JP2019107637A - Soil purification system - Google Patents

Abstract

To provide a soil purification system that purifies contaminated soil with washing water containing a chelator while classifying it and to provide means which makes it possible to recover the chelator attached to fine-grained soil or the like and reduce a site area of a chelator recovery facility.SOLUTION: A soil purification system 1 has a soil washing classification unit 2, a chelator regeneration unit 3, a chelator recovery unit 4, a rinse water generation unit 5, and a washing water supply unit 7. The chelator recovery unit 4 washes fine-grained soil or the like discharged from the soil washing classification unit 2 with rinse water, to remove and recover a chelator attached to the fine-grained soil or the like. The rinse water generation unit 5 removes the chelator from part of washing water discharged from the chelator regeneration unit 3, to generate rinse water for supply to the chelator recovery unit 4. The rinse water generation unit 5 has a reverse osmosis membrane separation device that separates the washing water into permeable water (rinse water) and concentrated water through a reverse osmosis membrane.SELECTED DRAWING: Figure 1

Description

  The present invention cleans the soil, which contains straw, sand and fine soil and is contaminated with harmful metals and / or compounds thereof, with washing water containing a chelating agent, It relates to a soil remediation system that classifies into soil.

  In recent years, for example, harmful metals such as chromium, lead, cadmium, selenium, mercury and / or compounds thereof (hereinafter, these are collectively referred to as "harmful metals etc.") The problem of soil pollution due to soil pollution in the country or illegal dumping of industrial waste containing harmful metals and the like has become a problem. And soil contaminated with harmful metals (hereinafter referred to as "toxic metal-contaminated soil") is a position where the harmful metal-contaminated soil actually exists (hereinafter referred to as "in-situ position"), for example, insolubilization of harmful metals etc. It is quite difficult to clean up effectively by containment, electrical repair, etc. For this reason, harmful metal-contaminated soil is generally removed from the in-situ site by drilling and purified at an external soil purification facility.

  As a method of purifying harmful metal-contaminated soil at such an in-situ soil remediation facility, a cleaning method for removing harmful metals etc. by washing the harmful metal-contaminated soil with washing water or washing solution has been widely used. There is. Thus, the applicant cleans the contaminated soil contaminated with harmful metals and the like with washing water containing a chelating agent to remove harmful metals and the like, while the washing water after the washing removes solid metals from the washing water as solid phase adsorbents. There have been proposed various closed system soil remediation facilities that do not discharge wash water to the outside of the facility, which reuses the wash water or the chelating agent repeatedly by removing etc. (See Patent Documents 1 to 5).

Patent No. 5736094 gazette Patent No. 5771342 Patent No. 5771343 gazette Patent No. 6022103 Patent No. 6026702

  By the way, in the soil purification facilities disclosed in Patent Documents 1 to 3 pertaining to the applicant of the present invention, the soil contaminated with harmful metals and the like and the washing water containing the chelating agent are mixed and stirred to adhere to the soil. Hazardous metals and the like are separated from the soil and captured by a chelating agent, and the soil is classified to form fine-grained soil and the like to be reused as agricultural soil for farming and the like.

  And although the washing water containing a chelating agent adheres to the fine-grained soil produced | generated in this way, the fine-grained soil containing a chelating agent is not so preferable as a culture soil etc. for agriculture. In addition, the chelating agent in the soil remediation facility will be reduced by the amount carried away by the fine soil. Therefore, even if the chelating agent is regenerated and used repeatedly, it is necessary to replenish the chelating agent in an amount corresponding to the chelating agent carried away by the fine soil. For this reason, in a soil purification facility for purifying a large amount of polluted soil (for example, 1000 tons / day), there is a problem that it is necessary to always replenish a considerable amount of chelating agent, which increases the cost of treating the soil. .

  By the way, in the soil purification facilities disclosed in Patent Documents 4 to 5 according to the present applicant, the fine grained soil (filter cake), which is discharged from the filter press and to which the cleaning liquid containing the chelating agent adheres, is rinsed with rinse water. The chelating agent is removed from the fine grained soil. Then, the cleaning waste water containing the chelating agent is evaporated in the atmosphere by the evaporation sand in the sand storage unit to make the chelating agent remain and accumulate on the evaporation sand, and the evaporation sand containing the chelating agent is introduced into the soil treatment system. The chelating agent is recovered (so-called salt field method). However, since a large amount of rinse water is required to wash the fine soil to which the washing solution containing the chelating agent adheres, a very large area sand container is required to evaporate the large amount of washing wastewater generated. Do. For this reason, there is a problem that a large site is required to set up a chelating agent recovery facility.

  The present invention has been made to solve the above-mentioned conventional problems, and soils contaminated with harmful metals and the like are purified with washing water containing a circulating chelating agent, while fine soils etc. To prevent or reduce the external removal of the chelating agent by fine soil to the closed system type soil purification facility where it is separated and reused, and the site area of the facility for recovering the chelating agent is It is an issue to be solved to provide means that make it possible to significantly reduce.

  A soil purification system according to the present invention made to solve the above problems comprises a soil washing classification unit, a chelating agent regenerating unit, a chelating agent recovery unit, a rinse water generation unit, and a wash water supply unit. There is. Here, the soil washing and classification part is composed of straw, sand and fine grain soil, and soil contaminated with harmful metals, etc. (harmful metals and / or compounds thereof) or these ions with wash water containing a chelating agent. It is cleaned and cleaned, and classified into gravel, sand and fine-grained soil. The chelating agent regenerating unit regenerates the chelating agent by removing harmful metals and the like or ions thereof from the chelating agent capturing harmful metals and the like in the washing water discharged from the soil washing and classification unit. The chelating agent recovery unit removes and recovers the chelating agent adhering to the fine-grained soil by rinsing the fine-grained soil discharged from the soil washing and sorting part with rinsing water.

  The rinse water generation unit introduces a part of the washing water discharged from the chelating agent regeneration unit and separates it into concentrated water concentrated with a chelating agent by a reverse osmosis membrane and permeated water containing no chelating agent It has a separation device and supplies the permeated water as rinse water to the chelating agent recovery part. The wash water supply unit includes wash water other than the wash water introduced into the rinse water generation unit among the wash water discharged from the chelating agent regeneration unit, the concentrated water discharged from the rinse water generation unit, and the chelating agent recovery unit The waste water from fine grain soil discharged from the soil is received and mixed, and the mixed water is supplied (returned) to the soil washing classification part as washing water.

  In the soil purification system according to the present invention, the washing water supply unit may have, for example, a mixing tank, and a pump and a pipeline. In this case, in the mixing tank, the wash water other than the wash water introduced into the rinse water generation unit among the wash water discharged from the chelating agent regeneration unit, the concentrated water discharged from the rinse water generation unit, and the chelating agent recovery Receive and mix with the fine soil washing wastewater discharged from the department. In addition, the pump and the pipeline supply (return) the mixed water in the mixing tank to the soil washing classification part as washing water.

  In the soil purification system according to the present invention, the soil washing classification unit preferably includes a mixing device, a first classification device, a second classification device, a sedimentation separation device, and a filtration device. In this case, the mixing device mixes and stirs the soil containing moss, sand and fine soil with washing water, and harmful metals and the like adhering to the soil or these ions are released from the soil and chelated. Let the agent capture. The first classification device receives the mixture containing the soil and wash water discharged from the mixing device and separates the straw from the mixture. The second classifier receives the mixture containing the sand, fine soil and washing water discharged from the first classifier and separates the sand from the mixture. The settling and separating apparatus separates the mixture containing the fine soil and the washing water discharged from the second classification apparatus into the supernatant water and the sludge containing the fine granular soil by settling and separation. The filtration device filters the sludge discharged from the sedimentation device to produce a filtrate and a filter cake (fine grained soil).

  Also, in this case, the chelating agent regenerating unit has a higher complexing power than the chelating agent, and when it comes in contact with the supernatant water discharged from the sedimentation device, it adsorbs harmful metals and the like in the supernatant water or solid ions. It has a phase adsorbent, and has a chelating agent regenerating apparatus for removing harmful metals and the like or ions thereof from the chelating agent in the supernatant water to regenerate the chelating agent. The chelating agent recovery unit has a fine grain soil rinsing device that sprays or sprays rinse water on the filter cake containing fine grain soil discharged from the filtering device to wash away the chelating agent held in the fine grain soil.

  According to the soil remediation system according to the present invention, the fine-grained soil discharged from the soil washing classification unit is washed with the permeated water (rinsing water) generated by the reverse osmosis membrane separation device in the chelating agent recovery unit, The chelating agent adhering to the soil is removed and recovered. Therefore, a high quality fine grain soil which does not contain a chelating agent can be obtained. Then, the cleaning wastewater containing the chelating agent generated by the cleaning of fine soil in the chelating agent recovery unit is returned to the soil cleaning classification unit via the cleaning water supply unit and is not discharged out of the soil purification system, so The loss of the agent out of the soil remediation system is reliably prevented.

  On the other hand, the installation area of the reverse osmosis membrane separation apparatus which comprises a rinse water production | generation part is very small. In addition, the wash water supply unit that mixes wash water, concentrated water and wash wastewater and supplies (returns) to the soil wash classification unit as wash water comprises, for example, a mixing tank such as a simple concrete pit, a pump, a pipeline, etc. The footprint that can be done is very small. Therefore, the installation of the collection facility for the chelating agent does not require a large site such as the sand container disclosed in Patent Documents 4 and 5, for example. Thus, the fine soil can prevent the chelating agent from being carried out of the soil purification system, and the site area of the equipment for recovering the chelating agent can be made extremely small.

It is a block diagram showing composition of a soil purification system concerning the present invention. It is a block diagram which shows the structure of the soil washing classification part which is a component of the soil purification system shown in FIG. It is a typical elevation view which shows the structure of the chelating agent reproduction | regeneration part which is a component of the soil purification system shown in FIG. It is a typical side view of the rinse agent which is a component of a chelating agent collection | recovery part. It is a schematic side view of the sand rinse apparatus which is a component of a chelating agent collection | recovery part. It is a typical side view of the fine grain soil rinse device which is a component of a chelating agent recovery part. It is a typical elevation view of the rinse water production | generation part of the soil purification system shown in FIG. 1, and the apparatus around it. It is a figure which shows an example of the flow of soil, water, and a chelating agent in the important point of a soil purification system. It is a figure which shows an example of the flow of soil, water, and a chelating agent in the important point of a chelating agent collection | recovery part and a rinse water production | generation part, and a chelating agent density | concentration.

Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.
First, with reference to FIG. 1, the whole structure of the soil purification system 1 which concerns on this invention is demonstrated. The soil remediation system 1 includes a soil washing classification unit 2, a chelating agent regenerating unit 3, a chelating agent recovery unit 4, a rinsing water generating unit 5, a chelating agent replenishment unit 6, and a washing water supply unit 7. There is.

  Here, the soil washing classification part 2 is a washing water containing a chew, sand, sand and fine soil and containing soil contaminated with harmful metals and the like (toxic metals and / or compounds thereof) or ions thereof. Wash and purify with, and classify into sand, sand and fine-grained soil. The chelating agent regenerating unit 3 regenerates the chelating agent by removing harmful metals and the like from the chelating agent capturing harmful metals and the like in the washing water discharged from the soil washing classification unit 2. The chelating agent recovery unit 4 is a chelating agent adhering to the gravel, sand and / or fine grain soil by rinsing the gravel, sand and / or fine grain soil discharged from the soil washing and sorting part 2 with rinse water. Remove and recover The rinse water generation unit 5 introduces a part of the washing water discharged from the chelating agent regeneration unit 3 and separates it into concentrated water in which the chelating agent is concentrated by the reverse osmosis membrane and permeated water containing no chelating agent. The permeation membrane separation apparatus 110 (see FIG. 7) is provided, and the permeated water is supplied to the chelating agent recovery unit 4 as rinse water.

  When the chelating agent is depleted, the chelating agent replenishment unit 6 replenishes and supplies the reduced amount of chelating agent to the washing water returned to the soil washing classification unit 2, and the chelating agent concentration of the washing water is set in advance. To maintain. The wash water supply unit 7 includes wash water other than the wash water introduced to the rinse water generation unit 5 among the wash water discharged from the chelating agent regeneration unit 3 and the concentrated water discharged from the rinse water generation unit 5; The waste water from the gravel, sand and / or fine soil discharged from the chelating agent recovery part 4 is received and mixed, and the mixed water is supplied (returned) to the soil washing classification part 2 as washing water.

  If it demonstrates in more detail, the soil washing classification part 2 has the mixing apparatus 11, the 1st classification apparatus 12, the 2nd classification apparatus 13, the sedimentation separator 14, and the filtration apparatus 15. As shown in FIG. Here, the mixing device 11 mixes and stirs the soil containing moss, sand and fine soil, and the washing water containing the chelating agent, and the harmful metal etc. or these ions adhering to the soil are mixed. It is released from the soil and captured by a chelating agent. The first classification device 12 receives the mixture of soil and wash water discharged from the mixing device 11 and separates the gravel from the mixture. The second classification device 13 receives the mixture of sand, fine-grained soil and washing water discharged from the first classification device 12, and separates the sand from this mixture. The sedimentation separation device 14 separates the washing water containing the fine-grained soil discharged from the second classification device 13 into the supernatant water and the sludge containing the fine-grained soil by sedimentation. The filtration device 15 filters the sludge discharged from the sedimentation device 14 to form a filtrate and a filter cake (separate fine soil).

  The chelating agent regenerating part 3 is a solid phase adsorbent which adsorbs harmful metals or the like in the supernatant water or these ions when contacting with the supernatant water discharged from the sedimentation separation device 14 with a higher complexing power than the chelating agent. It has a wash water regenerating apparatus 41 (see FIG. 3) for removing harmful metals and the like from the chelating agent in the supernatant water and regenerating the supernatant water as washing water. The solid phase adsorption material has a cyclic molecule supported on a carrier, and the cyclic molecule has multipoint interaction by coordination bond and hydrogen bond modified with a chelate ligand, and harmful metal etc. or these ions can be selectively selected It is what it takes. In addition, since harmful metals and the like or ions thereof adsorbed to the solid phase adsorbent can be removed by an acid solution (for example, dilute nitric acid and dilute sulfuric acid), regeneration of the solid phase adsorbent is easy.

  The chelating agent recovery unit 4 sprays or sprays rinse water to the weir separated by the first classification device 12 to remove the chelating agent held in the weir, and the second classification device 13 removes the chelating agent. Sand sanding device 17 which sprays or sprays rinse water to the separated sand to remove the chelating agent held in the sand, and the crushed cake (filtered soil) separated by the filtering device 15 And a fine soil rinse device 18 for spraying or spraying rinse water thereon to remove the chelating agent held in the fine soil.

  The rinse water generation unit 5 has a reverse osmosis membrane separation device 110 (see FIG. 7) as will be described in detail later. The reverse osmosis membrane separation device 110 introduces (accepts) a part of the washing water discharged from the chelating agent regenerating unit 3 and includes concentrated water in which the chelating agent is concentrated by the reverse osmosis membrane, and the chelating agent Not separated into permeate and water.

  Hereinafter, the specific configuration and function of the soil washing classification unit 2 will be described with reference to FIG. In the soil washing classification part 2, soil (contaminated soil) collected by excavating ground contaminated with harmful metals and the like (toxic metals and / or compounds thereof) or these ions is received in the input hopper 21. Then, the soil in the input hopper 21 is introduced into the mixer 22 and mixed with the washing water containing the chelating agent in the mixer 22. Here, the soil includes straw, sand and fine-grained soil (silt or clay having a particle size of 0.075 mm or less). In the mixer 22, harmful metals and the like adhering to the soil or these ions are released from the soil and captured by the chelating agent.

  The mixture of soil and wash water generated by the mixer 22 (hereinafter referred to as "soil-wash water mixture") is transferred to the wet mill breaker 23. For example, a rod mill can be used as the mill breaker 23. The mill breaker 23 applies an impact force, a shear force, a frictional force and the like to the weir and sand. At that time, harmful metals and the like adhering to or contained in the gravel and sand are exfoliated or removed, and are released into the washing water. Harmful metals and the like or these ions that are released from the surface of the soil are captured by the chelating agent in the wash water. In addition, harmful metals and the like adsorbed on or adhering to the fine-grained soil or ions thereof are also separated from the fine-grained soil and captured by the chelating agent in the washing water. The mixer 22 and the mill breaker 23 correspond to the mixing device 11 in FIG.

  As a chelating agent, for example, EDTA (ethylenediaminetetraacetic acid), HIDS (3-hydroxy-2,2'-iminodisuccinic acid), IDS (2,2'-iminodisuccinic acid), MGDA (methylglycine diacetic acid), EDDS (EDCS (methylglycinediacetic acid) A sodium salt of ethylenediaminediacetic acid) or GLDA (L-glutamic acid diacetic acid) can be used. The chelating agent traps (chelates) harmful metals or the like or these ions adsorbed or attached to the soil. When treating the soil, a chelating agent suitable for the treatment is selected according to the types of harmful metals and the like contained in the soil. The higher the concentration of the chelating agent in the washing water, the higher the amount of trapped harmful metals etc. or these ions, but practically it is in the range of 0.005 to 0.1 mol / l, preferably 0.01 to 0. It is set in the range of .05 mol / liter.

  The soil and wash water mixture discharged from the mill breaker 23 is introduced into the trommel 24. Although not shown in detail, the trommel 24 is a wet sieving device having a receiving tank capable of storing washing water, and a substantially cylindrical drum screen disposed obliquely to the horizontal surface, The drum screen can be rotated about its central axis by a motor. In addition, washing water can be sprayed in the form of a spray into the drum screen. The trommel 24 corresponds to the first classification device 12 in FIG.

  When the mixture of soil and washing water flows through the inside of the rotating drum screen of the trommel 24, soil particles finer than the mesh of the drum screen pass through the mesh of the drum screen together with the washing water and go out of the drum screen and the receiving tank Get inside. On the other hand, soil particles coarser than the mesh of the drum screen are discharged out of the drum screen via the lower open end of the drum screen. In the trommel 24, the soil particles in the soil-wash water mixture rub against each other, so that harmful metals and the like remaining and adhering to the surface of the soil particles are exfoliated and released into the wash water. The harmful metals and the like or these ions released into the wash water are trapped by the chelating agent in the wash water.

  In this embodiment, the classification diameter (opening) of the mesh of the drum screen of the trommel 24 is set such that soil particles having a particle size of less than 2 mm pass through the mesh of the drum screen. Therefore, in the trommel 14, soil particles having a particle size of 2 mm or more, ie, straw, are separated or recovered from the soil-wash water mixture. The crucible separated by the trommel 24 is transferred to the crucible rinsing device 16 (see FIGS. 1 and 4). The mesh size (opening) of the drum screen of the trommel 24 is not limited to the above, and is arbitrarily set in accordance with the particle size of the relatively large soil particle to be obtained. be able to.

  A soil / wash water mixture containing soil particles having a particle size of less than 2 mm and wash water contained in the receiving tank of the trommel 24 is introduced into the cyclone 25 (hydrocyclone). Cyclone 25 is a mixture of soil and washing water with a mixture of relatively small particle size (eg, less than 0.075 mm) fine soil and washing water, and relatively large particle size (eg, 0.075 mm or more) soil particles To separate. A mixture of fine soil and washing water (hereinafter referred to as “fine grain soil-containing water”) is discharged from the upper end of the cyclone 25, and soil particles having a relatively large particle size are discharged from the lower end of the cyclone 25. . The fine-grained soil contained in the fine-grained soil-containing water is, for example, a silt or clay whose particle size is less than 0.075 mm. The cyclone 25 corresponds to the second classification device 13 in FIG.

  The relatively large particle size soil particles discharged from the lower end of the cyclone 25 are introduced into the sand clean 26 (rinsing device). The relatively large soil particle size is, for example, sand having a particle size of 0.075 to 2 mm. The sand clean 26 allows washing water to flow at a predetermined pressure and amount of water to rinse and wash soil particles having a relatively large particle size, that is, sand, and to remove residual floating matter or foreign matter. The relatively large particle size soil particles that have been subjected to the rinsing process, i.e., sand, are transferred to the sand rinsing device 17 (see FIG. 1 and FIG. 5).

  Fine-grained soil-containing water discharged from the cyclone 25 is introduced into the pH adjustment tank 27. In addition, the washing water discharged from the sand clean 26 is also introduced into the pH adjustment tank 27 and mixed with the fine-grained soil-containing water. Then, in the pH adjustment tank 27, the pH (hydrogen index) of the fine-grained soil-containing water uses a pH adjuster such as an acidic solution (eg, sulfuric acid, hydrochloric acid etc.) and an alkaline solution (eg sodium hydroxide aqueous solution etc.) The pH is adjusted to be approximately neutral or a predetermined pH (e.g., pH 7 to 8).

  The fine-grained soil-containing water whose pH is adjusted by the PH adjustment tank 27 is introduced into the aggregation tank 28. In the coagulation tank 28, polyaluminum chloride solution (PAC), a polymer flocculant, and a pH adjuster (acidic solution or alkaline solution) are added to the fine-grained soil-containing water. As a result, a large number of flocs in which the water-insoluble metal hydroxide and the fine-grained soil are mixed are generated in the coagulation tank 28. At that time, water pollutants in the wash water are adsorbed to the floc or adhere to the floc. The polyaluminum chloride solution and the polymer coagulant may be added to the fine-grained soil-containing water at pH adjustment 27 instead of the coagulation tank 28.

  The fine-grained soil-containing water in the flocculation tank 28 is introduced into the thickener 30 after floating matter is removed by the floating matter recovery device 29. Thickener 30 allows non-water-soluble floc or fine-grained soil to settle by gravity while the fine-grained soil-containing water is almost stationary, and the sludge layer (solid content ratio: 5 to 10%) located in the lower part And forms a supernatant (washing water) that is located at the top and contains almost no floc or fine-grained soil. The floating oil floating on the surface of the supernatant water is removed by overflowing a small amount of supernatant water from the top of the thickener 30. The thickener 30 corresponds to the sedimentation device 14 in FIG.

  The sludge staying or settling in the lower part of the thickener 30 is withdrawn by a sludge pump or the like, transferred to the intermediate tank 31, and temporarily stored in the intermediate tank 31. Then, the sludge in the intermediate tank 31 is transferred to the filter press 32 intermittently or continuously. The filter press 32 pressure filters the sludge received from the intermediate tank 31 to produce a filter cake and a filtrate. The filtration pressure of the filter press 32 is set, for example, such that the water content of the filter cake is 30 to 40%. The filtrate of the filter press 32 is returned to the thickener 30. The filter press 32 corresponds to the filtration device 15 in FIG.

  On the other hand, the supernatant water (washing water) in the chicna 30 is introduced into the washing water tank 33 and temporarily stored. When the washing water tank 33 is full, the spare water tank 34 is used. The washing water stored in the washing water tank 33 is introduced into the chelating agent regenerating unit 3 (see FIGS. 1 and 3). When the washing water stored in the washing water tank 33 is reduced due to evaporation or the like, the washing water tank 33 is appropriately replenished with tap water, industrial water or the like.

  Hereinafter, the specific configuration and function of the chelating agent regenerating unit 3 will be described with reference to FIG. The chelating agent regenerating unit 3 has a packed tower type filled with solid adsorbent particles or a packing (solid phase adsorbent) immobilized therein as a means for regenerating the washing water or the chelating agent. A wash water regenerating apparatus 41 (chelating agent regenerating apparatus) is provided. Further, the chelating agent regenerating unit 3 is provided with a regenerated cleaning water storage tank 43 for storing the regenerated cleaning water, an acid liquid storage tank 44 for storing the acid solution, and a water storage tank 45 for storing water.

  Then, when the wash water (chelating agent) is regenerated, the wash water stored in the wash water tank 33 is transferred to the wash water regenerating apparatus 41, while the wash water regenerated by the wash water regenerating apparatus 41 is regenerated. A pump 46 for transfer to 43 and a series of multiple lines 47-50 are provided. Furthermore, there is a pump 51 and a pipeline 52 for returning the wash water stored in the reclaimed wash water storage tank 43 to the soil wash classification unit 2 (see FIG. 1) via the wash water supply unit 7 (see FIG. 1). It is provided.

  Furthermore, when the solid phase adsorbent is regenerated, the chelating agent regeneration unit 3 transfers the acid solution stored in the acid solution storage tank 44 to the washing water regeneration device 41 while the acid discharged from the washing water regeneration device 41 A pump 53 for returning the liquid to the acid liquid storage tank 44 and a plurality of pipelines 54, 55 are provided. In addition, when washing the solid phase adsorbent regenerated with the acid solution in the chelating agent regeneration unit 3, the water stored in the water storage tank 45 is transferred to the cleaning water regeneration device 41 while the washing water regeneration device 41 A pump 56 and a plurality of pipelines 57, 58 are provided for returning the water discharged from the reservoir to the water reservoir 45.

  Pipes 47, 48, 54, 57 for transferring wash water, acid solution or water to the wash water regenerating apparatus 41 are provided with valves 61, 62, 63, 64 for opening and closing the corresponding pipes, respectively. It is done. On the other hand, in the pipelines 49, 50, 55, 58 for discharging the flush water, the acid liquid or the water from the flush water regenerating apparatus 41, valves 65, 66, 67, 68 for opening and closing the corresponding pipelines are provided. It is interposed. By switching the open / close state of these valves 61 to 68, it is possible to supply / discharge either the wash water, the acid liquid or the water to the wash water regenerating apparatus 41. In addition, opening and closing of these valves 61-68 are controlled automatically by the controller which is not shown in figure.

  Hereinafter, an example of the operation method of the chelating agent regenerating unit 3 will be described. The operation method described below is merely an example, and it is a matter of course that the operation method of the chelating agent regenerating unit 3 according to the present invention is not limited to the following. When the wash water (chelating agent) is regenerated, the valves 61, 62, 65, 66 provided in the conduits 47 to 50 are opened, while the other valves 63, 64, 67, 68 are closed. The pump 46 is operated. As a result, the wash water in the wash water tank 33 flows in the wash water regenerating apparatus 41 and is transferred to the regenerated wash water storage tank 43.

  Thus, in the wash water regenerating apparatus 41, wash water containing a chelating agent capturing harmful metals and the like is brought into contact with a solid phase adsorbent (solid phase adsorbent particles) having a higher complexing power than the chelating agent. As a result, harmful metals and the like trapped in the chelating agent are released from the chelating agent and adsorbed or extracted by the solid phase adsorbent. As a result, harmful metals and the like are removed and recovered from the wash water, while the chelating agent becomes able to capture the harmful metals and the like again, and the wash water is regenerated. The washing water stored in the reclaimed washing water storage tank 43 is returned by the pump 51 to the soil washing classification unit 2 through the pipe line 52.

  Solid phase adsorbents having higher complexing power than chelating agents are in solid form such as, for example, a gel, and generally, when contacted with an aqueous solution containing a chelating agent capturing a metal, coordination bond with the chelating agent The metal ion has a strong avidity other than the degree of covalent bonding that can release the metal ion from the chelating agent and transfer it to the solid phase adsorbent. As such a solid phase adsorbent, for example, a solid support of a cyclic molecule on a carrier such as silica gel or resin, and a modification of a chelate ligand to this cyclic molecule, and the like can be mentioned. When such a solid phase adsorbent is used, a plurality of various bonds and interactions such as coordination bonds and hydrogen bonds are caused by adjacent cyclic molecules and chelate ligands, resulting in multipoint interaction and metal ion On the other hand, stronger chemical bonds occur than chelating agents, and metal ions can be selectively incorporated by the nature of cyclic molecules.

  While the amount of adsorption of harmful metals and the like in the solid phase adsorbent increases with the regeneration of the washing water, the adsorption capacity of the solid phase adsorbent has an upper limit. For this reason, when the adsorption amount of harmful metals and the like in the solid phase adsorbent reaches a saturated state or in the vicinity thereof, the solid phase adsorbent is regenerated. That is, an acid solution (for example, dilute nitric acid, dilute sulfuric acid, etc.) is poured into the wash water regenerating apparatus 41 in a state where wash water is removed, and harmful metals etc. adsorbed on the solid phase adsorbent are removed by the acid solution. Regenerate solid phase adsorbent. Thus, while harmful metals and the like are recovered by the acid solution, the solid phase adsorbent is regenerated to be in a state capable of adsorbing or extracting the harmful metals and the like or these ions again. The solid phase adsorbent is regenerated by the acid solution and then washed with water to remove a small amount of the acid liquid adhering to the solid phase adsorbent.

  When the adsorption amount of harmful metal or the like of the solid phase adsorbent in the washing water regenerating apparatus 41 is saturated or reaches its vicinity and the solid phase adsorbent is regenerated with the acid solution, the pipelines 54, 48, 49, 55 The other valves 61, 64, 66, 68 are closed, and the pump 53 is operated, while the valves 63, 62, 65, 67 installed in the valve are opened. As a result, the acid liquid in the acid liquid storage tank 44 circulates in the wash water regenerating apparatus 41 and is returned to the acid liquid storage tank 44. Before starting the regeneration operation of the solid phase adsorbent, the washing water in the washing water regeneration device 41 is eliminated. In addition, if a plurality of washing water reclamation apparatuses 41 are arranged in parallel, even when the supply of washing water to a part of the washing water reclamation apparatus 41 is stopped, the washing water can be continuously regenerated. . Whether or not the harmful metal adsorption amount of the solid phase adsorbent has reached a saturated state or in the vicinity thereof can be determined by detecting the content of harmful metals or the like in the wash water discharged from the wash water regenerating apparatus 41 it can.

  The time for flowing the acid solution into the wash water regenerating apparatus 41 is preferably set in accordance with the size or shape of the wash water regenerating apparatus 41, the size of the solid phase adsorbent particles, and the like. The acid solution circulates and flows in the acid solution storage tank 44 and the washing water regenerating apparatus 41. At this time, the solid phase adsorbent in the wash water regenerating apparatus 41 comes in contact with the acid solution, and harmful metals and the like adsorbed on the solid phase adsorbent are released into the acid solution. That is, while harmful metals and the like are recovered by the acid solution, the solid phase adsorbent is regenerated and is in a state capable of adsorbing harmful metals and the like again.

  When the solid phase adsorbent is washed with water after the regeneration of the solid phase adsorbent by the acid solution is finished, the valves 64, 62, 65, 68 interposed in the conduits 57, 48, 49, 58 are opened. , The other valves 61, 63, 66, 67 are closed, and the pump 56 is operated. Thereby, the water in the water storage tank 45 circulates in the wash water regenerating apparatus 41 and returns to the water storage tank 45. Before starting the water washing operation of such a solid phase adsorbent, the acid solution in the washing water regenerating apparatus 41 is eliminated. Water circulates and flows between the water storage tank 45 and the flush water regenerator 41. At this time, the solid phase adsorbent in the wash water regenerating apparatus 41 comes in contact with water, and the acid solution adhering to the solid phase adsorbent is washed. After this, the regeneration of the wash water is resumed.

Hereinafter, the specific configuration and function of the chelating agent recovery unit 4 will be described with reference to FIGS. 4 to 6.
As shown in FIG. 4, the crucible rinsing device 16 forming a part of the chelating agent recovery unit 4 includes a belt conveyor 74, a crucible feeding device 75, a rinse water spraying device 76, and a cleaning wastewater receiving tank 77. .

  The belt conveyor 74 includes a substantially cylindrical drive roller 78 coaxially attached to a shaft 78a rotationally driven by an electric motor (not shown) and a substantially cylindrical shaft coaxially attached to a shaft 79a not connected to a drive source. A cylindrical follower roller 79, a ring-like or endless (endless) conveyor belt 80 wound around a drive roller 78 and a follower roller 79, a number of support rollers 81 for supporting or guiding the conveyor belt 80, and the belt And a guide plate 82 for guiding a weir discharged from the conveyor 74. The rinsing device 16 sprays or sprays rinse water on the soot discharged from the trommel 24 (see FIGS. 1 and 2) forming a part of the soil washing classification portion 2 and is held or adhered to the soot. Wash away any chelating agent.

  The driving roller 78 and the driven roller 79 have the same diameter and are arranged at the same height. The transport belt 80 is formed of a porous material, a mesh-like material, a fibrous material or a cloth-like material that can be curved in an annular shape that allows rinse water to pass through but not wrinkles. The rinse water spraying device 76 sprays rinse water to the weir being transported by the transport belt 80 in a region of a predetermined length (for example, 1 to 2 m) in the moving direction of the transport belt 80. The spray amount of rinse water from the rinse water spray device 76 is preferably set so that almost all the washing water adhering to the crucible can be washed away. For example, 2 to 3 times as much rinse water as the amount of wash water adhering to the cocoon is sprayed. As a specific example, for example, in the case of transporting 20 tons of water having a water content ratio of 15% per hour (dry basis), 6 to 9 tons of rinse water is dispersed per hour.

  The weir supply device 75 supplies the weir discharged from the trommel 24 onto the transport belt 80 near the driven roller 79 at a predetermined flow rate. The crucible thus supplied is conveyed by the conveyor belt 80, falls downward via the guide plate 82 at a position corresponding to the drive roller 78, and is stored in a crucible storage area (not shown). Rinsed water is sprayed from the rinse water spray device 76 onto the basket being transported by the transport belt 80, and the rinse water moves downward through the gaps between the particles of the tub and passes through the transport belt 80 to receive the washing wastewater. Flow down to 77. At that time, the washing water containing the chelating agent adhering to the cocoon is washed down by the rinse water and falls or flows into the washing wastewater receiving tank 77, but a part of the rinse water is retained in the interstices of cocoon particles. Ru. That is, the wash water containing the chelating agent held or adhered to the crucible is replaced with the rinse water containing no chelating agent. That is, the chelating agent contained in or attached to the cocoon is washed away by the rinse water, and is stored in the washing wastewater receiving tank 77 along with a part of the rinse water. The washing wastewater containing the chelating agent contained in the washing wastewater receiving tank 77 is introduced into the washing wastewater tank 83 (see FIG. 7). Thus, a clean storage container (not shown) stores a clean storage container substantially free of chelating agents and harmful metals.

  As shown in FIG. 5, the sand rinsing device 17 forming a part of the chelating agent recovery unit 4 includes a belt conveyor 84, a sand feeding device 85, a rinsing water scattering device 86, and a washing wastewater receiving tank 87. . Here, the belt conveyor 84 is coaxially attached to a substantially cylindrical drive roller 88 coaxially attached to a shaft 88a rotationally driven by a motor (not shown) and a shaft 89a not connected to a drive source. And a ring-like or endless conveyor belt 90 wound around a drive roller 88 and a follower roller 89, and a large number of support rollers 91 for supporting or guiding the conveyor belt 90. And a guide plate 92 for guiding the sand discharged from the belt conveyor 84. The sand rinsing device 17 sprays or jets rinse water on sand discharged from the sand clean 26 (see FIGS. 1 and 2) which forms a part of the soil washing classification portion 2 and is held in the sand or Wash off any adhering chelating agent.

  The driving roller 88 and the driven roller 89 have the same diameter and are arranged at the same height. The transport belt 90 is formed of a porous material, a mesh-like material, a fibrous material or a cloth-like material that can be curved in an annular shape that allows rinse water to pass but not sand particles. The rinse water spray device 86 sprays rinse water on sand transported by the transport belt 90 in a region of a predetermined length (for example, 1 to 2 m) in the moving direction of the transport belt 90. The amount of application of the rinse water from the rinse water spray device 86 is preferably set so that almost all the washing water adhering to the sand can be washed away. For example, 2 to 3 times the amount of rinse water adhering to the sand is sprayed. As a specific example, for example, when sand having a water content ratio of 20% is transported at 35 tons (on a dry basis) per hour, 14 to 21 tons of rinse water is dispersed per hour.

  The sand feeding device 85 feeds the sand discharged from the sand clean 26 onto the transport belt 90 near the driven roller 89 at a predetermined flow rate. The sand supplied in this manner is conveyed by the conveyance belt 90, falls downward via the guide plate 92 at a position corresponding to the drive roller 88, and is stored in a sand storage area (not shown). The sand transported by the transport belt 90 is sprayed with rinse water from the rinse water spray device 86, and the rinse water moves downward through the gaps between the sand particles, passes through the transport belt 90, and receives the washing wastewater Flow down to 87. At that time, the washing water containing the chelating agent adhering to the sand is washed down by the rinse water and falls or flows into the washing wastewater receiving tank 87, but a part of the rinse water is retained in the gaps of the sand particles. Ru. That is, the wash water containing the chelating agent held or adhered to the sand is replaced with the rinse water containing no chelating agent. That is, the chelating agent contained in or adhered to the sand is washed away by the rinse water, and is stored in the washing wastewater receiving tank 87 along with a part of the rinse water. The washing wastewater containing the chelating agent contained in the washing wastewater receiving tank 87 is introduced into the washing wastewater tank 83 (see FIG. 7). Thus, clean sand is stored in the sand storage area (not shown) which is substantially free of chelating agents and harmful metals.

  As shown in FIG. 6, the fine-grained soil rinsing device 18 forming a part of the chelating agent recovery unit 4 includes a crusher 93 and a crushed soil washing machine 94. The crusher 93 crushes the filter cake (fine-grained soil) discharged from the filter press 32 (see FIG. 2) to form granular or powdery crush soil (fine-grained soil). The crushed soil cleaner 94 sprays or jets rinse water on the crushed soil generated by the crusher 93 to remove (recover) the chelating agent held in the crushed soil.

  The crusher 93 crushes the filter cake discharged from the filter press 32 into a large number of filter cake pieces having a particle diameter of, for example, several mm (for example, 1 to 3 mm) by means of a high-speed rotating blade 95. As the crusher 93 for crushing the filter cake in this way, it is possible to use, for example, a "dewatered cake crusher" related to Taiyo Kiko Co., Ltd. or a "dewatered cake recycling device" related to Shoko Co., Ltd. it can.

  The crushed soil washing machine 94 includes a belt conveyor 96, a crushed soil receiving unit 97, a rinse water spraying device 98, and a washing wastewater receiving tank 99. Here, the belt conveyor 96 is coaxially attached to a substantially cylindrical drive roller 100 coaxially attached to a shaft 100a rotationally driven by an electric motor (not shown) and a shaft 101a not connected to a drive source. An endless or endless (consecutive) conveyor belt 102 wound around the drive roller 100 and the follower roller 101; a large number of support rollers 103 for supporting or guiding the conveyor belt 102; , And a guide plate 104 for guiding the crushed soil discharged from the belt conveyor 96.

  The driving roller 100 and the driven roller 101 have the same diameter and are arranged at the same height. The transport belt 102 is formed of a porous material, mesh material, fibrous material or cloth material capable of being curved in an annular shape that allows rinse water to pass but not crushed particles to pass. The rinse water spray device 98 sprays rinse water on the crushed soil being transported by the transport belt 102 in a region of a predetermined length (for example, 1 to 2 m) in the moving direction of the transport belt 102. The spray amount of rinse water from the rinse water spray device 98 is preferably set so that almost all the wash water adhering to the crushed soil can be washed away. For example, 2 to 3 times as much rinse water as the amount of wash water adhering to the crushed soil is sprayed. As a specific example, for example, when the crushed soil with a water content ratio of 40% is transported at 25 tons (on a dry basis) per hour, 20 to 30 tons of rinse water is dispersed per hour.

  The crushed soil receiving unit 97 supplies the crushed soil discharged from the crusher 93 onto the transport belt 102 in the vicinity of the driven roller 101 at a predetermined flow rate. The crushed soil supplied in this manner is conveyed by the conveying belt 102, falls downward via the guide plate 104 at a position corresponding to the driving roller 100, and is stored in a fine grain storage (not shown). Ru. The crushed soil being conveyed by the conveyance belt 102 is sprayed with rinse water from the rinse water spray device 98, and the rinse water moves downward through the gaps of the particles of the crushed soil and passes through the conveyance belt 102 for cleaning. It flows down to the waste water receiving tank 99. At that time, the washing water containing the chelating agent adhering to the crushed soil is washed down by the rinse water and flows down to the washing wastewater receiving tank 99. Here, part of the rinse water is retained in the gaps of the crushed soil particles. That is, the wash water containing the chelating agent retained or adhered to the crushed soil is replaced with the rinse water. That is, the chelating agent contained in or adhered to the crushed soil is washed away by the rinse water, and is stored in the washing wastewater receiving tank 99 together with the rinse water (partially). The washing wastewater containing the chelating agent contained in the washing wastewater receiving tank 99 is introduced into the washing wastewater tank 83 (see FIG. 7). Thus, the fine-grained soil storage site (not shown) stores fine-grained soil free of chelating agents and harmful metals.

  Hereinafter, the configurations and functions of the rinse water generation unit 5 and the wash water supply unit 7 (the mixing tank 111, the pump 112, the pipe line 113, and the like) will be described with reference to FIG. The rinse water generation unit 5 has a reverse osmosis membrane separation device 110. A part of the washing water in the regenerated washing water storage tank 43 is introduced to the reverse osmosis membrane separation device 110 by the pump 118 and the pipe line 119. In this embodiment, the reverse osmosis membrane separation device 110 receives a part of the washing water discharged from the chelating agent regenerating part 3 and is pressurized by an attached high pressure pump (not shown) (for example, 0. 5 to 1.5 MPa) The reverse osmosis membrane produces concentrated water concentrated with a chelating agent and permeated water containing no chelating agent. That is, the reverse osmosis membrane separation device 110 separates the washing water into concentrated water in which the chelating agent is concentrated and permeated water which does not contain the chelating agent. Then, the concentrated water is introduced into the mixing tank 111 forming a part of the washing water supply unit 7 via the pipe line 109. The washing water other than the washing water introduced into the reverse osmosis membrane separation device 110 among the washing water discharged from the chelating agent regenerating unit 3 is a part of the washing water supply unit 7 by the pump 51 and the pipe line 52. It is introduced into the mixing tank 111.

  The reverse osmosis membrane of the reverse osmosis membrane separation device 110 is, for example, a three-layer structure in which a polysulfone supporting layer and a crosslinked aromatic polyamide dense layer are laminated on the surface of a polyester non-woven fabric (100 to 120 μm thick). It can be used. The cross-linked aromatic polyamide dense layer has a large number of pores with a pore diameter of approximately 0.5 to 1.5 nm, and is permeable to water but impermeable to the chelating agent (eg, 0.2 to 0.2 nm) 0.25 μm) semipermeable membrane. Also, the polysulfone support layer is a relatively thick (e.g., 40 to 50 [mu] m) porous membrane to support or protect a very thin crosslinked aromatic polyamide dense layer to prevent its failure.

The reverse osmosis membrane separation device 110 is of a spiral type, and includes a plurality of reverse osmosis membrane elements in which a spirally wound reverse osmosis membrane is accommodated in a cylindrical container. For example, it is practical that each reverse osmosis membrane element has a total length of about 1 to 2 m and an outer diameter of about 0.2 to 0.4 m. For example, the effective membrane area of the reverse osmosis membrane in a commercially available reverse osmosis membrane element of this type having a total length of about 1 m and an outer diameter of about 0.2 m (for example, manufactured by Austentec Co., Ltd., Nakatsugawa City, Gifu Prefecture) It is about 40 m ² . In the case of this reverse osmosis membrane element, the amount of produced permeated water is estimated to be about 1.5 m ³ / hr when wash water having a chelating agent concentration of about 1% by mass is supplied at a pressure of about 1 MPa. Therefore, in order to produce, for example, 60 m ³ of permeated water per hour under the above conditions, 40 of the reverse osmosis membrane elements may be connected in parallel. When each reverse osmosis membrane element is horizontally disposed in multiple stages (for example, 8 rows and 5 stages), the area of the site required for the installation is about 10 to 20 m ² .

  The reverse osmosis membrane separation device 110 is a continuous type, and the operating conditions such as the supply amount and supply pressure (operating pressure) of washing water and the discharge amount of concentrated water or permeated water are 30 to 50% of the supply amount of washing water It is set to produce a flow of permeate. That is, concentrated water having a flow rate of 50 to 70% of the supply amount of washing water is generated, and this concentrated water is introduced into the mixing tank 111 via the pipe line 109. Thus, the chelating agent contained in the concentrated water is returned to the soil washing classification unit 2 via the mixing tank 111 and is not discharged out of the soil purification system.

  The permeated water discharged from the reverse osmosis membrane separation device 110 is supplied to the chelating agent recovery unit 4 as rinse water. Specifically, the permeated water, though not shown in detail, is a rinse water spray device 76 of the weir rinse device 16 and a rinse water spray of the sand rinse device 17 through a pump and a pipe (permeate water supply means). It is supplied as rinse water to the apparatus 86 and the rinse water spray apparatus 98 of the fine grain soil rinse apparatus 18. The washing wastewater discharged from the chelating agent recovery unit 4 is introduced into the washing wastewater tank 83 and temporarily stored. As described above, in the chelating agent recovery unit 4, since the gravel, sand or fine soil is washed with the rinse water which is 2 to 3 times the wash water adhering to or held on these, the chelate of the washing wastewater The concentration of the agent is considerably lower than that of the washing water (approximately 1/2 to 1/3). The washing wastewater in the washing wastewater tank 83 is introduced into the mixing tank 111 forming a part of the washing water supply unit 7 by the pump 116 and the pipe line 117.

  Thus, of the wash water discharged from the wash water regenerating apparatus 41 (see FIG. 3) to the mixing tank 111 forming a part of the wash water supply unit 7, other than the wash water introduced to the reverse osmosis membrane separation apparatus 110. The washing water, the concentrated water discharged from the reverse osmosis membrane separation device 110, and the washing wastewater discharged from the chelating agent recovery unit 4 are introduced, and these waters are mixed in the mixing tank 111. Then, the mixed water in the mixing tank 111 is supplied (returned) as washing water to the soil washing classification unit 2 by the pump 112 and the pipe line 113. When it becomes necessary to increase the chelating agent concentration of the wash water for some reason, the chelating agent is supplied (replenished) from the chelating agent replenishment unit 6 to the mixing tank 111. It should be noted that the installation of the reverse osmosis membrane separation device 110, the mixing tank 111, and the like that constitute the rinse water generation unit 5 does not require a very large site.

  As described above, the soil purification system 1 is a completely closed system that does not discharge waste water outside the soil purification system by using washing water in circulation. Moreover, in the soil purification system 1, the chelating agent contained in the wash water is not discharged outside the soil purification system, and is repeatedly used while being regenerated. For this reason, the running cost of the soil purification system 1 can be made very low.

As shown in FIG. 8, in the soil washing classification part 2, when washing and classifying 100 tons of soil per hour with washing water containing 1.0 mass% of a chelating agent, the soil at the key point of the soil remediation system 1 An example of the flow of water, and a chelating agent is shown. The total flow rate of washing water supplied to the soil washing classification unit 2 is 450 m ³ / hr. In this example, 100 tons of soil comprises 20 tons of straw, 35 tons of sand, 25 tons of fine-grained soil, and 20 tons of water, with a water content of 25%. In addition, the moisture content of the straw discharged from the trommel 24 is 15%, the moisture content of the sand discharged from the sand clean 26 is 20%, and the fine grain soil (filter cake) discharged from the filter press 32 is The water content is 40%. As apparent from FIG. 8, in this example, 0.2 tons of chelating agent per hour is carried away from the soil washing and sorting part 2 by the gravel, sand and fine soil. However, since these chelating agents are recovered by the chelating agent recovery unit 4 and introduced into the wash water supply unit 7 together with the washing wastewater, they are returned to the soil washing classification unit 2 and therefore are not discharged out of the soil purification system.

FIG. 9 shows an example of the flow rate of the washing water, rinse water, washing wastewater, chelating agent and the like in the chelating agent recovery unit 4 and the rinse water generation unit 5 in the case of FIG. In this example, it is set so as to generate 50% of the flow rate (60 m ³ / hr) of the flow rate of the wash water (120 m ³ / hr) supplied at a pressure of about 1 MPa. The total effective membrane area of the reverse osmosis membrane of the reverse osmosis membrane separation device 110 is about 1600 m ² . Therefore, for example, 40 of the reverse osmosis membrane elements (about 1 m in length and about 0.2 m in outer diameter) having an effective membrane area of about 40 m ² may be connected in parallel. As apparent from FIG. 9, all chelating agent (0.2 ton per hour) carried away from the soil washing classification part 2 by straw, sand and fine grained soil is returned to the washing water and returned to the soil washing classification part 2 It is done.

  As mentioned above, according to the soil purification system 1 which concerns on embodiment of this invention, the gravel, sand, and / or the fine-grained soil which were discharged | emitted from the soil washing classification part 2 are the reverse osmosis membrane separation apparatuses 110 in the chelating agent collection part 4. It is washed with permeated water (rinsing water) to remove and recover the chelating agent adhering to the gravel, sand and / or fine grained soil. Therefore, high quality straw, sand and / or fine soil free of chelating agents and harmful metals can be obtained. Then, the washing wastewater containing the chelating agent generated by the washing of the gravel, sand and / or the fine-grained soil in the chelating agent recovery unit 4 is returned to the soil washing classification unit 2 via the washing water supply unit 7 to clean the soil Since it is not discharged out of the system, loss of the chelating agent out of the soil purification system is surely prevented.

  On the other hand, the installation area of the reverse osmosis membrane separation apparatus 110 which comprises the rinse water production | generation part 5 is very small. The washing water supply unit 7 that mixes washing water, concentrated water and washing wastewater and supplies (returns) to the soil washing classification unit 2 as washing water is, for example, a mixing tank 11 such as a simple concrete pit, a pump 112, The installation area constituted by the pipeline 113 and the like is very small. Therefore, the installation of the collection facility for the chelating agent does not require a large site such as the sand container disclosed in Patent Documents 4 and 5, for example. Therefore, it is possible to prevent the chelating agent from being carried out of the soil purification system by the gravel, sand and / or fine soil, and to minimize the area of the facility for recovering the chelating agent.

  1 soil purification system, 2 soil washing classification part, 3 chelating agent regeneration part, 4 chelating agent recovery part, 5 rinse water generation part, 6 chelating agent replenishment part, 7 washing water supply part, 11 mixing device, 12 first classification device , 13 second classification device, 14 sedimentation separation device, 15 filtration device, 16 rinsing device, 17 sand rinsing device, 18 fine grain soil rinsing device, 21 feeding hopper, 22 mixer, 23 mill breaker, 24 trommel, 25 cyclone , 26 sand clean, 27 PH adjustment tank, 28 flocculation tank, 29 floating material recovery device, 30 thickener, 31 intermediate tank, 32 filter press, 33 washing water tank, 34 spare water tank, 41 washing water reproduction device, 43 reclaimed washing water storage tank , 44 acid solution storage tank, 45 water storage tank, 46 pump, 47 to 50 pipeline, 51 pump, 52 pipeline, 53 Pumps 54, 55, 56, 57, 58, 61 to 68, valves 74, belt conveyors 75, feeders 76, rinse water sprayers, 77 Washing waste water receiving tanks, 78 drive rollers, 78a shaft, 79 driven roller, 79a shaft, 80 conveyance belt, 81 support roller, 82 guide plate, 84 belt conveyor, 85 sand feeder, 86 rinse water sprayer, 87 washing waste water receiving tank, 88 driving roller, 88a shaft, 89 Driven roller, 89a shaft, 90 conveyor belt, 91 support roller, 92 guide plate, 93 crusher, 94 crusher, 95 blade, 96 belt conveyor, 97 crusher, 98 rinse water sprayer, 99 rinse wastewater Receiving tank, 100 drive roller, 100a shaft, 101 driven roller Laura, 101a shaft, 102 conveyor belt, 103 support roller, 104 guide plate, 109 pipeline, 110 reverse osmosis membrane separation device, 111 mixing tank, 112 pump, 113 pipeline, 116 pump, 117 pipeline, 118 pump, 119 pipelines.

Claims (3)

A soil wash which is cleaned and cleaned with wash water containing a chelating agent, and which is classified into gravel, sand and fine soil, and which is soiled with firewood, sand and fine soil and contaminated with harmful metals or compounds thereof Classification department,
A chelating agent regenerating unit that removes harmful metals or compounds thereof from the chelating agent capturing harmful metals or compounds thereof in the wash water discharged from the soil washing classification unit, and regenerating the chelating agent;
A chelating agent recovery unit that recovers a chelating agent adhering to the fine-grained soil by rinsing the fine-grained soil discharged from the soil washing classification unit with rinsing water;
It has a reverse osmosis membrane separation device that introduces a part of the washing water discharged from the chelating agent regeneration unit and separates it by the reverse osmosis membrane into concentrated water where the chelating agent is concentrated and permeated water that does not contain the chelating agent A rinse water generation unit that supplies permeated water as rinse water to the chelating agent recovery unit;
The washing water other than the washing water introduced into the rinse water generation unit among the washing water discharged from the chelating agent regeneration unit, the concentrated water discharged from the rinse water generation unit, and the drainage from the chelating agent recovery unit A soil purification system comprising: a washing water supply unit which receives and mixes the washing waste water of the fine-grained soil and supplies the mixed water as washing water to the soil washing classification unit. The washing water supply unit
The washing water other than the washing water introduced into the rinse water generation unit among the washing water discharged from the chelating agent regeneration unit, the concentrated water discharged from the rinse water generation unit, and the drainage from the chelating agent recovery unit A mixing tank for receiving and mixing with the washed fine soil waste water;
The soil purification system according to claim 1, further comprising: a pump and a pipeline for supplying mixed water in the mixing tank as washing water to the soil washing classification unit. The soil washing classification section
A mixing device which mixes and stirs soil containing sand, sand and fine soil with washing water and separates the harmful metal or its compound adhering to the soil from the soil and captures it with a chelating agent;
A first classification device that receives a mixture containing soil and wash water discharged from the mixing device and separates soot from the mixture;
A second classification device for receiving a mixture containing sand, fine soil and washing water discharged from the first classification device, and separating the sand from the mixture;
A sedimentation separation device for separating a mixture containing fine grain soil and wash water discharged from the second classification device into supernatant water and sludge containing fine grain soil by sedimentation separation;
And d) filtering the sludge discharged from the settling device;
The chelating agent regenerating unit has a solid phase adsorbent that adsorbs harmful metals in the supernatant water or the compound thereof when in contact with the supernatant water discharged from the sedimentation separation device with higher complexing power than the chelating agent. A chelating agent regenerating apparatus for regenerating the chelating agent by removing harmful metals or compounds thereof from the chelating agent in the supernatant water,
The chelating agent recovery unit has a fine grain soil rinsing device that sprays or sprays rinse water on a filter cake containing fine grain soil discharged from the filtration device to wash away the chelating agent held in the fine grain soil. The soil purification system according to claim 1 or 2, characterized in that

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