containing liquid processing apparatus 100 is not limited to this, The different structure for performing the different contact processing from the 1st processing tank 10 and the 2nd processing tank 20 may be provided.
A processed liquid tank 128 is provided on the downstream side of the second processing tank 20. The second treatment tank 20 and the treated liquid tank 128 communicate with each other through a water supply pipe 126. After the second adsorption step is performed in the second treatment tank 20, the treatment liquid 120 discharged from the discharge port 14 provided in the second treatment tank 20 is guided to the treated liquid tank 128 through the water supply pipe 126. Stored.
An open / close valve 124 is provided at an arbitrary location near the discharge port 14 of the water supply pipe 126. The on-off valve 124 is closed when the second adsorption step is being performed, and is opened after the second adsorption step is completed, and the treatment liquid 120 that has been treated to have a very low urea concentration is contained in the second treatment tank. 20 is discharged.

  By providing a disposal device for discarding the treatment liquid 120 discharged from the second treatment tank 20 directly in the treated liquid tank 128 or continuously to the treated liquid tank 128, the urea-containing liquid treatment apparatus 100 is treated as a waste liquid treatment. It can also be a device.

In addition, after completion | finish of this processing method, the strongly acidic cation exchange resins 30 and 40 accommodated in the 1st processing tank 10 and the 2nd processing tank 20 are provided in each of the 1st processing tank 10 and the 2nd processing tank 20. It takes out from the taken out outlet 16. Then, by accommodating the new strong acid cation exchange resins 30 and 40 in the first treatment tank 10 and the second treatment tank 20, this treatment method can be performed again in the urea-containing liquid treatment apparatus 100.
Or after completion | finish of this processing method, the urea adsorb | sucked by the exchange group is poured by flowing an appropriate process liquid through the strong acidic cation exchange resin 30 and 40 accommodated in the 1st processing tank 10 and the 2nd processing tank 20. It may be washed away and regenerated, and this treatment method may be carried out again by the urea-containing liquid treatment apparatus 100.

<Third embodiment>
Next, the continuous urea-containing liquid treatment method of the present invention will be described as a third embodiment of the present invention. In the description of the third embodiment, a continuous urea-containing liquid processing apparatus 200 will be described as an example using FIG. 3 as appropriate. FIG. 3 is a schematic view of a urea-containing liquid processing apparatus 200 used in the third embodiment of the present invention. For the urea-containing liquid treatment method according to the third embodiment, the description of the treatment method described in the first embodiment is referred to as appropriate.

  In the present treatment method according to the third embodiment, the first adsorption step and the second adsorption step have a plurality of processes including a liquid supply process, a contact process, a separation process, and a discharge process, and the plurality of processes are performed in parallel. Then, it is carried out by a continuous process performed continuously. The liquid supply process is a process of supplying the urea-containing liquid or the processing intermediate liquid to the strongly acidic cation exchange resin. The contact process is a process of bringing the urea-containing liquid or the process intermediate liquid supplied by the liquid supply process into contact with the strongly acidic cation exchange resin. The separation treatment is a treatment for separating the urea-containing liquid or the treatment intermediate liquid and the strongly acidic cation exchange resin that are in contact with each other by contact treatment. The discharge process is a process of discharging the urea-containing liquid or the process intermediate liquid separated by the separation process.

  In the present processing method according to the third embodiment, the first adsorption step to the second adsorption step are continuously performed. The plurality of processes included in the first adsorption process are continuously performed from the upstream to the downstream of the process, and from the last process of the first adsorption process to the second adsorption process are continuously performed. The plurality of processing steps included in the second adsorption step are continuously performed from the upstream to the downstream of the processing step. This processing method is performed in parallel when the first process of the first adsorption process and the final process of the second adsorption process are performed in parallel, and either one has started or ended. Including the case where there is no.

As in the third embodiment, in the present treatment method in which the first adsorption step to the second adsorption step are continuously performed, until the urea concentration in the urea-containing liquid reaches a substantially equilibrium in the first adsorption step, the strongly acidic cation is used. The exchange resin and the urea-containing liquid may be contacted. For example, the above approximate equilibrium can be achieved by appropriately adjusting the flow rate of the urea-containing liquid that is flowed in the first adsorption step, the amount of the strongly acidic ion exchange resin used, and the like.
The fact that the equilibrium is reached in the first adsorption step of the present treatment method, which is a continuous type, means that the treatment intermediate liquid initially discharged from the first adsorption step has a urea equilibrium concentration. At this time, it is usually preferable that the processing intermediate liquid finally discharged from the first adsorption step also reaches the urea equilibrium concentration.
In order to achieve the above-described equilibrium in the first adsorption step of the present treatment method, which is a continuous type, for example, the urea equilibrium concentration when a urea-containing liquid having a predetermined concentration is adsorbed on a strongly acidic ion exchange resin in advance is batchwise. It is good to confirm by processing. Then, the flow rate of the urea-containing liquid and the amount of the strongly acidic ion exchange resin used so that the treatment intermediate liquid discharged first from the first adsorption step of the treatment method, which is a continuous type, has the confirmed urea equilibrium concentration. Check in advance. By implementing this processing method that is a continuous type according to the confirmed processing conditions, the above-described approximate equilibrium can be achieved.

The urea-containing liquid processing apparatus 200 is an example of a urea-containing liquid processing apparatus that is the third aspect of the present invention. The urea-containing liquid treatment apparatus 200 includes a first treatment tank 50 and a second treatment tank 60 that are ion exchange resin columns filled with strong acid cation exchange resins 30 and 40, respectively, as tanks for contact treatment. Different from the urea-containing liquid processing apparatus 100.
In the urea-containing liquid treatment apparatus 200, the housing position of the strong acid cation exchange resins 30 and 40 is substantially fixed to the first treatment tanks 50 and 60, and with respect to the fixed strong acid cation exchange resin 30, The urea-containing liquid 110 is passed. That is, the contact process in the urea-containing liquid processing apparatus 200 is one aspect of the fixed bed type process.

In the urea-containing liquid processing apparatus 200, n second processing tanks 60 (where n is an integer of 1 or more) are provided. Specifically, in the present embodiment, there is one second processing tank 60.
The urea-containing liquid processing apparatus 200 includes an opening / closing valve 132 in the middle of the water supply pipe 116 that connects the stock solution tank 112 and the first processing tank 50. By opening the on-off valve 132 and supplying the urea-containing liquid 110 from the water supply pump 114, the urea-containing liquid 110 is sent from the stock solution tank 112 to the first treatment tank 50 through the water supply pipe 116.

  The urea-containing liquid 110 sent to the first treatment tank 50 passes between the strong acid cation exchange resin 30 filled in the first treatment tank 50 at an appropriate speed, and the urea-containing liquid 110 and the strong acid cation exchange resin. 30 contacts. As a result, urea is adsorbed on the exchange groups in the strongly acidic cation exchange resin 30 and ion exchange is performed. The flow rate of the urea-containing liquid 110 is not particularly limited, and is appropriately determined within a range in which the urea-containing liquid 110 and the strong acid cation exchange resin 30 are sufficiently brought into contact with each other and ion exchange is performed in the first treatment tank 50. be able to.

  The first treatment tank 50 and the second treatment tank 60 are linked by a water supply pipe 122 so that the treatment intermediate liquid (not shown) discharged from the first treatment tank 50 flows continuously into the second treatment tank 60. It is configured. Although not shown, the urea-containing liquid treatment apparatus 200 may omit the water supply pipe 122 and directly link the first treatment tank 50 and the second treatment tank 60. The processing intermediate liquid discharged from the first processing tank 50 is configured to continuously flow to the second processing tank 60, whereby continuous processing is performed.

  By continuously processing the first adsorption step and the second adsorption step through the urea-containing liquid 110 (processing intermediate solution) continuously in the first processing tank 50 and the second processing tank 60, the processing time is shortened and the apparatus is reduced. Can be made compact.

  Although the first to third embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and improvements as long as the object of the present invention is achieved. This embodiment is also included. In all the drawings shown in this specification, the same components are denoted by the same reference numerals, and redundant description will be appropriately omitted. The various components of the urea-containing liquid processing apparatus of the present invention do not have to be individually independent, but a plurality of components are formed as one member, and one component is a plurality of members. It is allowed to be formed, a certain component is a part of another component, a part of a certain component overlaps a part of another component, and the like.

Example 1
The urea-containing liquid treatment method of the present invention was performed as follows.
In other words, ^two conical stoppered flasks with a capacity of 200 ml each having an average pore diameter of 1 nm to 90 nm, a specific surface area of 10 m ² / gdry to 800 m ² / gdry, and containing 10 g of strongly acidic cation exchange resin each. Were prepared as a first flask and a second flask, respectively.
Commercially available urea was added to pure water to prepare a urea-containing liquid having a urea concentration of 360 mg / l, and 50 ml of the urea-containing liquid was added to the first flask.
As described above, the stirrer was put into the first flask to which the adsorbent and the urea-containing liquid had been added, and the adsorbing treatment was performed by stirring at room temperature under stirring conditions of 500 rpm for 3 hours. Centrifugation was performed after stirring, and after that, the adsorbent and the liquid (treatment liquid) were separated by filtration with a 50 μm filter, and the first adsorption step was completed to obtain a treatment intermediate liquid.
The whole amount of the processing intermediate solution was added to the second flask, the same treatment as that of the first flask was performed, the second adsorption step was completed, and a processing solution was obtained to obtain Example 1.

(Example 2)
Prepare two glass chromatograph tubes with an inner diameter of 12 mm and a length of 300 mm, equipped with a water pipe with a two-way cock at the bottom, and 10 g of the adsorbent 1 packed in series, as shown in FIG. Connected. Example 2 was obtained by dropping 50 ml of a urea-containing solution having a urea concentration of 345.7 mg / l into the upper chromatographic tube over about 1 hour to obtain a treatment liquid discharged from the lower chromatographic tube. The urea-containing liquid was supplied to the upper chromatographic tube, and the flow rate was adjusted to be about 2 hours until the processing liquid was completely discharged from the lower chromatographic tube.

(Example 3)
Prepare two glass chromatograph tubes with an inner diameter of 12 mm and a length of 300 mm, equipped with a water pipe with a two-way cock at the bottom, and 20 g of adsorbent 4 filled in, as shown in FIG. Connected. Example 3 was obtained by dropping 50 ml of a urea-containing solution having a urea concentration of 345.7 mg / l into the upper chromatographic tube over about 1 hour to obtain a treatment liquid discharged from the lower chromatographic tube. The urea-containing liquid was supplied to the upper chromatographic tube, and the flow rate was adjusted to be about 2 hours until the processing liquid was completely discharged from the lower chromatographic tube.

(Comparative Example 1)
A treatment was performed in the same manner as in Example 1 except that the second adsorption step in Example 1 was not performed without using the second flask, and a treatment liquid was obtained as Comparative Example 1 (that is, in Example 1). The treatment intermediate solution was used as the treatment solution in Comparative Example 1).

(Comparative Example 2)
The treatment was performed in the same manner as in Example 1 except that the second adsorption step in Example 1 was not performed without using the second flask, and that the stirring time was 24 hours. It was.

(Comparative Example 3)
The same treatment as in Example 1 except that the second adsorption step in Example 1 was not performed without using the second flask and that the amount of the strongly acidic cation exchange resin contained in the first flask was 20 g. And a treatment liquid was obtained and used as Comparative Example 3.

(Evaluation) The urea concentrations of the treatment liquids obtained in Examples and Comparative Examples were analyzed as follows, and the urea removal rate was calculated.
[Kjeldahl method]
Each of the Examples and Comparative Examples obtained above was collected in a decomposition container, added with a specified reagent (such as concentrated sulfuric acid) and thermally decomposed, and the organic nitrogen compound in the test solution was changed to an ammonium salt form. A strong alkali was then added. Thereafter, ammonia was recovered as an aqueous solution by steam distillation and diluted to an appropriate concentration to obtain a test solution for ion chromatography measurement. In addition, the Kjeldahl decomposition apparatus and distillation apparatus by Nihon Büch Co., Ltd. were used for the above-mentioned thermal decomposition and steam distillation.
[Ion chromatography]
Next, the test solution and ammonium ion standard solution obtained by the above-mentioned Kerule method were introduced into an ion chromatograph, and the concentration of ammonium ions in the test solution was determined by a calibration curve method. From the obtained ammonium ion concentration, the nitrogen content (mg / l) in the test solution (treatment solution) was calculated, and the urea concentration was converted by the following formula 1. As an ion chromatograph, an ICS3000 type ion chromatograph manufactured by Nippon Dionex Co., Ltd. was used.
(Formula 1) Urea concentration (mg / l) = nitrogen content (mg / l) × (60.06 / 28.01)
The urea removal rate was calculated from the post-treatment urea concentration with respect to the pre-treatment urea concentration.

  The total amount (g) of the adsorbent used in the examples and comparative examples described above in Table 1, presence / absence of the first adsorption step and the second adsorption step, stirring time (treatment time (hr)), urea in the urea-containing liquid Concentration (urea concentration before treatment (mg)), urea concentration of treatment liquid (urea concentration after treatment (mg / l)), removal rate of urea removed from urea-containing liquid by adsorption treatment (urea removal rate (%)) Are shown in Table 3.

  As shown in Table 3, Examples 1 to 3 showed extremely high urea removal rates. The pretreatment urea concentration is 360 mg / l in Example 1 and 345.7 mg / l in Examples 2 and 3. That is, all of the urea-containing liquids used in this example have a urea concentration comparable to the urea concentration (about 133 mg / l to 320 mg / l) in adult used dialysate. Since an extremely high urea removal rate of 98% to over 99% was shown from the urea-containing solution having such a concentration, this treatment method removes urea to such an extent that reuse of used dialysate can be realized. It was confirmed that

Since Comparative Examples 1 to 3 used an excellent strong acid cation exchange resin having an average pore diameter and a specific surface area within a predetermined range found in the study of the present invention, compared with the prior art. Although a high adsorption removal rate was shown, none of them was equivalent to Example 1.
That is, when Example 1 was compared with Comparative Example 1, it was confirmed that the urea removal rate of Example 1 was significantly increased by performing the second adsorption step.
Further, Comparative Example 2 in which the treatment process time was increased by a factor of 8 to the first adsorption process of Example 1 showed only a urea removal rate comparable to Comparative Example 1. From this, it was confirmed that the urea concentration reached equilibrium in the first adsorption step (or Comparative Example 1) of Example 1. It was also confirmed that the urea removal rate did not increase even if the treatment step was lengthened in a state where the urea concentration reached equilibrium.
Further, when Example 1 and Comparative Example 3 were compared, the urea removal rate was clearly high in Example 1 although the amount of the strongly acidic cation exchange resin used was the same. From this result, it was confirmed that the amount of urea removed can be further increased by repeating the adsorption step a plurality of times, rather than increasing the amount of adsorbent used in one adsorption step.

The above embodiment includes the following technical idea.
(1) A urea-containing liquid treatment method for adsorbing and separating urea on a strongly acidic cation exchange resin,
The strongly acidic cation exchange resin has an average pore diameter of 1 nm or more and 90 nm or less, and a specific surface area of 10 m ² / gdry or more and 800 m ² / gdry or less,
A first adsorption step in which the strong acid cation exchange resin is brought into contact with the untreated urea-containing liquid to adsorb urea contained in the urea-containing liquid onto the strong acid cation exchange resin;
A second adsorption step in which the strong acid cation exchange resin is brought into contact with the treatment intermediate solution that has undergone the first adsorption step to adsorb urea contained in the treatment intermediate solution onto the strong acid cation exchange resin. The urea-containing liquid treatment method is characterized in that the second adsorption step is performed n times (where n is an integer of 1 or more).
(2) The urea-containing liquid according to (1), wherein the strongly acidic cation exchange resin and the urea-containing liquid are brought into contact with each other until the urea concentration in the urea-containing liquid reaches substantially equilibrium in the first adsorption step. Processing method.
(3) The urea-containing liquid processing method according to (1) or (2), wherein the urea concentration of the urea-containing liquid used in the first adsorption step is 1200 mg / L or less.
(4) The urea-containing liquid treatment method according to any one of (1) to (3), wherein the urea-containing liquid is a used artificial dialysis liquid.
(5) The strong acid cation exchange resin used in the first adsorption step and the strong acid cation exchange resin used in the second adsorption step include the same resin,
Any of (1) to (4) above, wherein the total amount of the strongly acidic cation exchange resin used in the second adsorption step is less than the total amount of the strong acid cation exchange resin used in the first adsorption step. The urea-containing liquid treatment method according to one item.
(6) The first adsorption step and the second adsorption step are
A liquid supply process for supplying the urea-containing liquid or the processing intermediate liquid to the strongly acidic cation exchange resin;
A contact treatment in which the urea-containing liquid or the treatment intermediate liquid fed by the liquid feed treatment is brought into contact with the strongly acidic cation exchange resin;
A separation process for separating the urea-containing liquid or the processing intermediate liquid and the strongly acidic cation exchange resin that are in contact with each other by the contact process; and the urea-containing liquid or the processing intermediate liquid separated by the separation process is discharged. A plurality of processes including a discharge process,
The urea-containing liquid treatment method according to any one of (1) to (5), wherein the treatment is performed by batch-type treatment in which the plurality of treatments are performed as one cycle.
(7) The first adsorption step and the second adsorption step are
A liquid supply process for supplying the urea-containing liquid or the processing intermediate liquid to the strongly acidic cation exchange resin;
A contact treatment in which the urea-containing liquid or the treatment intermediate liquid fed by the liquid feed treatment is brought into contact with the strongly acidic cation exchange resin;
A separation process for separating the urea-containing liquid or the processing intermediate liquid and the strongly acidic cation exchange resin that are in contact with each other by the contact process; and the urea-containing liquid or the processing intermediate liquid separated by the separation process is discharged. A plurality of processes including a discharge process,
The urea-containing liquid processing method according to any one of (1) to (5), wherein the processing is performed by a continuous process in which the plurality of processes are continuously performed in parallel.
(8) The urea-containing liquid treatment method according to (6) or (7), wherein the contact treatment is any one of a stirring and mixing treatment, a fixed bed treatment, a moving bed treatment, and a fluidized bed treatment.
(9) The urea-containing liquid processing method according to any one of (1) to (8), further including a disposal step of discarding the processing liquid obtained in the second adsorption step.
(10) A treatment liquid obtained by performing the urea-containing liquid treatment method according to any one of (1) to (8) above.
(11) A urea-containing liquid treatment apparatus for adsorbing and separating urea on a strongly acidic cation exchange resin,
The strongly acidic cation exchange resin having an average pore diameter of 1 nm or more and 90 nm or less and a specific surface area of 10 m ² / gdry or more and 800 m ² / gdry or less is accommodated, and an untreated urea-containing liquid is supplied. A first treatment tank;
A second treatment tank in which the strongly acidic cation exchange resin is accommodated and a treatment intermediate liquid that has passed through the first treatment tank is supplied, and the number of the second treatment tanks is n (where n is A urea-containing liquid treatment apparatus, which is an integer of 1 or more.

DESCRIPTION OF SYMBOLS 10 ... 1st processing tank 12 ... Supply port 14 ... Discharge port 16 ... Outlet 18 ... Stirring blade 20 ... 2nd processing tank 30, 40 ... Strong acid positive Ion exchange resins 50, 60 ... first treatment tank 100, 200 ... urea-containing liquid treatment device 110 ... urea-containing liquid 112 ... stock solution tank 114 ... water pump 116 ... water pipe 117 ... top plate 118 ... open / close valve 120 ... treatment liquid 122 ... water supply pipe 124 ... open / close valve 126 ... water supply pipe 128 ... treated liquid tank 132 ... open / close valve

Claims (11)

A urea-containing liquid treatment method for adsorbing and separating urea on a strongly acidic cation exchange resin,
The strongly acidic cation exchange resin has an average pore diameter of 1 nm or more and 90 nm or less, and a specific surface area of 10 m ² / gdry or more and 800 m ² / gdry or less,
A first adsorption step in which the strong acid cation exchange resin is brought into contact with the untreated urea-containing liquid to adsorb urea contained in the urea-containing liquid onto the strong acid cation exchange resin;
A second adsorption step in which the strong acid cation exchange resin is brought into contact with the treatment intermediate solution that has undergone the first adsorption step to adsorb urea contained in the treatment intermediate solution onto the strong acid cation exchange resin. The urea-containing liquid treatment method is characterized in that the second adsorption step is performed n times (where n is an integer of 1 or more).   The urea-containing liquid treatment method according to claim 1, wherein the strongly acidic cation exchange resin and the urea-containing liquid are brought into contact with each other until the urea concentration in the urea-containing liquid reaches substantially equilibrium in the first adsorption step.   The urea-containing liquid processing method according to claim 1 or 2, wherein the urea concentration of the urea-containing liquid used in the first adsorption step is 1200 mg / L or less.   The urea-containing liquid treatment method according to any one of claims 1 to 3, wherein the urea-containing liquid is a used artificial dialysis liquid. The strong acid cation exchange resin used in the first adsorption step and the strong acid cation exchange resin used in the second adsorption step include the same resin,
The total amount of the strongly acidic cation exchange resin used in the second adsorption step is smaller than the total amount of the strong acid cation exchange resin used in the first adsorption step. The urea-containing liquid processing method as described. The first adsorption step and the second adsorption step are
A liquid supply process for supplying the urea-containing liquid or the processing intermediate liquid to the strongly acidic cation exchange resin;
A contact treatment in which the urea-containing liquid or the treatment intermediate liquid fed by the liquid feed treatment is brought into contact with the strongly acidic cation exchange resin;
A separation process for separating the urea-containing liquid or the processing intermediate liquid and the strongly acidic cation exchange resin that are in contact with each other by the contact process; and the urea-containing liquid or the processing intermediate liquid separated by the separation process is discharged. A plurality of processes including a discharge process,
The urea-containing liquid processing method according to claim 1, wherein the urea-containing liquid processing method is performed by a batch-type process in which the plurality of processes are performed as one cycle. The first adsorption step and the second adsorption step are
A liquid supply process for supplying the urea-containing liquid or the processing intermediate liquid to the strongly acidic cation exchange resin;
A contact treatment in which the urea-containing liquid or the treatment intermediate liquid fed by the liquid feed treatment is brought into contact with the strongly acidic cation exchange resin;
A separation process for separating the urea-containing liquid or the processing intermediate liquid and the strongly acidic cation exchange resin that are in contact with each other by the contact process; and the urea-containing liquid or the processing intermediate liquid separated by the separation process is discharged. A plurality of processes including a discharge process,
The urea-containing liquid processing method according to any one of claims 1 to 5, wherein the urea-containing liquid processing method is performed by a continuous process in which the plurality of processes are continuously performed in parallel.   The urea-containing liquid treatment method according to claim 6 or 7, wherein the contact treatment is any one of a stirring and mixing treatment, a fixed bed treatment, a moving bed treatment, and a fluidized bed treatment.   The urea-containing liquid processing method according to any one of claims 1 to 8, further comprising a discarding step of discarding the processing liquid obtained by the second adsorption step.   A treatment liquid obtained by carrying out the urea-containing liquid treatment method according to claim 1. A treatment apparatus for urea-containing liquid that adsorbs and separates urea on a strongly acidic cation exchange resin,
The strongly acidic cation exchange resin having an average pore diameter of 1 nm or more and 90 nm or less and a specific surface area of 10 m ² / gdry or more and 800 m ² / gdry or less is accommodated, and an untreated urea-containing liquid is supplied. A first treatment tank;
A second treatment tank in which the strongly acidic cation exchange resin is accommodated and a treatment intermediate liquid that has passed through the first treatment tank is supplied, and the number of the second treatment tanks is n (where n is A urea-containing liquid treatment apparatus, which is an integer of 1 or more.

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