JP2013186025A - Treatment apparatus and treatment method of decontamination waste liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily separate and collect purified water from which solid matters and radioactive substances are efficiently removed without increasing secondary waste quantity when treating radioactive waste solution in which contaminated water and sludge coexist, and also to collect the solid matters as dry matter allowed to be stably stored for a long period.SOLUTION: A decontamination waste liquid treatment apparatus for treating decontamination waste liquid contaminated with radioactive substances containing soluble contaminant and granular suspended matter includes: a decontamination waste liquid tank filled with the decontamination waste liquid contaminated with the radioactive substances containing the soluble contaminant and the granular suspended matter; a filter unit for separating the decontamination waste liquid from the decontamination waste liquid tank into filtered residue and filtered water; a reverse osmosis membrane purification unit for separating the filtered water from the filter unit into concentrated water and purified water; and a drying unit for drying and solidifying the concentrated water supplied from the reverse osmosis membrane purification unit.

Description

  The present invention relates to a decontamination waste liquid processing apparatus and a processing method therefor, and in particular, treatment of a decontamination waste liquid suitable for processing a decontamination waste liquid containing a radioactive substance, a cleaning agent, and solids such as soil, dust, and algae. The present invention relates to an apparatus and a processing method thereof.

  In general, in a decontamination operation of a facility or the like contaminated with a radioactive substance, an operation of removing the radioactive substance with water containing high-pressure water or a liquid containing various cleaning agents is performed. In addition, when radioactive material is taken into the concrete wall, cleaning with high-pressure water may be performed after the concrete is scraped off. In the case of these decontamination operations, waste liquid containing crushed concrete powder is generated.

  Furthermore, when cleaning roads and roofs contaminated with radioactive materials, waste liquid containing soil, dust, etc. is generated, while when decontaminating pools, lakes, etc. contaminated with radioactive materials, Waste liquid containing mud and algae containing soil is generated.

  In the case of waste liquid containing concrete powder, soil, dust, algae, etc. in addition to radioactive substances, solid-liquid separation is difficult. For example, if a decontamination waste liquid containing a large amount of various solids is subjected to adsorption using a normal filter filtration and an adsorbent, the filter and adsorbent become secondary waste containing radioactive materials, and new It is not preferable because it increases the amount of waste.

  In particular, the decontamination waste liquid contains organic solids such as microorganisms and algae when decontaminating fine soil (mud) mixed in when decontaminating roads, gutters and roofs, or lake water. (Hereinafter, these solid contents are collectively referred to as sludge).

  Since the decontamination waste liquid containing sludge has the characteristic of easily blocking the filter, it is necessary to frequently replace the filter element, and it is difficult to efficiently proceed with the waste liquid treatment.

  Furthermore, if the solid content separated from the decontamination waste liquid contains moisture, the storage container may be corroded during the storage period of the waste, and it is expected that the stored material will flow out when the storage container is corroded. For this reason, in order to stably store the solid content collected from the decontamination waste liquid, it is desired to collect the solid content in a dry state.

  In addition, there exist some which were described in patent documents 1 thru | or 4 as a prior art which processes the waste-liquid process containing a radioactive substance. That is, Patent Document 1 describes that a filter, an activated carbon adsorbent, and a reverse osmosis membrane purification device are provided as a device for removing radioactive substances from waste liquid. Patent Document 2 discloses a radioactive waste liquid separation device and a radioactive ion exchange resin processing system equipped with the same, by removing radioactive substances from the supernatant of a tank storing radioactive waste liquid using an ion exchange resin, and depositing the tank. An apparatus for cementing and processing slag is described. Furthermore, in Patent Document 3, as a method for treating radioactive laundry waste liquid, the additive is added to the radioactive waste liquid, and the waste liquid in which the precipitate is generated is treated with a centrifugal thin film dryer or a spray dryer, thereby reducing the volume. A processing method is described in which the precipitate is dried into a powder. Further, in Patent Document 4, chemical cleaning waste liquid containing a chelate compound and an ammonia generating compound stored in a waste liquid storage tank is concentrated by a reverse osmosis membrane apparatus, and this concentrated liquid is heated by a heating and drying apparatus without pH control. It is described to dry.

JP 2008-26023 A JP 2004-28903 A JP-A-63-253298 JP 2007-90337 A

  In order to treat the decontamination waste liquid in which contaminated water and sludge coexist, it is necessary to first separate the contaminated water and sludge. However, when a general-purpose filtration device is used, since the fine pores of the filtration device are blocked in a short time by the sludge of fine particles, continuous treatment becomes difficult. Therefore, it is desirable to efficiently separate contaminated water and sludge from waste liquid in which sludge water and sludge coexist.

  Next, water-soluble contaminants are dissolved in the filtered water together with radioactive substances. Separating contaminants and moisture from the filtered water containing soluble contaminants, and finally recovering water-soluble contaminants as solids (dry matter) makes it possible to easily store and store the recovered contaminants . At this time, if the concentration of contaminants in the filtered water is high, it is possible to perform a direct drying process, but if the concentration of contaminants in the filtered water is dilute, the concentration operation is performed first, followed by a drying process. There is a need. Therefore, it is effective to combine a facility capable of concentrating waste liquid and a facility capable of drying treatment as a treatment facility for filtered water containing soluble contaminants. Furthermore, it is desirable that the above-described concentration equipment and drying equipment are equipment that does not generate secondary waste, and that equipment that can handle waste liquid containing various and various pollutants is selected.

  Ultimately, as a result of separating and concentrating the contaminants, it is considered that a small amount of radioactive material is transferred to the generated water vapor. Therefore, after making water vapor into condensed water, it is also necessary to consider removing a trace amount of radioactive material contained in the condensed water and then using purified water as the final treated water.

  Furthermore, considering that the cake layer obtained by filtering sludge and the contaminants evaporated and solidified by a dryer are filled and stored in a metal storage container, the dryness of the storage container can be maintained for a long period of time. It is also effective to keep the moisture content in the inside low.

  However, in processing the decontamination waste liquid containing solids, the filter and adsorbent described in Patent Document 1 described above, and further, the radioactivity separation / removal using a reverse osmosis membrane purification device, or the ions described in Patent Document 2 Radioactive separation / removal using an adsorbent with an exchange resin has a radioactivity separation effect on solution waste liquid, but the radioactivity from slurry waste liquid with high suspendability such as sludge. Separation is difficult. In addition, since the filter and the adsorbent become secondary waste, new radioactive waste is produced. As described in Patent Document 2, the amount of waste can be reduced by simply solidifying the precipitate. Become more. Furthermore, as described in Patent Document 3, waste can be reduced by treating the waste liquid in the form of a precipitate with a centrifugal thin film dryer or a spray dryer. In order to increase efficiency, treatment with a dehydrator is required. In general, the moisture content after drying is about 50%, and there is a possibility of microbial growth, which is not suitable for long-term storage. Moreover, in the drying by a spray dryer, when particles of various sizes are included like sludge, there is a possibility that the spraying device may block, so that it is difficult to apply to sludge. Moreover, in patent document 4, since the waste liquid in a waste liquid storage tank is directly processed with a reverse osmosis membrane apparatus, it is not considered at all with respect to the waste liquid containing solid content.

  The present invention has been made in view of the above-mentioned points, and the object of the present invention is to efficiently treat solid waste and radioactive substances without increasing the amount of secondary waste in processing radioactive waste liquid in which contaminated water and sludge coexist. It is an object of the present invention to provide a decontamination waste liquid treatment apparatus and a treatment method thereof, which can be easily separated and collected into purified water from which water has been removed, and solid matter can be stably collected as a dry matter that can be stored for a long period of time.

  In order to achieve the above object, the decontamination waste liquid treatment apparatus of the present invention treats a decontamination waste liquid that treats a decontamination waste liquid contaminated with radioactive substances including soluble contaminants and particulate suspended substances. In the apparatus, the decontamination waste liquid tank filled with the decontamination waste liquid contaminated with the radioactive substance including the soluble contaminant and the particulate suspended substance, and the decontamination waste liquid from the decontamination waste liquid tank are filtered. A filter unit that separates the residue and filtered water, a reverse osmosis membrane purification unit that separates filtered water from the filter unit into concentrated water and purified water, and concentrated water from the reverse osmosis membrane purification unit is supplied. And a drying unit for drying and solidifying.

  The decontamination waste liquid treatment method of the present invention is a decontamination waste liquid for treating a decontamination waste liquid contaminated with radioactive substances including soluble contaminants and particulate suspended substances in order to achieve the above object. In the treatment method, the decontamination waste liquid from the decontamination waste liquid tank filled with the decontamination waste liquid contaminated with the radioactive substance including the soluble contaminant and the particulate suspended substance is filtered with a filter unit. Separating the filtered water from the filter unit into concentrated water and purified water with a reverse osmosis membrane purification unit, and drying the concentrated water from the reverse osmosis membrane purification unit with a drying unit. And a step of drying and solidifying.

  According to the present invention, when processing radioactive waste liquid in which contaminated water and sludge coexist, it is possible to easily separate and recover the purified water from which solids and radioactive substances have been efficiently removed without increasing the amount of secondary waste. The solid can be recovered as a dry product that can be stored stably for a long period of time.

It is a whole block diagram which shows Example 1 of the processing apparatus of the decontamination waste liquid of this invention. It is a block diagram which shows the drying unit in the processing apparatus of the decontamination waste liquid of this invention. It is the characteristic view which compared the filtration amount with the filtration time of the various filter media employ | adopted for the filter unit of the processing apparatus of the decontamination waste liquid of this invention, and a general filter medium. It is a figure for demonstrating the concentration operation of the waste liquid in the reverse osmosis membrane apparatus unit of the processing apparatus of the decontamination waste liquid of this invention. It is a characteristic view which shows the relationship between the chlorine concentration with process time in a reverse osmosis membrane apparatus unit demonstrated in Fig.4 (a), and a process tank guess. The present inventors have supplied test water to which a scale component extracted from concrete powder has been added to the reverse osmosis membrane device unit of the decontamination waste liquid treatment device of the present invention, and shows a test facility that has been circulated. is there. FIG. 6 is a result of a test performed in the test facility of FIG. 5A, and is a diagram illustrating a relationship between a test time and a scale recovery rate. It is a characteristic view which shows the relationship between the concentration rate at the time of adjusting pH of test water, and pH of test water. It is a figure which shows the processing flow of the processing method of the decontamination waste liquid of this invention.

  The decontamination waste liquid treatment apparatus and treatment method of the present invention will be described below based on the illustrated embodiments.

  FIG. 1 shows a first embodiment of a treatment apparatus for decontamination waste liquid according to the present invention. As shown in the figure, the decontamination waste liquid treatment apparatus of this example is contaminated with radioactive contaminants including soluble contaminants and particulate suspended matter, such as cleaning agents, concrete powder, soil, sand dust, and algae. The decontamination waste liquid tank 20 in which the decontamination waste liquid is filled from the line L1, the filter unit 24 for separating the decontamination waste liquid from the decontamination waste liquid tank 20 into a filtration residue 45 and filtered water, and a filter unit The reverse osmosis membrane purification unit 35 that separates the filtered water from 24 into concentrated water and purified water, and the drying unit 1 that is supplied with the concentrated water from the reverse osmosis membrane purification unit 35 to dry and solidify. .

  The decontamination waste liquid tank 20 filled with the decontamination waste liquid to be treated including sludge and the like is provided with an agitator 21 inside, and the decontamination waste liquid is agitated by the agitator 21. The waste liquid sufficiently stirred and suspended in the decontamination waste liquid tank 20 is transferred to the filter unit 24 by the sludge transfer pump 22.

  The filter unit 24 includes a reverse filter 26 loaded with a hydrophobic filter medium 27, a compressor 29 that pressurizes the upper part of the reverse filter 26 with compressed air, and separates the waste liquid containing the suspension into a solid-liquid separation, The decontamination waste liquid transferred to the filter unit 24 by the sludge transfer pump 22 is composed of a filtration residue collection container 31 that collects the filtration residue 45 that has been filtered and remains in the reverse filter 26. Introduced into the vessel 26. Thereafter, the filter inlet valve 23 is closed, and the upper part of the reverse filter 26 is pressurized with the compressed air of the compressor 29, and the waste liquid containing the suspension is solid-liquid separated. After the filtration process in the reverse filter 26 is completed, the simple joint 25 provided at the inlet of the reverse filter 26 and the simple joint 28 provided at the outlet of the reverse filter 26 are removed, and the reverse filter 26 is removed. The filter residue 45 inside the reverse filter 26 is recovered in the filter residue recovery container 31 by turning upside down. At this time, it is also effective to send compressed air by the compressor 29 so that the filtration residue 45, which is a solid matter in the reverse filter 26, is efficiently discharged.

  In this embodiment, an example is shown in which one reverse filter 26 is installed in the filter unit 24. However, a plurality of reverse filters 26 may be installed in accordance with the processing capacity of the waste liquid to be processed. Absent. Further, as a method for separating the water from the filtration residue 45, it is possible to use a filter press machine instead of the reverse filter 26.

  The filtered water filtered by the filter unit 24 is collected and stored in the filtered water receiving tank 32 by the pressure of the compressed air of the compressor 29. The filtered water in the filtered water receiving tank 32 is cooled by the cooler 33, and stable operation is possible. The filtered water can be transferred by providing a transfer pump.

  Next, the filtered water stored in the filtered water receiving tank 32 is concentrated in the reverse osmosis membrane purification unit 35.

  The reverse osmosis membrane purification unit 35 separates filtered water from the filtrate receiving tank 32 into purified water that is purified by permeating the reverse osmosis membrane and concentrated water that does not permeate the reverse osmosis membrane; A concentrated water receiving tank 39 for storing the concentrated water from the reverse osmosis membrane device 37, and the concentrated operation of the filtrate from the filtered water receiving tank 32 is performed by the reverse osmosis membrane device 37, and the reverse osmosis membrane device. The concentrated water concentrated in 37 is stored in the concentrated water receiving tank 39, and a part of the concentrated water in the concentrated water receiving tank 39 is returned to the reverse osmosis membrane device 37 via the circulation line 40.

  It is also possible to collect the concentrated liquid in the filtered water receiving tank 32 and circulate it between the filtered water receiving tank 32 and the reverse osmosis membrane device 37 for concentration. Further, when a large amount of scale component is contained in the filtered water, the pH in the concentrated water receiving tank 39 may be adjusted to 5 or less. The pH is adjusted by measuring the pH in the concentrated water receiving tank 39 with a pH meter 52. When pH is detected to be 5 or more, hydrochloric acid, nitric acid or the like is supplied from the acid supply tank 50 using the pump 51, and the pH meter is measured. When the measured value of 52 reaches 5 or less, the addition of the acid is stopped. The concentration of the filtrate is adjusted within a range that can be supplied to the drying unit 1 in a later process described later.

  Next, the filtered water after concentration (referred to as treated water) is transferred to the drying unit 1. As shown in detail in FIG. 2, the drying unit 1 heats the preheater 4 for preheating the treated water from the concentrated water receiving tank 39, the circulation tank 5 for storing and circulating the preheated treated water, and the circulation tank 5. A circulating tank heating container 6, a heating rotating plate 12 that separates the treated water from the circulating tank 5 into steam and dry solids, a spray nozzle 9 that supplies the treated water from the circulating tank 5 to the heating rotating plate 12, and heating A boiler 14 for supplying steam to the rotating flat plate 12, a scraper 10 for scraping off solute adhering to the surface of the heated rotating flat plate 12, and a dry sludge discharge container 13 for recovering dry sludge scraped off and powdered by the scraper 10. It consists of and.

  The treated water from the concentrated water receiving tank 39 is sent to the preheater 4 by the supply pump 3 and preheated, and is supplied to the circulation tank 6 after preheating. The treated water supplied from the circulation tank 5 through the pipe 8 by the circulation pump 7 is supplied to the surface of the heating rotary plate 12 by the spray nozzle 9 installed at the tip of the pipe 8. The heating rotary plate 12 is heated using the steam supplied from the boiler 14 as a heat source, the moisture in the treated water supplied by being heated by the steam evaporates, and the treated water is separated into steam and dry solids. The

  On the other hand, the solute contained in the solution adheres to the surface of the heated rotating plate 12 during drying and solidification, but the solute attached to the surface of the heated rotating plate 12 is scraped off by the rotational force of the heated rotating plate 12 and the scraper 10, It is pulverized and collected in the dry sludge discharge container 13.

  The steam generated on the surface of the heated rotating flat plate 12 is discharged from the exhaust pipe 47 (open to the atmosphere), and when the radioactive material in the steam contains a regulation value or more, the filtered water receiving tank 32 is connected via the pipe 48. It is made to condense by mixing with the filtered water in the filtered water receiving tank 32, and also collect | recovering a radioactive substance simultaneously. In addition, when the water vapor is transferred to the filtered water receiving tank 32, the filtered water in the filtered water receiving tank 32 is cooled, so that the cooler 33 is provided to enable stable operation.

  Further, the steam used for heating the heating rotary plate 12 is guided to the circulation tank heating vessel 6 through the pipe 17 and supplied as a heat source for the preheater 4 through the temperature rise of the treated water and the pipe 18. As a result, the thermal efficiency of the boiler 4 is improved. Further, the steam from the preheater 4 is discharged as drain through the pipe 19, and a part thereof is returned to the boiler 4 through the circulation line 41.

  Further, the filtration residue 45 in the filtration residue collection container 31 collected by the reverse filter 26 is transferred to a dryer 42 and dried and then stored in the dryer 42, or the reverse filter 26 is used. It is effective to remove from the connection pipe by the simple joints 25 and 28, connect the exhaust from the boiler 14 to this and use it as a dryer, and dry and collect and store the filtration residue 45 in the reverse filter 26. In the present embodiment, an example of a drying system in which the combustion gas of the boiler 14 that heats the heating rotary plate 12 is supplied to the dryer 42 via the pipe 43 as a heat source of the dryer 42 is shown.

  By adopting such a configuration of the present embodiment, the sludge containing radioactive substances in the decontamination waste liquid tank 20 is reduced in volume by the filter unit 24, the reverse osmosis membrane purification unit 35 and the drying unit 1, The radioactive substance contained in the solid matter and the supernatant liquid is recovered in the dry sludge discharge container 13 and the filtration residue recovery container 31, and the purified water from which the radioactive substance has been removed can be released.

  Next, the processing method of the decontamination waste liquid of this invention is demonstrated using the processing flow shown in FIG.

  As shown in the figure, in processing the decontamination waste liquid (S1) containing the suspended matter such as sludge and the radioactive material filled in the decontamination waste liquid tank 20, first, the filter unit 24 performs the filtration process (S2 The suspended substance is recovered as a filtration residue (S3). The filtration residue (S3) can be stably stored for a long period of time when a drying process (S4) is additionally performed with hot air in the dryer 42 and recovered as a dried product (S5).

  In the filtered water (S6) separated by the filtration process (S2) in the filter unit 24, radioactive substances and other impurities are dissolved in the waste liquid. As a pretreatment for recovering radioactive substances and other impurities in the filtered water as dry matter, the reverse osmosis membrane purification unit 35 is concentrated (S7), and separated into purified water (S8) and concentrated water (S9). To do. By the concentration treatment (S7) in the reverse osmosis membrane purification unit 35, it becomes possible to reduce the water in the treated water, and the effect of shortening the drying treatment time in the subsequent process can be obtained and the treatment becomes easy.

  The treated water after concentration in the reverse osmosis membrane purification unit 35 is supplied to the drying unit 1 to perform a drying process (S10), and is separated into a dried product (S11) and a steam (S12), and the dried product (S11) is Collected. In this example, a method was selected in which the solution was evaporated and concentrated on the heated rotating flat plate 12 and finally the dissolved component was recovered as a dried product (S11).

  In addition, when a waste liquid contains many scale components, such as calcium, since it is accompanied by the differential pressure | voltage rise of a reverse osmosis membrane, it is good to perform a direct drying process without performing concentration operation. On the other hand, in order to prevent precipitation of scale components, it is possible to adjust the pH of the treated water by adding a commercially available scale inhibitor or an acid such as hydrochloric acid, sulfuric acid or nitric acid.

  Furthermore, during the drying process (S10), the water in the waste liquid is separated as a vapor (S12). This vapor (S12) can be discharged directly into the atmosphere or returned to filtered water (S6) and cooled. It can be recovered as condensed water. Here, when the condensed water contains a slight amount of radioactive substance, it can be purified again by the reverse osmosis membrane purification unit 35 and recovered as purified water containing no radioactive substance. In addition, the radioactive substance concentrated in the reverse osmosis membrane is returned to the filtrate tank again as concentrated water, and the concentration and drying treatment is repeated again. By this repetition, radioactive substances such as cesium are dried together with the dried substance. It becomes possible to collect.

  By treating the decontamination waste liquid by these processes, the decontamination product can be recovered as a dry product suitable for long-term storage and storage while reducing secondary waste as much as possible.

  According to the present embodiment described above, when processing radioactive waste liquid in which contaminated water and sludge coexist, without increasing the amount of secondary waste, it is easily separated into purified water from which solids and radioactive substances have been efficiently removed, Of course, the solid can be recovered as a dry product that can be stored stably for a long period of time.

  In addition, as in the above-described embodiments, the heating flat plate type rotary drying unit can easily be used for sea salt from various waste liquids including not only dissolved components such as seawater but also fine powder such as ceramic powder and oil. It can be separated into mixed components such as ceramics and oils and water vapor. In addition, the heated flat-plate rotary dryer has a flat dry surface and is scraped with a scraper continuously, so that the dry matter does not accumulate. It is possible to avoid obstructions such as blockage and damage to rotating equipment. Therefore, it is suitable for concentration and drying treatment of decontamination waste liquid containing an unspecified number of dissolved components.

  In addition, in the test conducted by the inventors who measured the amount of cesium transferred into the steam using 20 L of simulated waste liquid containing 1000 g of cesium chloride (CsCl) added, as shown in Table 1. The ratio of transition to steam with respect to cesium was 4% or less.

  From these results, it was confirmed that 96% or more of the radioactive cesium present in the waste liquid can be recovered as a dry matter. Therefore, it was confirmed that the heating flat plate rotary dryer also works effectively as a radioactive substance separation and recovery device.

  In the above-described embodiments, in order to separate and remove radioactive substances from washing waste liquid containing particulate suspended substances such as soil, in the filtration operation using a filter and the adsorption treatment of radioactive substances, particulate suspended substances are used. Substance becomes an obstacle. For this reason, in order to efficiently treat the waste liquid treatment, it is necessary to separate the suspended solids from the decontamination waste liquid containing particulate suspended solids.

  The present inventors performed a test by filtering 1 L of a simulated test solution containing 10% of soil using a general paper (hydrophilic) filter medium. The result is shown in FIG.

  As shown in the figure, when the simulated liquid in which the soil is suspended is filtered using a general paper (hydrophilic) filter medium, as shown in FIG. It took 14 minutes, and after 14 minutes, the suction force with a vacuum of 700 mmHg caused a blockage, making it difficult to continue the filtration process.

  As shown in this test result, since soil and the like also contain fine particles of clay, the filter medium pores are clogged with fine particles and the filtration differential pressure rises in a short time in a filtration operation using a general filter material. Not only a large amount of filter media is consumed, but also a facility having a large overarea is required.

  Therefore, the present inventors have selected a filter medium that can perform efficient filtration. The test was judged by comparing the filtration times when 1 L of a simulated test solution containing 10% of soil was filtered using a general paper (hydrophilic) filter medium (this is (A) in FIG. 3). As a result, as shown in FIG. 3, when a hydrophobic filter medium was used ((B) of FIG. 3), all 1 L of test water could be treated in about 11 minutes.

  From these results, compared to the case of using a general paper (hydrophilic) filter medium (A), by using a hydrophobic filter medium (B), there is no clogging of the filtration layer and the suspension. It was found that the separation time of the substance was shortened by 5 times or more. In addition, as a hydrophobic filter material, tetrafluoroethylene resin or glass fiber can be applied.

  Furthermore, sea sand was added to the upper part of the hydrophobic filter medium in a thickness of about 5 mm as a volume filter medium ((C) in FIG. 3), and the same test as described above was performed. As a result, as shown in FIG. 3, the filtration rate was suppressed from lowering the filtration rate compared to the hydrophobic filter medium alone, and the 1 L filtration treatment time was reduced by about 35%. In addition to the sea sand used in the test, diatomaceous earth, zeolite powder, powder ion exchange resin, and the like can be used as the volume filter material.

  From the above examination results, it is possible to achieve an efficient solid-liquid separation process by using hydrophobic filter media and volume filter media when separating suspended materials from decontamination waste liquid containing suspended materials. Understood.

  Furthermore, it is desirable that the recovered filtration residue is dried to a water content that can be stably stored. For the drying treatment, a method using a high-temperature gas is effective, but it is efficient to use a high-temperature combustion gas such as a boiler.

  Next, the waste liquid concentration operation when using the reverse osmosis membrane device will be described with reference to FIGS. 4 (a) and 4 (b).

  As shown in FIG. 4A, a salt water adjusted to a chlorine concentration of about 100 ppm is prepared in a 1000 L treated water tank 60, and the flow rates of the concentrated water and purified water of the reverse osmosis membrane 61 are each set to 20 L / min. Then, a concentration test was performed using a test apparatus. Since the purified water is released at 20 L / min, as shown in FIG. 4B, the amount of water (D) in the processing tank 60 decreases as the purification time elapses, and the chlorine concentration (E) increases. After about 40 minutes, the amount of water in the treated water tank 60 decreased to about 200 L, and the chlorine concentration reached about 4.9 ppm.

  From these results, the chlorine separation rate of the reverse osmosis membrane was about 99%. As seen in the test results, soluble impurities can be efficiently concentrated using a reverse osmosis membrane.

  Furthermore, the waste liquid containing sludge and the waste liquid after washing the concrete surface contain scale components such as calcium (Ca), magnesium (Mg), and silica (Si). When a waste liquid containing a large amount of these components is concentrated with a reverse osmosis membrane, precipitation of scale components occurs, the water flow pressure of the reverse osmosis membrane increases, and eventually the recovery rate decreases.

  Therefore, the inventors supplied test water to which a scale component extracted from concrete powder was added to a reverse osmosis membrane using a test facility as shown in FIG. The test result was evaluated by the change in the recovery rate defined by the following formula (1).

Recovery rate (%) = Demineralized water flow rate (Y) / (Demineralized water flow rate (Y) + Concentrated water flow rate (X)) (1)
As a result of the test, as shown in FIG. 5 (b), when test water that does not adjust the pH of the test solution is passed through the reverse osmosis membrane, the recovery rate decreases after about 10 hours of circulation time, The clogging phenomenon occurred due to the deposition of scale components in the pores. On the other hand, after adjusting the pH to 5 by adding hydrochloric acid to the test water, the circulation operation was similarly performed. As a result, as shown in FIG. 5 (b), in the test water in which the pH of the test water was adjusted to 5, the phenomenon that the recovery rate during the 90-hour operation period was not significantly decreased was not observed, and scale precipitation was avoided. I confirmed that I can do it.

  When these scale components such as calcium (Ca), magnesium (Mg), and silica (Si) are concentrated by the reverse osmosis membrane, the pH rises and changes to alkaline, and the pH rises. This is thought to be due to the fact that the carbon dioxide in the atmosphere and the amount of dissolution increase, so that the scale component easily precipitates as carbonate. In order to alleviate these behaviors, it is effective to adjust in advance to a pH at which no dissolution of carbon dioxide occurs even when concentration of scale components occurs.

  Specifically, as seen in the test results of FIG. 6, the pH of the test water containing the extracted components of the concrete powder was adjusted to 6 ((F) in FIG. 6) and 5 ((G) in FIG. 6). The test solution was concentrated 2 times, 4 times, 6 times and 8 times. As a result, the pH of the test water whose pH was adjusted to 6 ((F) in FIG. 6) increased with the progress of concentration.

  This phenomenon is caused by the decrease in the concentration of carbonate ions initially contained in the test water as it is evaporated, and the remaining alkali components such as calcium (Ca), magnesium (Mg), and silica (Si) that are not evaporated. The result showed that the increase in concentration was balanced.

  On the other hand, the test water whose pH was adjusted to 5 ((G) in FIG. 6) decreased in pH almost depending on the concentration rate. This result showed that there was almost no dissolution of carbonate ions when the pH was adjusted to 5 ((G) in FIG. 6).

  From these results, it is understood that when the decontamination waste liquid containing scale components is concentrated, stable operation is possible by adjusting the pH of the treated water to 5 or less.

  In addition, it is also effective to add a commercially available scale inhibitor to suppress scale formation.

  Next, the function of the reverse osmosis membrane purification apparatus 35 applied as a radioactive substance purification apparatus will be described below.

  That is, the reverse osmosis membrane method generally blocks solutes and ions in the solution and allows only the solvent to permeate. A translucent film is used as the film, and it is generally used for the production of seawater desalination or ultrapure water. Therefore, in addition to radioactive materials such as cesium dissolved as an ionic component in water by the reverse osmosis membrane method, it is possible to separate the radioactive component of fine particles.

  Table 2 shows that the cesium purification performance using the reverse osmosis membrane purification apparatus 35 performed by the present inventors shows that the radioactive cesium is reduced to 1/80 (about 98% in terms of removal rate) by the reverse osmosis membrane. Purified.

  Based on the above results, compared to the case of using radioactive material adsorbents such as zeolite to purify radioactive materials, the use of reverse osmosis membranes avoids the generation of secondary waste such as adsorbents and achieves waste liquid treatment. it can.

  In addition, when the waste liquid in which the suspension of fine particles exists in the treated water is treated by the reverse osmosis membrane device 37, it is assumed that the pores of the reverse osmosis membrane are blocked by the fine particles and the reverse osmosis membrane needs to be replaced. Is done. For this reason, as for the treated water of a reverse osmosis membrane apparatus, it is desirable to make into the waste liquid which does not contain microparticles | fine-particles.

  In the case of the present embodiment, it is effective to apply as a facility for purifying a radioactive substance contained in a trace amount in the steam separated by the heating flat plate rotary dryer 11 described above. In this case, the purification rate of radioactive cesium in the case where the heating flat plate rotary dryer 11 and the reverse osmosis membrane device 37 are combined can be expected to be about 99.9%.

  By the way, in order to stably store the filtration residue obtained by the filtration operation using the hydrophobic filter material described above with reference to FIG. 3 and the dry matter recovered with the drying unit 1 described with reference to FIG. It is necessary to maintain a dry condition.

When the collected material is stored in a stainless steel storage container, it is desirable to maintain a dryness capable of suppressing atmospheric corrosion cracking due to chlorides and the like. For example, according to a study by Shoji et al. (Exhibition: Anticorrosion Technology, 38 , 92 (1989)), when sea salt adheres to the surface of stainless steel, atmospheric corrosion cracking occurs when the relative humidity of the atmosphere is 20% to 40%. It has been reported.

  On the other hand, in the filtration residue and dried product collected from the decontamination waste liquid, components such as sand dust that does not have hygroscopicity and components that have hygroscopicity including more moisture than moisture in the atmosphere are mixed. For this reason, even if a large amount of salt content is contained in the filtration residue and the dried product, the relative humidity of the atmosphere in the storage container is reduced to 20% or less by drying the moisture content of the recovered product to 20% or less. Can be maintained.

  From the above results, it is desirable to dry the collected filtration residue and the moisture content of the dried product until the water content is 20% or less.

  If the filter unit 24, the reverse osmosis membrane purification unit 35 and the drying unit 1 described in this embodiment are mounted on a vehicle such as a truck or a trailer, the mobility is improved and the range of use can be expanded. Moreover, it cannot be overemphasized that the processing apparatus of the decontamination waste liquid of this invention is effective also in the process of the waste liquid which does not contain a radioactive substance.

  DESCRIPTION OF SYMBOLS 1 ... Drying unit, 3 ... Supply pump, 4 ... Preheater, 5 ... Circulating tank, 6 ... Circulating tank heating container, 7 ... Circulating pump, 8, 15, 17, 18, 19, 36, 38, 43, 48 ... Piping, 9 ... spray nozzle, 10 ... scraper, 11 ... heated flat plate rotary dryer, 12 ... heated rotating flat plate, 13 ... dried sludge discharge container, 14 ... boiler, 16, 30 ... valve, 20 ... decontamination waste liquid tank 21 ... Stirrer, 22 ... Sludge transfer pump, 23 ... Filtration inlet valve, 24 ... Filter unit, 25, 28 ... Simple joint, 26 ... Reverse filter, 27 ... Hydrophobic filter medium, 29 ... Compressor, 31 ... Filtration residue collection container, 32 ... Filtrated water receiving tank, 33 ... Cooler, 35 ... Reverse osmosis membrane purification unit, 37 ... Reverse osmosis membrane device, 39 ... Concentrated water receiving tank, 40, 41 ... Circulation line, 42 ... Dryer 45 ... Kazan渣, 46 ... sludge, 47 ... exhaust pipe, 50 ... acid feed tank, 51 ... pump, 52 ... pH meter, 60 ... treated water tank, 61 ... a reverse osmosis membrane.

Claims (26)

In the decontamination waste liquid treatment equipment for treating decontamination waste liquid contaminated with radioactive substances including soluble contaminants and particulate suspended matter,
The decontamination waste liquid tank filled with the decontamination waste liquid contaminated with radioactive substances including the soluble contaminants and particulate suspended substances, and the decontamination waste liquid from the decontamination waste liquid tank, the filtration residue and the filtration A filter unit that separates into water, a reverse osmosis membrane purification unit that separates filtered water from the filter unit into concentrated water and purified water, and a concentrated water from the reverse osmosis membrane purification unit is supplied to dry and solidify An apparatus for treating decontamination waste liquid, comprising a drying unit. In the processing apparatus of the decontamination waste liquid of Claim 1,
An apparatus for treating a decontamination waste liquid, comprising: a filtered water receiving tank for storing filtered water filtered by the filter unit; and a cooler for cooling the filtered water in the filtered water receiving tank. In the processing apparatus of the decontamination waste liquid of Claim 1 or 2,
The filter unit includes a filter loaded with a filter medium, a compressor that pressurizes the filter and separates the liquid waste containing the soluble contaminants and particulate suspended solids, and the filter A decontamination waste liquid treatment apparatus comprising: a collection container that is subjected to filtration treatment to collect a filtration residue. In the processing apparatus of the decontamination waste liquid of Claim 3,
The said filter is an inversion filter which inverts up and down, and the said filter medium loaded into this inversion filter is a hydrophobic filter medium, The processing apparatus of the decontamination waste liquid characterized by the above-mentioned. In the processing apparatus of the decontamination waste liquid of Claim 4,
The said hydrophobic filter material consists of tetrafluoroethylene resin or glass fiber, The processing apparatus of the decontamination waste liquid characterized by the above-mentioned. In the processing apparatus of the decontamination waste liquid of Claim 4 or 5,
An apparatus for treating a decontamination waste liquid, wherein any one of sea sand, diatomaceous earth, zeolite powder, and powder ion exchange resin is installed as a volume filter medium on the hydrophobic filter medium. In the processing apparatus of the decontamination waste liquid of Claim 1 or 2,
The reverse osmosis membrane purification unit separates filtered water from the filter unit or the filtrate water receiving tank into purified water that passes through the reverse osmosis membrane and is purified and concentrated water that does not pass through the reverse osmosis membrane. An apparatus for treating a decontamination waste liquid comprising a membrane device and a concentrated water receiving tank for storing concentrated water from the reverse osmosis membrane device. In the processing apparatus of the decontamination waste liquid of Claim 7,
A part of the concentrated water in the concentrated water receiving tank is recirculated to the reverse osmosis membrane device. In the processing apparatus of the decontamination waste liquid of Claim 7 or 8,
A pH meter for measuring the pH in the concentrated water receiving tank, and an acid is supplied when the pH meter detects a pH of 5 or more, and an acid is supplied when the pH meter detects a pH of 5 or less. A treatment apparatus for decontamination waste liquid, comprising: an acid supply tank in which supply is stopped. In the processing apparatus of the decontamination waste liquid of any one of Claims 1 thru | or 9,
The drying unit includes a preheater for preheating the treated water from the concentrated water receiving tank, a circulation tank for storing and circulating the treated water preheated by the preheater, and drying the treated water from the circulation tank with steam. A decontamination waste liquid comprising: a heating rotating plate that separates into solids; a spray nozzle that supplies treated water from the circulation tank to the heating rotating plate; and a boiler that supplies steam to the heating rotating plate. Processing equipment. In the processing apparatus of the decontamination waste liquid according to claim 10,
A scraper that scrapes off the solute adhering to the surface of the heated rotating flat plate, and a dry sludge discharge container that collects dry sludge scraped off and powdered by the scraper. Processing equipment. In the processing apparatus of the decontamination waste liquid of Claim 10 or 11,
Vapor generated on the surface of the heated rotating plate is released to the atmosphere through an exhaust pipe, and if the vapor contains a radioactive material that exceeds the regulation value, it is transferred to the filtered water receiving tank via a pipe. The decontamination waste liquid treatment apparatus is condensed by mixing with the filtrate in the filtrate water receiving tank. In the processing apparatus of the decontamination waste liquid of Claim 10 or 12,
A circulation tank heating container for heating the treated water in the circulation tank is provided, and the steam used for heating the heating rotary plate is led to the circulation tank heating container to raise the temperature of the treated water in the circulation tank. At the same time, steam from the circulation tank heating vessel is supplied as a heat source for the preheater, and a decontamination waste liquid treatment apparatus. In the processing apparatus of the decontamination waste liquid according to claim 13,
The steam supplied as a heat source of the preheater is discharged as a drain through a pipe, and a part of the steam is returned to the boiler. In the processing apparatus of the decontamination waste liquid according to claim 10,
A dryer having the combustion gas from the boiler as a heat source is provided, and the filtration residue in the recovery container recovered by the reverse filter is recovered and stored after being transferred to the dryer and dried. Decontamination waste liquid, characterized in that the reverse filter is removed from the connection pipe, the exhaust from the boiler is connected to this and used as a dryer, and the filtration residue in the reverse filter is dried and collected and stored. Processing equipment. In the processing apparatus of the decontamination waste liquid of any one of Claims 1 thru | or 15,
An apparatus for treating a decontamination waste liquid, wherein the filter unit, the reverse osmosis membrane purification unit, and the drying unit are mounted on a vehicle and are movable. In the decontamination waste liquid treatment method for treating decontamination waste liquid contaminated with radioactive substances including soluble contaminants and particulate suspended solids,
The decontamination waste liquid from the decontamination waste liquid tank filled with the decontamination waste liquid contaminated with radioactive substances including the soluble contaminants and particulate suspended matter is separated into filtration residue and filtered water by the filter unit. Separating the filtered water from the filter unit into concentrated water and purified water using a reverse osmosis membrane purification unit, and drying and solidifying the concentrated water from the reverse osmosis membrane purification unit using a drying unit; A decontamination waste liquid treatment method comprising: In the processing method of the decontamination waste liquid of Claim 17,
The decontamination waste liquid transferred to the filter unit is introduced into the reverse filter, the filter inlet valve is closed, and the upper part of the reverse filter is pressurized with a compressor, and the waste liquid containing the suspension And after the filtration process in the reverse filter is completed, the reverse filter is turned upside down to collect the filtration residue in the reverse filter in a collection container. Processing method of dyeing waste liquid. In the processing method of the decontamination waste liquid of Claim 18,
The method for treating a decontamination waste liquid, wherein the filtration process in the reverse filter is performed using a hydrophobic filter medium or a hydrophobic filter medium and a volume filter medium. In the processing method of the decontamination waste liquid of any one of Claims 17 thru | or 19,
The filtered water transferred from the filter unit or the filtered water receiving tank to the reverse osmosis membrane purification unit is purified water that passes through the reverse osmosis membrane and is purified by the reverse osmosis membrane device, and concentrated water that does not pass through the reverse osmosis membrane. And a concentrated water from the reverse osmosis membrane device is stored in a concentrated water receiving tank. In the processing method of the decontamination waste liquid according to claim 19,
The pH in the concentrated water receiving tank is measured with a pH meter. When the pH meter detects a pH of 5 or more, an acid is supplied from the acid supply tank, and the pH meter detects a pH of 5 or less. In this case, the method for treating the decontamination waste liquid is characterized in that the supply of acid from the acid supply tank is stopped. In the processing method of the decontamination waste liquid of any one of Claims 17 thru | or 20,
The treated water transferred from the reverse osmosis membrane purification unit is sent to a preheater by a supply pump to be preheated, supplied to a circulation tank after preheating by the preheater, and from the circulation tank by a circulation pump. The treated water supplied through the piping is supplied to the surface of the heating rotary plate by the spray nozzle and heated, and the treated water supplied by being heated by the steam is separated into steam and dry solid. A method for treating a decontamination waste liquid. In the processing method of the decontamination waste liquid according to claim 21,
A method for treating a decontamination waste liquid, wherein the solute adhering to the surface of the heated rotating flat plate is scraped off by the rotational force of the heated rotating flat plate and a scraper, and is powdered and collected in a dry sludge discharge container. In the processing method of the decontamination waste liquid of Claim 21 or 22,
The method for treating a decontamination waste liquid, wherein the heating rotating flat plate is heated using steam supplied from a boiler as a heat source. In the processing method of the decontamination waste liquid of any one of Claims 21 thru | or 23,
The steam used for heating the heating rotary plate is led to a circulation tank heating container for heating the treated water in the circulation tank, and the temperature of the treated water in the circulation tank is raised, and from the circulation tank heating container A method for treating a decontamination waste liquid, wherein steam is supplied as a heat source of the preheater. In the processing method of the decontamination waste liquid according to claim 21,
The filtration residue in the collection container collected by the reverse filter is collected and stored after being transferred to a dryer using combustion gas from the boiler as a heat source and dried or connected to the reverse filter. A method for treating a decontamination waste liquid, comprising: removing from the boiler, connecting to the exhaust from the boiler, and using it as a dryer, drying and collecting and storing the filtration residue in the reverse filter.

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