JP2016065787A - Contaminated water treatment method and contaminated water treatment system - Google Patents

Abstract

Disclosed is a method for treating contaminated water that can selectively remove strontium from contaminated water containing radioactive strontium and alkaline earth metals other than strontium.
The method includes a step of supplying contaminated water containing radioactive strontium and an alkaline earth metal other than strontium to a movable adsorption unit 30, and the adsorption unit is filled with an adsorbent that selectively adsorbs strontium. A plurality of adsorption towers 32a to 32c.
[Selection] Figure 1

Description

  The present invention relates to a contaminated water treatment method and a contaminated water treatment system.

  Contaminated water containing radioactive elements such as radioactive cesium and radioactive strontium is not allowed to be discharged unless the radioactive elements are removed in order to prevent environmental destruction. Conventional treatment methods for radioactive element-containing contaminated water include a step of removing radioactive cesium and non-radioactive isotopes by SARRY (Simplely Activated Water Retrieve and Recovery System) and iron coprecipitation treatment. Radioactive strontium by removing alpha nuclide (alpha decaying nuclear material), removing alkaline earth metals such as calcium and magnesium by carbonate precipitation treatment, and adsorption treatment using adsorption tower packed with adsorbent And a step of removing remaining radioactive elements such as radioactive iodine, radioactive cesium, and radioactive antimony.

  By the way, among radioactive elements, strontium is classified as an alkaline earth metal and has properties similar to those of an alkaline earth metal other than strontium such as calcium. For this reason, since strontium precipitates with alkaline earth metals other than strontium in the carbonate precipitation treatment, the separated precipitate contains radioactive strontium. Therefore, both the iron hydroxide slurry separated by the iron coprecipitation treatment and the carbonate slurry separated by the carbonate precipitation treatment contain radioactive elements, so that they are sealed in a predetermined container as final radioactive waste. Need to be disposed of. As a result, a large amount of radioactive waste is discharged in the conventional method for treating contaminated water containing radioactive substances.

  Here, in order to reduce the slurry-like radioactive waste as described above, an adsorbent for strontium that selectively adsorbs strontium (including non-radioactive isotopes) without using a carbonate precipitation treatment is used. It has also been proposed to remove radioactive strontium (Japanese Patent No. 5073111). However, radioactive element-containing contaminated water may contain suspended solids (SS) or oil. In many cases, suspended solids and oil cannot be completely removed by iron coprecipitation treatment, and adhere to the adsorbent for strontium, thus reducing the performance (water flow capacity) of the adsorbent. For this reason, when using the adsorbent for strontium, the adsorption tower filled with the adsorbent must be frequently replaced, and the operation rate may be lowered.

Japanese Patent No. 5073111

  In view of the above disadvantages, the present invention provides a contaminated water treatment method and a contaminated water treatment system that can selectively remove strontium from contaminated water containing radioactive strontium and alkaline earth metals other than strontium. Is an issue.

  The invention made to solve the above-mentioned problems is a contaminated water treatment method for removing the radioactive strontium from the contaminated water containing radioactive strontium and an alkaline earth metal other than strontium, the contaminated water being movable A step of supplying to the adsorption unit, the adsorption unit having a plurality of adsorption towers filled with an adsorbent that selectively adsorbs strontium.

  In the contaminated water treatment method, radioactive strontium can be removed by using an adsorbent that selectively adsorbs strontium without going through a step of removing an alkaline earth metal other than strontium. For this reason, since the contaminated water treatment method does not discharge alkaline earth metal waste containing radioactive elements, the total amount of radioactive waste to be finally disposed of can be suppressed. Moreover, since the said contaminated water treatment method uses the adsorption | suction unit which has a some adsorption tower, discharge | emission of a radioactive waste can be suppressed also by being able to utilize effectively the adsorption agent with which each adsorption tower was filled. Further, since the contaminated water treatment method uses a movable adsorption unit, a contaminated water treatment system including the adsorption unit can be easily installed and removed in the vicinity of the water tank storing the contaminated water, and the adsorption unit can be easily removed. Since it can be exchanged, the operation rate of contaminated water treatment can be increased.

  The treated water discharged from the adsorption unit may be returned to the water tank in which the contaminated water is stored. In this way, by treating the treated water back to the contaminated water tank, the contaminated water treatment method can reduce the degree of contamination by radioactive elements in the tank that stores the treated water, and the maintenance, dismantling, and removal of the tank. Dyeing becomes easy. Moreover, it is not necessary to install another water tank which receives treated water by recirculating treated water, and does not expand pollution.

  The plurality of adsorption towers may be connected in series. Thus, if the adsorption towers are connected in series, the radioactive strontium removal rate can be increased by removing the radioactive strontium from the treated water step by step.

  A step of removing the most upstream adsorption tower and adding a new adsorption tower on the most downstream side may be further provided. In this way, by removing the most upstream adsorption tower and adding a new adsorption tower on the most downstream side, an adsorption tower with sufficient adsorption capacity is placed on the downstream side to back up a relatively old adsorption tower on the upstream side. By doing so, removal of radioactive strontium can be ensured, so that the adsorption capacity of the adsorbent in the adsorption tower on the upstream side can be used up.

  The contaminated water may further include a step of removing a radioactive element other than the radioactive strontium in the treated water discharged from the adsorption unit with an adsorbent, further including a radioactive element other than radioactive strontium. Thus, removal of radioactive elements can be made more complete by providing a post-process for removing radioactive elements other than radioactive strontium remaining in the treated water.

  The adsorption tower may be further filled with an adsorbent that selectively adsorbs cesium. In this way, the removal of radioactive elements can be made more complete by removing cesium (radioactive cesium and non-radioactive isotopes) remaining after treatment with SARRY (simple contaminated water treatment system) in the adsorption tower of the adsorption unit. can do.

  The contaminated water may further include suspended solids or oil, and the adsorption tower may be filled with a filter medium that filters the suspended solids or oil. In this way, by filling the adsorption tower with the filter medium, it is possible to prevent suspended substances and oils from hindering the function of the post-process.

  Another invention made to solve the above problems is a contaminated water treatment system for removing radioactive strontium from contaminated water containing radioactive strontium and alkaline earth metals other than radioactive strontium, The adsorption unit includes a plurality of adsorption towers that are filled with an adsorbent that selectively adsorbs strontium.

  The contaminated water treatment system does not need to remove alkaline earth metals other than strontium by using an adsorbent that selectively adsorbs strontium. For this reason, since the contaminated water treatment system does not discharge alkaline earth metal waste containing radioactive elements, the total amount of radioactive waste to be finally disposed of can be suppressed. In addition, the contaminated water treatment system can suppress the amount of radioactive waste to be finally disposed of by efficiently using a plurality of adsorption units. Furthermore, since the contaminated water treatment system includes a movable adsorption unit, installation and removal and replacement of the adsorption unit are easy, so that the operating rate can be increased.

  A movable pump unit having a pump for supplying contaminated water to the plurality of adsorption towers and a self-propelled carriage on which the pump is mounted may be further provided. Thus, by having a movable pump unit, it is easy to install and remove the pump unit in the vicinity of the water tank that stores the contaminated water, similar to the adsorption unit. As a result, the operating rate of the contaminated water treatment system can be increased.

  In the contaminated water treatment method and the contaminated water treatment system of the present invention, the use of an adsorbent that selectively adsorbs strontium eliminates the need to remove alkaline earth metals other than strontium, thereby reducing the total amount of radioactive waste. it can. In addition, since the contaminated water treatment method and the contaminated water treatment system use a movable adsorption unit, the adsorption unit can be easily installed, removed, and replaced, and the operation rate of the contaminated water treatment can be increased.

It is a process flow figure showing the composition of the contaminated water treatment system of one embodiment of the present invention. It is a process flow figure which shows the connection of the adsorption | suction unit of the contaminated water processing system of FIG. It is a flowchart which shows the procedure of the contaminated water processing method of one Embodiment of this invention. It is a process flow figure which shows the structure of the contaminated water treatment system of embodiment different from FIG. It is a process flow figure which shows the valve pattern of the adsorption | suction unit of the contaminated water processing system of FIG. It is a process flow figure which shows the valve pattern at the time of adsorption tower replacement | exchange of the adsorption | suction unit of the contaminated water processing system of FIG. It is a process flow figure showing the next valve pattern of Drawing 5B of the adsorption unit of the contaminated water treatment system of Drawing 4.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

[First embodiment]
The contaminated water treatment system of FIG. 1 includes a raw water tank 10, a movable pump unit 20, a movable adsorption unit 30, and a treated water tank 40 that stores treated water discharged from the adsorption unit 30. The raw water tank 10, the pump unit 20, the adsorption unit 30, and the treated water tank 40 are connected via a pipe constituting the flow path.

<Raw water tank>
The raw water tank 10 is subjected to a primary treatment for removing radioactive cesium by SARRY (simple type contaminated water treatment system) and a secondary treatment for removing organic matter and α-nuclide by iron coprecipitation treatment. Water (hereinafter simply referred to as contaminated water) is stored.

  The contaminated water treatment system is a tertiary treatment that mainly removes radioactive strontium from contaminated water containing radioactive strontium and alkaline earth metals other than strontium without removing alkaline earth metal by treatment such as carbonate precipitation treatment. It is a system for performing.

  As the contaminated raw water, for example, cooling water leaked from the reactor, groundwater, seawater mixed with various foreign substances, radioactive elements such as radioactive strontium and radioactive cesium, and radioactive strontium such as calcium and magnesium A thing containing alkaline earth metal, suspended solids (SS), such as organic matter, and oil is assumed.

  Such a raw water tank 10 may be provided with a large number of, for example, a capacity of 1000 kL or more when the amount of contaminated raw water is large.

<Pump unit>
The pump unit 20 includes one or a plurality of water supply pumps 21 for sending contaminated water from the raw water tank 10 and a self-propelled carriage (automobile) 22 on which the one or a plurality of water supply pumps 21 are placed. Moreover, the pump unit 20 may have an engine, a generator, etc. for driving the feed water pump 21, and may receive supply of electric power from the outside. The type of the water supply pump 21 is not particularly limited, but is preferably a completely sealed pump that does not leak contaminated water to the outside. A plurality of pump units 20 may be connected in parallel.

<Suction unit>
The adsorption unit 30 includes a dolly (automobile) 31 that can be self-propelled and three adsorption towers 32 a, 32 b, and 32 c that are arranged on the dolly 31. The adsorption towers 32a, 32b, and 32c are filled with a strontium adsorbent that selectively adsorbs strontium. A plurality of suction units 30 may be connected in parallel or in series.

(Adsorbent for strontium)
As the adsorbent for strontium, for example, a capsule adsorbent that has a film that does not transmit calcium and magnesium but selectively transmits strontium on the surface and has an inorganic material that adsorbs strontium inside can be used.

  Examples of the membrane that selectively permeates strontium include a calcium alginate membrane.

  Examples of the inorganic material that adsorbs strontium include A-type zeolite and X-type zeolite.

  Such an adsorbent for strontium is preferably supported on a porous body that also functions as a filter medium for filtering out suspended substances and oil. Examples of such a carrier include activated carbon and zeolite.

  In addition, the adsorption towers 32a, 32b, and 32c may be filled with a filter medium that filters out floating substances and oil components, in addition to the adsorbent support for strontium.

  Further, the adsorption towers 32a, 32b, and 32c are preferably filled with a cesium adsorbent that selectively adsorbs cesium in addition to the strontium adsorbent.

  Examples of the adsorbent for cesium include zeolite and metal ferrocyanide compounds. Zeolite is not particularly high in cesium selectivity, but is suitable because it can adsorb other radioactive elements and functions as the carrier and the filter medium. In addition, since the metal ferrocyanide compound has a high cesium adsorption effect in salt water, it is particularly effective when the contaminated water contains seawater or the like. Examples of the ferrocyanide compound include ferric ferrocyanide, cobalt ferrocyanide, nickel ferrocyanide, and the like, and iron ferrocyanide having excellent radiocesium adsorption ability is particularly preferable.

  In the adsorption unit 30, the adsorption towers 32a, 32b, and 32c are connected, for example, as shown in FIG. The adsorption towers 32a, 32b, 32c have water supply three-way valves 33a, 33b, 33c on the water supply side and drain three-way valves 34a, 34b, 34c on the water discharge side.

  A supply flow path (pipe) 35 to which contaminated water is supplied from the pump unit 20 is connected to one port of each of the water supply three-way valves 33a, 33b, and 33c. In addition, one port of each drainage three-way valve 34 a, 34 b, 34 c is connected to the treated water tank 40 via a discharge channel (pipe) 36. On the other hand, the other port of the discharge three-way valve 34a of the first adsorption tower 32a is connected to the other port of the water supply three-way valve 33b of the second adsorption tower 32b via the first intermediate flow path 37a. . The other port of the discharge three-way valve 34b of the second adsorption tower 32b is connected to another port of the water supply three-way valve 33c of the third adsorption tower 32c via the second intermediate flow path 37b. . The other port of the discharge three-way valve 34c of the third adsorption tower 32c is connected to the other port of the water supply three-way valve 33a of the first adsorption tower 32a via the third intermediate flow path 37c. .

<Treatment water tank>
The treated water tank 40 is a water tank that stores treated water discharged from the adsorption unit 30. As this treated water tank 40, a new tank that has not been used for storing contaminated water, a tank decontaminated after discharge of contaminated water, or a contaminated water sufficiently stored in the raw water tank 10 is used. Tanks storing contaminated water with low content are used.

  The treated water stored in the treated water tank 40 is, for example, after it is confirmed that no radioactive element remains, or after the remaining radioactive element is removed in the next treatment step of removing the remaining radioactive element, for example, Released into the ocean.

[Contaminated water treatment method]
From this, the contaminated water processing method using the contaminated water processing system of FIG. 1 is demonstrated.

  As shown in FIG. 3, the contaminated water treatment method includes a cesium removal step by SARRY (step S1), an organic matter and α nuclide removal step by iron coprecipitation treatment (step S2), and strontium removal by the contaminated water treatment system. A process (step S3) and the residual radioactive element removal process (step S4) by adsorption processing are provided.

<Cesium removal process>
In the cesium removal process of step S1, radioactive cesium (and non-radioactive isotopes) are adsorbed and removed from the contaminated raw water by SARRY. Since SARRY is publicly known, detailed description thereof is omitted. The intermediate polluted water from which radioactive cesium has been removed at least partially in the cesium removing step is stored in a water tank (not shown).

<Organic substance and α nuclide removal process>
In the organic matter and α nuclide removal step of step S2, the organic matter and α nuclide are precipitated and removed by iron coprecipitation treatment. Since the iron coprecipitation process is known, a detailed description thereof will be omitted. The intermediate polluted water from which the organic matter and α nuclide have been further removed in the organic matter and α nuclide removal step is stored in the raw water tank 10 of FIG.

<Strontium removal process>
The strontium removal process of step S3 includes a process of assembling the contaminated water treatment system, a process of supplying contaminated water to the adsorption towers 32a, 32b, and 32c of the adsorption unit 30, and a radiation dose of the treated water discharged. And the step of replacing the adsorption unit 30 and the step of removing the contaminated water treatment system.

(Assembly process)
In assembling the contaminated water treatment system, first, the carriage 22 of the pump unit 20 and the carriage 31 of the adsorption unit 30 are self-propelled, and the pump unit 20 and the adsorption unit 30 are parked in the vicinity of the raw water tank 10. Next, piping between the raw water tank 10 and the pump unit 20, between the pump unit 20 and the adsorption unit 30, and between the adsorption unit 30 and the treated water tank 40 is connected.

(Contaminated water supply process)
In the contaminated water supply step, the water supply pump 21 of the pump unit 20 is driven to extract the contaminated water from the raw water tank 10 and supply it to the adsorption towers 32a, 32b, 32c of the adsorption unit 30. For example, when the radioactivity concentration in the raw water tank 10 is about 100,000 becquerels, it is considered that the radioactivity concentration of the treated water discharged from the adsorption unit 30 is 100 becquerels or less in this strontium removal step.

(Suction unit replacement process)
Further, in the contaminated water treatment method, the treatment flow rate of the contaminated water treatment system is monitored, and the treated water is periodically sampled from the discharge flow path 36 to measure the radiation amount of the treated water. When the treatment flow rate becomes equal to or lower than the predetermined lower limit value and when the radiation amount of the treated water becomes equal to or higher than the predetermined upper limit value, the drive of the water supply pump 21 is interrupted and the adsorption unit 30 is replaced with a new one. Exchange. The upper limit value of the radiation dose is set to a sufficiently low value in consideration of the sampling interval and the time required for measuring the radiation dose.

  In order to replace the adsorption unit 30, the old adsorption unit 30 is self-propelled and removed from the wastewater treatment system, and thereby the new adsorption unit 30 is self-propelled and arranged in an empty space. Moreover, you may move to the place which processes a radioactive waste by making the old adsorption | suction unit 30 removed self-propelled as it is.

(Removal process)
If all the contaminated water in the raw water tank 10 can be treated, each pipe between the raw water tank 10 and the pump unit 20, between the pump unit 20 and the adsorption unit 30, and between the adsorption unit 30 and the treated water tank 40. And the pump unit 20 and the adsorption unit 30 are self-propelled to remove the contaminated water treatment system.

  Moreover, the contaminated water treatment system which makes the removed pump unit 20 and adsorption | suction unit 30 self-propelled, moves to the vicinity of another raw water tank 10, and removes radioactive strontium from the contaminated water stored in another raw water tank 10. May be used to assemble.

<Residual radioactive element removal process>
In the residual radioactive element removal step of step S4, the residual radioactive element is removed from the treated water stored in the treated water tank 40 using an adsorbent that adsorbs the radioactive element. Since the conditions of the residual radioactive element removing step such as the adsorbent to be used are known, a detailed description is omitted. Note that this residual radioactive element removal step may be omitted when the cesium removal step in Step S1, the organic matter and α-nuclide removal step in Step S2, and the strontium removal step in Step S3 are sufficiently high.

<Advantages>
In the contaminated water treatment method, strontium in the treated water is selectively adsorbed in the adsorption towers 32a, 32b, and 32c of the contaminated water treatment system without performing pretreatment such as carbonate precipitation treatment on the treated water. The radioactive strontium can be removed from the treated water without producing sludge as radioactive waste.

  In the contaminated water treatment system, the pump unit 20 and the adsorption unit 30 can be self-propelled, so that heavy equipment such as a crane truck is not required for assembly and removal of the contaminated water treatment system and replacement of the adsorption unit 30. . For this reason, the contaminated water treatment system has a short downtime and a high operating rate.

  In the contaminated water treatment system, the adsorption towers 32a, 32b, and 32c are filled with an adsorbent that selectively adsorbs strontium, so that even if calcium or magnesium is present in the contaminated water, radioactive strontium (and (Non-radioactive isotopes) can be removed efficiently. As a result, the contaminated water treatment system does not require the removal of alkaline earth metal by the carbonate precipitation treatment, so the carbonate slurry containing radioactive elements is not discharged, and the amount of radioactive waste to be disposed of is reduced. Can be reduced.

  In the contaminated water treatment system, suspended substances and oil in the contaminated water can also be removed by filling the adsorption towers 32a, 32b, and 32c with a filter medium. For this reason, radioactive elements remaining in the next step can be easily removed.

  In the contaminated water treatment system, the adsorption towers 32a, 32b, and 32c are also filled with a cesium adsorbent, so that radioactive cesium that cannot be completely removed by SARRY but remains in the contaminated water can also be removed. Thereby, the load of SARRY can be reduced.

  In particular, since radioactive cesium is a radioactive element that emits γ-rays, if it remains in the treated water, the γ-rays leak to the outside of the water tank that stores the treated water, and thus it is desirable to remove them completely. Therefore, it is preferable that the contaminated water treatment system also has a radioactive cesium removal capability. Thus, leakage of radiation from the treated water tank can be prevented by removing radioactive cesium and radioactive strontium by the contaminated water treatment system. For this reason, even if the treated water of the contaminated water treatment system is stored in a treated water tank, the risk associated with radioactivity is relatively small, so the final treatment can be delayed.

  Moreover, in the said contaminated water treatment system, the radioactive element density | concentration of the treated water tank 40 can be made low enough. Thereby, when this treated water tank 40 is disassembled and decontaminated in the future, the operation becomes easy.

[Second Embodiment]
The contaminated water treatment system of FIG. 4 includes a movable pump unit 20 that sends out contaminated water from the raw water tank 10, and a movable adsorption unit 30 that is supplied with contaminated water by the pump unit 20. The discharged treated water is returned to the raw water tank 10.

  In the contaminated water treatment system of FIG. 4, the configurations of the raw water tank 10, the pump unit 20, and the adsorption unit 30 are the same as the configurations of the raw water tank 10, the pump unit 20, and the adsorption unit 30 in the contaminated water treatment system of FIG. The overlapping description is omitted.

[Contaminated water treatment method]
The contaminated water treatment method using the contaminated water treatment system of FIG. 4 is also based on a cesium removal step by SARRY, an organic matter and α nuclide removal step by iron coprecipitation treatment, a strontium removal step by the contaminated water treatment system, and an adsorption treatment. And a residual radioactive element removing step.

  Since this contaminated water treatment method is different from the contaminated water treatment method of FIG. 3 only in the strontium removal step, the description of the cesium removal step, the organic matter and α-nuclide removal step, and the residual radioactive element removal step is omitted.

<Strontium removal process>
The strontium removal step by the contaminated water treatment system of FIG. 4 is connected to the most upstream of the step of assembling the contaminated water treatment system, the step of supplying the contaminated water to the adsorption unit 30, and the adsorption towers 32a, 32b, 32c. And removing a contaminated water treatment system, and removing a contaminated water treatment system.

(Assembly process)
In the assembly of the contaminated water treatment system, first, the carriage 22 of the pump unit 20 and the carriage 31 of the adsorption unit 30 are self-propelled, and the pump unit 20 and the adsorption unit 30 are parked in the vicinity of the raw water tank 10. Next, pipes between the raw water tank 10 and the pump unit 20, between the pump unit 20 and the adsorption unit 30, and between the adsorption unit 30 and the raw water tank 10 are connected.

(Contaminated water supply process)
In the contaminated water supply step, the water supply pump 21 of the pump unit 20 is driven to extract the contaminated water from the raw water tank 10 and supply it to the adsorption towers 32a, 32b, 32c of the adsorption unit 30.

(Adsorption tower removal and additional process)
In this step, one of the adsorption towers 32a, 32b, and 32c is exchanged according to the procedure shown in FIGS. 5A to 5C.

  In the contaminated water treatment method, the treatment flow rate of the contaminated water treatment system is monitored, and the treated water is periodically sampled from the discharge flow path 36 to measure the radiation amount of the treated water. When the treatment flow rate becomes equal to or lower than the predetermined lower limit value and when the radiation amount of the treated water becomes equal to or higher than the predetermined upper limit value, the adsorption tower connected to the most upstream is removed, and a new adsorption is arranged at the most downstream side. Add a tower.

  FIG. 5A shows a state in which the contaminated water first passes through the first adsorption tower 32a, then the second adsorption tower 32b, and finally the third adsorption tower 32c. 5A to 5C schematically show the states of the adsorbents in the adsorption towers 32a, 32b, and 32c, so that the higher the saturation of the internal adsorbent, the more closely hatched.

  In the adsorption towers 32a, 32b, and 32c, the internal adsorbent adsorbs strontium, and this adsorbent is gradually saturated from the upstream side. When the radiation dose of the treated water in the discharge channel 36 reaches the upper limit, as shown in FIG. 5A, it is considered that the adsorbent of the adsorption tower 32a connected to the uppermost stream is completely saturated. The downstream adsorption towers 32b and 32c are not completely saturated, leaving a surplus in strontium adsorption capacity.

  Therefore, as shown in FIG. 5B, the feed water three-way valve 33a and the drainage three-way valve 34a of the adsorption tower 32a connected to the uppermost stream are shut off, and the supply channel 35 side of the feed water three-way valve 33b of the second adsorption tower 32b. And the flow path configuration is changed so that the contaminated water passes only through the two adsorption towers 32b and 32c other than the first. In this state, the saturated adsorption tower 32a is replaced with a new adsorption tower.

  Here, as shown in FIG. 5C, a valve pattern is selected such that the newly attached adsorption tower 32a is added to the most downstream side. Thus, the adsorption towers 32a, 32b, and 32c are connected in such an order that the degree of saturation is lower on the downstream side and the remaining capacity of the adsorption capacity is larger.

  Thereafter, every time the adsorption tower connected to the uppermost stream is saturated, the adsorption tower connected to the uppermost stream is sequentially removed and a new adsorption tower is added to the lowermost stream.

  As described above, in the contaminated water treatment system of FIG. 4, one of the adsorption towers 32a, 32b, and 32c is replaced while continuing the treatment of the contaminated water.

(Removal process)
In the contaminated water treatment system of FIG. 4, if the radioactive strontium concentration or radioactivity concentration of the contaminated water stored in the raw water tank 10 is measured and it is determined that the radioactive strontium in the contaminated water has been sufficiently removed, the raw water tank 10 and the pump unit 20, the pipes between the pump unit 20 and the adsorption unit 30 and between the adsorption unit 30 and the treated water tank 40 are removed, and the pump unit 20 and the adsorption unit 30 are allowed to self-run to cause the contaminated water treatment system. To remove.

<Advantages>
4 returns the treated water from the adsorption unit 30 to the raw water tank 10, so that the contaminated water is repeatedly supplied to the adsorption unit 30 and stored in the raw water tank 10 gradually. To lower. That is, the contaminated water treatment system does not need to have a constant radioactive strontium concentration of treated water discharged from the adsorption unit 30, and takes time even if the adsorption towers 32a, 32b, and 32c have low strontium adsorption capacity. The radioactive strontium concentration of contaminated water can be reduced to the target concentration.

  Therefore, the contaminated water treatment system of FIG. 4 can continue to operate even if the adsorption capacity of the adsorption towers 32a, 32b, and 32c decreases, so that the adsorption towers 32a, 32b, The useful life of 32c can be extended. Moreover, in the contaminated water treatment system of FIG. 4, when the lifetime of the adsorption towers 32a, 32b, and 32c is set to be the same as that of the contaminated water treatment system of FIG. 1, the capacity of the adsorption towers 32a, 32b, and 32c can be reduced. As a result, the contaminated water treatment system of FIG. 4 requires less total amount of adsorbent than the contaminated water treatment system of FIG.

  Moreover, since the contaminated water treatment system of FIG. 4 recirculates treated water to the raw water tank 10, it does not require a water tank in addition to the raw water tank 10, and does not contaminate another water tank.

  Moreover, in the said contaminated water processing method, since the radioactive strontium density | concentration of the raw | natural water tank 10 is reduced, after discharging a contaminated water from the raw | natural water tank 10 after a strontium removal process, the radioactive density | concentration of the raw | natural water tank 10 remaining becomes low. For this reason, maintenance, dismantling, decontamination and the like of the raw water tank 10 are facilitated.

  Further, in the contaminated water treatment method, it is not necessary to interrupt the strontium removal process for replacement of the adsorption towers 32a, 32b, and 32c, so that the operating rate can be further improved.

[Other Embodiments]
The said embodiment does not limit the structure of this invention. Therefore, in the above-described embodiment, the components of each part of the above-described embodiment can be omitted, replaced, or added based on the description of the present specification and the common general knowledge, and they are all interpreted as belonging to the scope of the present invention. Should.

  The adsorption unit of the contaminated water treatment system may be movable and may not have a self-propelled ability. Examples of the movable suction unit having no self-propelled ability include a unit that is pulled by another automobile or the like, and a unit that can be transported by a forklift or the like.

  For example, the number of adsorption towers is not limited to three and can be any number of two or more.

  In the contaminated water treatment method, when there are few suspended solids in the treated water and there is no risk of clogging, monitoring of the treatment flow rate of the contaminated water treatment system may be omitted.

  Further, the saturation of the adsorbent filled in the adsorption tower may be determined for each adsorption tower by measuring the radiation dose of the treated water discharged from each adsorption tower in an intermediate flow path or the like. In addition, the saturation of the adsorbent packed in the adsorption tower is not only the measurement of radiation dose, but also the values of strontium concentration, radioactivity concentration, metal ion concentration, etc. of treated water, or contaminated water and discharge supplied to each adsorption tower. It is possible to determine, as an index, a difference in radioactivity concentration, metal ion concentration, and the like from the treated water.

  5A to 5C may be applied to the wastewater treatment system having the apparatus configuration shown in FIG. 1, and the wastewater treatment system having the apparatus configuration shown in FIG. 4 may be replaced without replacing the adsorption tower. The adsorption unit may be replaced.

  Further, the strontium removal step may be divided into multiple stages. For example, the contaminated water treatment system may be connected in series so that the treated water tank of the previous stage contaminated water treatment system becomes the raw water tank of the next stage contaminated water treatment system. In this case, the strontium removal capability and the contaminated water flow rate of the adsorption unit of each stage of the contaminated water treatment system can be designed to be different.

  In this case, the contaminated water treatment system in the previous stage can continue to operate even if the adsorption unit's strontium removal capability decreases, so that the utilization rate of the adsorbent can be increased as a whole, and the life of the adsorption tower can be substantially extended. . In addition, the contaminated water treatment system in the previous stage does not intend to remove all of the strontium, so by increasing the flow rate of the contaminated water in the adsorption tower and reducing the high concentration contaminated water stored in the raw water tank more quickly. , Reduce the risk of contamination diffusion. In addition, when such an improvement in processing speed is not required, the capacity of each adsorption tower can be reduced.

  For example, if an adsorption unit used to a certain extent in the downstream contaminated water treatment system is used as the adsorption unit of the upstream contaminated water treatment system, the adsorbent of the upstream adsorption unit can be used up until it is saturated. Thereby, the utilization efficiency of an adsorption tower can further be raised and the quantity of the radioactive waste which should be finally disposed can be suppressed as a result.

  Moreover, the adsorption unit of the contaminated water treatment system may have an adsorption tower filled with an adsorbent for strontium and an adsorption tower filled with an adsorbent for cesium. In this case, it is preferable that the contaminated water is passed through an adsorption tower previously filled with an adsorbent for cesium and then passed through an adsorption tower filled with an adsorbent for strontium. This is because strontium is more difficult to remove than cesium, and cesium adsorbents can often adsorb strontium, so removing strontium with cesium adsorbent first improves strontium removal rate. Because it can.

  Moreover, the said contaminated water processing system may construct | assemble the nuclear reactor vessel, the containment vessel, etc. in an accident nuclear power plant as a raw water tank. Thereby, the radioactivity density | concentration of the circulating water for core cooling can be reduced.

  The contaminated water treatment system and the contaminated water treatment method of the present invention are suitably used for treating contaminated water containing radioactive strontium and alkaline earth metals other than strontium.

10 Raw water tank 20 Pump unit 21 Water supply pump 22 Carriage 30 Adsorption unit 31 Cars 32a, 32b, 32c Adsorption towers 33a, 33b, 33c Water supply three-way valve 34a, 34b, 34c Drain three-way valve 35 Supply flow path 36 Discharge flow path 37a, 37b 37c Intermediate channel 40 Treated water tank

Claims (9)

A contaminated water treatment method for removing the radioactive strontium from contaminated water containing radioactive strontium and an alkaline earth metal other than strontium,
A step of supplying the contaminated water to a movable adsorption unit;
The contaminated water treatment method, wherein the adsorption unit has a plurality of adsorption towers filled with an adsorbent that selectively adsorbs strontium.   The contaminated water treatment method according to claim 1, wherein the treated water discharged from the adsorption unit is returned to a water tank in which the contaminated water is stored.   The contaminated water treatment method according to claim 1 or 2, wherein the plurality of adsorption towers are connected in series.   The contaminated water treatment method according to claim 3, further comprising a step of removing the most upstream adsorption tower and adding a new adsorption tower downstream. The contaminated water further contains a radioactive element other than radioactive strontium,
The contaminated water treatment method according to any one of claims 1 to 4, further comprising a step of removing a radioactive element other than the radioactive strontium in the treated water discharged from the adsorption unit with an adsorbent.   The contaminated water treatment method according to any one of claims 1 to 5, wherein the adsorption tower is further filled with an adsorbent that selectively adsorbs cesium.   The contaminated water treatment method according to any one of claims 1 to 6, wherein the adsorption tower is filled with a filter medium for filtering out the suspended matter or oil. A contaminated water treatment system for removing the radioactive strontium from contaminated water containing radioactive strontium and an alkaline earth metal other than strontium,
Equipped with a movable adsorption unit,
The contaminated water treatment system, wherein the adsorption unit has a plurality of adsorption towers filled with an adsorbent that selectively adsorbs strontium.   The contaminated water treatment system according to claim 8, further comprising a movable pump unit having a pump for supplying contaminated water to the plurality of adsorption towers and a self-propelled carriage on which the pump is mounted.

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