JP2014071025A - Solid-liquid separation method and solid-liquid separation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of solid-liquid separation of solid suspension, which has a high concentration of solid contents with various particle diameters, without prolonging time required for solid-liquid separation.SOLUTION: A first solid-liquid separation device 50A comprises: a solid-liquid separation tank 3 which has an inner container 1, with a concave-shaped filter cloth section made of a filter cloth that allows liquid 7 to pass but does not allow a solid content 11 to pass therethrough and with a height to prevent a content from overflowing an upper edge of the filter cloth section, and an outer container 2 to store the inner container 1; a solid suspension supply line 5 which introduces solid suspension 12 into the inner container 1; and a liquid extraction line 8 which extracts the liquid 7, obtained from the solid suspension 12 through solid-liquid separation in the solid-liquid separation tank 3, out of the same.

Description

  The present invention relates to a solid-liquid separation method and a solid-liquid separation apparatus for solid-liquid separation of a substance after decontamination of a substance contaminated with a radioactive substance by a wet elution method.

  When a situation occurs in which radioactive material is scattered over a wide area, the radioactive material and its radionuclide are attached or absorbed over a wide range of soil, buildings, rivers, etc. Is caused. When soil and rivers are polluted by radioactive substances, the radioactive substances accumulate in the crops grown and the fish and shellfish that live there, and there is concern about internal exposure due to ingestion.

Examples of a substance assumed as a radionuclide include, for example, ¹³⁴ Cs and ¹³⁷ Cs of radioactive cesium (Cs). ¹³⁷ Cs has a long half-life of about 30.2 years, and if the contaminated state is left unattended, the possibility of exposure to the general public for a long time increases. For this reason, development of technology for removing radioactive substances from contaminated soil is required.

  In addition, treatment methods such as incineration ash and incineration fly ash that have increased the concentration of radioactive materials due to incineration have not been established and are subject to problems, so wet classification methods, melting treatment methods, wet elution methods, etc. Research and development of exposure dose reduction methods and decontamination methods are ongoing (for example, “Decontamination Technology Demonstration Test Project 2011”).

  The wet elution method is a method in which a radioactive substance or a compound thereof (hereinafter referred to as “radioactive substance or the like”) is dissolved from a target substance using water, an acidic solution, an alkaline solution or the like and extracted into an aqueous solution. An object with a low decontamination rate can be expected to improve the decontamination rate by repeated elution (see Non-Patent Document 1).

  After elution, there is a merit that the target substance after elution of the radioactive substance and the like and the eluent are separated into solid and liquid, and the radioactive substance in the eluent is recovered by an adsorbent or the like so that it can be buried.

  In addition, the wet elution method is particularly attracting attention because various objects can be decontaminated by changing the eluent. As eluent, oxalic acid and water are promising.

  The decontamination rate by the wet elution method mainly includes the time for elution of radioactive substances from the target substance, the time for solid-liquid separation of the target substance and eluent after elution of the radioactive substance, etc. It depends on the time to adsorb the substance to the adsorbent.

  Solid-liquid separation methods are roughly classified into filtration methods, squeezing methods, sedimentation separation methods, centrifugal separation methods, and flotation separation methods.

  The filtration method is a method in which a solid-liquid suspension is brought into contact with a filter cloth or a filter having pores and separated into a clarified liquid and a solid content. The larger the pore diameter, the faster the drainage time, while the solid content in the clarified liquid increases. Therefore, it becomes a subject to select an optimal pore diameter and filtration area.

  The compression method is a solid-liquid separation method similar to the filtration method, in which liquid passes through a solid-liquid suspension such as slurry, but is stored in a partition wall that does not allow solids to pass through, and this is compressed and dehydrated to form a compressed cake. It is a method of separating into liquid. It is usual to set a filter cloth on the partition wall, and it becomes a problem to select an optimal pore diameter and filtration area.

  The sedimentation separation method, the centrifugal separation method, and the flotation separation method are all solid-liquid separation methods using the difference in specific gravity between the solid and the liquid. Therefore, if the specific gravity difference is small, there is a problem that the time required for separation becomes long.

  In general, any of these methods or a combination of several methods is applied in the solid-liquid separation step.

  For example, in Patent Document 1, after adding water to a contaminated soil composed of soil particles, contaminants and contained water to form a slurry, the supernatant is continuously recovered from the upper part of the sedimentation tank by sedimentation separation, and the solid-liquid separation tank A method to continuously collect soil from the bottom is proposed.

  Patent Document 2 proposes solid-liquid separation by filtering suspended substances such as SS and BOD in raw water using a filter medium. By incorporating a coagulant precipitation step, the suspended substance removal performance is proposed. It is improving.

Japanese Patent No. 4372687 JP 2007-229658 A

Atomic Energy Society of Japan "Spring Annual Meeting 2012", L09, University of Fukui, March 19, 2012

  However, in the method described in Patent Document 1, the solid content having a large particle size can be separated in a short time, but since the sedimentation speed is reduced for the solid content having a small particle size, the time required for the sedimentation separation becomes long. There is a problem of end.

  Moreover, in the method described in patent document 2, the suspended substance is precipitated, and the cake layer of a suspended substance will be produced | generated on the surface of a filter medium, and there exists a subject that filtration takes time. In particular, in wet processing of soil, sludge, incineration ash, and incineration fly ash contaminated with radioactive substances, the amount of eluent containing radioactive substances will increase unless the solids concentration is high. There is a need for solid-liquid separation, that is, solid-liquid separation over a long time.

  The present invention has been made in consideration of the above-mentioned circumstances, and solid-liquid suspensions having various particle sizes and containing high-concentration solids can be solidified without increasing the solid-liquid separation time. An object of the present invention is to provide a solid-liquid separation method and a solid-liquid separation apparatus capable of liquid separation.

  In order to solve the above-described problem, the solid-liquid separation method according to the embodiment of the present invention is made of a filter cloth that allows liquid to pass through but does not pass through solids, and has a height that prevents the content from overflowing from the upper end. A solid-liquid suspension is introduced into the internal container of a solid-liquid separation tank having an internal container and an external container that accommodates the internal container, and the solid-liquid suspension is left in the solid-liquid separation tank and solidified. After solid-liquid separation into a liquid and a liquid, when the liquid is extracted, the liquid supernatant is filtered through a filter cloth on the side of the inner container and discharged from the inner container.

  In order to solve the above-described problems, a solid-liquid separation device according to an embodiment of the present invention has a concave filter cloth portion made of a filter cloth that allows liquid to pass through but does not pass through solids, and this filter cloth section. A solid-liquid separation tank having an inner container having a height that prevents the contents from overflowing from the upper end of the container, an outer container for housing the inner container, and a solid-liquid suspension for introducing the solid-liquid suspension into the inner container A liquid supply line; and a liquid extraction line for extracting the liquid obtained by solid-liquid separation from the solid-liquid suspension in the solid-liquid separation tank to the outside from the solid-liquid separation tank. .

  According to the present invention, it is possible to perform solid-liquid separation of a solid-liquid suspension having various particle sizes and containing a high concentration of solid content without increasing the solid-liquid separation time.

It is explanatory drawing of the solid-liquid separation apparatus which concerns on the 1st Embodiment of this invention, (A) is the schematic which shows the whole structure of a 1st solid-liquid separation apparatus, (B) is the arrow X of a solid-liquid separation tank An arrow view from the direction. Schematic of the solid-liquid separator which concerns on the 2nd Embodiment of this invention. Schematic of the solid-liquid separator which concerns on the 3rd Embodiment of this invention. Schematic of the solid-liquid separator which concerns on the 4th Embodiment of this invention.

  A solid-liquid separation device and a solid-liquid separation method according to an embodiment of the present invention will be described with reference to the drawings.

  The solid-liquid separation device and the solid-liquid separation method according to the embodiment of the present invention are a solid-liquid separation device and a solid-liquid separation method. Used in liquid separation.

[First embodiment]
<Configuration>
FIG. 1 is an explanatory diagram of a first solid-liquid separation device 50A that is an example of the solid-liquid separation device according to the first embodiment of the present invention, and FIG. 1 (A) shows the first solid-liquid separation device 50A. Schematic which shows the whole structure of this, (B) is an arrow line view from the arrow X direction of the solid-liquid separation tank 3. FIG.

  The first solid-liquid separation device 50A includes, for example, a solid-liquid separation tank 3 constituted by a double container having an inner container 1 and an outer container 2 that accommodates the inner container 1, and a solid-liquid suspension 12 inside. A solid-liquid suspension supply line 5 to be introduced into the container 1 and a liquid extraction line 8 for extracting the liquid 7 from the solid-liquid separation tank 3 to the outside are provided.

  The internal container 1 of the solid-liquid separation tank 3 has a filter cloth part formed in a concave shape with a filter cloth that allows liquid 7 to pass but not solid content 11, and has an upper end of the filter cloth part, that is, the inner container 1. The height of the solid content 11 and the liquid 7 in a suspended state from the upper end of the liquid is ensured so as not to overflow.

  Here, the liquid 7 means water, an acidic solution, or an alkaline solution. Examples of the acidic solution include an oxalic acid solution. Examples of the alkaline solution include an aqueous ammonium sulfate solution.

  Further, the solid content 11 means, for example, solid substances that may be attached or absorbed by radioactive substances such as soil and sludge, incineration ash and incineration fly ash, and are contaminated with radioactive substances. Including things.

  Since the filter cloth is desired to have good process condition temperature, liquid resistance, and wettability, the first solid-liquid separator 50A uses, for example, a filter cloth made of polypropylene. In addition to polypropylene, for example, polyethylene, polyester, nylon and the like have good process condition temperature, liquid resistance, and wettability, and these can be used as a filter cloth material instead of polypropylene. .

  The pore diameter of the filter cloth is a structure in which the liquid 7 passes but the solid content 11 does not pass, for example, when the particle diameter d of the solid content 11 is d1 <d <d2, the mesh size is less than d1. A shaped case is desired.

  If the pore diameter of the filter cloth is too small, the solid content 11 or the discharge time of the liquid 7 becomes long, so the pore diameter d of the filter cloth can be set to d3 slightly larger than d1. Here, d3 is assumed to be equal to the particle diameter on the lower side 1/100 of the mass-based particle diameter cumulative distribution of the solid matter.

  On the bottom surface of the solid-liquid separation tank 3, a liquid extraction line 8 for extracting the liquid 7 that has passed through the inner container 1 and accumulated in the outer container 2 is attached. Further, a liquid extraction valve 9 for opening and closing the liquid extraction line 8 is attached to the liquid extraction line 8.

  The liquid 7 separated from the solid-liquid suspension 12 is discharged to the outside of the solid-liquid separation tank 3 through the liquid extraction line 8 and is collected in the liquid recovery tank 10.

  The solid-liquid suspension storage tank 4 is a tank for storing the solid-liquid suspension 12 before solid-liquid separation. The solid-liquid suspension 12 is supplied from the solid-liquid suspension storage tank 4 through the solid-liquid suspension supply line 5 into the internal container 1 of the solid-liquid separation tank 3 by the solid-liquid suspension supply device 6.

  The size and shape of the inner container 1 and the outer container 2 are not particularly limited, but it is desirable that the volume of the gap portion between the inner container 1 and the outer container 2 is small.

  In addition, the inner container 1 and the outer container 2 shown in FIG. 1 are both circular in cross-sectional shape, but are arbitrary as long as the outer container 2 can be arranged in a state where the inner container 1 is accommodated. For example, the cross-sectional shapes of the inner container 1 and the outer container 2 may be configured in a polygonal shape. Moreover, the cross section of the inner container 1 may be configured in a polygonal shape, and the cross section of the outer container 2 may be configured in a circular shape.

  Furthermore, although the inner container 1 and the outer container 2 shown in FIG. 1 have an open system structure with the upper part opened, a non-open system structure may be used as long as the solid content 11 can be recovered. For example, a lid (not shown) that can be opened and closed may be attached.

  Furthermore, the entire inner container 1 does not necessarily need to be configured with a filter cloth that allows the liquid 7 to pass therethrough but does not allow the solid content 11 to pass therethrough, and a part thereof may be configured with metal. For example, a basket-like structure with a filter cloth part installed on the inside, and through-holes that prevent the structure from resisting the passage of liquid are on the entire surface including the side surface and the bottom surface, and have sufficient strength It may be a thing (for example, wire mesh or punching metal).

  The first solid-liquid separation device 50A configured in this way solid-liquid separates the solid-liquid suspension introduced from the solid-liquid suspension storage tank 4 into the inner container 1, and contains almost no solid content 11. This is a so-called batch-type solid-liquid separator that discharges the liquid 7 from the liquid extraction line 8.

  The recovery of the solid content 11 is performed by taking the inner container 1 out of the outer container 2 and inverting the inner container 1 upside down in a separately prepared solid content recovery tank (not shown). At this time, the inner container 1 may be washed with a washing liquid such as water to collect the solid content 11.

  In the first solid-liquid separation device 50A, a heating device 13 (13a, 13b) for heating the solid-liquid separation tank 3 and the solid-liquid suspension storage tank 4 may be additionally provided as appropriate. The solid-liquid separation tank heating device 13 a that heats the solid-liquid separation tank 3 may be attached to at least one of the outer side and the inner side of the solid-liquid separation tank 3. Similarly, the solid-liquid suspension storage tank heating device 13b for heating the solid-liquid suspension storage tank 4 may be attached to at least one of the outside and the inside of the solid-liquid suspension storage tank 4.

  Also in the first solid-liquid separation device 50A, as in the second solid-liquid separation device 50B described later, the stirring device 14 (FIG. 2) for stirring the inside of the solid-liquid separation tank 3 is replaced with the solid-liquid separation tank. 3 or solid-liquid suspension storage tank 4 may be additionally provided as appropriate.

<Action>
Next, the operation of the first solid-liquid separator 50A will be described.
In carrying out the solid-liquid separation method using the first solid-liquid separation device 50A, first, the inner container 1 having a filter cloth portion formed in a concave shape is a filter cloth through which the liquid 7 passes but the solid content 11 does not pass. Is placed (accommodated) in the outer container 2. In this state, the solid-liquid suspension supply device 6 is operated. Then, the solid-liquid suspension 12 stored in the solid-liquid suspension storage tank 4 is introduced into the internal container 1 of the solid-liquid separation tank 3 through the solid-liquid suspension supply line 5.

  At this time, if necessary, the temperature of the solid-liquid suspension 12 is adjusted by operating the solid-liquid separation tank heating device 13a and the solid-liquid suspension storage tank heating device 13b. If the viscosity coefficient of the solid-liquid suspension 12 is reduced by adjusting the temperature, the settling time of the solid content 11 can be shortened.

  By suspending the solid content 11 and the liquid 7 contaminated with the radioactive substance, the liquid 7 separated and recovered from the solid-liquid suspension 12 contains the radioactive substance. The liquid 7 discharged from the liquid extraction line 8 is a clean liquid containing almost no solid content 11.

<Effect>
According to the solid-liquid separation method using the first solid-liquid separation device 50A and the first solid-liquid separation device 50A, the liquid 7 in the solid-liquid suspension 12 is discharged from the liquid extraction line 8, and the solid content Since 11 is recovered in the solid content recovery tank, the solid content 11 containing almost no liquid 7 can be recovered.

  Further, according to the solid-liquid separation method using the first solid-liquid separation device 50A and the first solid-liquid separation device 50A, the inner container 1 passes through the filter cloth, and the liquid 7 is not only from the bottom surface but also from the side surface. Therefore, the solid content 11 containing almost no liquid 7 can be recovered in a short time.

[Second Embodiment]
<Configuration>
FIG. 2 is a schematic view of a second solid-liquid separation device 50B which is an example of the solid-liquid separation device according to the second embodiment of the present invention.

  The second solid-liquid separation device 50B is a stirrer 14 that stirs the inside of the inner container 1 of the solid-liquid separation tank 3 and a flocculant that stores the flocculant 15 with respect to the first solid-liquid separation device 50A. The difference is that the storage tank 16, the flocculant supply line 17, and the flocculant supply device 18 are further provided, but the other points are not substantially different from the first solid-liquid separation device 50 </ b> A. Therefore, in the second embodiment, the difference from the first solid-liquid separation device 50A will be mainly described, and the same reference numerals are given to the components that are not different from the components of the first solid-liquid separation device 50A. The description will be omitted or simplified.

  The stirring device 14 is a device having a function of stirring the contents in the tank. In the second solid-liquid separation device 50B, at least a stirring device 14 that stirs the contents introduced into the inner container 1 of the solid-liquid separation tank 3 is provided. Although not shown in FIG. 2, in the second solid-liquid separator 50 </ b> B, a stirring device 14 that stirs the solid-liquid suspension 12 stored in the solid-liquid suspension storage tank 4 is additionally provided. Also good.

  The flocculant 15 is added to the solid-liquid suspension 12 to prevent the formation of a cake layer having a solid content 11 on the side surface of the inner container 1, that is, the surface of the filter cloth. The flocculant 15 is supplied from the flocculant storage tank 16 through the flocculant supply line 17 into the inner container 1 by the flocculant supply device 18.

  The second solid-liquid separation device 50B configured as described above has the solid-liquid suspension introduced into the inner container 1 by the solid-liquid suspension supply device 4 and the inner container 1 by the flocculant supply device 18. After stirring the introduced flocculant 15 with the stirring device 14, the stirring device 14 is stopped, the solid content 11 is settled and separated, and the liquid 7 containing almost no solid content 11 is discharged through the liquid extraction line 8. This is a so-called batch type solid-liquid separator.

<Action>
Next, the operation of the second solid-liquid separator 50B will be described.
In carrying out the solid-liquid separation method using the second solid-liquid separation device 50B, first, the inner container 1 having a filter cloth portion formed in a concave shape is a filter cloth through which the liquid 7 passes but the solid content 11 does not pass. Is placed (accommodated) in the outer container 2. In this state, the solid-liquid suspension supply device 6 is operated to introduce the solid-liquid suspension 12 stored in the solid-liquid suspension storage tank 4 into the internal container 1 of the solid-liquid separation tank 3.

  Subsequently, the flocculant 15 is placed in the flocculant storage tank 16 and the flocculant supply device 18 is operated. Then, the coagulant 15 stored in the coagulant storage tank 16 is introduced into the inner container 1 of the solid-liquid separation tank 3 through the coagulant supply line 17.

  Subsequently, after the solid-liquid suspension 12 and the flocculant 15 are stirred by the stirring device 14, the stirring is stopped and the precipitate is separated. At this time, similarly to the first solid-liquid separation device 50A, the solid-liquid suspension 12 heating device 13a and the solid-liquid suspension storage heating device 13b are operated as necessary to change the temperature of the solid-liquid suspension 12. Adjust.

  By suspending the solid content 11 and the liquid 7 contaminated with the radioactive substance, the liquid 7 separated and recovered from the solid-liquid suspension 12 contains the radioactive substance. The liquid 7 discharged from the liquid extraction line 8 is a clean liquid containing almost no solid content 11.

<Effect>
According to the solid-liquid separation method using the second solid-liquid separation device 50B and the second solid-liquid separation device 50B, in addition to achieving the same effect as the first solid-liquid separation device 50A, In order to prevent the cake layer having the solid content 11 from being formed on the side surface of the container 1, the time required to pass through (filter) the filter cloth can be further shortened. That is, according to the solid-liquid separation method using the second solid-liquid separation device 50B and the second solid-liquid separation device 50B, the solid content 11 containing almost no liquid 7 can be recovered in a shorter time.

[Third embodiment]
<Configuration>
FIG. 3 is a schematic view of a third solid-liquid separator 50C which is an example of the solid-liquid separator according to the third embodiment of the present invention.

  The third solid-liquid separation device 50C includes a liquid recovery line 19 that recovers the liquid 7 that slightly contains the solid content 11 in the liquid recovery tank 10 and the liquid supply device with respect to the first solid-liquid separation device 50A. 20, filter 21, clarified liquid extraction line 23 for extracting clarified liquid 22, clarified liquid recovery tank 24, filter aid storage tank 26 for storing filter aid 25, and filter aid 25 in filter 21. It is different in that it further includes a filter aid supply device 27 to be supplied, and a filter aid circulation line 28 through which the filter aid 25 passes between the filter aid storage tank 26 and the filter 21.

  However, the third solid-liquid separation device 50C is not substantially different from the first solid-liquid separation device 50A except that the third solid-liquid separation device 50C has the above-described differences from the first solid-liquid separation device 50A. Therefore, in the third embodiment, differences from the first solid-liquid separation device 50A will be mainly described, and the same reference numerals are given to components that are not different from the components of the first solid-liquid separation device 50A. The description will be omitted or simplified.

  The liquid recovery line 19 is a flow path that guides the liquid 7 recovered in the liquid recovery tank 10 from the solid-liquid separation tank 3 through the liquid extraction line 8 to the filter 21. The liquid 7 is sent out from the liquid recovery tank 10 through the liquid recovery line 19 to the filter 21 by the liquid supply device 20.

  The filter 21 filters the liquid 7 to remove the remaining solid content 11. The clarified liquid 22 that is the liquid 7 after passing through the filter 21 becomes a clean liquid that does not contain the solid content 11 than the liquid 7 collected in the solid-liquid separation tank 3. The clarified liquid 22 is guided from the filter 21 to the clarified liquid extraction line 23 and collected in the clarified liquid collection tank 24.

  The filter aid 25 is used for improving filterability and preventing clogging of the filter medium when the liquid 7 is filtered by the filter 21. The filter aid 25 is preferably an inorganic substance such as diatomaceous earth. The filter aid 25 stored in the filter aid storage tank 26 is supplied to the filter 21 by the filter aid supply device 27.

  The filter aid circulation line 28 is a flow path through which the filter aid 25 circulates between the filter aid storage tank 26 and the filter 21. Of the filter aid 25 supplied from the filter aid storage tank 26 to the filter 21, the filter aid 25 that has passed through the filter 21 is returned to the filter aid storage tank 26 through the filter aid circulation line 28.

  The third solid-liquid separation device 50C configured as described above performs solid-liquid separation on the solid-liquid suspension 12 introduced into the inner container 1 by the solid-liquid suspension supply device 4, and the liquid extraction line 8 The so-called batch-type solid-liquid separation apparatus recovers the clarified liquid 22 by further passing the liquid 7 containing almost no solid content 11 discharged through the filter 21.

  Note that the third solid-liquid separation device 50C may further include a stirring device 14, a flocculant storage tank 16, a flocculant supply line 17, and a flocculant supply device 18.

<Action>
Next, the operation of the third solid-liquid separator 50C will be described.
In carrying out the solid-liquid separation method using the third solid-liquid separation device 50C, first, the inner container 1 having a filter cloth portion in which a filter cloth that passes the liquid 7 but does not allow the solid content 11 to pass is formed in a concave shape. Is placed (accommodated) in the outer container 2. In this state, the solid-liquid suspension supply device 6 is operated to introduce the solid-liquid suspension 12 stored in the solid-liquid suspension storage tank 4 into the internal container 1 of the solid-liquid separation tank 3.

  Subsequently, in a state where the filter aid 25 is put in the filter aid storage tank 26, the filter aid supply device 27 is operated, and the filter aid 25 stored in the filter aid storage tank 26 is supplied into the filter 21, Precoat.

  When the pre-coating is completed, the liquid supply device 20 is operated, and the liquid 7 recovered in the liquid recovery tank 10 is guided to the filter 21. The liquid 7 is collected in the clarified liquid collection tank 24 as the clarified liquid 22 after the fine solid content 11 that has passed through the filter cloth of the inner container 1 is filtered by the filter 21.

  If the differential pressure applied to the filter 21 increases as a result of using the third solid-liquid separation device 50C, water is supplied by the liquid supply device 20, the filter aid supply device 27, etc., and backwashing is performed. To eliminate the differential pressure. As the water used for eliminating the differential pressure, the clarified liquid 22 may be used.

<Effect>
According to the solid-liquid separation method using the third solid-liquid separation device 50C and the third solid-liquid separation device 50C, in addition to the same effects as the first solid-liquid separation device 50A, the clarification is further performed. Since the liquid 22 has a lower solid content 11 than the liquid 7 recovered in the solid-liquid separation tank 3, the liquid 22 is generated when the liquid 22 is passed through an adsorption device (not shown) that recovers radioactive substances contained in the liquid. The increase in the differential pressure can be further reduced.

[Fourth Embodiment]
<Configuration>
FIG. 4 is a schematic view of a fourth solid-liquid separation device 50D which is an example of the solid-liquid separation device according to the fourth embodiment of the present invention.

  The fourth solid-liquid separation device 50D includes a solid-liquid suspension recovery line 29 for recovering the solid-liquid suspension in the solid-liquid separation tank 3, and the solid-liquid separation with respect to the first solid-liquid separation device 50A. A suspension recovery device 30, a filter press 31, a cake extraction line 33 for extracting the cake 32, a cake recovery tank 34, and a separation liquid extraction line 35 for extracting the separation liquid separated by the filter press 31. Furthermore, it differs in the point which comprises.

  However, the fourth solid-liquid separation device 50D is not substantially different from the first solid-liquid separation device 50A except that the fourth solid-liquid separation device 50D has the above-described differences from the first solid-liquid separation device 50A. Therefore, in the fourth embodiment, the difference from the first solid-liquid separator 50A will be mainly described, and the same reference numerals are given to the constituent elements that are not different from the constituent elements of the first solid-liquid separator 50A. The description will be omitted or simplified.

  The solid-liquid suspension recovery line 29 is a flow path that guides the solid-liquid suspension 12 in the solid-liquid separation tank 3 from the solid-liquid separation tank 3 to the filter press 31. The solid-liquid suspension recovery device 30 sends the solid-liquid suspension 12 in the solid-liquid separation tank 3 to the filter press 31 through the solid-liquid suspension recovery line 29.

  The filter press 31 separates and collects the cake 32 from the solid-liquid suspension 12. The cake 32 separated by the filter press 31 is collected in a cake collection tank 34 via a cake extraction line 33. The cake 32 becomes a clean solid with less moisture than the solid content 11 collected in the solid-liquid separation tank 3.

  The separation liquid extraction line 35 is a flow path for extracting the separation liquid separated by the filter press 31 and returning it to the solid-liquid separation tank 3.

  The fourth solid-liquid separation device 50D configured as described above performs solid-liquid separation on the solid-liquid suspension 12 introduced into the inner container 1 by the solid-liquid suspension supply device 4, and almost eliminates the solid content 11. A part of the liquid 7 not included is discharged through the liquid extraction line 8, and then the solid-liquid suspension 12 remaining in the inner container 1 is supplied to the filter press 31 to recover the separated liquid and the cake 32. This is a solid-liquid separator of the type.

  Although the fourth solid-liquid separation device 50 </ b> D has been described as including the filter press 31, a centrifugal dehydrator may be included instead of the filter press 31.

  Further, the fourth solid-liquid separation device 50D may further include a stirring device 14, a flocculant storage tank 16, a flocculant supply line 17, and a flocculant supply device 18.

  Further, the fourth solid-liquid separation device 50D includes a liquid recovery line 19, a liquid supply device 20, a filter 21, a clarified liquid extraction line 23, a clarified liquid recovery tank 24, a filter aid storage tank 26, The structure which further comprises the filter aid supply apparatus 27 and the filter aid circulation line 28 may be sufficient.

<Action>
Next, the operation of the fourth solid-liquid separator 50D will be described.
In carrying out the solid-liquid separation method using the fourth solid-liquid separation device 50D, first, the inner container 1 having a filter cloth part formed in a concave shape with a filter cloth that passes the liquid 7 but does not allow the solid content 11 to pass therethrough. Is placed (accommodated) in the outer container 2. In this state, the solid-liquid suspension supply device 6 is operated to introduce the solid-liquid suspension 12 stored in the solid-liquid suspension storage tank 4 into the internal container 1 of the solid-liquid separation tank 3.

  Subsequently, the solid-liquid suspension 12 in the solid-liquid separation tank 3 is sent to the filter press 31 through the solid-liquid suspension recovery line 29 by the solid-liquid suspension recovery device 30. The filter press 31 separates and collects the cake 32 from the solid-liquid suspension 12, and the cake 32 is collected in the cake collection tank 34 via the cake extraction line 33. The separated liquid after separating the cake 32 from the solid-liquid suspension 12 is returned to the solid-liquid separation tank 3 through the separated liquid extraction line 35.

<Effect>
According to the solid-liquid separation method using the fourth solid-liquid separation device 50D and the fourth solid-liquid separation device 50D, in addition to the same effects as the first solid-liquid separation device 50A, the cake 32 can be separated and recovered. The cake 32 is a clean solid with less water than the solid content 11 collected in the solid-liquid separation tank 3, and therefore when the original solid content 11 contains a radioactive substance, the radioactivity concentration in the solid content after separation is reduced. Further reduction can be achieved.

  Examples are shown below. In addition, this invention is limited to the Example shown below and is not interpreted.

Example 1
A beaker having an inner diameter of 55 mm and a height of 250 mm was filled with a filter cloth only on the bottom surface or a container made entirely of filter cloth on the bottom surface and side surfaces. The container had an inner diameter of 40 mm and a height of 250 mm, and a filter cloth having a permeability of 25 cm ³ / cm ² / sec at 124.5 Pa was used. After putting 5 g of soil and 250 mL of water in the container and stirring well, the inner container was taken out from the outer container, and the time for completing drainage was measured. Table 1 shows the particle size distribution ratio of the soil, and Table 2 shows the measurement results of the solid-liquid separation time (drainage completion time).

  As shown in Table 2, when solid-liquid separation is performed with a container whose bottom and sides are all made of filter cloth (drainage completion time: 80 sec), when a container with only the bottom of the filter cloth is used (drainage completed) It can be seen that the discharge time can be greatly reduced as compared to the time (150 sec).

  In addition, solid-liquid suspensions for soil and water are separated using a solid-liquid separation device equipped with a solid-liquid suspension supply line, a liquid extraction line, and a solid content recovery device in the internal container. However, the same result as above can be obtained.

  Moreover, even if it isolate | separates with the metal-mesh-like solid-liquid separation apparatus which is the shape of a cage | basket | cabinet which installed the filter cloth inside, the result similar to the above will be obtained.

(Example 2)
A beaker having an inner diameter of 55 mm and a height of 250 mm was charged with a container whose bottom and side surfaces were all made of filter cloth. The container had an inner diameter of 40 mm and a height of 250 mm, and a filter cloth having a permeability of 25 cm ³ / cm ² / sec at 124.5 Pa was used. After 5 g of soil and 250 mL of water were placed in the container and stirred well, 25 mg of flocculant A containing diatomaceous earth as a main component and containing no organic matter was added, and the mixture was further stirred and allowed to stand for 30 seconds. The inner container was taken out from the outer container, and the time for completing drainage was measured. Table 3 shows the measurement results.

  As shown in Table 3, when the flocculant is added (drainage completion time: 40 seconds including the standing time) compared to the case where no flocculant is added (drainage completion time: 80 sec), The discharge time can be reduced.

  Further, the discharge time can be further reduced by discharging a part or all of the supernatant liquid with the discharger.

  Furthermore, for solid and liquid suspensions of soil and water, solid-liquid suspension supply line, liquid extraction line, solid content recovery device in the inner container, coagulant supply device and inner container in the solid-liquid separation tank Even if the separation is carried out by a solid-liquid separation device having a stirring device for mixing the solid-liquid suspension, the same result as above can be obtained.

  Furthermore, the same result as described above can be obtained even when the separation is performed by a wire net-like solid-liquid separation device in which the inner container has a basket-like shape with a filter cloth installed inside.

(Example 3)
10 g of soil, 200 mL of 0.5 M oxalic acid at 80 ° C., 50 to 200 mg / L of a flocculant containing shirasu or diatomaceous earth as a main component and not containing organic matter, mixed, placed in a graduated cylinder, allowed to stand for 30 seconds, and then supernatant The concentration of the liquid was measured to evaluate the solid content removal rate (%) (= (1−supernatant concentration / initial concentration) × 100). Table 4 shows the measurement results.

  As shown in Table 4, the solid content removal rate is significantly reduced by adding the flocculant. Therefore, when solid-liquid separation is performed using a container made of filter cloth, the discharge time can be reduced by adding a flocculant containing shirasu or diatomaceous earth as a main component and not containing organic substances.

  Moreover, discharge time can be reduced by adding 50-200 mg of flocculants with respect to 1 L of solid-liquid suspensions.

  The viscosity coefficient of the liquid decreases as the temperature increases. Therefore, the sedimentation rate of the solid matter is increased. Therefore, the higher the temperature, the faster the solid-liquid separation time. About 80-95 degreeC close | similar to the boiling point of water is preferable.

  Furthermore, for solid and liquid suspensions of soil and water, solid-liquid suspension supply line, liquid extraction line, solid content recovery device in the inner container, coagulant supply device and inner container in the solid-liquid separation tank Even if the separation is carried out by a solid-liquid separation device having a stirring device for mixing the solid-liquid suspension, the same result as above can be obtained.

Example 4
The solid content removal rate was measured when a soil suspension containing soil having a maximum particle size of 20 μm or less was passed through a spring filter at 1 liter per minute (= 1 L / min). The measurement of the solid content removal rate was performed when there was no pre-coating with diatomaceous earth, with pre-coating with diatomaceous earth, and with pre-coating (re-pre-coating) with diatomaceous earth after backwashing. Table 5 shows the measurement results. In addition, 10g of diatomaceous earth was used for the precoat. Moreover, the solid substance contained in backwash water was used for the re-precoat after backwashing as a filter aid.

  As shown in Table 5, about 40% of the soil can be removed without a diatomaceous earth precoat. However, when diatomaceous earth is precoated, the removal rate is further increased, and 99% of solid content can be removed.

  As shown in Table 5, assuming that a differential pressure has occurred, pre-coating the soil and diatomaceous earth contained in the backwash water after backwashing, and then removing the solid content, 97% solids Can be removed.

  A result similar to the above can be obtained by installing a backwash regenerative filter in the liquid extraction line of the solid-liquid separation tank.

(Example 5)
5 g of soil and 100 mL of water were put into a pressure holder in which a Millipore filter having a pore diameter of 0.45 μm was set, and pressure filtration was performed. Table 6 shows the relationship between the amount of water recovered until the drainage stops and the pressure.

  As shown in Table 6, it can be seen that the amount of water remaining in the soil decreases as the pressure is applied.

  Moreover, the result similar to the above is obtained by providing a filter press as a solid content recovery device in the inner container of the solid-liquid separation tank.

(Example 6)
A beaker having an inner diameter of 55 mm and a height of 250 mm was charged with a container whose bottom and side surfaces were all made of filter cloth. The container had an inner diameter of 40 mm and a height of 250 mm, and a filter cloth having a breathability of 25 cm ³ / cm ² / sec, 50 cm ³ / cm ² / sec, 120 cm ³ / cm ² / sec (all at 124.5 Pa) was used. . After putting 5 g of soil and 250 ml of water in the container and stirring well, the inner container was taken out from the outer container, and the time for completing drainage was measured. Table 7 shows the effect of filter cloth breathability on drainage completion time.

  As shown in Table 7, it can be seen that the better the breathability of the filter cloth (the larger the value), the shorter the drainage completion time.

  Since the solid content has a large amount of leakage from the bottom surface, solid-liquid separation is possible even as an internal container using a filter cloth with fine pores as a side surface and a filter cloth with coarse pores as a bottom surface.

  Since the solid content has a large amount of leakage from the bottom surface, solid-liquid separation is possible even as an internal container provided with a non-penetrating portion in which no through hole is formed on the bottom surface (an internal container having a structure in which no hole is formed on the bottom surface).

  The soil has a particle size distribution as shown in Table 1, for example. Therefore, it is preferable to make the pore diameter of the filter cloth smaller than the particle diameter at which the lower mass reference integrated amount becomes equal to the target solid content removal rate. For example, when a solid content removal rate of 99% is targeted, the pore size of the filter cloth is made smaller than the particle size on the lower side 1/100 of the mass-based particle size cumulative distribution of the solid matter.

(Example 7)
After immersing the filter cloth in 0.5 M oxalic acid at 80 ° C. for 150 hours, the filter cloth was set in a pressure holder, 100 mL of water was added, and the time until 90 mL was discharged was measured. The results are shown in Table 8.

  As shown in Table 8, the filter cloth having high air permeability is not affected by immersion in oxalic acid even if it is made of polyethylene, but if the air permeability is low, drainage completion time increases. On the other hand, polyester is not affected by oxalic acid immersion. From the above, polyethylene may be used, but a polyester filter cloth is preferred.

  As described above, according to the solid-liquid separation method using the first to fourth solid-liquid separation devices 50A to 50D and the first to fourth solid-liquid separation devices 50A to 50D, the solid content concentration, the solid content density, the solid content particle diameter Regardless, the solid-liquid separation time can be greatly shortened. Moreover, since solid content can be collect | recovered with an internal container, solid content recovery from a solid-liquid separation tank can be implemented easily and in a short time.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, additions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Internal container, 2 ... External container, 3 ... Solid-liquid separation tank, 4 ... Solid-liquid suspension storage tank, 5 ... Solid-liquid suspension supply line, 6 ... Solid-liquid suspension supply apparatus, 7 ... Liquid, DESCRIPTION OF SYMBOLS 8 ... Liquid extraction line, 9 ... Valve for liquid extraction, 10 ... Liquid recovery tank, 11 ... Solid content, 12 ... Solid-liquid suspension, 13 ... Heating device, 13a ... Heating device for solid-liquid separation tank, 13b ... heating device for solid-liquid suspension storage tank, 14 ... stirring apparatus, 15 ... flocculant, 16 ... flocculant storage tank, 17 ... flocculant supply line, 18 ... flocculant supply apparatus, 19 ... liquid recovery line, 20 ... liquid Supply device, 21 ... filter, 22 ... clarified liquid, 23 ... clarified liquid extraction line, 24 ... clarified liquid recovery tank, 25 ... filter aid, 26 ... filter aid storage tank, 27 ... filter aid supply device, 28 ... Filtration aid circulation line, 29 ... solid-liquid suspension recovery line, 30 ... solid-liquid suspension recovery device, 31 ... filter press, 3 ... Cake, 33 ... Cake extraction line, 34 ... Cake recovery tank, 35 ... Separation liquid extraction line, 50A ... First solid-liquid separation device, 50B ... Second solid-liquid separation device, 50C ... Third solid Liquid separation device, 50D: Fourth solid-liquid separation device.

Claims (21)

The solid-liquid separation tank has an inner container that is made of a filter cloth that allows liquid to pass but does not allow solids to pass, and has a height that prevents the contents from overflowing from the upper end, and an outer container that accommodates the inner container. Introduce a solid-liquid suspension into the inner container,
After leaving the solid-liquid suspension in the solid-liquid separation tank to separate into solid and liquid, the liquid supernatant is removed by a filter cloth on the side surface of the inner container. A solid-liquid separation method comprising filtering and discharging from the inner container. After the solid-liquid suspension is introduced into the inner container, a flocculant that promotes sedimentation of the solid content suspended in the solid-liquid suspension is added to the solid-liquid suspension in the inner container. The solid-liquid separation method according to claim 1. The solid-liquid separation method according to claim 2, wherein the flocculant is an inorganic flocculant mainly composed of shirasu or diatomaceous earth. The solid-liquid separation method according to claim 2 or 3, wherein the addition amount of the flocculant is 50 to 200 mg with respect to 1 L of the solid-liquid suspension. The solid-liquid separation method according to claim 4, wherein the temperature of the solid-liquid suspension is adjusted to 80 to 95 ° C. The solid-liquid suspension is allowed to stand in the solid-liquid separation tank, and after solid-liquid separation into solid and liquid, the residual solid contained in the liquid extracted from the solid-liquid separation tank is converted into the solid-liquid separation. 6. The solid-liquid separation method according to claim 1, wherein the liquid component of the liquid and the residual solid content are separated by a filter provided in a subsequent stage of the separation tank. When the liquid is separated from the liquid component and the residual solid content using the filter, when the residual solid content is accumulated in the filter and the flow resistance is increased, the processing liquid passed through the filter and The solid-liquid separation method according to claim 6, wherein any one of clean water is made to flow backward as a washing liquid, and the filter is backwashed and regenerated. The solid-liquid separation method according to claim 7, wherein the filter provided in the subsequent stage of the solid-liquid separation tank is a filter of a type in which a filter aid is precoated. After re-washing and regenerating the filter, performing the operation of pre-coating again the solid content contained in the back-wash solution of the filter as a filter aid, and if the flow resistance of the filter has increased after pre-coating, The solid-liquid separation method according to claim 8, wherein the backwash liquid is separated outside the system. Solid matter remaining in the internal container of the solid-liquid separation tank and, if a filter is provided in the subsequent stage of the solid-liquid separation tank, either one of the treatment liquid passed through the filter or clean water The dehydrated solid material is obtained by dehydrating the backwash liquid of the filter after backwashing and regenerating the filter by washing it back as a washing liquid. The solid-liquid separation method described. The solid-liquid separation method according to any one of claims 1 to 10, wherein at least a part of the supernatant of the liquid is discharged by a discharger. There is a concave filter cloth part made of a filter cloth through which liquid passes but solids do not pass, and the inner container has a height that prevents the contents from overflowing from the upper end of the filter cloth part. A solid-liquid separation tank having an external container to be accommodated;
A solid-liquid suspension supply line for introducing a solid-liquid suspension into the inner container;
A solid-liquid separation apparatus comprising: a liquid extraction line for extracting a liquid obtained by solid-liquid separation from a solid-liquid suspension in the solid-liquid separation tank to the outside from the solid-liquid separation tank. A flocculant supply device for supplying a flocculant that promotes sedimentation of solids suspended in the solid-liquid suspension into the internal container;
The solid-liquid separator according to claim 12, further comprising a stirring device that stirs the contents introduced into the inner container. The inner container further has a cage structure outside the filter cloth portion, and this cage structure does not become resistant when liquid obtained by solid-liquid separation from a solid-liquid suspension passes through. The solid-liquid separation device according to claim 12 or 13, wherein the through-hole is provided over the entire surface including the side surface and the bottom surface. The filter cloth portion of the inner container is configured such that the pores of the filter cloth located on the concave bottom surface are coarser than the pores of the filter cloth located on the concave side surface. 15. The solid-liquid separation device according to any one of items 14 to 14. The solid-liquid separator according to any one of claims 12 to 15, wherein a non-penetrating part in which a through hole is not formed is provided on a bottom surface of the inner container. The filter cloth according to any one of claims 12 to 16, wherein a filter cloth having a pore diameter smaller than a particle diameter at a lower side 1/100 of a mass-based particle diameter integrated distribution of solid matter is used. The solid-liquid separator described in 1. The solid-liquid separator according to any one of claims 12 to 17, wherein the filter cloth is a material including one or more materials selected from polypropylene and polyester. A backwash regenerative filter that further separates residual solids from the liquid obtained by solid-liquid separation from the solid-liquid suspension in the solid-liquid separation tank in the subsequent stage of the solid-liquid separation tank. The solid-liquid separation device according to any one of claims 12 to 18, wherein the solid-liquid separation device is provided in a subsequent stage. The filter further comprises any one of a filter press and a centrifugal dehydrator for collecting the solid content in the inner container, and the backwash liquid generated when backwashing the backwash filter is backwashed. The solid-liquid separation device according to any one of claims 12 to 19, further comprising a line for discharging from the liquid. The solid-liquid separation device according to any one of claims 12 to 20, further comprising a heating device for heating the solid-liquid separation tank.

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