JP2022125843A - Urea processor and pure water manufacturing system - Google Patents

Abstract

To provide a processor used in decomposition of urea and capable of reducing volume of a reaction tank as a whole.SOLUTION: A processor which receives water to be treated, decomposes urea included in water to be treated, and discharges treated water is assembled with addition means for adding a hypochlorite (e.g., NaClO) and a bromide salt (e.g., NaBr) as a urea decomposition agent to water to be treated, and a plurality of reaction tanks 20 where decomposition reaction of urea by the urea decomposition agent is progressed. A plurality of reaction tanks 20 are arranged parallel to each other with the decomposition reaction to be progressed in batch system in each reaction tank, or, are arranged in series to form a multistage complete blending continuous reaction tank to progress decomposition reaction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a treatment apparatus for decomposing urea in water to be treated and a pure water production system including this treatment apparatus.

A water purifying apparatus used for producing pure water from raw water such as tap water, groundwater, and industrial water is configured by combining, for example, a reverse osmosis apparatus, an ion exchange apparatus, an ultraviolet oxidation apparatus, and the like. When raw water contains urea, urea is a substance that is difficult to remove by any of a reverse osmosis device, an ion exchange device, and an ultraviolet oxidation device, so urea will remain in the produced pure water. As a result, the TOC (total organic carbon) concentration of the pure water increases. When producing ultrapure water with particularly high purity for applications such as semiconductor manufacturing, the upper limit of the TOC concentration in the resulting ultrapure water is strictly set. A step of removing urea from raw water is required as a pretreatment for the step of producing ultrapure water. As a process for removing urea contained in raw water, which is the water to be treated, bromide salt and hypochlorite, specifically, are added to the water to be treated, as described in Patent Documents 1 to 3. A process is known in which sodium bromide and sodium hypochlorite are added to generate hypobromous acid, and urea is decomposed by this hypobromous acid.

Japanese Patent No. 3546548 Japanese Patent No. 5678436 Japanese Patent No. 6279295

The step of adding bromide salt and hypochlorite to the water to be treated to decompose urea is a step with a slow reaction rate and a long reaction time. Therefore, conventionally, on the premise that treated water is continuously supplied to the downstream pure water production apparatus, bromide salt and hypochlorous acid are added while continuously receiving the water to be treated in a single large reaction tank. acid salt was added. However, in a single large reactor, flow control is not possible and imperfect plug flow is formed within the reactor, resulting in short-path effects resulting in short residence times and poor urea processing. Decreased performance. In order to secure a sufficient reaction time, the residence time in the reaction tank must be set excessively, so it was necessary to prepare a reaction tank larger than originally required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a treatment apparatus which is used for decomposing urea and which can reduce the volume of the reaction tank as a whole, and a pure water production system having such a treatment apparatus as a pretreatment apparatus.

The treatment apparatus of the present invention receives water to be treated, decomposes urea contained in the water to be treated, and discharges the treated water. An addition means for adding to the water to be treated and a plurality of reaction tanks for advancing the decomposition reaction of urea by the urea decomposing agent are provided. A bromide salt is for example sodium bromide and a hypochlorite is for example sodium hypochlorite.

In the processing apparatus of the present invention, a plurality of reaction vessels are provided in series or in parallel. When a plurality of reaction tanks are provided in series, an addition means is provided for each reaction tank, and the decomposition reaction proceeds as a multi-stage complete mixing continuous (CSTR) reaction apparatus as a whole. When multiple reaction tanks are provided in series, the concentration of urea in the water to be treated differs for each reaction tank, forming a concentration gradient of urea, making it possible to increase the reaction rate. can be made smaller. By increasing the number of reactors in series, the reaction as a whole approaches a plug flow reaction. On the other hand, when a plurality of reaction tanks are provided in parallel, each of them is used as a batch type (batch type) reaction tank, for example. When only one batch-type reaction tank is used, it is not possible to continuously receive the water to be treated or discharge the treated water continuously. It is used for receiving the water to be treated, and one of the remaining ones is used to discharge the treated water. For example, it is possible to continuously discharge the treated water while performing the decomposition treatment. The reaction in the batch mode, along with the reaction in the ideal plug flow, allows the reaction to proceed most efficiently. can reduce the volume of the entire reactor.

The pure water production system of the present invention is a pure water production system comprising at least an ion exchange device and a reverse osmosis device to which water that has passed through the ion exchange device is supplied, and the treatment device of the present invention is used as a pretreatment device. Prepare.

According to the present invention, it is possible to obtain a treatment apparatus that is used for decomposing urea and that can reduce the volume of the reaction tank as a whole, and a pure water production system that includes such a treatment apparatus as a pretreatment apparatus.

It is a figure which shows the processing apparatus of the 1st Embodiment of this invention. It is a figure which shows the processing apparatus of the 2nd Embodiment of this invention. It is a figure which shows an example of a pure water production system. 3 is a diagram showing a processing apparatus in Comparative Example 1; FIG.

Preferred embodiments of the present invention will now be described with reference to the drawings.

A treatment apparatus based on the present invention decomposes urea in water to be treated and continuously discharges the treated water, and is preferably used as a pretreatment apparatus in a pure water production system, for example. The treatment apparatus according to the present invention comprises addition means for adding bromide salt and hypochlorite as urea decomposition agents to the water to be treated, and a decomposition reaction of urea by the urea decomposition agent, more specifically generated by the urea decomposition agent. and a plurality of reaction tanks for advancing the decomposition reaction of urea with hypobromous acid or hypobromite. The ureolytic agent consists of a bromide salt and a hypochlorite salt, and the bromide salt is preferably water-soluble, such as sodium bromide (NaBr). As hypochlorite, for example, sodium hypochlorite (NaClO) is used. In the following description, the case of using sodium bromide and sodium hypochlorite as the urea decomposing agent will be described. In addition, in the present invention, a case of arranging a plurality of reaction vessels in parallel and a case of arranging them in series are conceivable. The embodiment of

(First embodiment)
FIG. 1 shows a processing apparatus according to a first embodiment of the invention. A processing apparatus 10 shown in FIG. 1 includes a plurality of reaction tanks 20 arranged in parallel, and each reaction tank 20 performs a urea decomposition reaction in a batch or semi-batch manner. The number of reaction vessels 20 arranged in parallel may be two, but preferably three or more. In the illustrated example, the number of reaction vessels 20 arranged in parallel is three. An inlet pipe 21 is provided in common to a plurality of reaction tanks 20 to which water to be treated is supplied. The inlet pipe 21 is provided for distributing the water to be treated to each reaction tank 20 , and the inlet of each reaction tank 20 is connected to the end of the inlet pipe 21 through a valve 23 . The valve 23 controls the supply of water to be treated to the corresponding reaction tank 20 . A urea decomposition agent, which is an aqueous solution containing sodium bromide and sodium hypochlorite, is injected into the inlet pipe 21 . The configuration for injecting and adding the urea decomposing agent to the water to be treated in this manner constitutes adding means. A line mixer 22 for making the concentration of the urea decomposing agent uniform in the water to be treated is provided at a position on the downstream side of the injection position of the urea decomposing agent in the inlet pipe 21 . By providing the line mixer 22, the concentration of the urea decomposing agent in the water to be treated becomes uniform when it flows into the reaction tank 20. Instead of the line mixer 22, a stirrer, a submersible pump, an aerator, or the like may be used to make the concentration of the urea decomposing agent in the water to be treated uniform.

The outlet of each reaction tank 20 is connected to an outlet pipe 25 through a valve 24 . The valve 24 controls the discharge from the reaction tank 20 of the treated water obtained by causing the urea decomposing agent to decompose urea in the water to be treated in the reaction tank 20 . Treated water from each reaction tank 20 is discharged to the outside of the treatment apparatus 10 through an outlet pipe 25 .

In the treatment apparatus 10 of the present embodiment, the valves 23 and 24 are operated to receive the water to be treated in at least one of the plurality of reaction tanks 20, except for the reaction tank 20 that receives the water to be treated. The treated water is discharged from at least one reaction tank 20, and when the discharge of the treated water is completed, the reaction tank 20 for receiving the water to be treated and the reaction tank 20 for discharging the treated water are alternated by rotation. Since the reaction tank 20 that discharges the treated water is alternated by rotation, the treated water is continuously discharged at a predetermined flow rate through the outlet pipe 25 even if the batch type treatment is performed in each reaction tank 20. can do.

When the urea decomposition reaction is performed batchwise in the reaction tank 20, the reaction tank 20 sequentially performs three steps of receiving the water to be treated, progressing the urea decomposition reaction, and discharging the treated water. . For example, when three reaction vessels 20 A to C are arranged in parallel, the water to be treated is received in the reaction vessel 20 A (that is, the water to be treated is charged), and at the same time, the reaction vessel B In 20, the urea decomposition reaction proceeds, the treated water is discharged in the reaction tank 20 of C, and when the discharge of the treated water from the reaction tank 20 of C is completed, the water to be treated is received in the reaction tank 20 of C. , and the urea decomposition reaction is allowed to proceed in the reaction tanks 20 of A, and the treated water is discharged from the reaction tank 20 of B. Furthermore, when the discharge of the treated water from the reaction tank 20 of B is completed, the water to be treated is received in the reaction tank 20 of B, the urea decomposition reaction is allowed to proceed in the reaction tank 20 of C, and from the reaction tank 20 of A Discharge the treated water. After that, the operation by this rotation is repeated. Each reaction tank 20 repeats the operation of receiving the water to be treated → urea decomposition reaction → discharging the treated water → receiving the water to be treated → . By shifting the rotation operation, it is possible to continuously receive the water to be treated and continuously discharge the treated water while executing the batch-type urea decomposition treatment. If the number of reaction tanks 20 provided in parallel is four or more, the urea decomposition reaction occurs in two or more reaction tanks 20 excluding the reaction tank 20 for receiving the water to be treated and the reaction tank 20 used for discharging the treated water. can be advanced, and the proportion of the urea decomposition reaction in the repetition period of the operation in each reaction tank 20 can be increased, and the efficiency of utilization of the reaction tank 20 is increased accordingly, so that the entire processing apparatus 10 The volume of the reaction vessel 20 can be reduced at .

In this embodiment, the number of reaction vessels 20 arranged in parallel can be two. In this case, for example, the water to be treated is supplied to one of the reaction tanks 20 in a short period of time, then the urea decomposition reaction proceeds in the reaction tank 20, and the treated water is continuously supplied from the other reaction tank 20. After draining and draining of treated water from the other reactor 20, the functions of both reactors 20 can be switched. In this case, the treated water can be discharged continuously, but the water to be treated cannot be received continuously. Alternatively, the water to be treated is continuously received in one reaction tank 20, the decomposition reaction of urea is allowed to proceed in the other reaction tank 20, and as soon as the decomposition reaction of urea is completed, the treated water is discharged in a short time, and the water to be treated is discharged. After receiving water and discharging treated water, the functions of both reactors 20 can be switched. In this case, the water to be treated can be continuously received, but the treated water cannot be discharged continuously.

In the example shown in FIG. 1, the inlet pipe 21 is provided with the line mixer 22, but instead of providing the line mixer 22, each reaction tank 20 may be provided with a stirring mechanism such as a stirrer, a submersible pump, or an aerator. good. 1, the urea decomposition agent is added to the water to be treated through the inlet pipe 21, but it is also possible to add the urea decomposition agent to each reaction vessel 20 instead of the inlet pipe 21. FIG. When adding the urea decomposition agent to the reaction tank 20, for example, when adding the urea decomposition agent to the same reaction tank 20 while injecting the water to be treated into the reaction tank 20, a semi-batch type (semi-batch type) is used. Since the urea decomposition treatment is performed, it is essential to provide the reaction tank 20 with a stirring mechanism. When performing a semi-batch type treatment in which the urea decomposition reaction proceeds while charging the water to be treated into the reaction tank 20, by changing the charging time of the water to be treated, the starting time of charging the water to be treated is used as a starting point. The reaction time required to reduce the urea concentration in the treated water to a predetermined value or less changes. Therefore, based on the performance of the pump used to supply the water to be treated to the reaction tank 20 and the reaction time, the numerical range of the charging time of the water to be treated can be determined.

It is known that the decomposition reaction of urea by hypobromous acid depends on the pH of the water to be treated, and the pH can be adjusted in the reaction tank 20 . Further, in the present embodiment, a circulation pipe for circulating the water in the reaction tank 20 is provided for each reaction tank 20, and a urea concentration meter is installed in the circulation pipe to monitor the urea concentration and treat the water from the reaction tank 20. You may make it determine the discharge|emission timing of water.

(Second embodiment)
FIG. 2 shows a processing apparatus according to a second embodiment of the invention. The processing apparatus 10 shown in FIG. 2 includes a plurality of reaction vessels 20 arranged in series, and is configured as a multi-stage complete mixing continuous reaction apparatus as a whole. In the figure, two reaction tanks 20 are provided in series, the inlet of the upstream reaction tank 20 is connected to an inlet pipe 21 for supplying water to be treated, and the outlet of the downstream reaction tank 20 is An outlet pipe 25 for discharging treated water is connected. Each reaction vessel 20 is provided with an addition means for injecting a urea decomposition agent, which is an aqueous solution containing sodium bromide and sodium hypochlorite, and is provided with a stirring mechanism (not shown). The stirring mechanism is composed of a stirrer, a submersible pump, an aerator, or the like.

When a plurality of reaction tanks 20 are provided in series, the urea concentration in the water in each reaction tank 20 is different for each reaction tank 20, so that a concentration gradient occurs when the treatment apparatus 10 is viewed as a whole, increasing the reaction rate. can be done. From that point of view, although two reaction vessels 20 are provided in series in the example shown in FIG. 2, it is more preferable to set the number of reaction vessels 20 provided in series to four or more.

In the processing apparatus 10 of the present embodiment, the amount of urea treatment agent to be injected into each reaction tank 20 can be changed for each reaction tank 20 . For example, the urea decomposition agent is always injected into the most upstream reaction tank 20 among the reaction tanks 20 connected in series, and the urea concentration in the water discharged from the most upstream reaction tank 20 is measured. When the urea concentration exceeds the specified value, the urea decomposition agent is also injected into the reaction tank 20 at the next stage, and depending on the situation, the injection rate of the urea decomposition agent is increased in the reaction tank 20 at the most upstream stage, When the urea concentration in the water discharged from the reaction tank 20 becomes equal to or less than the specified value, the injection of the urea decomposing agent in the next reaction tank 20 can be stopped. When the reaction tanks 20 are arranged in three or more stages, the urea concentration in the water discharged from each reaction tank 20 is measured to determine the injection amount of the urea decomposition agent in the front-stage reaction tank 20. It is also possible to automatically control the addition means of the reaction vessel 20 on the front stage side according to the determined injection amount.

(pure water production system)
The treatment device according to the invention can be used as a pretreatment device for pure water production. FIG. 3 shows a pure water production system incorporating a treatment device according to the invention. The illustrated pure water production system produces primary pure water from raw water. A treatment device 10 to which raw water discharged from a vessel 32 is supplied as water to be treated, a filter 33, an activated carbon device (ACF) 34, an ion exchange device 35, and a reverse osmosis membrane device (RO) 36. I have. As the processing device 10, for example, the processing device 10 shown in FIG. 1 or 2 is used. Filter 33 , activated carbon device 34 and ion exchange device 35 are connected in this order to the outlet of treatment device 10 . The ion exchange device 35 has a cation exchange resin tower (CER), a decarboxylation tower (DG) and an anion exchange resin tower (AER) arranged from the inlet side. The water discharged from the ion exchange device 35 is supplied to the upstream heat exchanger 31 and used as a heat source for raising the temperature of the raw water, and then supplied to the reverse osmosis membrane device 36 . Primary pure water is discharged from the reverse osmosis membrane device 36 . After all, in the pure water production system shown in FIG. 3, the treatment device 11 is provided as a pretreatment device for the pure water production device comprising the filter 33, the activated carbon device 34, the ion exchange device 35 and the reverse osmosis membrane device 36. It will be. Of course, the configuration of the pure water production device provided downstream of the processing device 10 is not limited to that shown in FIG.

The heat exchangers 31 and 32 will be explained. As will be apparent from the examples described later, the decomposition reaction of urea with hypobromous acid proceeds faster as the reaction temperature is raised. Therefore, the heat exchangers 31 and 32 are provided to heat the water to be treated. Water discharged from the ion exchange device 35 is supplied as a heat source to the heat exchanger 31 on the upstream side. The water discharged from the ion exchange device 35 is water obtained by passing the treated water from the treatment device 10 through the filter 33, the activated carbon device 34 and the ion exchange device 35, and is heated before the treatment device 10. However, it is difficult to raise the temperature of the water to be treated supplied to the treatment apparatus 10 to a predetermined temperature only by this. Therefore, a heat medium from a heat source having a higher temperature is supplied to the heat exchanger 32 on the downstream side. I am raising the temperature.

In the pure water production system shown in FIG. 3, the water discharged from the ion exchange device 35 and before being supplied to the reverse osmosis membrane device 36 is supplied to the heat exchanger 31 as a heat source. In which part of the pure water production apparatus provided in the subsequent stage, the water flowing through the heat exchanger 31 is supplied to the heat exchanger 31 can be appropriately determined according to the configuration of the pure water production apparatus. For example, when an activated carbon device is provided in the pure water production apparatus, if the water flowing downstream of the activated carbon device is supplied to the heat exchanger 31, the water supplied to the activated carbon device is in a heated state. Therefore, the activity of the biological activated carbon can be enhanced. Conversely, when water flowing upstream of the activated carbon device is supplied to the heat exchanger 31, the water temperature at the inlet of the activated carbon device is lowered, so the amount of adsorption in the activated carbon device can be increased. . In the case where a coagulation tank is provided in the pure water production apparatus, by supplying heated water discharged from the treatment apparatus 10 to the coagulation tank, poor coagulation due to low water temperature can be suppressed. can.

In a water purifier that produces pure water from raw water, it is common to place a tank for temporarily storing raw water at the inlet of the water purifier to smooth the supply of raw water to the water purifier. . In the pure water production system shown in FIG. 3, the reaction tank 20 in the treatment apparatus 10 also functions as a tank for temporarily storing raw water, so there is no need to provide a separate tank for temporarily storing raw water. .

The configuration in which the water to be treated is heated by the heat exchanger at the inlet of the treatment device 10 is also effective when the treatment device 10 is used alone, not as a pretreatment device in a pure water production system. In that case, in the treatment apparatus 10, a heat exchanger 31 for heating the water to be treated by the heat recovered from the treated water is provided in the piping for supplying the water to be treated to the plurality of reaction tanks 20, and the heat exchanger A heat exchanger 32 on the higher temperature side may be provided on the downstream side of 31 .

The present invention will be described in more detail below with reference to examples and comparative examples.

(Example 1)
A processing apparatus 10 as shown in FIG. 1 was assembled. The number of reaction tanks 20 arranged in parallel was three. Water having a urea concentration of 100 ppb is treated water, and a urea decomposing agent is added to the inlet pipe 21 so that the sodium bromide concentration in the treated water is 3 ppm and the sodium hypochlorite concentration is 3.5 ppm. was added to and mixed. The water to be treated to which the urea decomposing agent was added in this manner was supplied to one reaction tank 20, and the urea decomposition reaction was allowed to proceed under the conditions of pH 6.0 and temperature 22°C, and 2.3 hours elapsed. Afterwards, the urea concentration in the water in reactor 20 was less than 1 ppb. In addition, when three reaction tanks 20 were used to rotate the reception of the water to be treated, the progress of the urea decomposition reaction, and the discharge of the treated water, the water to be treated could be continuously received and treated continuously. I was able to get the water out. At this time, the hydraulic retention time (HRT) of the entire treatment apparatus 10 including the three reaction tanks 20 was 6.9 hours.

(Example 2)
A processing apparatus 10 shown in FIG. 2 was assembled. However, the number of reaction tanks 20 provided in series was four. Water to be treated containing 100 ppb of urea is supplied to the most upstream reaction tank 20, and each reaction tank 20 has a sodium bromide concentration of 3 ppm and a sodium hypochlorite concentration of 3.5 ppm in the water in the reaction tank 20. The urea decomposing agent was added so that Urea decomposition was carried out so that the pH in each reaction tank 20 was 6.0, the temperature was 22° C., and the total hydraulic retention time in the four reaction tanks 20 was 5 hours. The urea concentration in the treated water discharged from the reaction tank 20 was less than 1 ppb.

(Example 3)
Using the same treatment apparatus 10 as in Example 1, the water having a urea concentration of 100 ppb is used as the water to be treated. The urea decomposing agent was added to and mixed with the water to be treated so that The water to be treated to which the urea decomposing agent was added in this way was heated to 25° C. and supplied to one reaction tank 20, and then the urea decomposition reaction was allowed to proceed under the condition of pH 6.0. After a period of time, the urea concentration in the water in the reactor 20 was less than 1 ppb. The water to be treated was heated by installing a heat exchanger in the inlet pipe 21 and flowing a heat medium through the heat exchanger.

(Comparative example 1)
An eight-wall baffled reaction vessel 40 was assembled, the plan view of which is shown in FIG. Water with a urea concentration of 100 ppb was used as the water to be treated, and a ureolytic agent was added to and mixed with the water to be treated so that the sodium bromide concentration in the treated water was 3 ppm and the sodium hypochlorite concentration was 3.5 ppm. . The water to be treated to which the urea decomposing agent was added was passed through the reaction tank 40, and the urea decomposition reaction was carried out under the conditions of pH 6.0 and temperature of 22°C. The volume of the reaction tank 40 divided by the supply flow rate of the water to be treated was defined as the residence time RT, and the water to be treated was supplied to the reaction tank 40 so that RT was 5 hours. The urea concentration in the treated water discharged from tank 40 was 6 ppb. When the RT was allowed to be 7 hours, the urea concentration in the treated water discharged from the reactor 40 when steady state was reached was 2 ppb. When the RT was allowed to be 8 hours, the urea concentration in the treated water discharged from the reactor 40 was less than 1 ppb when steady state was reached.

Comparing Examples 1 and 2 with Comparative Example 1, the conditions for the urea decomposition reaction were the same, i.e., pH of 6 and temperature of 22° C., and the concentration of the urea decomposition agent was also the same. Comparing the HRT and RT until the urea concentration in the treated water as a whole is less than 1 ppb, the HRT was 6.9 hours in Example 1 and 5 hours in Example 2, whereas the HRT was 5 hours in Comparative Example 1 had an RT of 8.5 hours. A long HRT or RT means a correspondingly long residence time in the reactor. Assuming that the flow rate of the treated water is the same, the longer the residence time, the larger the total volume of the reaction tank. It can be seen that the volume of the reaction tank can be reduced.

(Example 4)
Urea was decomposed in the same manner as in Example 3 except that the urea decomposition reaction was carried out at a temperature of 10° C. without heating the water to be treated. As a result, after 12 hours had passed, the urea concentration in the water in the reaction tank 20 was less than 1 ppb. The time required for the urea decomposition reaction is longer than in Example 3, and this is considered to be due to the low reaction temperature. It was found that heating can accelerate the decomposition reaction of urea. That is, in the treatment apparatus 10 of the first and second embodiments, by arranging a heat exchanger in the inlet pipe 21 to heat the water to be treated, even if the residence time is shortened, the volume of the reaction vessel 20 is reduced. It was found that the urea can be degraded to a sufficiently low urea concentration even if the is made smaller.

10 treatment device 20, 40 reaction tank 21 inlet pipe 22 line mixer 23, 24 valve 25 outlet pipe 31, 32 heat exchanger 33 filter 34 activated carbon device 35 ion exchange device 36 reverse osmosis membrane device

Claims (9)

A treatment apparatus that receives water to be treated, decomposes urea contained in the water to be treated, and discharges treated water,
addition means for adding a bromide salt and a hypochlorite as a ureolytic agent to the water to be treated;
a plurality of reaction tanks for advancing the decomposition reaction of urea by the urea decomposing agent;
A processing device comprising: 2. The processing apparatus according to claim 1, wherein said plurality of reaction vessels are provided in series, and said adding means is provided for each of said reaction vessels. The plurality of reaction vessels are provided in parallel, and the water to be treated is distributed to the plurality of reaction vessels from an inlet pipe provided in common to the plurality of reaction vessels,
While receiving the water to be treated in at least one of the reaction tanks, discharging the water to be treated from at least one of the reaction tanks other than the reaction tank receiving the water to be treated;
discharging the treated water from the reaction tank when the decomposition reaction is completed in the reaction tank receiving the water to be treated;
2. The treatment apparatus according to claim 1, wherein the reaction tank from which the treated water has been discharged is then used for receiving the water to be treated. 4. The treatment apparatus according to claim 3, wherein said inlet pipe is provided with said adding means, and said inlet pipe is provided with a mechanism for uniformizing the concentration of said urea decomposing agent in said water to be treated. 4. The processing apparatus according to any one of claims 1 to 3, wherein each of said plurality of reaction vessels is equipped with a stirring mechanism. 6. A treatment apparatus according to any preceding claim, wherein the hypochlorite is sodium hypochlorite and the bromide salt is sodium bromide. 7. The piping for supplying the water to be treated to the plurality of reaction tanks is provided with a heat exchanger for heating the water to be treated by heat recovered from the water to be treated. The processing device according to . A pure water production system comprising at least an ion exchange device and a reverse osmosis device supplied with water that has passed through the ion exchange device,
A pure water production system comprising the treatment apparatus according to any one of claims 1 to 6 as a pretreatment apparatus. A pure water production system comprising at least an ion exchange device and a reverse osmosis device supplied with water that has passed through the ion exchange device,
The treatment apparatus according to claim 7 is provided as a pretreatment apparatus, and the water passing through the ion exchange apparatus and before being supplied to the reverse osmosis apparatus is the heat source for heating the water to be treated. A pure water production system that feeds the exchanger.

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