JP5651755B1 - Incineration fly ash cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sufficiently washing incineration fly ash while suppressing the amount of water used and rinsing drainage. The first cleaning wastewater discharged in the separation step of the first cleaning step and the first rinse wastewater discharged in the rinse step of the first cleaning step are performed after the first cleaning step. In the cleaning step in which at least the first rinse wastewater is reused as the wash water in the cleaning step, a larger amount of the wash water than the first rinse wastewater is used to perform the mixing step. Provide a way to be. [Selection] Figure 1

Description

  The present invention relates to a method for cleaning incineration fly ash, and more specifically, to a method for cleaning incineration fly ash for cleaning incineration fly ash containing radioactive cesium.

The incineration fly ash generated by incineration of the incineration object may contain harmful substances such as heavy metals and chlorine contained in the incineration object.
Incineration fly ash generated by incineration can be disposed of, for example, by landfill, but in order to prevent the release of the above-mentioned harmful substances after landfill, for example, before landfill, the contained harmful substances are reduced as much as possible. It has been landfilled since then.

  Conventionally, various methods for reducing harmful substances contained in incineration fly ash have been used. Specifically, for example, incineration fly ash for reducing harmful substances contained in incineration fly ash by washing the incineration fly ash with water. The cleaning method is used.

  As a method for cleaning this type of incineration fly ash, for example, a mixture step of mixing incineration fly ash and washing water to obtain a mixture, and solid-liquid separation of the mixture makes it more solid than the mixture. There has been proposed one having a separation step of obtaining a concentrate having a high concentration of water and a rinsing step of rinsing the concentrate with rinse water (for example, Patent Document 1).

  According to such incineration fly ash cleaning method, harmful substances such as chlorine contained in the incineration fly ash can be reduced.

  In addition, as a method of cleaning incineration fly ash, in order to suppress the amount of water used relative to the amount of incineration fly ash, the cleaning waste water discharged in the separation step and the rinse waste water discharged in the rinse step The method of utilizing as rinse water is proposed (for example, patent documents 2-4).

JP 2012-166170 A JP-A-8-126877 Japanese Patent No. 3368372 Japanese Patent No. 4834936

  However, in the conventional method, clean rinse wastewater is not fully utilized as compared with cleaning wastewater.

  Therefore, the present invention suppresses the amount of water used relative to the amount of incinerated fly ash, and further sufficiently cleans the incinerated fly ash containing radioactive cesium while fully utilizing the rinse waste water. It is an object to provide a method.

In the present invention, a plurality of cleaning steps including a first cleaning step and a second cleaning step performed after the first cleaning step are performed,
In each washing step, the incineration fly ash containing radioactive cesium and the washing water are mixed to obtain a mixture, and by solid-liquid separation of the mixture, the solid content concentration is higher than that of the mixture. A separation step to obtain a high concentrate, and a rinsing step of rinsing the concentrate with rinse water,
The volume of the rinse water used in the rinsing step is 0.25 times or more and less than 1.0 times the volume of the washing water used in the mixing step,
Another cleaning step in which the first cleaning wastewater discharged in the separation step of the first cleaning step and the first rinse wastewater discharged in the rinse step of the first cleaning step are performed after the first cleaning step. In the cleaning process in which the first rinse wastewater is reused as at least the first rinse wastewater, the mixing step is performed using a larger amount of wash water than the first rinse wastewater. It is in the method of cleaning incineration fly ash.

In such incineration fly ash cleaning method, the first cleaning wastewater discharged in the separation step of the first cleaning step and the first rinse wastewater discharged in the rinse step of the first cleaning step are the first By reusing it as washing water in another washing process carried out after the washing process, the amount of water used relative to the amount of incinerated fly ash can be suppressed.
In the incineration fly ash cleaning method, the volume of the rinse water used in the rinsing step is 0.25 times or more and less than 1.0 times the volume of the cleaning water used in the mixing step, and at least the In the cleaning process in which the first rinse wastewater is reused, the mixing process is performed by using a larger amount of the wash water than the first rinse wastewater, so that the rinse wastewater is fully utilized and radioactive. Incinerated fly ash containing cesium can be sufficiently washed.

  In the incineration fly ash cleaning method of the present invention, preferably, the first cleaning wastewater and the first rinse wastewater are reused in the second cleaning step.

Further, in the incineration fly ash cleaning method of the present invention, preferably, the first rinse wastewater is reused in a third cleaning step performed after the second cleaning step,
In the third cleaning step, the second rinse drain discharged in the rinse step of the second cleaning step is also reused.

  In the incineration fly ash cleaning method of the present invention, preferably, before the first cleaning wastewater is reused, an adsorption step of bringing the first cleaning wastewater into contact with an adsorbent that adsorbs radioactive cesium is performed. The

  Such an incineration fly ash cleaning method can reduce the concentration of radioactive cesium contained in the first washing wastewater before reusing the first washing wastewater, so that the incineration fly ash can be more sufficiently removed. Has the advantage that it can be cleaned.

  As described above, according to the present invention, the amount of water used with respect to the amount of incinerated fly ash is suppressed, and further, the incinerated fly ash containing radioactive cesium is sufficiently washed while fully utilizing the rinse drainage. Can do.

Schematic of a cleaning device. The figure which shows the relationship between the frequency | count of reuse, and a removal rate.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  In the incineration fly ash cleaning method of this embodiment, a plurality of cleaning steps including a first cleaning step and a second cleaning step performed after the first cleaning step are performed.

In each washing step, the incineration fly ash containing radioactive cesium and the washing water are mixed to obtain a mixture, and by solid-liquid separation of the mixture, the solid content concentration is higher than that of the mixture. A separation step to obtain a high concentrate and a step of rinsing the concentrate with rinse water are performed.
The volume of the rinse water used in the rinsing step is 0.25 times or more and less than 1.0 times the volume of the washing water used in the mixing step.
The total volume of the volume of the washing water used in the mixing step and the volume of the rinse water used in the rinsing step with respect to 1 kg of the mass of incinerated fly ash used in the mixing step (wet mass) is preferably 1-20L.
The incineration fly ash used for cleaning is humidified from the viewpoint of preventing the incineration fly ash from being scattered, and therefore, the moisture content is generally adjusted within the range of 20 to 30%. The incineration fly ash has a moisture content adjusted to a range of 20 to 25%. However, the incineration fly ash may be adjusted to a range in which the moisture content exceeds 30% in order to further suppress scattering of the incineration fly ash. Incineration fly ash may be adjusted to a moisture content of less than 20% if it is difficult to fly.

  The incinerated fly ash cleaning method of the present embodiment includes a first cleaning wastewater discharged in the separation step of the first cleaning step and a first rinse wastewater discharged in the rinse step of the first cleaning step. In the cleaning step, which is reused as cleaning water in another cleaning step performed after the first cleaning step, and at least the first rinse wastewater is reused, a larger amount than the first rinse wastewater. The mixing step is performed using washing water.

  The incineration fly ash cleaning method of the present embodiment can be performed using, for example, a cleaning facility 1 as shown in FIG.

As shown in FIG. 1, the cleaning facility 1 includes a mixing unit 2, a solid-liquid separation unit 3, a purification unit 4, a discharge water storage unit 5, a cleaning water storage unit 6, and a leachate storage unit 7. Prepare.
In addition, as shown in FIG. 1, the cleaning facility 1 includes a 1-1 transfer path 1a, a 1-2 transfer path 1b, a 1-3 transfer path 1c, a 1-4 transfer path 1d, 1st-5 transfer path 1e, 1-6th transfer path 1f, 1-7th transfer path 1g, 1-8th transfer path 1h, 1-9th transfer path 1i, 1st-10th transfer A path 1j and a 1-11th transfer path 1k are provided.
In addition, the code | symbol A in FIG. 1 represents the incineration fly ash containing the radioactive cesium purified by the cleaning method of this embodiment, and the code | symbol B represents the raw | natural water of the said rinse water.
Furthermore, the code | symbol C in FIG. 1 represents the fly ash after purification | cleaning, and the code | symbol D represents the discharged water discharged | emitted out of a washing | cleaning installation.

The 1-1 transfer path 1a is a path for transferring the incineration fly ash A containing radioactive cesium from the outside of the cleaning facility to the mixing unit 2 of the cleaning facility 1.
The mixing unit 2 into which the incineration fly ash A is introduced by the first-to-first transfer path 1a mixes the incineration fly ash A containing radioactive cesium and the wash water, thereby washing the wash water and the incineration fly ash. It is comprised so that the mixture containing A may be obtained.

The 1-2 transfer path 1b is a path for transferring the mixture from the mixing unit 2 to the solid-liquid separation unit 3.
The solid-liquid separation unit 3 into which the mixture is introduced by the first-second transfer path 1b separates the mixture into solid-liquid, so that the washed incineration fly ash having a radioactive cesium concentration lower than the incineration fly ash A is obtained. It is comprised so that the concentrate contained with the solid content concentration higher than the said mixture and the used water (used washing water) with a solid content concentration lower than the said mixture may be obtained. In addition, the solid-liquid separation unit 3 hydrates leachate which is rinse water into the concentrate, and rinses the incinerated fly ash washed with the rinse water, thereby rinsing the incinerated fly ash C and used water (used Rinse water). That is, the solid-liquid separation unit 3 is configured to discharge two waste waters, that is, the used cleaning water and the used rinse water. In the following, the used cleaning water is sometimes referred to as “cleaning drainage”, and the used rinse water is sometimes referred to as “rinsing drainage”.
The rinse water is not limited to leachate, and tap water, industrial water, ground water, and the like can also be used.

The 1-3 transfer path 1c in the present embodiment is a path for transferring the cleaning wastewater from the solid-liquid separation unit 3 to the purification unit 4.
And the purification | cleaning part 4 is comprised so that the density | concentration of the radioactive cesium contained in this 1st waste_water | drain may be reduced by purifying the washing | cleaning waste_water | drain obtained in the solid-liquid separation part 3. FIG.

The discharge water storage unit 5 is configured to store the used water purified by the purification unit 4 as discharge water D.
The 1-4 transfer path 1d is a path for transferring the washed waste water having a reduced concentration of radioactive cesium as discharged water D from the purification unit 4 to the discharged water storage unit 5, and the first-5 transfer path 1e is This is a path for transferring the discharged water D from the discharged water storage section 5 to the outside of the cleaning facility 1.

The cleaning water storage unit 6 is configured to store cleaning water for use in the mixing unit 2.
The leachate storage section 7 stores the rinse water used in the solid-liquid separation section 3, and the leachate leached from the waste landfill as the raw water B is introduced from outside the facility and subjected to various treatments. It is comprised so that water can be supplied to the said solid-liquid separation part 3 as said rinse water.

  The 1-6th transfer path 1f is a path for transferring the raw water B (leached water) from the outside of the cleaning facility 1 to the leachate storage part 7 of the cleaning facility 1. The 1-7th transfer path 1g is a path for transferring a part of the leachate subjected to various treatments as discharge water D from the leachate storage part 7 to the discharge water storage part 5. The first 1-8 transfer path 1h is a path for transferring the remaining portion of the leachate subjected to various treatments from the leachate storage part 7 to the solid-liquid separation part 3. The 1-9 transfer path 1 i is a path for transferring the cleaning water from the cleaning water storage unit 6 to the mixing unit 2. The first 1-10 transfer path 1j is a path for transferring the used rinse water from the solid-liquid separation unit 3 to the washing water storage unit 6. The first 1-11 transfer path 1k is a path for transferring the rinsed incineration fly ash C from the solid-liquid separation unit 3 to the outside of the cleaning facility 1.

  Hereinafter, the main configuration of the cleaning facility 1 will be described in more detail.

The mixing unit 2 includes a bag breaker 21, a primary pulverizer 22, a secondary pulverizer 23, and a mixture storage tank 24 in this order from the upstream side in the process flow direction. That is, the 1-1 transfer path 1a is a path for transferring the bag containing the incineration fly ash A from the outside of the cleaning facility 1 to the bag breaker 21 of the cleaning facility 1.
The mixing unit 2 includes a plurality of mixture dissolution tanks 25 arranged in parallel on the downstream side of the mixture storage tank 24. In the present embodiment, the mixing unit 2 includes a plurality of mixture dissolution tanks 25, but the mixing unit 2 may include only one mixture dissolution tank 25.

  The mixing unit 2 includes a 2-1 transfer path 2a, a 2-2 transfer path 2b, a 2-3 transfer path 2c, and a 2-4 transfer path 2d.

  The bag breaker 21 is a machine that breaks the bag transferred through the first transfer path 1a and takes out the mass of the incinerated fly ash A from the bag. Note that the incineration fly ash A is usually transferred in a sealed state in a bag for the purpose of preventing scattering. The incinerated fly ash A is usually compressed by its own weight or the pressure received when the bags are stacked while being stored in a bag, and agglomerates are formed in the bag.

  The 2-1 transfer path 2a is a path for transferring the incineration fly ash containing such agglomerates from the bag breaker 21 to the primary crusher 22.

The primary crusher 22 is a machine that performs a process of crushing a lump with respect to the incineration fly ash A containing the lump introduced from the bag breaker 21 through the 2-1 transfer path 2a.
The 2-2 transfer path 2 b is a path for transferring the incineration fly ash crushed by the primary pulverizer 22 from the primary pulverizer 22 to the secondary pulverizer 23.

The secondary pulverizer 23 is a machine that further crushes the incineration fly ash A crushed by the primary pulverizer 22 to make the incineration fly ash A into a powder form. In the present embodiment, the 1-9 transfer path 1i connecting the mixing unit 2 and the washing water storage unit 6 is connected to a secondary pulverizer 23, and the mixing unit 2 is connected to the secondary crusher 23. The pulverizer 23 is configured to perform wet pulverization of the incineration fly ash A using washing water.
The secondary pulverizer 23 includes a container for storing the incineration fly ash A, a rod-shaped rotating shaft portion having one end portion arranged in the container and rotated about an axis, and the one end portion of the rotating shaft portion. The incinerated fly ash A is pulverized in the container by the blade portion when the rotating shaft portion rotates.
Further, the secondary pulverizer 23 pulverizes the incineration fly ash A while mixing the incineration fly ash A crushed by the primary pulverizer 22 and the washing water, thereby cleaning the incineration fly ash A that has been pulverized. It is comprised so that water may be mixed and a slurry-like mixture may be obtained. The secondary pulverizer 23 is configured to further pulverize the incineration fly ash A while mixing the incineration fly ash A crushed by the primary pulverizer 22 and the washing water. As compared with the case where dry pulverization is carried out without the above, the incineration fly ash A can be prevented from adhering to the inner wall and blade portion of the container.
Further, the secondary pulverizer 23 uses the wet pulverization method as the pulverization method of the incineration fly ash A, so that the incineration fly ash A is scattered outside the container as compared with the case of adopting the dry pulverization method. There is also an advantage that it is easy to suppress.
As the cleaning water, for example, tap water, industrial water, ground water and the like can be used. In addition, as the washing water, used washing water used for washing incineration fly ash and used rinsing water used for rinsing washed incineration fly ash are also used.
The mixing part 2 uses the crushed thing as the incineration fly ash A to be mixed with the washing water, so that the specific surface area of the incineration fly ash A is increased and is easily dissolved in water. Cesium, calcium carbonate, sodium chloride, potassium chloride, etc.) are easily dissolved, and as a result, the volume of incinerated fly ash can be reduced, and the piping for transporting the mixture can be prevented from clogging. Has the advantage.
In addition, you may make it the washing | cleaning equipment 1 supply the water of the washing water storage tank 6 and the water of the used water flow volume adjustment tank 41 mentioned later to the mixture dissolution tank 25 instead of the secondary crusher 23, for example. .

  The 2-3 transfer path 2 c is a path for transferring the mixture from the secondary pulverizer 23 to the mixture storage tank 24. The mixture storage tank 24 is a tank that stores the mixture before it is distributed to each mixture dissolution tank 25.

  The 2-4 transfer path 2d is for transferring the mixture to a plurality of mixture dissolution tanks 25 arranged in parallel on the downstream side of the mixture storage tank 24, and from the mixture storage tank 24 to the individual mixture dissolution tanks 25. A plurality of pipes are provided so that the mixture can be transferred.

The mixture dissolution tank 25 is a tank for reducing the concentration of radioactive cesium in the incineration fly ash by mixing and stirring the mixture transferred from the mixture storage tank 24 for a predetermined time to dissolve radioactive cesium and the like contained in the incineration fly ash of the mixture. It is. Moreover, the mixture dissolution tank 25 is also a tank that further reduces radioactive cesium concentration in the incineration fly ash by further dissolving radioactive cesium and the like from the incineration fly ash contained in the second mixture described later. The cleaning equipment 1 includes a stirring blade provided in the mixture dissolution tank 25, and is configured to mix and stir incineration fly ash and cleaning water with the stirring blade.
In the present embodiment, in the mixture dissolution tank 25, in order to enhance the cleaning effect, washing water is further added to the mixture (first mixture) transferred from the mixture storage tank 24, and the mixture is mixed and stirred for a predetermined time. 2 mixtures) may be obtained. Moreover, when producing a 2nd mixture, you may extract a part of washing water from a 1st mixture before adding washing water to a 1st mixture.
Moreover, you may make it neutralize the pH of the water in a mixture by mixing an acid in a mixture in the mixture dissolution tank 25. FIG. Examples of the acid include sulfuric acid, nitric acid, hydrochloric acid and the like. The pH of the mixture transferred from the mixture storage tank 24 is usually 11-12. By neutralizing the water of this mixture with an acid, components (calcium carbonate and the like) contained in the incineration fly ash that are easily dissolved in water near neutrality are easily dissolved. Thereby, there exists an advantage that the volume of incineration fly ash can be reduced. In addition, there is an advantage that radioactive cesium that is easily dissolved in water near neutrality and confined in components contained in the incineration fly ash is easily dissolved in water. As pH of the water in the mixture after neutralization, 5-9 are preferable and 6-7 are more preferable.
Although the addition of the acid for neutralization can be performed once, it is preferable to add it at intervals in a plurality of times. If the acid is added at a time and the pH becomes too low, the wall of the mixture dissolution tank 25 may be corroded. Moreover, after adding an acid, if it stirs for a fixed period, the calcium carbonate in fly ash will melt | dissolve and the pH of the water in a mixture will become high. Therefore, by adding the acid stepwise, the easily dissolved component in the fly ash can be reliably dissolved in water, and the amount of fly ash to be finally disposed of in landfill can be reduced.

  The 1-2 transfer path 1b includes a plurality of pipes that transfer the mixture from each mixture dissolution tank 25 to the solid-liquid separation unit 3.

The solid-liquid separation unit 3 has a filter cloth, and includes a filter press machine that separates an object into a solid and liquid by a filter press (squeezing) using the filter cloth.
The solid-liquid separation unit 3 pumps the mixture obtained in the mixture 2 to the filter press machine by a pump, and thereby concentrates the mixture with a higher solid content than the mixture through the filter cloth of the filter press machine. And used water (used washing water) having a solid content lower than that of the mixture.
The solid-liquid separation unit 3 normally concentrates a small amount of water containing radioactive cesium on the filter cloth together with the washed incinerated fly ash having a reduced content of radioactive cesium compared to the incinerated fly ash A introduced into the washing facility 1. Since it is contained in the product, rinsing can be performed by rinsing water having a radioactive cesium concentration lower than that of water contained in the concentrate.
That is, the solid-liquid separation unit 3 performs hydration by causing the rinse water to flow down to the concentrate on the filter cloth by pumping the leachate B, which is rinse water in the leachate storage unit, to the filter press with a pump. The water containing the radioactive cesium adhering to the surface of the washed incineration fly ash is washed away, and the rinse process of the washed incineration fly ash can be performed.
In addition, after the rinsing water is added to the concentrate, the solid-liquid separation unit 3 further performs dehydration treatment on the washed incineration fly ash by pressing with the filter press machine, and the rinsed incineration fly ash C and In addition, it is configured to be capable of solid-liquid separation into used water (used rinse water).
The solid-liquid separation unit 3 may include a belt press machine that has a filter cloth instead of the filter press machine and separates an object from the solid and liquid by a belt press using the filter cloth.

  The cleaning equipment 1 of the present embodiment is configured to be able to transfer the first waste water generated by solid-liquid separation before adding the rinse water to the purification unit 4 through the first to third transfer path 1c, and rinse The second drainage generated by the solid-liquid separation after the start of the water flow until the filter press is completed is configured to be transferred to the washing water reservoir 6 through the 1-10 transfer path 1j.

The purification unit 4 includes a used water flow rate adjustment tank 41, an adsorption tower raw water storage tank 42, an adsorption tower part 43, an MF membrane part 44, and an MF membrane permeated water in order from the upstream side along the processing flow. A storage tank 45.
The purification unit 4 includes a 4-1 transfer path 4a, a 4-2 transfer path 4b, a 4-3 transfer path 4c, and a 4-4 transfer path 4d.

  As described above, the purifying unit 4 of the present embodiment has the used water flow rate adjustment tank 41 on the most upstream side, so that the first to third transfer path 1c is introduced into the water flow rate adjustment tank 41 in order to introduce the washing waste water. And is connected to the solid-liquid separation unit 3. The used water flow rate adjustment tank 41 is a tank that accommodates cleaning wastewater and adjusts the flow rate of cleaning wastewater to be transferred downstream.

The 4-1 transfer path 4a is a path for transferring used water from the used water flow rate adjustment tank 41 to the raw water storage tank 42 for the adsorption tower.
The adsorption tower raw water storage tank 42 is a tank for storing washing wastewater as raw water for the adsorption tower.

The 4-2 transfer path 4b is a path for transferring the washing waste water as the adsorption tower raw water from the adsorption tower raw water storage tank 42 to the adsorption tower 43.
The adsorption tower unit 43 includes a tower having an adsorbent. Further, the adsorption tower unit 43 is configured to reduce the concentration of radioactive cesium contained in the adsorption tower raw water by bringing the washing waste water, which is the adsorption tower raw water, into contact with the adsorbent and adsorbing the radioactive cesium to the adsorbent. It is configured to be able to.
Examples of the adsorbent include inorganic adsorbents such as zeolite, ion exchange resins that adsorb cations, or ferrocyanide metal compounds such as ferrocyanide cobalt, ferrocyanide copper, or ferric ferrocyanide. Is adopted. As the adsorbent, zeolite is preferable in that it is relatively inexpensive and has excellent radiocesium adsorption performance.
The purification unit 4 may include an RO membrane unit having an RO membrane, and the RO membrane unit is provided in front of the adsorption tower unit 43. In this case, the purification unit 4 may be configured to supply only the concentrated water generated in the RO membrane unit to the adsorption tower. In this case, the purifying unit 4 may reuse the permeated water generated in the RO membrane unit as rinse water or washing water, or may transfer it as outflow water outside the washing facility.

The 4th-3 transfer path 4c is a path for transferring used water whose radioactive cesium concentration has been reduced in the adsorption tower section 43 from the adsorption tower section 43 to the MF membrane section 44.
The MF membrane unit 44 is configured to perform membrane treatment on the washing wastewater with a reduced concentration of radioactive cesium with a microfiltration membrane (MF membrane) to obtain MF membrane permeated water. By treating with the MF membrane, even if the adsorbent flows out of the adsorption tower and the MF membrane permeated water contains the adsorbent, the adsorbent can be separated from the MF membrane permeated water with the MF membrane. .

The fourth 4-4 transfer path 4 d is a path for transferring the MF membrane permeated water from the MF membrane portion 44 to the MF membrane permeated water storage tank 45.
The MF membrane permeated water storage tank 45 is configured to store the MF membrane permeated water obtained by the MF membrane portion 44.

  The first to fourth transfer paths 1d are paths for transferring the MF membrane permeated water from the MF membrane permeated water storage tank 45 to the discharge water storage unit 5.

Moreover, the washing | cleaning equipment 1 is provided with the 1-12 1st transfer path | route 11 as shown in a figure.
The 1-12 transfer path 11 is a path for transferring the first drainage from the water flow rate adjusting tank 41 to the secondary pulverizer 23 as necessary.

  The leachate storage unit 7 supplies leachate subjected to biological treatment, precipitation separation, sand filtration, activated carbon adsorption treatment, chelate treatment, and reverse osmosis filtration to the solid-liquid separation unit 3 as rinse water. A leaching water flow rate adjustment tank 71 in the order of processing flow from the raw water B introduction side to the rinsing water supply side to the solid-liquid separation unit 3, a biological treatment unit 72, , A coagulation sedimentation unit 73, a sand filtration unit 74, an activated carbon treatment unit 75, a chelate treatment unit 76, a chelate water storage tank 77, an RO membrane part 78, and an RO membrane permeated water storage tank 79.

  That is, the 1-6 transfer path 1f is a path for transferring the raw water B (leached water) from the outside of the cleaning facility to the leachate flow rate adjusting tank 71.

  The leachate storage unit 7 includes a 7-1 transfer path 7a, a 7-2 transfer path 7b, a 7-3 transfer path 7c, a 7-4 transfer path 7d, and a 7-5 transfer. A path 7e, a 7-6 transfer path 7f, a 7-7 transfer path 7g, and a 7-8 transfer path 7h are further provided.

The leachate flow rate adjustment tank 71 is a tank that accommodates the leachate that is the raw water B of the rinse water and adjusts the flow rate of the leachate that is transferred downstream.
The raw water B is not particularly limited as long as it is leachable water leached from a waste landfill, and for example, the landfill of the incinerated fly ash C that has been rinsed from the cleaning facility 1 of the present embodiment. Leached water leached from may be used.

The 7-1 transfer path 7 a is a path for transferring leachate from the leachate flow rate adjustment tank 71 to the biological treatment unit 72.
The biological treatment unit 72 is configured to obtain biologically treated water by biologically treating the leachate B from the leachate flow rate adjustment tank 71. The biological treatment is a treatment for decomposing organic matter and ammonia contained in water by biological species such as bacteria, protozoa and metazoans. Moreover, as the biological treatment part 72, the biological treatment apparatus etc. which were equipped with the tank and the support | carrier which was distribute | arranged in the tank and the biological species adhered were mentioned. The carrier may be a stationary carrier or a fluid carrier. Moreover, the aspect which equips the biological treatment part 72 with a biological species without providing a support | carrier according to the density | concentration of the organic substance contained in leachate may be sufficient.

The seventh-second transfer path 7 b is a path for transferring biologically treated water as leachable water from the biological treatment unit 72 to the coagulation sedimentation unit 73.
The coagulation sedimentation unit 73 mixes the biologically treated water and the coagulant, thereby coagulating the solids contained in the biologically treated water with the coagulant and removing the aggregates, thereby coagulating the sedimentation treated water as a supernatant liquid. Is configured to get. Examples of the flocculant include polyaluminum chloride and ferric chloride.

The seventh-third transfer path 7c is a path for transferring the coagulation sedimentation treated water as leachate from the coagulation sedimentation section 73 to the sand filtration section 74.
The sand filtration unit 74 includes a sand layer, and is configured to obtain sand filtered water by filtering the coagulated sediment treated water through the sand layer.

The seventh to fourth transfer path 7d is a path for transferring sand filtrate water as leachate from the sand filtration unit 74 to the activated carbon treatment unit 75.
The activated carbon treatment unit 75 includes activated carbon, makes sand filtered water contact the activated carbon, and contains hardly-decomposable organic substances contained in the sand filtered water (organic substances or biological species that could not be decomposed by the biological species in the biological treatment unit 72). By adsorbing the metabolites etc. discharged from the activated carbon to the activated carbon, activated carbon treated water having a lower organic matter concentration than the sand filtered water is obtained.

The seventh to fifth transfer path 7e is a path for transferring activated carbon treated water as leachate from the activated carbon treatment unit 75 to the chelate treatment unit 76.
The chelate treatment unit 76 mixes the activated carbon-treated water with the chelating agent to bind the metal ions contained in the activated carbon-treated water with the chelating agent, and removes the bound substance, thereby making the metal more active than the activated carbon-treated water. It is configured to obtain chelated water having a low ion concentration. Examples of the chelating agent include polymeric resins having functional groups such as iminodiacetic acid type, aminophosphoric acid type, amidoxime type, glucamine type, special metal support type, polyamine type, thiourea type, and dithiocarbamic acid type.

The seventh-sixth transfer path 7f is a path for transferring the chelate-treated water that is leached water from the chelate treatment unit 76 to the chelate-treated water storage tank 77.
The chelated water storage tank 77 is a tank that stores the chelated water.

The seventh to seventh transfer path 7g is a path for transferring a part of the chelate-treated water as leachate from the chelate-treated water storage tank 77 to the RO membrane part 78.
The RO membrane part 78 is configured to obtain RO membrane permeated water and RO membrane concentrated water by subjecting chelate-treated water to membrane filtration with a reverse osmosis membrane (RO membrane). In addition, the RO membrane in this specification is a concept including a nanofiltration membrane (NF membrane).

The seventh to eighth transfer path 7h is a path for transferring the RO membrane permeate as leachable water from the RO membrane portion 78 to the RO membrane permeate storage tank 79.
The RO membrane permeated water storage tank 79 is a tank that stores the RO membrane permeated water.
In addition, although RO membrane permeated water is used as rinsing water or washing water as described later, the chelating water may be used as rinsing water or washing water without membrane treatment with the RO membrane.

The 1-7th transfer path 1g is a path for transferring a part of the chelate treated water from the chelate treated water storage tank 77 to the discharged water storage section 5 as the discharged water D.
The first 1-8 transfer path 1h is a path for transferring the RO membrane permeated water as rinse water from the RO membrane permeated water storage tank 79 to the solid-liquid separation unit 3.
In this embodiment, the chelate-treated water that is leached water is discharged without membrane treatment with the RO membrane. However, the permeated water is obtained by membrane treatment of the leachate water with the RO membrane, and the permeated water that is leachable water. May be released.

Further, the cleaning facility 1 includes a 1-13 transfer path 1m as shown in the figure.
The 1-13th transfer path 1m is a path for transferring the RO membrane concentrated water as leachate from the RO membrane portion 78 to the raw water storage tank 42 for the adsorption tower. The cleaning facility 1 purifies the RO membrane concentrated water, which is leachable water, as the raw water for the adsorption tower in the same manner as the cleaning wastewater, and discharges the purified RO membrane concentrated water in the same manner as the purified cleaning wastewater. The water D is transferred to the outside of the cleaning facility 1.
In the cleaning facility 1, the RO membrane concentrated water that is leached water and the first drainage may be purified together, or the RO membrane concentrated water that is leached water and the first drainage may be purified separately.

  Furthermore, in the leachate storage part 7, the treatment method of the leachate is not limited to the described method, and various known methods can be employed. For example, as a treatment method for the leachate, an immersion membrane activated sludge method using an immersion membrane as a biological treatment may be performed. Moreover, when there is much salt in leachate, you may perform processes, such as evaporation concentration, as a processing method of the leachate.

Next, the incineration fly ash cleaning method for cleaning the incineration fly ash using the above-described cleaning equipment 1 will be described.
In the incineration fly ash cleaning method, the mixing unit 2 mixes the incineration fly ash and washing water to obtain mixed water, and the solid-liquid separation unit 3 generates a dehydrated cake by solid-liquid separation. Thus, a concentrate having a solid content higher than that of the mixed water is obtained, and the solid-liquid separation unit 3 performs a rinsing step of rinsing the concentrate with rinse water.
More specifically, the incineration fly ash is washed as follows.

First, the bag containing the incineration fly ash A is transferred from the outside of the cleaning equipment 1 to the bag breaking machine 21 of the cleaning equipment 1 through the 1-1 transfer path 1a. The lump of incineration fly ash A is taken out from the bag accommodated.
Then, the mass of the incinerated fly ash A is transferred from the bag breaker 21 to the primary pulverizer 22 through the 2-1 transfer path 2a, and the mass of the incinerated fly ash A is crushed by the primary pulverizer 22.
In this way, pretreatment of the incinerated fly ash A supplied to the secondary pulverizer 23 through the 2-2 transfer path 2b is performed by the primary pulverizer 22.

  On the other hand, fresh water such as industrial water is prepared in the washing water storage unit 6 as washing water supplied to the secondary pulverizer 23. As will be described later, leachate, first drainage, second drainage, and the like can be used as the wash water supplied to the secondary pulverizer 23.

The rinse water is prepared as follows.
First, leachate is transferred from the outside of the cleaning facility 1 to the leachate flow rate adjustment tank 71 via the 1-6 transfer path 1f.
Then, the flow rate of the leachate transferred to the biological treatment unit 72 is adjusted by the leachate flow rate adjustment tank 71, and the leachate is transferred from the leachate flow rate adjustment tank 71 to the biological treatment unit 72 through the 7-1 transfer path 7a. Biologically treated water is obtained by biologically treating the leachate with the biological treatment unit 72.
Next, the biologically treated water is transferred from the biological treatment unit 72 to the coagulation / sedimentation unit 73 through the seventh-second transfer path 7b, and the biologically treated water and the coagulant are mixed in the coagulation / sedimentation unit 73. Get.
Then, the coagulation sedimentation treated water is transferred from the coagulation sedimentation unit 73 to the sand filtration unit 74 through the seventh-third transfer path 7c, and the coagulation sedimentation treatment water is filtered through the sand layer of the sand filtration unit 74, thereby sand filtration water. Get.
Next, the sand filtered water is transferred from the sand filtering unit 74 to the activated carbon treatment unit 75 through the seventh to fourth transfer path 7d, and the sand filtered water and activated carbon are brought into contact with each other at the activated carbon treatment unit 75 to obtain activated carbon treated water.
Then, the activated carbon treated water is transferred from the activated carbon treatment unit 75 to the chelate treatment unit 76 through the 7-5 transfer path 7e, and the activated carbon treatment water and the chelating agent are mixed in the chelate treatment unit 76 to obtain chelate treated water. .
Next, the chelate-treated water is transferred from the chelate treatment unit 76 to the chelate-treated water storage tank 77 through the seventh-sixth transfer path 7f.
Then, a part of the chelate treated water is transferred as effluent water D through the 1-7 transfer path 1g from the chelate treated water storage tank 77 to the effluent water storage part 5, and the remainder is chelated by the 7-7 transfer path 7g. It is transferred from the storage tank 77 to the RO membrane part 78 and membrane-filtered by the RO membrane of the RO membrane part 78.
RO membrane permeated water and RO membrane concentrated water are obtained by membrane filtering the chelate-treated water with the RO membrane.
Next, the RO membrane concentrated water is transferred from the RO membrane section 78 to the adsorption tower raw water storage tank 42 through the 1-13 transfer path 1 m.
Then, the RO membrane permeated water is transferred from the RO membrane portion 78 to the RO membrane permeated water storage tank 79 through the seventh to eighth transfer path 7h, and this is prepared as rinse water.

In such a state, the incinerated fly ash A is supplied from the primary pulverizer 22 to the secondary pulverizer 23 through the 2-2 transfer path 2b, and the cleaning water is stored in the cleaning water reservoir 6 through the 1-9 transfer path 1i. The incinerated fly ash A transferred to the secondary pulverizer 23 and mixed by the secondary pulverizer 23 while the incinerated fly ash A crushed by the primary pulverizer 22 and the washing water are mixed by the secondary pulverizer 23. A slurry-like mixture containing crushed and fly ash and washing water is obtained.
At this time, it is preferable that the mixture has a solid content concentration of 5% by mass to 65% by mass in terms of easy transportation of the slurry-like mixture.

Then, the mixture is transferred from the secondary pulverizer 23 to the mixture storage tank 24 through the 2-3 transfer path 2c, the mixture is further transferred from the mixture storage tank 24 to the mixture dissolution tank 25, and the mixture is further mixed in the mixture dissolution tank 25. Is stirred at a temperature of 0 ° C. to 40 ° C. for 10 minutes to 24 hours, and components (radioactive cesium, calcium carbonate, sodium chloride, potassium chloride, etc.) contained in the incineration fly ash are dissolved in water. In the mixture dissolution tank 25, the mixture and the acid are mixed to neutralize the water in the mixture so as to have the preferred pH as described above, thereby reducing the volume of the washed incineration fly ash and incineration flying. The radioactive cesium contained in the center of the ash particles may be more efficiently eluted.
As described above, since the cleaning equipment 1 includes a plurality of the mixture dissolution tanks 25, even if the dissolution in the mixture dissolution tank 25 is performed in a batch manner, the mixture dissolution tank 25 can be sequentially charged with the mixture. Also, there is an advantage that one solid-liquid separation unit 3 can be used efficiently.
Next, the mixture is pumped from the mixture dissolution tank 25 to the solid-liquid separation unit 3 using a pump in the first-second transfer path 1b, so that the mixture is obtained using the filter cloth of the filter press machine of the solid-liquid separation unit 3. Is filtered to separate the concentrate containing the washed incineration fly ash and the used washing water (first waste water).
After that, the washed incineration fly ash on the filter cloth is caused to flow down using the pump as the RO membrane permeated water transferred from the RO membrane permeated water storage tank 79 using the pump, and the washed incinerated fly ash is rinsed with rinse water.
In the rinsing step, the dehydrated cake containing the rinsed incinerated fly ash C and the used rinse water (secondary) are further dehydrated by dehydrating the washed incinerated fly ash that has been in contact with the rinse water by a filter press in a filter press machine. Drainage).
At this time, since the used washing water contains radioactive cesium, it is possible to remove as much used washing water as possible from the washed incineration fly ash before adding the rinse water to the concentrate. preferable. On the other hand, if the concentrate has an excessively high solid content, the permeability of the rinsing water is lowered and the rinsing effect may be lowered.
Therefore, it is preferable to carry out the rinsing water immediately after filtering the mixture as the timing of flowing down the rinse water with respect to the concentrate.
This rinsing step is preferably performed such that the radioactive cesium concentration of the used rinse water finally separated from the rinsed incineration fly ash C by a filter press is 10000 Bq / L or less.
The radioactive cesium concentration of the used rinse water can be measured using a measuring device using a NaI (TI) scintillation counter as a detector.
Moreover, it is preferable to implement the said pressing so that the moisture content may be 85 mass% or less for the dewatering cake containing the rinsed incineration fly ash C.
The first drainage is transferred to the used water flow adjusting tank 41 through the first to third transfer path 1c, and then transferred to the secondary crusher 23 through the first to twelfth transfer path 1l, thereby storing the washing water. The used rinsing water, which will be described later, is sufficiently stored in the incinerator fly ash A until it is sufficiently stored in the section 6. In addition, after repeatedly using the first waste water several times for cleaning the incineration fly ash A, after being transferred from the solid-liquid separation unit 3 to the used water flow rate adjustment tank 41 in the 1-3 transfer path 1c, Perform a purification process.
Washing water usually exhibits sufficient detergency for incineration fly ash A if the salt concentration is 20% by mass or less, so that the consumption of water in the washing facility 1 (the amount of discharged water from the washing facility 1) can be reduced. In order to achieve this, it is preferable to use repeatedly until the above state is obtained.
That is, the rinsed incinerated fly ash C is transferred from the solid-liquid separation unit 3 to the outside of the cleaning facility 1 through the 1-11 transfer path 1k, and the used cleaning water (first drainage) is transferred through the 1-3 transfer path 1c. It is transferred from the solid-liquid separator 3 to the used water flow rate adjustment tank 41.
The first wastewater transferred to the used water flow rate adjusting tank 41 is reused as cleaning water or purified as described later.
Here, although the form which transfers the 1st waste_water | drain from the used water flow volume adjustment tank 41 to the secondary crusher 23 via the 1-12 transfer path | route 1l was demonstrated, it is not limited to this, It wash | cleans In addition to the used water flow rate adjustment tank 41, the facility 1 is provided with a first drainage storage tank for storing the first drainage, and when the first drainage is reused, the first drainage obtained from the solid-liquid separation unit 3 is used. After the first drainage is supplied to the first drainage storage unit and temporarily stored in the first drainage storage unit, the first drainage is transferred from the first drainage storage unit to the secondary pulverizer 23, and the first drainage is discharged. It may be reused as cleaning water.
Further, the first waste water may be transferred to the mixture dissolution tank 25 as well.

In the used water flow rate adjustment tank 41, the flow rate of the cleaning wastewater transferred to the adsorption tower raw water storage tank 42 is adjusted, and the used waste water flow adjustment tank is used as the adsorption water for the adsorption tower in the 4-1 transfer path 4a. 41 is transferred to the raw water storage tank 42 for the adsorption tower.
Next, radioactive cesium contained in the cleaning wastewater is transferred from the raw water storage tank 42 for the adsorption tower to the adsorption tower 43 through the 4-2 transfer path 4b, and the cleaning wastewater and the adsorbent are brought into contact with each other. Reduce the concentration of.
Then, the washing waste water with reduced concentration of radioactive cesium is transferred from the adsorption tower section 43 to the MF film section 44 through the 4-3 transfer path 4c, and the water with reduced concentration of radioactive cesium is transferred to the MF of the MF film section 44. Membrane treatment is performed with a membrane to obtain MF membrane permeated water.
Next, the MF membrane permeated water is transferred from the MF membrane portion 44 to the MF membrane permeated water storage tank 45 through the 4-4 transfer path 4d, and the MF membrane permeated water is further discharged as the first to fourth transfer paths 1d. Then, it is transferred from the MF membrane permeated water storage tank 45 to the discharge water storage section 5.

In the present embodiment, since the washing water is repeatedly used, the washing water has a weight loss corresponding to the amount of water contained in the concentrate every batch.
Therefore, each time the cleaning water (first drainage) is repeatedly used, a portion of the rinse drainage from the cleaning water storage unit 6 to the secondary pulverizer 23 or the mixture dissolution tank 25 by an amount corresponding to the reduced amount of the cleaning water. The amount of industrial water corresponding to the reduced amount may be added to the secondary pulverizer 23 or the mixture dissolution tank 25.
Then, when the rinse water in the washing water storage section 6 is equal to or larger than the amount of washing water used in the mixing step, the washing water used repeatedly is adsorbed tower raw water storage tank 42 through the 4-1 transfer path 4a. Transport to. In addition, the amount of the washing water used in the mixing step for the rinse water is transferred from the washing water storage unit 6 to the secondary pulverizer 23 and the mixture dissolution tank 25.
Note that the rinse waste water obtained in one cleaning step may be used as washing water in the next cleaning step, and the deficiency may be supplemented with the cleaning waste water obtained in the one cleaning step.

In the incineration fly ash cleaning method of the present embodiment, the first cleaning wastewater discharged in the separation step of the first cleaning step and the first rinse wastewater discharged in the rinse step of the first cleaning step are the first cleaning. By being reused as washing water in another washing step performed after the step, the amount of water used relative to the amount of incinerated fly ash can be suppressed.
Further, in the incineration fly ash cleaning method of the present embodiment, the volume of the rinse water used in the rinsing step is 0.25 times or more and less than 1.0 times the volume of the cleaning water used in the mixing step, and at least the first rinsing. In the cleaning process in which wastewater is reused, a larger amount of cleaning water is used than in the first rinse wastewater, and the mixing process is performed, so that the incineration fly containing radioactive cesium is fully utilized while rinsing wastewater is fully utilized. The ash can be thoroughly washed.

  In the incineration fly ash cleaning method of the present embodiment, the first cleaning waste water and the first rinse waste water are reused in the second cleaning step.

  Further, the first rinse wastewater is reused in the third cleaning step performed after the second cleaning step, and the second rinse wastewater discharged in the rinse step of the second cleaning step is also reused in the third cleaning step. The

  The cleaning method for incineration fly ash according to the present embodiment includes a mixing step of mixing incineration fly ash containing radioactive cesium and washing water to obtain a mixture, and solid-liquid separation of the mixture to complete cleaning. A separation step for obtaining incineration fly ash and a rinse step for rinsing washed incineration fly ash with rinsing water are provided, and in the rinsing step, leachate leached from the landfill of waste is used as the rinse water. Washed incineration fly ash can be washed using leachate.

  The incineration fly ash cleaning method of the present embodiment uses the permeated water obtained by membrane filtration of the leachate leached from the landfill site of the waste with the RO membrane in the rinsing step as rinse water. The concentration of impurities contained in the rinsing water is reduced, and the cleaning effect of the washed incinerated fly ash in the rinsing process can be enhanced.

Furthermore, the cleaning method for incinerated fly ash according to the present embodiment includes a purification step that reduces the concentration of radioactive cesium contained in the cleaning wastewater discharged from the cleaning step, thereby facilitating handling of the cleaning wastewater after the purification step. Can be.
In the present embodiment, the membrane treatment with the MF membrane is further performed after the purification process in the adsorption tower 43, but instead of the membrane treatment with the MF membrane, the device of the leachate storage unit 7 is used instead of the membrane treatment after the purification step. Further purification treatment may be performed on the washing waste water.
For example, the cleaning waste water after the purification process is transferred to the sand filtration unit 74, and sand filtration in the sand filtration unit 74, adsorption treatment in the activated carbon treatment unit 75, and ion removal in the chelate treatment unit 76 are performed, and the discharged water. D can be discharged out of the cleaning facility.
At this time, since the purification process is performed on the washing waste water, the sand filtration unit 74 and the like can be prevented from being contaminated with radioactive cesium.
In the point that such an effect can be exhibited more remarkably, the purification step is preferably performed so that the washing waste water after passing through the adsorption tower 43 has a radioactive cesium concentration of 100 Bq / L or less, It is particularly preferable to carry out so that the radioactive cesium concentration is 10 Bq / L or less.
Moreover, the cleaning method of the incineration fly ash of this embodiment may reuse the cleaning waste water after the purification process as the cleaning water in the mixing process.
That is, the incineration fly ash cleaning method of the present embodiment includes an adsorption step of bringing the first cleaning wastewater into contact with an adsorbent that adsorbs radioactive cesium before the first cleaning wastewater is reused as cleaning water in the mixing step. You may implement. The incineration fly ash cleaning method of the present embodiment can reduce the concentration of radioactive cesium contained in the first cleaning wastewater before reusing the first cleaning wastewater. It has the advantage that it can be cleaned more fully.
Moreover, the cleaning method for incinerated fly ash according to the present embodiment may reuse the cleaning waste water after the purification step as rinse water for the rinsing step.
After purifying the cleaning wastewater, it can be reused as rinse water, thereby minimizing the amount of water supplied from the outside into the system (inside the cleaning equipment). That is, the washing waste water is reused as rinse water after purification, and is reused as washing water after becoming used rinse water. By circulating in this way, the amount of water supplied from outside the system can be reduced.

Moreover, the cleaning method of the incineration fly ash of this embodiment is the mass of the incineration fly ash that is cleaned in the separate cleaning process that is performed after the first cleaning process. The divided value is preferably 0.9 to 1 / 0.9, and more preferably 1.0.
Furthermore, the cleaning method of the incinerated fly ash according to the present embodiment uses the volume of cleaning water used in the mixing step of the first cleaning step as the cleaning water used in the mixing step of another cleaning step performed after the first cleaning step. The value divided by the volume is preferably 0.9 to 1 / 0.9, more preferably 1.0.
Moreover, the washing | cleaning method of the incineration fly ash of this embodiment uses the volume of the rinse water used at the rinse process of a 1st washing process, and the rinse water used at the rinse process of another washing process implemented after this 1st washing process. The value divided by the volume is preferably 0.9 to 1 / 0.9, more preferably 1.0.

In the preferred embodiment as described above, since further purification of the washing wastewater can be performed as described above, in the above embodiment, the permeated water obtained by membrane filtration with the RO membrane is used. Although the case where it uses as rinse water is illustrated, it also has the advantage that it becomes easy to utilize the leachable water in the middle of the process in the leachate water storage part 7, or a completely unprocessed leachate, for example.
That is, the leaching water is used as the rinsing water in the state of the raw water B, and the rinsing wastewater generated in the rinsing process using the rinsing water is used as the cleaning water, and the purification process is performed on the cleaning effluent generated in the mixing process using the cleaning water. After the implementation, the waste water after the purification step may be subjected to sand filtration or chelation treatment to obtain the discharged water D.

  Although the incineration fly ash cleaning method of the present embodiment has the above-described advantages due to the above configuration, the incineration fly ash cleaning method of the present invention is not limited to the above configuration, and can be appropriately changed in design. It is.

That is, in this embodiment, the case where the leachate leached from the landfill of waste is used exclusively as rinse water, and the rinse water used as the rinse water is used as part of the wash water is illustrated. However, in the method for cleaning incinerated fly ash according to the present invention, part or all of the cleaning water may be used as the leachate supplied from the leachate storage unit 7.
That is, mixing the incineration fly ash containing radioactive cesium and washing water, mixing step to obtain a mixture, and separation step to obtain the washed incineration fly ash by solid-liquid separation of the mixture. In the mixing step, the leachate leached from the landfill site of waste is used as the washing water, and in the incineration fly ash washing method, the leachate is used in the same manner as the incineration fly ash washing method exemplified above. Incineration fly ash can be washed while utilizing.
Moreover, also when using the leachate supplied from the leachate storage part 7 as washing water, the said purification process is implemented by implementing the purification process which reduces the density | concentration of radioactive cesium with respect to the washing waste_water | drain discharged | emitted by a isolation | separation process. It is the same as the incinerated fly ash cleaning method described above in that it is easy to handle the cleaning waste water later and it is easy to perform further purification using each device of the leachate storage section 7.

  Although no further detailed description will be given here, the conventionally known technical matters regarding the fly ash treatment method and the water treatment method can be adopted in the present invention as long as the effects of the present invention are not significantly impaired. Is a matter of course.

<Test Example 1>
(Washing process: first time (only once))
First, incineration fly ash containing 25% water content (concentration of radioactive cesium: 25000 Bq / kg) containing radioactive cesium is mixed with washing water (clean water) while crushing with a pulverizer (amount of washing water: incineration flying) A mixture (concentration of solid content: 14% by mass) was obtained by mixing 5 L) (25 ° C., 60 minutes) with respect to 1 kg of ash mass (wet mass) (mixing step).
Next, the mixed water was transferred to a filter press machine, and separated into a concentrate and washing waste water by pump pressurization using a filter cloth of the filter press machine (separation process). In addition, the quantity of the obtained washing | cleaning waste_water | drain was about 4L with respect to 1 kg of incineration fly ash used at the mixing process.
Then, rinse water (clean water) is allowed to flow down to the concentrate on the filter cloth by pump pressurization (amount of rinse water: 5 L with respect to 1 kg of incinerated fly ash mass used in the mixing step), and the concentrate has been washed. The incinerated fly ash was rinsed with rinse water, and the dehydrated cake containing rinsed incinerated fly ash and rinse drainage were obtained by dehydrating the concentrate that had been in contact with the rinse water using a filter press in a filter press machine. Rinse process). In addition, the quantity of the obtained rinse waste_water | drain was about 5L with respect to 1 kg of mass of the incineration fly ash used at the mixing process.

<Test Example 2>
(Washing process: 1st time)
The cleaning process was performed in the same manner as the first cleaning process in Test Example 1 except that the amount of rinse water used in the rinsing process was 2.5 L with respect to 1 kg of the mass of incinerated fly ash used in the mixing process. did.
In addition, the quantity of the washing | cleaning waste_water | drain obtained is about 4L with respect to the mass of 1 kg of the incineration fly ash used at the mixing process, and the quantity of the obtained rinse waste water is the mass of 1 kg of the incineration fly ash used at the mixing process. About 2.5 L.

(Washing process: 2nd time) (Number of reuse: 1st time)
The cleaning process was performed in the same manner as the first cleaning process of Test Example 2 except that the cleaning wastewater obtained in the first cleaning process of Test Example 2 was used as the cleaning water (amount of cleaning water: incineration flying) 5 L for 1 kg of ash). In addition, clean water was replenished as a deficient wash water.

<Test Example 3>
(Washing process: 1st time)
The washing process was carried out in the same manner as the first washing process of Test Example 1 except that the amount of washing water used in the mixing process was 10 L with respect to 1 kg of the mass of incinerated fly ash used in the mixing process.
In addition, the quantity of the washing | cleaning waste_water | drain obtained is about 9L with respect to the mass of 1 kg of incineration fly ash used at the mixing process, and the quantity of the obtained rinse waste water is the mass of 1 kg of incineration fly ash used at the mixing process. It was about 5L.

(Washing process: 2nd time) (Number of reuse: 1st time)
The cleaning process was performed in the same manner as the first cleaning process of Test Example 3 except that the cleaning wastewater obtained in the first cleaning process of Test Example 3 was used as the cleaning water (amount of cleaning water: incineration flying) 10 L for 1 kg of ash). In addition, clean water was replenished as a deficient wash water.

<Test Example 4>
(Washing process: 1st time)
The cleaning process was carried out in the same manner as the first cleaning process in Test Example 3, except that the amount of rinse water used in the rinsing process was 2.5 L with respect to 1 kg of the mass of incinerated fly ash used in the mixing process. did.
In addition, the quantity of the washing | cleaning waste_water | drain obtained is about 9L with respect to the mass of 1 kg of incineration fly ash used at the mixing process, and the quantity of the obtained rinse waste water is the mass of 1 kg of incineration fly ash used at the mixing process. About 2.5 L.

(Washing process: 2nd time) (Number of reuse: 1st time)
The cleaning process was carried out in the same manner as the first cleaning process of Test Example 4 except that the cleaning wastewater obtained in the first cleaning process of Test Example 4 was used as the cleaning water (amount of cleaning water: incineration flying) 10 L for 1 kg of ash). In addition, clean water was replenished as a deficient wash water.

(Washing process: 3rd time) (Number of reuse: 2nd time)
The cleaning process was performed in the same manner as the first cleaning process of Test Example 4 except that the cleaning wastewater obtained in the second cleaning process of Test Example 4 was used as the cleaning water (amount of cleaning water: incineration flying) 10 L for 1 kg of ash). In addition, clean water was replenished as a deficient wash water.

(Washing process: 4th time) (Number of reuse: 3rd time)
The cleaning process was performed in the same manner as the first cleaning process of Test Example 4 except that the cleaning wastewater obtained in the third cleaning process of Test Example 4 was used as the cleaning water (amount of cleaning water: incineration flying) 10 L for 1 kg of ash). In addition, clean water was replenished as a deficient wash water.

<Method for measuring the concentration of radioactive cesium in incineration fly ash>
The concentration of radioactive cesium in the incineration fly ash was measured using a measuring device using a NaI (TI) scintillation counter as a detector. The sample amount was 1 L (a 1 L marinelli container was used), and the measurement time was 10 minutes.

<How to determine the removal rate>
The removal rate was determined by the following formula.
Removal rate (%) = (Concentration of radioactive cesium in incineration fly ash before washing-Concentration of radioactive cesium in incineration fly ash after washing) / Concentration of radioactive cesium in incineration fly ash before washing x 100%

  The results are shown in FIG.

1: Cleaning equipment, 1a: 1-1 transfer path, 1b: 1-2 transfer path, 1c: 1-3 transfer path, 1d: 1-4 transfer path, 1e: 1-5 transfer path, 1f: 1-6th transfer route, 1g: 1-7th transfer route, 1h: 1-8th transfer route, 1i: 1st-9th transfer route, 1j: 1-10th transfer route, 1k: 1st-1 11 transfer route, 1l: 1st-12th transfer route, 1m: 1-13th transfer route,
2: mixing unit, 2a: 2-1 transfer path, 2b: 2-2 transfer path, 2c: 2-3 transfer path, 2d: 2-4 transfer path,
3: Solid-liquid separation unit,
4: Purification section, 4a: 4-1 transfer path, 4b: 4-2 transfer path, 4c: 4-3 transfer path, 4d: 4-4 transfer path,
5: Effluent water storage part,
6: Wash water reservoir,
7: leachate storage section, 7a: 7-1 transfer route, 7b: 7-2 transfer route, 7c: 7-3 transfer route, 7d: 7-4 transfer route, 7e: 7-5 transfer Path, 7f: 7-6 transfer path, 7g: 7-7 transfer path, 7h: 7-8 transfer path,
21: bag breaking machine, 22: primary pulverizer, 23: secondary pulverizer, 24: mixture storage tank, 25: mixture dissolution tank,
41: Used water flow rate adjustment tank, 42: Raw water storage tank for adsorption tower, 43: Adsorption tower section, 44: MF membrane section, 45: MF membrane permeated water storage tank,
71: Flow control tank, 72: Biological treatment section, 73: Coagulation sedimentation section, 74: Sand filtration section, 75: Activated carbon treatment section, 76: Chelate treatment section, 77: Chelate treatment water storage tank, 78: RO membrane section, 79: RO membrane permeated water storage tank,
A: Incinerated fly ash, B: Leached water, C: Rinsed incinerated fly ash, D: Effluent water

Claims (4)

A plurality of cleaning steps including a first cleaning step and another cleaning step performed after the first cleaning step are performed,
In each washing step, the incineration fly ash containing radioactive cesium and the washing water are mixed to obtain a mixture, and by solid-liquid separation of the mixture, the solid content concentration is higher than that of the mixture. A separation step to obtain a high concentrate, and a rinsing step of rinsing the concentrate with rinse water,
The volume of the rinse water used in the rinsing step is 0.25 times or more and less than 1.0 times the volume of the washing water used in the mixing step,
A first cleaning wastewater discharged in the process of separating the first cleaning step, first rinsing waste water and is discharged in the rinse step of the first washing step is reused as washing water before Symbol another washing step And at least in the cleaning process in which the first rinse wastewater is reused, the incineration fly ash cleaning method, wherein the mixing process is performed using a larger amount of cleaning water than the first rinse wastewater. A second cleaning step is performed after the first cleaning step;
The incineration fly ash cleaning method according to claim 1, wherein the first cleaning wastewater and the first rinse wastewater are reused in the second cleaning step. A second cleaning step is performed after the first cleaning step;
The first rinse drainage is reused in a third cleaning step performed after the second cleaning step,
The method for cleaning incinerated fly ash according to claim 1 or 2, wherein in the third cleaning step, the second rinse waste water discharged in the rinse step of the second cleaning step is also reused.   The incineration according to any one of claims 1 to 3, wherein an adsorption step of bringing the first cleaning wastewater into contact with an adsorbent that adsorbs radioactive cesium is performed before the reuse of the first cleaning wastewater. How to clean fly ash.

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