JP2019107640A - 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 separated 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 separated by 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 washing water or the like 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 or the like 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. Of a closed system soil purification facility that separates and reuses the soil, prevents the chelating agent from being carried away by fine soil and greatly increases the area of the facility for recovering the chelating agent. The problem to be solved is to provide means that make it possible to reduce the

  The soil purification system according to the present invention, which was made to solve the above problems, comprises a soil washing classification unit, a chelating agent regeneration unit, a chelating agent recovery unit, a mixing tank, a rinse water generation unit, and a wash water supply unit. And have. Here, the soil washing classification part contains the sand, the sand and the fine-grained soil, and the washing water containing the chelating agent, the soil contaminated with harmful metals (harmful metals and / or compounds thereof) or these ions And cleanse and separate (sort) into gravel, sand and fine-grained soil.

  In addition, the chelating agent regeneration unit 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 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 separated by the soil washing and sorting part with rinsing water. The mixing tank receives and mixes the washing water discharged from the chelating agent regeneration unit and the washing wastewater generated by the washing of the fine grain soil in the chelating agent collection unit. The rinse water generation unit receives the mixed water of the washing water and the washing wastewater in the mixing tank and separates it by the reverse osmosis membrane into concentrated water concentrated with the chelating agent and permeated water containing no chelating agent. It has a device and supplies the permeated water as rinse water to the chelating agent recovery part. The wash water supply unit supplies (returns) the concentrated water discharged from the rinse water generation unit to the soil wash classification unit as wash water.

  In the soil purification system according to the present invention, the wash water supply unit supplies the storage tank storing the concentrated water discharged from the rinse water generation unit as the wash water and the wash water in the storage tank to the soil wash classification unit (return Preferably have a pump and a conduit.

  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 the straw, sand and fine grain soil and the washing water, separates the harmful metals and the like adhering to the soil from the soil, and causes the chelating agent to trap. 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 unit filters the sludge discharged from the sedimentation unit to produce a filtrate and a filter cake.

  The chelating agent regenerating part has a solid phase adsorbent which has higher complexing power than the chelating agent and which adsorbs harmful metals and the like in the supernatant water when in contact with the supernatant water discharged from the sedimentation device. It is preferable to have 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. In addition, the chelating agent recovery unit has a fine soil soil rinsing device that sprays or sprays rinse water on the filter cake containing the fine particulate soil discharged from the filtration device to wash away the chelating agent held in the fine particulate soil. Is preferred.

  According to the soil remediation system according to the present invention, the fine-grained soil separated in 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 granular soil is removed and recovered. Therefore, a high quality fine grain soil which does not contain a chelating agent can be obtained. And the washing wastewater containing the chelating agent which arose by washing of fine grain soil in a chelating agent recovery part is introduced into a reverse osmosis membrane separation device via a mixing tank. For this reason, the chelating agent in the washing wastewater is returned to the soil washing classification part along with the concentrated water (washing water) and is not discharged out of the soil purification system. Therefore, the loss of the chelating agent out of the soil purification system is reliably prevented.

  On the other hand, the installation area of the reverse osmosis membrane separation device is very small. In addition, the mixing tank and the washing water supply unit have a very small installation area. Therefore, the installation of a chelating agent recovery facility does not require a large site. 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. Furthermore, although the soil purification system 1 is not shown in detail in FIG. 1, the soil remediation system 1 includes a mixing tank 43 (see FIGS. 3 and 7).

  The soil washing classification part 2 is washed with washing water containing a chelating agent, which contains moss, sand and fine grained soil and which is contaminated with harmful metals (harmful metals and / or compounds thereof) or these ions. As well as classification and classification into gravel, 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 mixing tank 43 receives and mixes the washing water discharged from the chelating agent regeneration unit 3 and the washing wastewater generated by the washing of the gravel, sand and / or fine soil in the chelating agent collection unit 4. The rinse water generation unit 5 receives the mixed water of the washing water and the washing wastewater in the mixing tank 43, and separates it by the reverse osmosis membrane into concentrated water in which the chelating agent is concentrated and permeated water which does not contain the chelating agent. The 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. The washing water supply unit 7 supplies (returns) the concentrated water discharged from the rinse water generation unit 5 to the soil washing classification unit 2 as washing 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 supplied (returned) to the soil washing classification unit 2, and sets the chelating agent concentration of the washing water in advance. Keep it at the same value.

  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 apparatus 11 mixes and stirs the soil containing straw, sand and fine grain soil with the washing water, and the harmful metals and the like adhering to the soil are detached from the soil and used as a chelating agent. Let me capture. The first classification device 12 receives the mixture of soil and washing 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 the 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 unit 15 filters the sludge discharged from the sedimentation unit 14 to form a filter cake and a filtrate (separate fine soil).

  The chelating agent regenerating unit 3 has a solid phase adsorbent that adsorbs harmful metals and the like in the supernatant water when contacting with the supernatant water discharged from the sedimentation separation device 14 with a higher complexing power than the chelating agent. A chelating agent regenerating apparatus 41 (see FIG. 3) is provided which removes harmful metals and the like from the chelating agent in the clear water and regenerates 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 these ions adsorbed to the solid phase adsorbent can be removed by an acid solution (for example, dilute nitric acid, dilute sulfuric acid), the solid phase adsorbent is regenerated and reused. Or it is easy to use repeatedly.

  The chelating agent recovery unit 4 sprays or sprays rinse water to the weir separated by the first classification device 12 to remove and recover the chelating agent held in the weir, and a second classification device The sand separated by 13 is sprayed or sprayed with rinse water to remove and recover the chelating agent held in the sand, and the filter cake (fine soil) produced by the filter unit 15 is removed. A fine-grained soil rinsing device 18 is provided which is crushed and then sprayed or sprayed with rinse water to remove and recover the chelating agent held in the fine grained soil.

  In the soil purification system 1, the rinse water production unit 5 has a reverse osmosis membrane separator 110 (see FIG. 7) as will be described later. The reverse osmosis membrane separation device 110 receives the mixed water of the washing water and the washing wastewater in the mixing tank 43, and separates it into permeate water and concentrated water by the reverse osmosis membrane. Then, the rinse water generation unit 5 supplies the permeated water discharged from the reverse osmosis membrane separation device 110 to the chelating agent recovery unit 4 as rinse water. The concentrated water discharged from the reverse osmosis membrane separation device 110 is supplied (returned) as washing water to the soil washing classification unit 2 by the washing water supply unit 7. In addition, the washing water supply unit 7 includes a storage tank and 111 for temporarily storing the concentrated water discharged from the reverse osmosis membrane separation device 110 as washing water, and the washing water in the storage tank 111 to the soil washing classification unit 2. It has a pump 112 and a pipe line 113 to supply (return) (see FIG. 7).

  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 (for example, 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 or the like to the weir or sand. At that time, harmful metals and the like adhering to or contained in the sand or 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. 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. Chelating agents capture (chelate) harmful metals and the like or these ions adhering 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). The cyclone 25 is a mixture of soil and washing water, a mixture of fine soil having a relatively small particle size (for example, less than 0.075 mm) and washing water, and soil particles having a relatively large particle size (for example, 0.075 mm or more). 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.

  On the other hand, soil particles having a relatively large particle size 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 or sand subjected to the rinsing process are transferred to the sand rinsing device 17 (see FIG. 1 and FIG. 5) to remove the attached chelating agent. This sand is used or sold as reclaimed sand.

  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 flocculant 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 cake or fine soil discharged from the filter press 32 is transferred to the fine soil rinsing device 18 (see FIG. 1 and FIG. 6) to remove the adhering chelating agent. 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 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 chelating agent or washing water. A chelating agent regenerating apparatus 41 is provided. In addition, the chelating agent regenerating unit 3 is provided with an acid liquid storage tank 44 for storing an acid liquid and a water storage tank 45 for storing water.

  Then, when the chelating agent or the washing water is regenerated, the washing water stored in the washing water tank 33 is transferred to the chelating agent regeneration device 41 while the washing water regenerated by the chelating agent regeneration device 41 is A pump 46 for transfer and a series of multiple conduits 47-50 are provided. The cleaning wastewater discharged from the chelating agent recovery unit 4 is also transferred to the mixing tank 43. In addition, the pump 51 and a pipe are provided to supply the mixed water of the washing water and the washing wastewater stored in the mixing tank 43 to the reverse osmosis membrane separation device 110 (see FIG. 7) which is a component of the rinse water generating unit 5. A passage 52 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 chelating agent regeneration device 41 while the acid discharged from the chelating agent 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 the solid phase adsorbent regenerated with the acid solution is washed with water, the chelating agent regeneration unit 3 transfers the water stored in the water storage tank 45 to the chelating agent regeneration device 41 while the chelating agent 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 washing water, acid liquid or water to the chelating agent 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 conduits 49, 50, 55, 58 for discharging washing water, acid liquid or water from the chelating agent regenerating apparatus 41, valves 65, 66, 67, 68 for opening and closing the corresponding conduits are provided respectively. It is interposed. By switching the open / close state of these valves 61 to 68, it is possible to supply or discharge the wash water, the acid liquid or the water to the chelate 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 chelating agent or washing water 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, and the pump 46 are driven. As a result, the wash water in the wash water tank 33 flows in the chelating agent regenerating apparatus 41 and is transferred to the mixing tank 43.

  Thus, in the chelating agent regenerating apparatus 41, the washing water containing the chelating agent capturing the harmful metal or the like is brought into contact with the 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.

  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 chelating agent regenerating apparatus 41 in a state where washing 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 chelating agent regenerating apparatus 41 is saturated or reaches its vicinity and the solid phase adsorbent is regenerated with the acid liquid, the pipelines 54, 48, 49, 53 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 chelating agent 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 chelating agent regeneration device 41 is eliminated. In addition, if a plurality of chelating agent regenerating apparatuses 41 are arranged in parallel, even when the supply of the cleaning water to some of the chelating agent regenerating apparatuses 41 is stopped, the cleaning 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 the harmful metal or the like in the washing water discharged from the chelating agent regenerating apparatus 41 it can.

  The time for flowing the acid solution into the chelating agent regenerating apparatus 41 is preferably set in accordance with the size or shape of the chelating agent regenerating apparatus 41, the size of the solid phase adsorbent particles, and the like. The acid solution circulates and flows between the acid solution storage tank 44 and the chelating agent regenerating apparatus 41. At this time, the solid phase adsorbent in the chelating agent regenerating apparatus 41 comes into 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. Thus, the water in the water storage tank 45 circulates in the chelating agent regenerating apparatus 41 and is returned to the water storage tank 45. Before starting the water washing operation of such a solid phase adsorbent, the acid solution in the chelating agent regenerating apparatus 41 is eliminated. Water circulates and flows between the water storage tank 45 and the chelating agent regenerator 41. At that time, the solid phase adsorbent in the chelating agent 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 large number of support rollers 81 for supporting or guiding the conveyor belt 80, and a belt conveyor And 74 a guide plate for guiding the user to discharge the waste. The rinsing device 16 sprays or sprays rinse water on the soot discharged from the trommel 24 (see FIG. 2) which is a part of the soil washing classification portion 2, and the chelating agent held or adhered to the soot Rinse and remove.

  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 (see FIG. 2) 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, the storage depot (not shown) stores clean storage which is substantially free of chelating agents and contaminants.

  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 FIG. 2) which is a part of the soil washing classification portion 2 and is held or adhered to the sand. Wash away any 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, the sand storage area (not shown) stores clean sand which is substantially free of chelating agents and contaminants.

  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 sprays rinse water on the crushed soil generated by the crusher 93 to remove and recover the chelating agent held in the crushed soil.

  The crusher 93 disintegrates the filter cake discharged from the filter press 32 (see FIG. 2) into a large number of filter cake pieces having a particle size of, for example, several mm (for example, 1 to 3 mm) by a high-speed rotating blade 95. Crush. 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, a fine-grained soil without a chelating agent is stored in the fine-grained soil reservoir (not shown).

  Hereinafter, the configurations and functions of the rinse water generating unit 5 and the cleaning water supply unit 7 will be described with reference to FIG. 7. The rinse water generation unit 5 has a reverse osmosis membrane separation device 110. The mixed water of the washing water and the washing wastewater in the mixing tank 43 is introduced to the reverse osmosis membrane separation device 110 by the pump 51 and the pipe line 52. In this embodiment, the reverse osmosis membrane separation device 110 receives all the washing water discharged from the chelating agent regeneration unit 3. The reverse osmosis membrane separation device 110 pressurizes the mixed water introduced by a high pressure pump (not shown) attached thereto (for example, 0.5 to 1.5 MPa) and the chelating agent is concentrated by the reverse osmosis membrane The separated concentrated water and the chelating agent-free permeate water are formed (separated). Then, the concentrated water is introduced into the storage tank 111 forming a part of the washing water supply unit 7 through the pipe line 109.

  On the other hand, 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 is not shown in detail, but through the pump and the pipeline, the rinse water spray device 76 of the weir rinse device 16, the rinse water spray device 86 of the sand rinse device 17, and fine particles It is supplied as rinse water to the rinse water sprayer 98 of the soil rinse unit 18 (see FIGS. 4 to 6). The washing wastewater discharged from the chelating agent recovery unit 4 is introduced into the washing wastewater tank 83 and temporarily stored. The washing wastewater in the washing wastewater tank 83 is transferred to the mixing tank 43 by the pump 116 and the pipe line 117. In the chelating agent recovery unit 4, since the soot, sand or fine soil is washed with 2 to 3 times as much rinse water as the wash water adhering to or held on these, the chelating agent concentration of the washing wastewater is It is considerably lower than the chelating agent concentration of water (approximately 1/2 to 1/3).

The degree of concentration of the chelating agent of the concentrated water to the mixed water (washing water and washing wastewater) in the reverse osmosis membrane separation device 110 corresponds to the flow rate of the mixed water supplied to the reverse osmosis membrane separation device 110 and the reverse osmosis membrane separation device 110 It is uniquely determined by the flow rate of the permeate (or retentate) produced by For example, when the flow rate of mixed water is 510 m ³ / hr and the flow rate of permeated water is 60 m ³ / hr (flow rate of concentrated water is 450 m ³ / hr) (see FIG. 9), concentration of chelating agent for concentrated water The degree is 1.13 times (510/450 = 1.13). Thus, the degree of concentration of the chelating agent in the concentrated water is so small that the water permeation rate of the reverse osmosis membrane is relatively large. Therefore, the area of the reverse osmosis membrane can be made relatively small, or the supply pressure of the mixed water can be made relatively low.

  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, permeation is carried out when wash water with a chelating agent concentration of about 1% by mass is supplied at a pressure of about 1 MPa and the concentration of the chelating agent in concentrated water is set to 1.1 to 1.2. The water production is estimated to be about 1.5 m ³ / hr. 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 reverse osmosis membrane elements are arranged horizontally in multiple stages (for example, eight rows and five stages), the area of a site required for the installation is about 10 to 20 m ² .

  The concentrated water discharged from the reverse osmosis membrane separation device 110 is introduced into the storage tank 111 as wash water via the pipe line 109. Then, the washing water in the storage tank 111 is supplied (returned to the mixer 22, the trommel 24 and the sand clean 26 which constitute the soil washing classification part 2 by the pump 112 and the pipe line 113 which constitute the washing water supply part 7 ). When it is necessary to increase the concentration of the chelating agent in the wash water for some reason, the chelating agent is supplied (replenished) from the chelating agent replenishment unit 6 to the storage tank 111.

  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 introduced into the reverse osmosis membrane separation device 110 via the mixing tank 43. For this reason, the chelating agent in the washing wastewater is finally returned to the soil washing classification unit 2 along with the concentrated water or washing water and is not discharged out of the soil purification system. Therefore, the loss of the chelating agent out of the soil purification system is reliably prevented. Further, as described above, since the degree of concentration of the chelating agent of the concentrated water to the mixed water is very small, the water permeation rate of the reverse osmosis membrane becomes relatively large, and the discharge pressure of the high pressure pump of the reverse osmosis membrane separation device 110 accordingly Can be reduced, or the total surface area of the reverse osmosis membrane can be reduced. The installation of the reverse osmosis membrane separation device 110, the mixing tank 43, the storage tank 111, etc. 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. In this example, the total flow rate of washing water supplied to the soil washing classification unit 2 is 450 m ³ / hr, and 100 tons of soil has 20 tons of straw, 35 tons of sand, and 25 tons of fine-grained soil And 20 tons of water, the water content of which is 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, these chelating agents are recovered by the chelating agent recovery unit 4 and returned to the soil washing classification unit 2 via the mixing tank 43, the reverse osmosis membrane separation device 110, and the washing water supply unit 7, It is not discharged outside the purification system.

FIG. 9 shows an example of the flow rate and the chelating agent concentration of wash water, rinse water, wash wastewater, chelating agent and the like in the chelating agent recovery unit 4 and the rinse water generating unit 5 in the case of FIG. In this example, 60 m ³ / hr of permeated water is generated from the mixed water (wash water and washing wastewater) supplied at 510 m ³ / hr 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, the chelating agent (0.2 ton per hour) carried away from the soil washing classification part 2 by the gravel, sand and fine grained soil is all returned to the soil washing classification part 2.

  As mentioned above, according to the soil purification system 1 which concerns on this invention, the persimmon, the sand and / or the fine-grained soil which were discharged | emitted from the soil washing classification part 2 are the permeated water of the reverse osmosis membrane separation apparatus 110 in the chelating agent collection part 4. It is washed with rinse water to remove the chelating agent adhering to the gravel, sand and / or fine grained soil. Thus, high quality chew, sand and / or fine soil free of chelating agents can be obtained. And, since the cleaning waste water containing the chelating agent generated by the washing of the gravel, sand and / or fine soil in the chelating agent recovery part 4 is not discharged out of the soil purification system, the loss of the chelating agent can be surely prevented. it can.

  On the other hand, the installation area of the reverse osmosis membrane separation device 110, the mixing tank 43, the storage tank 111, etc. is very small. Therefore, the installation of a chelating agent recovery facility does not require a large site. 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 flotage collection device, 30 thickener, 31 intermediate tank, 32 filter press, 33 washing water tank, 34 spare water tank, 41 chelating agent regenerator, 43 mixing tank, 44 Acid liquid storage tank, 45 water storage tank, 46 pump, 47 to 50 pipeline, 51 pump, 52 pipeline, 53 pong , 54 pipelines, 55 pipelines, 56 pumps, 57 pipelines, 58 pipelines, 61 to 68 valves, 74 belt conveyors, 75 tank feeders, 76 rinse water sprayers, 77 washing wastewater receiving tanks, 78 drive rollers, 78a shaft, 79 driven roller, 79a shaft, 80 conveyance belt, 81 support roller, 82 guide plate, 83 washing waste tank, 84 belt conveyor, 85 sand feeding device, 86 rinse water spraying device, 87 washing waste water receiving tank, 88 driving roller , 88a shaft, 89 driven roller, 89a shaft, 90 conveyance belt, 91 support roller, 92 guide plate, 93 crusher, 94 crusher, 95 blade, 96 belt conveyor, 97 crusher, 98 rinse water spray Equipment, 99 Washing Waste Water Receiving Tank, 100 Drive Rollers, 100a Shaft, 101 driven roller, 101a shaft, 102 conveyance belt, 103 support roller, 104 guide plate, 109 pipeline, 110 reverse osmosis membrane separation device, 111 reservoir, 112 pump, 113 pipeline, 116 pump, 117 pipeline.

In addition, the chelating agent regeneration unit 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 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 separated by the soil washing and sorting part with rinsing water. The mixing tank receives and mixes all of the washing water discharged from the chelating agent regeneration unit and the washing wastewater generated by the fine grain soil washing in the chelating agent collection unit. The rinse water generation unit receives the mixed water of the washing water and the washing wastewater in the mixing tank and separates it by the reverse osmosis membrane into concentrated water concentrated with the chelating agent and permeated water containing no chelating agent. It has a device and supplies the permeated water as rinse water to the chelating agent recovery part. The wash water supply unit supplies (returns) the concentrated water discharged from the rinse water generation unit to the soil wash classification unit as wash water.

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 the chelating agent adhering to the fine-grained soil by rinsing the fine-grained soil separated in the soil washing and classification section with rinse water;
A mixing tank for receiving and mixing the washing water discharged from the chelating agent regeneration unit and the washing wastewater generated by the washing of fine grain soil in the chelating agent collection unit;
It has a reverse osmosis membrane separation device that receives the mixed water of washing water and washing wastewater in the mixing tank and separates it into concentrated water concentrated with a chelating agent and permeated water containing no chelating agent by a reverse osmosis membrane, A rinse water generation unit that supplies permeated water as rinse water to the chelating agent recovery unit;
And a cleaning water supply unit for supplying the concentrated water discharged from the rinse water generation unit as the cleaning water to the soil cleaning and classification unit. The washing water supply unit
A storage tank storing concentrated water discharged from the rinse water generation unit as cleaning water;
The soil purification system according to claim 1, further comprising: a pump and a pipeline for supplying wash water in the storage tank 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 a filtration device for filtering the sludge discharged from the sedimentation device to produce a filtrate and a filter cake,
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 device 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

Images