JP2018176152A - Soil remediation system and soil remediation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil remediation facility for remediation of contaminated soil with a chelating agent, the facility provided with means that can reduce the amounts of the chelating agent stored and used and the footprint of equipment for recovering the chelating agent.SOLUTION: A soil remediation system comprises: a soil classification part to classify contaminated soil into gravel, sand and earth; and a sand and gravel remediation part 2 for remediation of the separated sand and gravel with a chelating cleaning solution. The sand and gravel remediation part 2 comprises a sand cleaning part 14, a gravel cleaning part 15, a chelating agent regeneration part 16, a sand rinsing part 17, a gravel rinsing part 18, and a chelating agent recovery part 19. The sand cleaning part 14 and the gravel cleaning part 15 respectively clean the sand and the gravel with the chelating cleaning solution. The chelating agent regeneration part 16 regenerates the chelating cleaning solution and returns it to the sand cleaning part 14 and the gravel cleaning part 15. The chelating agent recovery part 19 recovers the chelating agent from cleaning wastewater discharged from the sand rinsing part 17 and the gravel rinsing part 18.SELECTED DRAWING: Figure 3

Description

  The present invention classifies soil contaminated with harmful metals or compounds thereof into soot, sand and soil in a soil classification section, and sand and soot separated in the soil classification section, a chelating cleaning solution containing a chelating agent and water The present invention relates to a soil remediation system and a soil remediation method for remediation using

  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 with soil pollution in Japan is due to soil pollution or dumping of industrial waste including harmful metals. 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 digging or the like, and purified at an external soil purification facility.

  As a method of purifying harmful metal-contaminated soil at such an in-situ soil purification facility, a soil purification method in which harmful metal-contaminated soil is washed with a cleaning liquid to remove harmful metals etc. is widely used. ing. Thus, the inventor of the present invention adheres or bonds to soil while being wet-classified as moss, sand and soil, by circulatingly using soil contaminated with harmful metals and the like, and a chelating cleaning solution containing a chelating agent and water as a cleaning solution. Various types of closed system soil remediation facilities or soil remediation methods have been proposed which remove harmful metals and the like and do not discharge the cleaning solution to the outside (see Patent Documents 1 to 14).

Patent No. 5771342 Patent No. 5771343 gazette Patent No. 6022102 Patent No. 6022103 Patent No. 6022104 Patent No. 6026700 gazette Patent No. 6026701 Patent No. 6026702 Patent No. 6052942 Patent No. 6052943 Patent No. 6052944 Patent No. 6052945 gazette Patent No. 6052946 gazette Patent No. 60 529 47

Geotechnical Engineering Laboratory, Tokyo University of Science, Geomechanics I, II Lecture Material, Chapter 2, "Various Properties of Unsaturated Soil", pp. 1-18. rs. noda. tus. ac. jp / soil / lecture / SoilMechanics / 02_Unsaturated / H23unsaturated. pdf Development Ichiro, "Experiments on the behavior of water in the capillary zone and groundwater outflow," Report of the University of Tsukuba Reasoning Experiment Center, No. 11, 1987, 79-83. Kiyozawa Hideki "On the estimation method of soil surface evaporation based on soil temperature change" Bulletin of Mie University, Faculty of Agriculture, Mie University, 1984, 68, 25-40

  By the way, in the soil purification facility disclosed in Patent Documents 1 to 14, the cleaning solution circulating in a series of distribution systems including a mill breaker, trommel, cyclone, thickener, cleaning solution storage tank and the like has a predetermined concentration (for example, 0.3 to 1.0 mass%) of a chelating agent. On the other hand, since a series of distribution systems of the soil purification apparatus hold a large amount of washing solution (for example, 1000 to 2000 tons), the preparation of such washing solution requires a large amount of chelating agent, and the cost of treating the soil There is a problem of rising. Furthermore, there is a problem that if it is necessary to discard or replace the cleaning solution in a series of distribution systems for some reason, it is necessary to process a large amount of chelating agent contained in the cleaning solution.

  In addition, sand and gravel separated in the soil treatment facility are usually reused as civil engineering and building materials, but sand or gravel to which a cleaning liquid containing a chelating agent is attached in this way is as civil engineering and building materials Is not desirable. In addition, since the chelating agent in the soil purification facility is reduced by the amount carried away by sand and gravel, even if the chelating agent is regenerated and used repeatedly, the amount corresponding to the chelating agent carried away by sand and gravel It is necessary to replenish the chelating agent. For this reason, in a soil purification facility that purifies a large amount of contaminated soil (for example, 1000 tons / day), it is necessary to continue replenishing a large amount of chelating agent, and the cost of treating soil in the soil purification facility becomes extremely high. There's a problem.

  Therefore, in the soil remediation facilities described in Patent Documents 3, 6, 9, 12 according to the applicant of the present invention, sand containing a chelating agent discharged from a hydrocyclone and a crucible containing a chelating agent discharged from a trommel are rinsed It is washed with water to remove the chelating agent. On the other hand, the cleaning wastewater containing the chelating agent is evaporated to the atmosphere by the evaporation sand in the sand storage section, and the chelating agent is left and accumulated on the evaporation sand (so-called salt field system), and the evaporation sand containing the chelating agent is It is introduced into the treatment system to recover the chelating agent. However, since a large amount of rinse water is required to wash sand and gravel containing a chelating agent, there is a problem that a large site is required to set up a sand storage unit to evaporate a large amount of washing wastewater. .

  The present invention has been made to solve the above-mentioned conventional problems, and it purifies soil contaminated with harmful metals and the like with a chelating agent, and separates sand and straw from the soil for reuse. It is possible to reduce the amount of retention or flow of chelating agent in the soil purification facility in a closed system type soil purification facility, and to prevent the chelating agent from being carried out of the soil purification facility by sand and gravel or The problem to be solved is to provide a means that can be reduced and that can reduce the area of the facility for the recovery of the chelating agent.

  A soil remediation system according to the present invention, which has been made to solve the above problems, comprises soil, sand and soil, and is used to purify soil contaminated with harmful metals (ie harmful metals and / or compounds thereof). It has a soil classification section that classifies into sand, sand and soil, and a sand / soil purification section that cleans and cleans the sand and the sand separated in the soil classification section with a chelating agent and a chelating agent containing water. ing.

  In this soil treatment system, the soil classification unit comprises a mixing device, a trommel, a hydrocyclone, a thickener and a filter press. Here, the mixing device mixes the soil and washing water supplied to the soil classification unit. The trommel separates the straw from the mixture of soil and wash water discharged from the mixing device. The hydrocyclone separates sand from the mixture of sand, soil and wash water discharged from the trommel. The chicna separates the mixture of soil and wash water discharged from the hydrocyclone into supernatant water and sludge containing soil by sedimentation. The filter press filters the sludge discharged from the thickener to separate the soil.

  The sand and straw purification unit has a sand washing unit, a straw washing unit, a chelating agent regeneration unit, a sand rinsing unit, a straw rinsing unit, and a chelating agent recovery unit. Here, the sand washing unit is used to wash the sand discharged from the hydrocyclone with a chelate washing solution to remove harmful metals and the like from the sand. The crucible cleaning unit cleans the crucible drained from the trommel with a chelate cleaning solution to remove harmful metals or compounds thereof from the crucible. The chelating agent regeneration unit removes harmful metals and the like from the chelating agent in the chelate washing solution discharged from the sand washing unit and the tub washing unit to regenerate the chelate washing solution, and returns it to the sand washing unit and the tub washing unit. The sand rinsing unit rinses the sand discharged from the sand washing unit with rinsing water to remove the chelating agent. The beard rinsing unit rinses the beak discharged from the beard washing unit with rinsing water to remove the chelating agent. The chelating agent recovery unit recovers the chelating agent from the washing wastewater containing the chelating agent discharged from the sand rinsing unit and the crucible rinsing unit.

  And a sand washing part has a distribution type mixing stirrer, a vibrating sieve, and a belt press device. The mixing stirrer mixes and stirs the sand discharged from the hydrocyclone and the chelate washing solution, and causes the chelating agent to trap harmful metals or the like adhering to or bound to the sand. The vibrating sieve removes the chelate washing solution from the mixture of sand and the chelate washing solution discharged from the mixing stirrer. The belt press apparatus has an upper belt mechanism and a lower belt mechanism facing each other provided with a porous endless belt (or a porous endless belt equipped with a filter medium) wound around a plurality of rollers and traveling around. The sand wet with the chelate washing liquid discharged from the vibrating screen is received and conveyed by being sandwiched between the upper belt mechanism and the lower belt mechanism. In this belt press apparatus, pressurized air is supplied to the upper surface of the endless belt of the upper belt mechanism at the portion facing the lower belt mechanism, and the pressurized air is supplied to the upper belt. Flow downward through the endless belt of the mechanism, the layer of sand sandwiched between the upper belt mechanism and the lower belt mechanism, and the endless belt of the lower belt mechanism to reduce the ratio of sand cleaning solution A pressurized air supply system is provided.

  The crucible cleaning unit has a chelate cleaning solution tank for holding a chelate cleaning solution, and a crucible transfer device for moving a crucible container containing crucibles horizontally in a state where the container is immersed in the chelate cleaning solution in the chelate cleaning solution tank. ing. Here, the bottom and / or the side of the crucible container is formed of a screen having an eye dimension not to allow the crucible to pass through.

  The chelating agent regenerating unit has a complexing power higher than that of the chelating agent, and a solid phase that adsorbs harmful metals and the like in the chelating cleaning solution when the chelating cleaning solution discharged from the sand washing unit and the tub washing unit has a higher complexing power than the chelating agent. It has an adsorbent, and has a chelate washing solution regenerating apparatus which regenerates the chelate washing solution by removing harmful metals and the like from the chelating agent in the chelate washing solution. The sand rinsing unit has a sand rinsing device that sprays or jets rinse water on the sand discharged from the sand washing unit to remove the chelating agent held in the sand. The weir rinse unit has a weir rinse device that sprays or jets rinse water to the weir discharged from the weir washing unit to remove the chelating agent held in the weir.

  The chelating agent recovery unit has a washing waste water storage tank, a sand storage part, a roof, a gutter, a washing waste water return path, and a water level holding device. The washing wastewater storage tank receives and stores washing wastewater containing the chelating agent discharged from the sand rinsing unit and the crucible rinsing unit. The sand storage portion is disposed on the ground, and is disposed in a space formed by the peripheral wall, the bottom wall coupled to the lower end portion of the peripheral wall, and the peripheral wall and the bottom wall to pass cleaning wastewater but not sand. It has a perforated plate and is in the form of a container opened at the upper side, which contains sand for water evaporation on the perforated plate in its inner space. A roof is disposed above the sand receiving portion to prevent rainwater from falling to the sand receiving portion. The side groove is disposed adjacent to the outer surface of the peripheral wall of the sand storage portion, and the internal space thereof communicates with the internal space of the sand storage portion via a communication hole formed in the peripheral wall below the porous plate. The washing wastewater supply device supplies the washing wastewater stored in the washing wastewater storage tank to the gutter. The washing wastewater return path refluxes the washing wastewater in the gutter to the washing wastewater storage tank. The water level holding device holds the water level of the washing wastewater in the gutter at a preset sand soaking upper end position. Here, the water evaporation sand is located between the sand immersion upper end position and the position of the upper surface of the water evaporation sand contained in the inner space of the sand containing portion to form a capillary water zone. It is set to

  The soil purification system according to the present invention further includes water evaporation sand transfer means and water evaporation sand supply means. In the water evaporation sand transfer means, the cleaning wastewater is supplied from the gutter to the water evaporation sand contained in the sand storage unit over a predetermined period, and the water of the cleaning wastewater supplied to the water evaporation sand evaporates in the air When the chelating agent is accumulated in the water evaporation sand, the water evaporation sand in which the chelating agent in the sand container is accumulated is transferred to the sand washing unit. The water evaporation sand supply means supplies part of the sand discharged from the sand rinse unit to the sand storage unit as water evaporation sand.

  On the other hand, the soil remediation method according to the present invention is used in a soil remediation facility or a soil remediation system that remediates the soil contaminated with harmful metals and the like, including sand, sand and soil. Here, the soil remediation facility or soil remediation system using the soil remediation method according to the present invention has substantially the same configuration as the soil remediation system according to the present invention (sand transfer means for water evaporation and sand supply for water evaporation) Except the means).

  Thus, in the soil remediation method according to the present invention, the water level holding device holds the water level of the cleaning drainage in the gutters at the sand immersion upper end position to form a capillary water zone in the sand layer above the sand immersion upper end position. The water of the washing waste water adhering to the water evaporation sand in the capillary water zone is evaporated in the air and removed from the sand container. Then, the sand for water evaporation used for a predetermined period in the sand storage unit and having the chelating agent accumulated therein is introduced into the sand washing unit, and the chelating agent accumulated in the sand for water evaporation is recovered. On the other hand, a part of the sand discharged from the sand rinse unit is used as water evaporation sand stored in the sand storage unit. In the soil purification method according to the present invention, it is preferable to separate fine sand from the sand discharged from the sand rinsing unit and use the fine sand as a water evaporation sand to be stored in the sand storage unit.

  According to the soil remediation system or the soil remediation method of the present invention, the sand discharged from the hydrocyclone and the trommel are not added to the large amount of washing water circulating in the series of distribution systems in the soil remediation system without adding the chelating agent. Since the excreted soot is washed with the chelate washing solution, the amount of chelating agent retained in the soil purification system can be greatly reduced. Then, since the sand and the crucible washed with the chelating solution are rinsed with rinse water in the sand rinsing unit and the bowl rinsing unit respectively, it is possible to obtain the sand and the crucible which are suitable for reuse without the chelating agent. In addition, since the chelating agent in the washing wastewater discharged from the sand rinsing unit and the weir rinsing unit is returned to the sand washing unit by the chelating agent recovery unit, the amount of the chelating agent used can be significantly reduced. Furthermore, since the pressurized washing machine in the belt press apparatus reduces the content of the chelate washing liquid of the sand wet with the chelating washing liquid, the amount of rinse water used in the sand rinsing unit, ie, the quantity of washing wastewater to be evaporated is reduced. It is possible to reduce the site area of the sand storage unit in the chelating agent recovery unit.

It is a block diagram showing a schematic structure of a soil purification system concerning the present invention. It is a schematic plan view which shows schematic structure of the soil classification part which makes a part of soil purification system shown in FIG. It is a block diagram which shows schematic structure of the sand and agate purification part which makes a part of soil purification system shown in FIG. It is a typical elevation view of the sand washing part which makes a part of sand and dregs purification | cleaning part shown in FIG. FIG. 4 is a schematic partial cross-sectional side view of a crucible cleaning unit that forms a part of the sand and crucible cleaning unit shown in FIG. 3; It is a typical elevation view which shows the structure of the chelating agent reproduction | regeneration part which makes a part of sand and dregs purification | cleaning part shown in FIG. It is a typical partial cross section side view which shows the structure of the sand rinse part which makes a part of sand and agate purification | cleaning part shown in FIG. It is a typical partial cross section side view which shows the structure of the coffin rinse part which makes a part of sand and cocoon purification part shown in FIG. It is a schematic plan view which shows the structure of the soil purification system (except a chelating agent reproduction | regeneration part) shown in FIG. It is a typical cross section elevational view of a sand accommodation part, a roof, and a gutter which was cut by a plane perpendicular to a longitudinal direction (front-back direction) of a sand accommodation part. It is a schematic plan view of an important part of a sand seat part and a gutter in the state where a perforated panel and a sand layer were removed.

Hereinafter, a soil remediation system and a soil remediation method according to an embodiment of the present invention will be specifically described with reference to the attached drawings.
As shown in FIG. 1, according to an embodiment of the present invention, a soil purification system S that purifies soil that contains moss, sand, and soil and that is contaminated with harmful metals (that is, harmful metals and / or compounds thereof) The soil classification part 1 which wet-classifies contaminated soil into cocoon, sand and soil using washing water, and the sand and cocoon separated by the soil classification part 1 are washed with a chelate washing solution containing a chelating agent and water. And sand purification unit 2 to be cleaned.

  As shown in FIG. 2, in the soil classification unit 1, the soil (contaminated soil) collected by excavating the ground contaminated with harmful metals or contaminated with other pollutants is received by the input hopper 3. Be Then, the soil in the feeding hopper 3 is first loaded into the container-like mixer 4 and mixed with the washing water in the mixer 4. Here, the soil is made up of various particle sizes of straw (particle size is 2 to 75 mm), sand (particle size is 0.075 to 2 mm), and soil (silt or clay having a particle size of 0.075 mm or less). Is included. The soil in the input hopper 3 is contaminated with harmful metals and the like, and in some cases, further contaminated with other contaminants. Here, examples of the harmful metals and the like include chromium, lead, cadmium, selenium, mercury, metal arsenic and compounds thereof. The chelate washing solution to be described later can effectively capture (remove) such harmful metals and the like.

  The mixture of soil and washing water generated by the mixer 4 (hereinafter referred to as “soil / water mixture”) is transferred to the mill breaker 5. For example, a rod mill can be used as the mill breaker 5. The rod mill is a device in which a plurality of rods are disposed in the drum, although not shown in detail, and the rods roll parallel to one another by the rotation of the drum and make line contact, the impact force, friction force, etc. Remove harmful metals etc. adhering to or adhering to the eyelid by this and let it separate from the eyelid. Most of the harmful metals and the like released into the washing water adhere to the surface of sand and soil (fine-grained soil) particles.

  The soil-water mixture discharged from the mill breaker 5 is introduced into the trommel 6. Although not shown in detail, the trommel 6 is a wet sieving device having a receiving tank capable of storing washing water and a substantially cylindrical drum screen disposed to be inclined with respect to a horizontal surface. The drum screen can be rotated about its central axis by a motor. Also, washing water can be sprayed in a spray form into the drum screen.

  As the soil-water mixture flows through the inside of the rotating drum screen of Trommel 6, soil particles (sand, soil) finer than the mesh of the drum screen pass through the mesh of the drum screen with the washing water and go out of the drum screen Go out into the receiving tank. On the other hand, soil particles (soot) which are coarser than the mesh of the drum screen can not pass through the mesh of the drum screen and are therefore discharged outside the drum screen via the lower open end of the drum screen. The soot discharged from the trommel 6 is transferred to the sand and soot purification unit 2 (see FIG. 3).

  The classification diameter (opening) of the mesh of the drum screen is set, for example, such that soil particles (sand, soil) having a particle size of less than 2 mm pass through the mesh of the drum screen. Therefore, in trommel 6, soil particles having a particle size of 2 mm or more (i.e., straw) are separated from the soil-water mixture. The mesh size (opening) of the drum screen of the trommel 6 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 / water mixture containing soil particles (sand, soil) having a particle size of less than 2 mm and contained in the receiving tank of the trommel 6 and washing water is introduced into the hydrocyclone 7. Although not shown in detail, the hydrocyclone 7 pumps the soil-water mixture into a generally conical cylinder that narrows downward to generate a swirling flow, and the centrifugal force generated thereby is used. A soil-water mixture, a mixture of relatively small particle size soil (eg, particle size less than 0.075 mm) and wash water (mostly wash water), and a relatively large particle size sand (eg, 0.075 mm) Or higher) and a mixture of washing water (the proportion of washing water is small). A mixture of soil and wash water (hereinafter referred to as "soil containing water") is discharged from the upper end of the liquid cyclone 7, and a mixture of sand and wash water is discharged from the lower end of the cyclone 7. Then, the soil-containing water is transferred to the PH adjustment tank 8. The soil contained in the soil-containing water is, for example, silt or clay having a particle size of less than 0.075 mm. The mixture of sand and washing water discharged from the lower end of the hydrocyclone 7 is transferred to the sand and scale purification unit 2 (see FIG. 3) after reducing the ratio of washing water using, for example, a vibrating sieve. .

  The soil-containing water discharged from the cyclone 7 is introduced into the pH adjustment tank 8 and the pH (hydrogen index) thereof is adjusted to a pH adjuster such as an acid solution (eg, sulfuric acid, hydrochloric acid etc.) and an alkali solution (eg sodium hydroxide) The solution is adjusted to be approximately neutral or a predetermined pH (e.g., pH 7 to 8) using an aqueous solution or the like. Although not shown, in the pH adjustment tank 8, the pH of the soil-containing water is automatically adjusted by an automatic control device equipped with a pH meter and the like.

  Soil-containing water whose pH has been adjusted by the PH adjustment tank 8 is introduced into the aggregation tank 9. In the coagulation tank 9, a polyaluminum chloride solution (PAC), a polymer flocculant, and a pH adjuster (acid solution or alkali solution) are added to the soil-containing water. As a result, a large number of flocs in which the water-insoluble metal hydroxide and the soil are mixed are generated in the coagulation tank 9.

  Soil-containing water containing a large number of flocs in the coagulation tank 9 is introduced into the thickener 10. Although the thickener 10 is not shown in detail, the floc or soil is caused to settle by gravity while the soil-containing water is almost stationary, and the sludge layer located at the lower part (for example, the solid content ratio is 5 to 10% And a floe or soil-free supernatant water (wash water) located at the top. In addition, when floating oil is floating on the surface of the supernatant water, for example, floating oil may be removed by floating the oil absorption mat etc. on the water surface of the chicna 10 and recovering the oil absorption mat appropriately. it can.

  Supernatant water in the thickener 10 is introduced into the flush water storage tank 11 and stored. The wash water stored in the wash water storage tank 11 is supplied to the mixer 4 and the trommel 6. When the cleaning water stored in the cleaning water storage tank 11 is reduced due to evaporation or the like, water (industrial water, tap water, etc.) is appropriately replenished.

  On the other hand, the sludge deposited on the lower part of the thickener 10 is transferred to the intermediate tank 12 and temporarily stored. Then, the sludge in the intermediate tank 12 is transferred to the filter press 13 appropriately or continuously. Although not shown in detail, the filter press 13 is a batch type or semi-continuous type pressure filter, and pressure filters the sludge received from the intermediate tank 12 to filter cake (soil) and filtrate (washing Water) to produce. The filtration pressure of the filter press 13 is preferably set, for example, so that the water content of the filter cake is 30 to 40%. Here, the filtrate of the filter press 13 is returned to the thickener 10. Thus, the washing water is circulated and used in the soil classification unit 1 and is not discharged to the outside. That is, the soil classification part 1 is a closed system regarding wash water.

  As shown in FIG. 3, the sand and soot purification unit 2 includes a sand washing unit 14, a straw washing unit 15, a chelating agent regenerating unit 16, a sand rinsing unit 17, a straw rinsing unit 18, and a chelating agent recovery unit And 19. Here, the sand washing unit 14 cleans the sand discharged from the liquid cyclone 7 with a chelate washing solution containing a chelating agent and water to remove harmful metals and the like from the sand. The soot washing unit 15 wash the soot discharged from the trommel 6 with a chelate washing solution to remove harmful metals or compounds thereof from the soot. The chelating agent regenerating unit 16 removes harmful metals and the like from the chelating agent in the chelate washing solution discharged from the sand washing unit 14 and the tub washing unit 15 to regenerate the chelate washing solution, and the sand washing unit 14 and the tub washing unit 15 I will return it. The sand rinsing unit 17 rinses the sand discharged from the sand washing unit 14 with rinsing water to remove the chelating agent. The bottle rinsing unit 18 rinses the bottle discharged from the bottle washing unit 15 with rinsing water to remove the chelating agent. The chelating agent recovery unit 19 recovers the chelating agent from the cleaning wastewater containing the chelating agent discharged from the sand rinsing unit 17 and the crucible rinsing unit 18.

  As shown in FIG. 4, the sand washing unit 14 includes a flow type mixing and stirring device 14A, a vibrating screen 14B, and a belt press device 14C. The mixing stirrer 14A is a device for mixing and stirring the sand discharged from the liquid cyclone 7 and the chelate washing solution, and causing the chelating agent to trap harmful metals and the like attached or bonded to the sand. The vibrating sieve 14B is a device for removing most of the chelate washing liquid from the mixture of sand and the chelate washing liquid discharged from the mixing stirrer 14A. The belt press device 14C receives the sand wet with the chelate washing solution discharged from the vibrating sieve 14B, and reduces the content ratio (or the content of the chelate washing solution) of the washing solution while transporting the sand, as described in detail later. It is a device to make

  Specifically, the mixing stirrer 14A includes an elongated substantially cylindrical main body portion 20 having a central axis extending in the vertical direction, and a plurality of baffle plates 21 (baffle plates) attached to the inner peripheral surface of the main body portion 20. A stirrer 22 disposed in the main body 20 and a motor 23 for rotationally driving the stirrer 22 are provided. Each baffle plate 21 is basically in the shape of a ring having a hole formed in its center, but in order to facilitate the downward movement of sand, it is tapered in such a way as to descend downward. It is formed.

  The stirrer 22 has a plurality of stirrers or blades attached to a vertically extending rotary shaft. The shape or size of the agitating blades is set so as to be able to pass through the holes of the baffles 21. Here, the baffle plates 21 and the stirring blades of the stirrer 22 are arranged alternately in the vertical direction.

  The dimensions (for example, diameter, height, etc.) of the main body portion 20 ensure that the chelate cleaning liquid and sand particles flowing in the main body portion 20 have a preset residence time (for example, 0.1 to 0.3 hours) It is preferably set to be able to Further, the number, shape, rotational speed and the like of the respective stirring blades of the stirrer 22 are such that the degree of turbulence (eg, Reynolds number 20000 to 100000) that sand particles are substantially uniformly dispersed in the chelate washing solution in the main body 20 Is preferably set to achieve.

  Then, sand and a chelate washing solution are supplied to the upper end opening of the main body 20, and the chelate washing solution and the sand particles are stirred and mixed by the stirrer 22. As a result, a mixture (hereinafter referred to as "sand-washing solution mixture") in which sand particles are substantially uniformly dispersed in the chelate washing solution is generated, and this sand-washing solution mixture is stirred by the plurality of stirring blades of the stirrer 22. It flows downward in the main body 20 at a slow speed. Thus, in the mixing stirrer 14A (the main body 20), the sand particles are brought into contact with the chelate washing solution, and harmful metals and the like attached to the surface of the sand particles in the sand and washing solution mixture are removed. The baffle plate 21 increases the degree of turbulence (Reynolds number) of the sand / washing liquid mixture in the main body 20, thereby promoting removal or separation of harmful metals and the like from the sand particles.

  As a chelating agent used for the chelate washing solution, for example, EDTA (ethylenediaminetetraacetic acid), or HIDS (3-hydroxy-2,2'-iminodisuccinic acid), IDS (2,2'-iminodisuccinic acid), MGDA (methylglycine) And sodium salts of EDDS (ethylenediaminediacetic acid) or GLDA (L-glutamic acid diacetic acid). All these chelating agents are capable of effectively trapping (chelating) harmful metals and the like attached to or bound to sand particles. In addition, the chelating agent suitable for the process is selected according to the kind of harmful metal etc. which adhere | attach or couple | bonded with sand, or multiple types of chelating agents are used.

  After the harmful metals and the like are thus removed from the sand, the sand and washing solution mixture is introduced from the lower end opening of the main body 20 to the vibrating screen 14B, and most of the chelate washing solution is separated from the sand and washing solution mixture. . As the vibrating screen 14 </ b> B, an inclined vibrating screen is used in which a wire mesh 24 having a preset aperture (diameter) is disposed in an inclined manner in the casing 25. A circular vibrating sieve or the like may be used. Moreover, you may use not a vibrating screen but a stationary inclined screen. As the wire mesh 24 of the vibrating screen 14B, a mesh having an opening (aperture) which does not allow sand particles to pass therethrough is used. The chelate washing solution having passed through the wire mesh 24 is introduced into the washing solution storage tank 27 through the pipe line 26 and stored. The chelate cleaning liquid stored in the cleaning liquid storage tank 27 is transported to the chelating agent regenerating unit 15 described later.

  On the other hand, sand which can not pass through the wire mesh 24 of the vibrating screen 14B is introduced into the belt press 14C. The sand introduced into the belt press 14C is wetted with the chelate washing liquid, and the content of the chelate washing liquid is considerably high (for example, 20 to 40%). Therefore, this sand is processed by the belt press 14C to reduce the content ratio of the chelate cleaning liquid as much as possible.

  The belt press device 14C is a double belt press device provided with a lower belt mechanism 28 and an upper belt mechanism 29 disposed above the lower belt mechanism 28 so as to be opposed to the lower belt mechanism 28 in the vertical direction. The lower belt mechanism 28 includes a lower drive roller 30 and a lower driven roller 31. The lower drive roller 30 is rotationally driven by a motor (not shown) at a predetermined rotational speed in the direction indicated by the arrow (clockwise direction in FIG. 4). A flexible porous lower endless belt 32 (hereinafter simply referred to as a “belt 32”) is wound around the lower drive roller 30 and the lower driven roller 31. The belt 32 travels in a circular orbit between the lower drive roller 30 and the lower driven roller 31.

  On the other hand, the upper belt mechanism 29 is provided with an upper driving roller 33 and an upper driven roller 34. The upper drive roller 33 is rotationally driven at the same peripheral speed as the lower drive roller 30 by a motor (not shown) in the direction indicated by the arrow (counterclockwise in FIG. 4). A flexible porous upper endless belt 35 (hereinafter, referred to as “belt 35” for short) is wound around the upper driving roller 33 and the upper driven roller 34. The belt 35 travels on an orbit between the upper drive roller 33 and the upper driven roller 34.

  The belt 32 of the lower belt mechanism 28 and the belt 35 of the upper belt mechanism 29 are respectively formed of a flexible (flexible) porous material which allows passage of the chelate washing solution and air but not sand. There is. As the belts 32, 35, a filter material mounting belt may be used, in which a filter material such as a filter cloth is mounted on a porous belt.

  In the lower belt mechanism 28, the chelate cleaning solution receiving tank 36 is disposed between the upper horizontal traveling path and the lower horizontal traveling path of the belt 32. The chelate washing solution receiving tank 36 is a container having an upper opening, and receives the chelate washing solution which has been separated from the sand and passed downward on the belt 32. The chelate washing solution in the chelate washing solution receiving tank 36 flows down to the washing solution storage tank 27 by gravity via the drain pipe 37. In the upper horizontal traveling path, the belt 32 is supported by a plurality of (multiple) support rollers and travels substantially horizontally.

  In the upper belt mechanism 29, a pressure chamber 38 is provided between the upper horizontal traveling path and the lower horizontal traveling path of the belt 35. The pressurizing chamber 38 is a container-like chamber whose lower portion is opened, and the lower opening of the pressurizing chamber 38 is closed by a belt 35 traveling on a lower horizontal traveling path. The pressurizing chamber 38 is connected to an air pump 40 (blower) via an air supply pipe 39. During operation of the belt press device 14C, pressurized air is supplied from the air pump 40 to the pressurizing chamber 38, and the inside of the pressurizing chamber 38 is pressurized.

  During the operation of the belt press device 14C, the lower drive roller 30 rotates at a predetermined rotational speed in the direction indicated by the arrow (clockwise direction), while the same as the upper drive roller 33 in the direction indicated by the arrow (counterclockwise direction). Rotate at circumferential speed. Since the diameters of both drive rollers 30, 33 are the same, both drive rollers 30, 33 rotate in opposite directions at the same rotational speed. As a result, in the positional relationship shown in FIG. 4, the belt 32 travels in the clockwise direction, and the belt 35 travels in the counterclockwise direction. Therefore, at the portions where the two belts 32 and 35 are close to each other in the vertical direction and opposed to each other, the belts 32 and 35 travel in a straight line in the same direction while maintaining a predetermined interval.

  Thus, the belt pressing device 14C receives the sand wet with the chelate cleaning solution discharged from the vibrating screen 14B, and the sand is placed between the two belts 32, 35 at the portion where the lower belt mechanism 28 and the upper belt mechanism 29 face each other. Hold and transport. At that time, pressurized air is supplied to the inner surface (rear surface) of the belt 35 of the upper belt mechanism 29, and this pressurized air includes the belt 35, a layer of sand sandwiched between the belts 32 and 35, and the belt At the same time, the solution is circulated downward at a high speed through 32 and the majority of the chelate washing solution adhering to the sand is released from the sand and allowed to flow or fall into the chelate washing solution receiving tank 36. Thereby, the content of chelate washing solution in sand becomes very small (for example, 5 to 10%). The sand thus having a reduced content of chelate washing solution is scraped off by a scraper and transferred to a sand rinsing unit 16 described later.

  As shown in FIG. 5, the weir washing unit 15 is horizontal in a state in which the chewable washing solution tank 41 holding the chelate washing solution and the weir container 44 containing weirs are immersed in the chelate washing solution in the chelating wash solution tank 41. And a weir transport device 43 for moving in the direction. The bottom and the side of the crucible container 44 are formed of a screen (wire mesh or the like) having a size that prevents passage of the crucible.

  The crucible conveying device 43 conveys a plurality of crucible containers 44 containing crucibles continuously or intermittently in the direction indicated by the arrow P, and immerses the chelate cleaning solution in the chelate cleaning solution tank 41 in the horizontal direction. Move it. In the following description of the crucible cleaning unit 15, for convenience, the side in which the crucible container 44 is moving (the positional relationship in FIG. 5) with respect to the transport direction P of the crucible container 44 (generally rightward in the positional relationship in FIG. 5). Then, the right side is called "front", and the opposite side (left side in the positional relationship in FIG. 5) is called "rear".

  The chelate cleaning solution tank 41 has an inlet-side inclined portion 41a located at the rear end, an outlet-side inclined portion 41b located at the front end, and a horizontal portion 41c located between the inclined portions 41a and 41b and having a constant depth. And. The depth of the horizontal portion 41 c is set so that the crucible container 44 can be completely immersed in the chelate cleaning solution in the chelating solution cleaning tank 41. The length (the dimension in the front-rear direction) of the horizontal portion 41 c of the chelate washing solution tank 41 is such that harmful metals and the like are almost completely removed from the crucible contained in the crucible container 44 according to the transport speed of the container 44. It is set to be able to secure an immersion time that can be captured by the agent. The width (the dimension in the horizontal plane perpendicular to the front-rear direction) of the chelate cleaning solution tank 41 is set so that the chelating solution cleaning tank 41 can accommodate the crucible container 44 with a margin in the width direction.

  The crucible transfer device 43 is attached to a rail 45, a part of which is disposed above the chelate washing solution tank 41, a plurality of traveling tools 46 capable of traveling along the rail 45, and each traveling tool 46, A hanger 47 for holding 44 and a tow chain 48 for pulling each traveling tool 46 and traveling along the rail 45 are provided. Although the rail 45 is not shown in detail, it forms a loop in plan view, and forms the crucible container 44 above the chelate cleaning solution tank 41 so that the crucible container 44 can be immersed in the chelate cleaning solution in the chelating solution cleaning tank 41. It is done. That is, above the chelate washing solution tank 41, the rail 45 is roughly undulated corresponding to the shape of the bottom surface of the chelate washing solution 41. Therefore, when the traveling tool 46 travels along the rail 45 in the direction indicated by the arrow P, the crucible container 44 is immersed in the chelate cleaning liquid in the chelate cleaning liquid tank 41.

  Although not shown in detail, the chelating agent cleaning unit 16 continuously supplies the chelating agent cleaning solution at a predetermined flow rate to the front end of the chelating agent cleaning solution tank 41 while the rear end portion of the chelating agent cleaning solution tank 41 The chelate washing solution from which the sputum has been washed is continuously discharged at a predetermined flow rate (averagely the same as the supply flow rate). The chelate washing solution thus discharged is returned to the chelating agent regeneration unit 16.

  Thus, the entire flow of the chelate cleaning solution from the front side to the rear side occurs macroscopically in the chelate cleaning solution tank 41. As a result, the crucible and the chelate washing solution in the crucible container 44 come into solid-liquid contact in a countercurrent flow in the front-rear direction. At this time, in the vicinity of the front end portion of the chelate washing solution tank 41, the crucible from which most of harmful metals and the like have already been removed in the rear or middle part of the chelate washing solution tank 41 comes in contact with the chelate washing solution not capturing harmful metals and the like. Therefore, harmful metals and the like in the crucible can be almost completely removed.

  As shown in FIG. 6, in the chelating agent regenerating part 16, as a means for regenerating the chelate washing solution or the chelating agent, solid adsorbent particles or a packing (packing) to which the solid adsorbent is immobilized is provided. A packed tower 51 (chelate cleaning fluid regenerator) is provided. In addition, the chelating agent regenerating unit 16 includes an intermediate storage tank 52 for storing the chelate cleaning liquid to be regenerated, a reproduction chelating cleaning liquid storage tank 53 for storing the regenerated chelate cleaning liquid, an acid liquid storage tank 54 for storing the acid liquid, water And a water storage tank 55 for storing water.

  The intermediate storage tank 52 temporarily stores chelate cleaning liquid introduced from the cleaning liquid storage tank 27 (see FIG. 4) and the chelate cleaning liquid tank 41 (see FIG. 5). Then, when the chelate washing solution is regenerated, a pump 56 for transferring the chelate washing solution stored in the intermediate storage tank 52 to the packed column 51 while transferring the chelate washing solution regenerated in the packed column 51 to the regenerated chelate washing solution storage tank 53. And a series of conduits 57-60 are provided. Furthermore, a pump 61 and a pipeline 62 are provided for returning the chelate washing solution stored in the regenerated chelate washing solution storage tank 53 to the sand washing unit 14 (mixing stirrer 21) and the tub washing unit 15 (chelation washing solution tank 41). .

  Further, when the solid phase adsorbent is regenerated to the chelating agent regenerating unit 16, the acid solution stored in the acid solution storage tank 54 is transferred to the packed tower 51, while the acid solution discharged from the packed tower 51 is acidified. A pump 63 and a plurality of pipelines 64, 65 for returning to the liquid storage tank 54 are provided. In addition, when the solid phase adsorbent regenerated with the acid solution is washed with water, the chelating agent regenerating unit 16 transfers the water stored in the water storage tank 55 to the packing tower 51 while discharging the water from the packing tower 51. A pump 66 and a plurality of lines 67, 68 are provided for returning water to the water reservoir 55.

  Here, in the conduits 57, 58, 64 and 67 for transferring the chelate washing solution, the acid solution or the water to the packed column 51, valves 71, 72, 73 and 74 for opening and closing the corresponding conduits are interposed, respectively. It is set up. On the other hand, in the pipelines 59, 60, 65, 68 for discharging the chelate washing solution, the acid solution or the water from the packed column 51, valves 75, 76, 77, 78 for opening and closing the corresponding pipelines are interposed, respectively. It is done. By switching the open / close states of these valves 71 to 74 and 75 to 78, it is possible to supply or discharge the chelate washing solution, the acid solution or the water to the packing tower 51. The opening and closing of these valves 71 to 74 and 75 to 78 are automatically controlled by a controller (not shown).

  Hereinafter, an example of the operation method of the chelating agent regenerating unit 16 will be described. The operation method described below is merely an example, and it goes without saying that the operation method of the chelating agent regenerating unit 16 according to the present invention is not limited to the following. When the chelating cleaning solution (chelating agent) is regenerated, the valves 71, 72, 75, 76 provided in the conduits 57 to 60 are opened while the other valves 73, 74, 77, 78 are closed, The pump 56 is operated. As a result, the chelate washing solution in the intermediate storage tank 52 flows through the inside of the packed tower 51 and is transferred to the regenerated chelate washing solution storage tank 53.

  Thus, in the packing tower 51, the chelate washing solution containing the chelating agent capturing harmful metals and 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 chelate washing solution, while the chelating agent becomes able to capture harmful metals and the like again, and the chelate washing solution is regenerated. The chelate washing solution stored in the regenerated chelate washing solution storage tank 53 is returned by the pump 61 to the sand washing unit 14 and the tub washing unit 15 through the pipe line 62.

  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.

  Although the adsorption amount of harmful metals and the like in the solid phase adsorbent gradually increases with the regeneration of the chelate washing solution, 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, the acid solution is flowed into the packed column 51 in a state where the chelate washing solution is removed, and harmful metals and the like adsorbed on the solid phase adsorbent are removed by the acid solution to regenerate the 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 amount of adsorption of harmful metals or the like of the solid phase adsorbent in the packed column 51 reaches a saturated state or in the vicinity thereof and the solid phase adsorbent is regenerated with the acid solution, The provided valves 73, 72, 75, 77 are opened, while the other valves 71, 74, 76, 78 are closed, and the pump 63 is operated. As a result, the acid liquid in the acid liquid storage tank 54 flows through the inside of the packed tower 51 and is returned to the acid liquid storage tank 54. Before starting the regeneration operation of the solid phase adsorbent, the chelate washing solution in the packed column 51 is eliminated. In addition, if the plurality of packing towers 51 are arranged in parallel, even when the supply of the chelate washing liquid to a part of the packing towers 51 is stopped, the chelate washing liquid 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 chelate washing solution discharged from the packed column 51 .

  The time for flowing the acid solution into the packed column 51 is preferably set according to the size or shape of the packed column 51, the size of the solid phase adsorbent particles, and the like. The acid liquid circulates and flows in the acid liquid storage tank 54 and the packed tower 51. At this time, the solid phase adsorbent in the packed column 51 comes in contact with the acid solution, and harmful metals and the like adsorbed on the solid phase adsorbent are released into the acid liquid. 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 regeneration of the solid phase adsorbent by the acid solution is finished, the valves 74, 72, 75, 78 interposed in the conduits 67, 58, 59, 68 are opened. , The other valves 71, 73, 76, 77 are closed and the pump 66 is operated. Thereby, the water in the water storage tank 55 circulates in the filling tower 51 and returns to the water storage tank 55. The acid solution in the packed column 51 is eliminated before starting the water washing operation of the solid phase adsorbent. Water circulates and flows between the water storage tank 55 and the packed tower 51. At that time, the solid phase adsorbent in the packed column 51 comes in contact with water, and the acid liquid adhering to the solid phase adsorbent is washed. After this, regeneration of the chelate washing solution is resumed.

  As shown in FIG. 7, the sand rinsing unit 17 (sand rinsing device) includes a belt conveyor 80, a sand feeding device 81, a rinsing water scattering device 82, and a washing wastewater receiving tank 83. Here, the belt conveyor 80 is coaxially attached to a substantially cylindrical drive roller 84 coaxially attached to a shaft 84a rotationally driven by an electric motor (not shown) and a shaft 85a not connected to a drive source. A generally cylindrical follower roller 85, an annular or endless conveyor belt 86 wound around a drive roller 84 and a follower roller 85, and a large number of support rollers 87 for supporting or guiding the conveyor belt 86. And a guide plate 88 for guiding the sand discharged from the belt conveyor 80.

  The driving roller 84 and the driven roller 85 have the same diameter and are arranged at the same height. The transport belt 86 is formed of a porous material, mesh material, fibrous material or cloth material capable of being curved in an annular shape which allows rinse water to pass but not sand particles. The rinse water spraying device 82 sprays rinse water on sand transported by the transport belt 86 in a region of a predetermined length (for example, 1 to 2 m) in the moving direction of the transport belt 86. The spray amount of rinse water from the rinse water spray device 82 is preferably set so that almost all the chelate cleaning solution adhering to the sand can be washed away. For example, 1.5 to 2.0 times the amount of the chelate washing solution adhering to the sand is sprayed with rinse water. As a specific example, for example, in the case of transporting sand having a chelating cleaning solution content ratio of 10% at 5 tons per hour (dry basis), it is preferable to spray 0.75 to 1.0 tons of rinse water per hour. Become.

  The sand supply device 81 supplies the sand discharged from the sand washing unit 14 onto the conveyance belt 86 near the driven roller 85 at a predetermined flow rate. The sand thus supplied is conveyed by the conveying belt 86, falls downward via the guide plate 88 at a position corresponding to the driving roller 84, and is stored in a sand storage area (not shown). The sand conveyed by the conveyance belt 86 is sprayed with rinse water from the rinse water spray device 82. The rinse water travels downward through the gaps between the sand particles, passes through the transport belt 86, and flows down or falls as cleaning wastewater into the cleaning wastewater receiving tank 83. At this time, the chelate washing solution adhering to the sand is washed downward by the rinse water, and flows into or falls into the washing wastewater receiving tank 83.

  Thus, sand containing no chelating agent is stored in the sand storage tank (not shown). On the other hand, the washing wastewater containing the chelating agent in the washing wastewater receiving tank 83 of the sand rinsing unit 17 is introduced into the washing wastewater evaporation device 101 (see FIG. 9) of the chelating agent recovery unit 19. Then, the chelating agent is recovered from the cleaning wastewater by the cleaning wastewater evaporation device 101, and the chelating agent is returned to the sand cleaning unit 14 together with the sand.

  A vacuum suction type belt conveyor may be used as the belt conveyor 80 in order to further reduce the amount of rinse water used in the sand rinse unit 17, that is, the amount of discharge of cleaning wastewater. The vacuum suction type belt conveyer reduces the moisture content of the sand by vacuum suction of the sand through the filter material attachment belt while conveying the sand by the filter material attachment belt. In this case, the air flowing at a high speed into the decompression chamber through the interparticle space of the sand layer on the filter material attachment belt promotes the downward movement of the rinse water or the washing wastewater, so the amount of rinse water used is greatly increased. It can be reduced.

  As shown in FIG. 8, the crucible rinsing unit 18 (a crucible rinsing device) includes a belt conveyor 90, a crucible supply device 91, a rinse water dispersion device 92, and a rinse water receiving tank 93. Here, the belt conveyor 90 is coaxially attached to a substantially cylindrical drive roller 94 coaxially attached to a shaft 94a rotationally driven by a motor (not shown) and a shaft 95a not connected to a drive source. A generally cylindrical follower roller 95, an annular or endless conveyor belt 96 wound around the drive roller 94 and the follower roller 95, and a large number of support rollers 97 for supporting or guiding the conveyor belt 96. And a guide plate 98 for guiding the waste discharged from the belt conveyor 90, and a waste storage (not shown).

  The configuration and function of the crucible rinsing unit 18 are substantially the same as the sand rinsing unit 17 shown in FIG. 7 except that the object to be rinsed with rinse water is not sand but a crucible. Therefore, in order to avoid the repetition of the description, the detailed description of the eyelid rinsing unit 18 is omitted.

  Thus, the washing wastewater (rinsing water containing a chelating agent) contained in the rinsing water receiving tanks 83 and 93 of the sand rinsing unit 17 and the weir rinsing unit 18 is introduced into the washing wastewater evaporation device 101 of the chelating agent recovery unit 19 . Then, the chelating agent is recovered from the washing wastewater by the washing wastewater evaporation device 101 and returned to the sand washing unit 14.

Hereinafter, the configuration and function of the cleaning wastewater evaporation device 101 of the chelating agent recovery unit 19 will be specifically described.
As shown in FIGS. 9 to 11, the washing wastewater evaporation device 101 of the chelating agent recovery unit 19 includes a washing wastewater receiving tank 83 (see FIG. 7) of the sand rinsing unit 17 and a washing wastewater receiving tank 93 of the weir rinsing unit 18 (see FIG. A washing waste water storage tank 104 is provided which receives washing waste water containing the chelating agent discharged from 8) through the washing waste water passage 103. The cleaning waste water storage tank 104 is a concrete water storage tank embedded in the ground and having a rectangular planar shape. A roof (not shown) is provided above the washing wastewater storage tank 104 to prevent rainwater from falling onto the washing wastewater storage tank 104. In the following, in order to clearly show the positional relationship of facilities or devices in the chelating agent recovery unit 19 or the washing wastewater evaporation device 101, the direction of the washing wastewater storage tank 104 and the washing wastewater passage 103 are arranged in FIG. Regarding the positional relationship, regarding the left and right direction), the side where the cleaning wastewater storage tank 104 is located is referred to as "left", and the side where the cleaning wastewater passage 103 is located is referred to as "right".

  Furthermore, a container-like sand storage unit 105 for storing sand is disposed in the cleaning wastewater evaporation device 101 at an appropriate distance from the cleaning wastewater storage tank 104 in the direction perpendicular to the left-right direction. In this embodiment, fine sand (sand having a particle size of 0.075 to 0.25 mm) is used as such sand. In the following, in order to clearly show the positional relationship of the facilities or devices in the chelating agent recovery unit 19, the cleaning wastewater storage tank 104 is arranged in the direction in which the cleaning wastewater storage tank 104 and the sand storage unit 105 are arranged (direction perpendicular to the left and right direction). The side on which the sand container unit 105 is located is referred to as “front”, and the side on which the sand accommodation unit 105 is positioned is referred to as “rear”.

  The sand storage portion 105 has a front end wall 106, a rear end wall 107, a left side wall 108, a right side wall 109, and a bottom wall 110, and has a relatively short length in the left-right direction and a relatively long length in the front-rear direction. It is a concrete container installed on the ground or embedded in the ground having a rectangular planar shape and a depth capable of containing an appropriate amount of water evaporation sand. A side groove 111 is provided on the left side of the sand containing portion 105, and the side groove 111 is disposed adjacent to the outer surface (left surface) of the left side wall 108 of the sand containing portion 105. The side groove 111 is made of concrete and is integrally formed with the sand storage portion 105.

  Further, the washing wastewater evaporation apparatus 101 is supplied with the washing wastewater supplying device 112 for supplying the washing wastewater stored in the washing wastewater storage tank 104 to the gutter 111, and the surplus washing wastewater in the gutter 111 is returned to the washing wastewater storage tank 104. A washing wastewater return path 113 and a water level holding device 114 for holding the water level of the washing wastewater in the side groove 111 at a sand immersion upper end position in the sand storage unit 105 set in advance. Here, the water evaporation sand is located between the sand immersion upper end position and the position of the upper surface of the water evaporation sand contained in the sand immersion upper end position and the inner space of the sand containing portion 105 (capillary water zone It is set to form a sand layer in a saturated moisture state).

  Hereinafter, the specific configuration and function of the cleaning wastewater evaporation device 101 will be described. The sand accommodating portion 105 for accommodating the water evaporation sand is made of concrete, and is buried in the ground 120 so that the upper end portion and its vicinity are exposed to the atmosphere. The sand accommodation portion 105 has a rectangular shape having a relatively short length (for example, 20 to 50 m) in the left-right direction and a relatively long length (for example, 100 to 200 m) in the front view. Is set to accommodate an appropriate amount of water evaporation sand (for example, 0.8 to 1.0 m), the front end wall 106, the rear end wall 107, the left side wall 108, the right side wall 109, and the bottom wall 110 It is a box-like container which has The length in the left-right direction and the front-rear direction of the sand storage unit 105 is preferably set according to the amount of cleaning waste water evaporated in the sand storage unit 105 or the like. As the water evaporation sand contained in the sand containing portion 105, sand (fine sand) discharged from the sand rinsing portion 17 is used.

  On the upper surface of the bottom wall 110, a plurality of bottom grooves 121 having a predetermined depth (for example, 10 to 15 cm) extending in parallel in the left-right direction at predetermined intervals in the front-rear direction are provided. Each of the bottom grooves 121 communicates with the internal space of the side groove 111 through a communication hole 122 formed in the left side wall 108. That is, the internal space (lower space) of the side groove 111 and the internal space (lower space) of the sand accommodation portion 105 communicate with each other via the communication hole 122 and the bottom groove 121 in the vicinity of their bottoms.

  Then, on the plurality of convex portions 123 positioned between the bottom grooves 121 in the front-rear direction, a porous plate 124 is disposed, through which cleaning wastewater is allowed to pass but sand for water evaporation is not allowed to pass. Here, the porous plate 124 is not a single plate-like member, but a large number of porous plates having dimensions suitable for manufacturing and transportation (for example, porous plates of 1 to 2 m, 2 to 5 m, and 5 to 10 mm thick) It consists of Then, on the porous plate 124, a sand layer 125 having a predetermined thickness (for example, 50 to 80 cm) is formed. Further, a roof 137 supported by the frame structure 136 and preventing rain water from falling to the sand accommodation unit 105 is provided above the sand accommodation unit 105.

  Thus, when the washing wastewater is introduced into the side groove 111, the washing wastewater flows into the sand storage portion 105 through the communication hole 122 and the bottom groove 121 and enters the gap between the sand particles. As a result, the sand layer 125 is completely immersed in the washing wastewater to a position L substantially at the same height as the water level of the washing wastewater in the gutter 111, and there is no air in the gaps between the sand particles and the water is completely washed. It is filled with waste water, and it becomes a state of sand immersion where buoyancy by washing waste water acts on each sand particle. Hereinafter, the upper end position of the sand layer 125 completely immersed in such cleaning wastewater will be referred to as “sand immersion upper end position L”.

In addition, above the sand immersion upper end position L, the capillary discharge wicks the washing wastewater into the sand layer 125 by capillary action, and most of the sand particle gaps are filled with the washing wastewater but there is also some air in the capillary water zone ( Or a saturated capillary water zone), ie, a sand layer 125 substantially in a saturated moisture state is formed. In such a capillary water zone, the evaporation of the washing wastewater from sand particles to the atmosphere becomes very large, for example, the evaporation from the water surface of the pond (0.5 to 1.0 m ³ / m ² · year) It is estimated to be three to five times as large as.

  The height or thickness of the capillary zone or saturated capillary zone increases as the particle size of the water evaporation sand decreases. For example, in Non-Patent Document 1, the height of the capillary water zone of sand having a particle diameter of 0.02 mm is 180 cm, and the height of the capillary water zone of sand having a particle diameter of 0.2 mm is 21 cm. There is a description. Further, Non-Patent Document 2 describes that the height of the capillary water zone of glass beads having a particle size of 0.1 mm is about 55 cm.

  In view of such a fact, in the present embodiment in which fine sand (particle diameter of 0.075 to 0.25 mm) is used as the water evaporation sand contained in the sand containing portion 105, the height of the capillary water zone is , About 0.2 to 0.4 m. Therefore, it is preferable to set the sand immersion upper end position L at a position in the range of 20 to 40 cm below the upper surface of the sand layer 125, for example. In the vicinity of the upper surface portion (for example, 2 to 3 cm downward from the upper surface of the sand layer) of the sand layer 125 in the sand storage unit 105, a large amount of air exists in the gaps of the sand particles, while the surface of the sand particles is cleaned It is presumed that a film water zone (sand layer in unsaturated moisture state) covered with a film of wastewater is formed.

  In the present invention, the water evaporation sand used in the sand storage unit 105 is not limited to fine sand, and it is a matter of course that sand different in particle diameter from fine sand may be used. In this case, the height of the capillary water zone corresponding to the particle size may be estimated, and the sand immersion upper end position L may be set based on this. For example, when using medium sand (particle diameter 0.25 to 0.85 mm), the sand immersion upper end position L may be set to a position in the range of 10 to 20 cm below the upper surface of the sand layer 125, for example.

  The side groove 111 is a water channel made of concrete integrally formed with the sand accommodation portion 105, and the bottom wall of the side groove 111 is at the same height as the bottom wall 110 of the sand accommodation portion 105 (bottom of the bottom groove 121). . Further, the upper end portion of the side groove 111 is at the same height as the upper end portion of the left side wall 108 of the sand accommodation portion 105. The width (the dimension in the left-right direction) of the side groove 111 is preferably, for example, about 0.5 to 1 m.

The water level holding device 114 is disposed between the water tank 130 and the washing waste water return path 113, which is connected to the gutter 111 and connected to the washing waste water return path 113, and the washing waste water in the water tank 130 is used for washing waste water. There is a weir 131 which overflows the reflux passage 113 and holds the water level of the water tank 130 and the gutter 111 at a constant value. Here, the water tank 130 is a concrete container installed on the ground 120 and opened at the top, and the upper end thereof is at the same height as the upper end of the side groove 111. The bottom of the water tank 130 is at a position (for example, 0.5 to 1.5 m lower) than the bottom of the side groove 111. The water tank 130 and the side groove 111 are connected and communicated with each other, and the water levels of the cleaning wastewater contained in these are equal to each other. The planar shape of the water tank 130 is preferably a rectangular, its water area is preferably for example 20 to 50 m ² approximately.

  The weir 131 is for maintaining the water level of the washing water of the water tank 130 and the gutter 111 constant, but this water level can be freely changed by changing the overflow height of the weir 131. The overflow height of the weir 131 is preferably set such that the water level of the water tank 130 and the side groove 111 coincides with the predetermined sand immersion upper end position L. The washing wastewater overflowing from the water tank 130 to the washing wastewater return path 113 via the weir 131 is returned to the washing wastewater storage 104.

  The washing waste water supply device 112 includes a washing waste water supply pump 132 and a washing waste water supply pipe 133 for continuously feeding the washing waste water in the washing waste water storage tank 104 to the water tank 130. Here, the washing wastewater supply pump 132 has the water tank 130 at a flow rate (for example, 10 to 20 times) that is sufficiently larger than the evaporation amount of the washing wastewater in the sand storage unit 105. Supply to Therefore, the water level of the water tank 130 and the side groove 111 is always maintained at the preset sand immersion upper end position L.

  Hereinafter, a method of treating the washing wastewater containing the chelating agent by the chelating agent recovery unit 19 or the washing wastewater evaporation device 101 will be specifically described. The cleaning wastewater containing the chelating agent discharged from the cleaning wastewater receiving tank 83 (see FIG. 7) of the sand rinsing unit 17 (see FIG. 7) and the cleaning wastewater receiving tank 93 of the weir rinsing unit 18 (see FIG. 8) evaporates naturally into the atmosphere (vaporization) To drain away from the cleaning wastewater storage tank 104 through the cleaning wastewater passage 103

  The washing waste water stored in the washing waste water storage tank 104 is continuously supplied to the water tank 130 by the washing waste water supply pump 132 via the washing waste water supply pipe 133. As described above, since the washing wastewater supply pump 132 supplies the washing wastewater to the gutter 111 at a flow rate sufficiently larger than the evaporation amount of the washing wastewater in the sand layer 125 in the sand container 105, the water levels of the water tank 130 and the gutter 111 are It is maintained at a fixed position corresponding to the overflow height of the weir 131, that is, at a preset sand immersion upper end position L. The excess washing wastewater overflows the weir 131 forward and is returned to the washing wastewater storage tank 104 via the washing wastewater return path 113.

  Thus, since the water level of the side groove 111 is maintained at the sand immersion upper end position L, the water level of the internal space of the sand accommodation portion 105 communicating with the internal space of the side groove 111 is also maintained at the sand immersion upper end position L. Along with this, a capillary water zone (sand layer in a saturated moisture state) is formed in the sand layer 125 above the sand immersion upper end position L. As described above, while fine sand is used in the present embodiment, since the upper end position L of the sand immersion is set to a position within the range of 20 to 40 cm from the upper surface of the sand layer 125, it is estimated that a coated water zone is formed. Capillary water zone above the sand immersion upper end position L, that is, a saturated moisture state (for example, water content ratio 30 to 35%) except the upper surface vicinity portion (a sand layer of 2 to 3 cm downward from the upper surface of the sand layer) Sand layer 125 is formed.

  Then, the cleaning wastewater held in the sand layer 125 above the sand immersion upper end position L evaporates (vaporizes) into the atmosphere. Thus, all the cleaning wastewater flowing into the cleaning wastewater storage tank 104 evaporates from the sand layer 125 into the atmosphere. At that time, the chelating agent contained in the washing wastewater remains in the sand layer 125. Therefore, the chelating agent contained in the washing wastewater is reliably recovered without being discharged to the outside. In addition, the area or dimension of the sand storage part 105 required in order to evaporate cleaning wastewater from the sand layer 125 is demonstrated later.

When the evaporation treatment of the cleaning wastewater is repeatedly performed, the chelating agent is gradually accumulated in the sand layer 125 in the sand storage unit 105. Therefore, the water evaporation sand in a predetermined area or section (for example, an area of 100 to 200 m ² ) in the sand storage unit 105 is removed every time a predetermined period elapses (for example, every 2 to 6 months). It is introduced into the sand washing unit 14 to recover the chelating agent. Then, the fine sand sifted from the sand obtained by the sand rinsing unit 17 is introduced into the section or region of the sand storage unit 105 from which the water evaporation sand has been removed. That is, the water evaporation sand containing the chelating agent in a predetermined section or area in the sand storage unit 105 is replaced with the fine sand containing no chelating agent screened from the sand obtained by the sand rinsing unit 17. Therefore, the loss of the chelating agent from the soil purification system S to the outside can be prevented or reduced. In addition, since a part of the sand that does not contain the chelating agent that comes out of the sand rinsing unit 17 is used as the water evaporation sand stored in the sand storage unit 105, the water evaporation sand used in the sand storage unit 105 can be easily procured. Can.

  Hereinafter, an example of the specifications (surface area, size, etc.) of the washing wastewater storage tank 104 and the sand storage unit 105 required to evaporate the washing wastewater from the sand layer 125 will be described. For example, the soil remediation system S purifies 100 tons of polluted soil (including water) per hour, and this polluted soil comprises 25 tons of straw (dry basis) and 30 tons of sand (dry basis), It contains 25 tons of soil (dry basis) and 20 tons of water (water content 25%). And when using this soil purification system S eight days a day and making it operate 250 days a year, the specification of the washing wastewater storage tank 104 and the sand storage part 105 can be set as follows, for example. The specifications described here are merely an example, and even if the soil treatment amount of the soil treatment system S, the operation time or the number of days of operation differ from these, the cleaning wastewater storage tank 104 and the sand storage portion 105 are Of course, specifications or dimensions can be set.

<Specifications of Cleaning Waste Water Storage Tank 104>
The specification of the washing wastewater storage tank 104 is set, for example, as follows.
-Rectangular storage tank (left and right dimensions: 15 m, front and back dimensions: 25 m, depth: 3 m)
・ Surface area 375 m ²
・ Maximum storage capacity about 1000 tons

<Specifications of Sand Storage Unit 105>
The specification of the sand accommodation unit 105 is set, for example, as follows.
-Rectangular shape (right and left dimensions: 50 m, front and back dimensions: 100 m, depth: 0.8 m)
・ Top area 5000 m ²
・ Sand capacity about 2500m ³

<Discharge of cleaning wastewater from sand rinse unit 17>
The chelating solution content ratio of the sand (30 tons / hr on a dry basis) discharged from the belt press device 14C of the sand washing unit 14 is 10%, and the usage amount of rinse water in the sand rinsing unit 17 is included in the sand or If it is set to 2.0 times the adhering chelate cleaning fluid, the discharge amount of the cleaning wastewater containing the chelating agent from the sand rinsing unit 17 is 12000 tons / year.
30 tons / hr × 0.1 × 8 hr × 250 days × 2.0 = 12,000 tons / year

<Discharge amount of cleaning wastewater from weir rinse unit 18>
The chelate washing solution content ratio of the glaze (25 tons / hr on a dry basis) discharged from the glaze washing unit 15 is 5%, and the amount of rinse water used in the glaze rinsing unit 18 is the chelate contained or attached to the glaze If it is 1.2 times as large as that of the cleaning solution, the discharge amount of the cleaning wastewater containing the chelating agent from the rinsing unit 18 is 3000 tons / year.
25 tons / hr × 0.05 × 8 hr × 250 days × 1.2 = 3000 tons / year

<Water evaporation amount in washing wastewater storage tank 104>
Generally, it is known that the amount of evaporation of water from the water surface in lakes and reservoirs, etc. is 0.5 to 1.0 tons per 1 m ^{2 of} water surface per year. Therefore, it is estimated that at least 187 tons of water evaporates from the washing wastewater storage tank 104 (surface area 375 m ² ).
0.5 ton / m ² · year x 375 m ² = 187 ton / year As described above, the maximum storage capacity of the washing wastewater storage tank 104 is about 1000 tons, but this is from the sand rinsing unit 17 and the weir rinsing unit 18 This corresponds to about 17 days of the discharge of washing wastewater (15,000 tons / year, ie, 60 tons / day at 250 days operation). On the other hand, since the washing wastewater stored in the washing wastewater storage tank 104 is treated daily by the sand storage unit 105, the washing wastewater storage tank 104 can store the washing wastewater with a sufficient margin without overflowing it. it can.

<Water evaporation amount in sand layer 125>
For example, in view of the disclosed contents (research results) of Non-Patent Document 3, the evaporation amount of water in the sand layer 125 in the sand accommodation unit 105 is 3.15 ton / m ² · year as described below. It is estimated. That is, Non-Patent Document 3 has a temperature of 14.2 ° C., a relative humidity of 59%, and an air flow rate of 250 cm / sec, and the water content ratio is 32.1% (saturated water state) the evaporation rate of water from the soil is disclosed to be ^{11.3 × 10 -6 g / cm 2} · sec. In addition, when the temperature is 14.8 ° C, the relative humidity is 57%, and the air flow rate is 170 cm / sec, the evaporation of water from the soil with a moisture ratio of 32.9% (saturated moisture state) The speed is disclosed to be 7.9 × 10 ⁻⁶ g / cm ² · sec.

In view of the disclosure of Non-Patent Document 3 as described above, when assuming that the average climatic condition in Japan is a temperature of 15 ° C., a relative humidity of 60%, and a wind speed of about 2 m / sec, The average amount of water evaporation from the sand layer 125 in the state is estimated to be approximately 10.0 × 10 ⁻⁶ g / cm ² s. The amount of evaporation is 3.15 tons / m ² / year in practical units.
10.0 × 10 ⁻⁶ g / cm ² · s = 10.0 × 10 ⁻⁶ × 10 ⁻⁶ × 10 ⁴ ton / m ² · s = 1.0 × 10 ⁻⁷ ton / m ² · s = 1 Therefore, 15750 tons of water per year are collected from the sand layer 125 (5000 m ² ) in the sand storage unit 105. 0 × 10 ^-7 × 3600 × 24 × 365 tons / m ² · year = 3.15 tons / m ² · year Evaporate.
3.15 tons / m ² / year × 5000 m ² = 15750 tons / year

<Balance of Water in Cleaning Waste Water Evaporator 101>
As described above, the amount of cleaning wastewater discharged from the sand rinsing unit 17 is estimated to be 12000 tons per year. In addition, the discharge amount of the cleaning wastewater from the weir rinse unit 18 is estimated to be 3,000 tons per year. On the other hand, the washing wastewater storage tank 104 can evaporate at least 187 tons of water a year, and the sand storage unit 105 can evaporate 15750 tons of water a year. Therefore, it is estimated that the washing wastewater evaporation device 101 can evaporate 15937 tons of water a year. Thus, in the washing waste water evaporation device 101, the entire amount of washing waste water to be evaporated is larger than the amount (15,000 tons a year) of washing waste discharged from the sand rinsing unit 17 and the weir rinsing unit 18 in one year. In principle, it is possible to evaporate and treat all the washing wastewater. However, for example, the evaporation amount of the cleaning wastewater decreases in winter or rainy season, so the size (100 m) in the front-rear direction or the size (50 m) in the left-right direction of the sand container 105 in the above specific example It is preferable to make it as long as%.

  As described above, according to the contaminated soil remediation system S or the contaminated soil remediation method according to the present invention, the chelating agent is not added to a large amount of washing water circulating in a series of distribution systems in the soil remediation system S, and the fluid is discharged from the liquid cyclone 7 Since the sand to be discharged and the crucible discharged from the trommel 6 are washed with the chelate washing solution, the amount of the chelating agent retained in the soil purification system S can be greatly reduced. Then, since the sand and the crucible washed with the chelate washing solution are rinsed with the rinse water in the sand rinsing unit 17 and the bowl rinsing unit 18, respectively, it is possible to obtain the sand and the crucible suitable for reuse without the chelating agent. . In addition, since the chelating agent in the washing wastewater discharged from the sand rinsing unit 17 and the weir rinsing unit 18 is returned to the sand washing unit 14 by the chelating agent recovery unit 19, the amount of the chelating agent used can be significantly reduced. it can.

  Further, the supply of pressurized air in the belt press 14C reduces the content of the chelate cleaning liquid of the sand wet with the chelating cleaning liquid, so that the amount of rinse water used in the sand rinse portion 17, ie the amount of cleaning wastewater to be evaporated. Can be reduced, and the site area of the sand accommodation unit 105 can be reduced.

  S Soil remediation system, 1 Soil classification part, 2 Sand and soot purification part, 3 input hopper, 4 mixer, 5 mill breaker, 6 trommel, 7 hydrocyclone, 8 PH adjustment tank, 9 flocculation tank, 10 chicna, 11 washing Water storage tank, 12 intermediate tank, 13 filter press, 14 sand washing unit, 14A mixing stirrer, 14B vibrating sieve, 14C belt press, 15 chelating agent regeneration unit, 16 sand rinsing unit, 17 chelating agent recovery unit, 20 main unit , 21 baffle plate, 22 stirrer, 23 motor, 24 wire mesh, 25 casing, 26 pipeline, 27 washing solution storage tank, 28 lower belt mechanism, 29 upper belt mechanism, 30 lower drive roller, 31 lower driven roller, 32 endless Belt, 33 upper drive roller, 34 upper driven roller, 35 endless belt, 36 chelate washing solution receiving tank , 37 drainage pipe, 38 pressure chamber, 39 air supply pipe, 40 air pump (blower), 41 chelating solution tank, 43 container transport device, 44 container, 45 rail, 46 traveling tool, 47 hanger, 48 traction chain , 51 packed tower, 52 intermediate storage tank, 53 regenerated chelate washing liquid storage tank, 54 acid liquid storage tank, 55 water storage tank, 56 pumps, 57 to 60 pipelines, 61 pumps, 62 pipelines, 63 pumps, 64 pipelines, 65 pipelines , 66 pumps, 67 pipelines, 68 pipelines, 71 to 78 valves, 80 belt conveyors, 81 sand feeders, 82 rinse water sprayers, 83 washing waste water receiving tanks, 84 drive rollers, 84a shafts, 85 driven rollers, 85a shafts , 86 transport belts, 87 support rollers, 88 guide plates, 90 belt conveyors, 91 礫 feeders, 92 Sprinkler sprayer, 93 washing waste water receiving tank, 94 driving roller, 94a shaft, 95 driven roller, 95 a shaft, 96 conveyance belt, 97 supporting roller, 98 guide plate, 101 washing waste water evaporation device, 103 washing waste water passage, 104 washing waste water Storage tank 105 Sand storage part 106 front end wall 107 rear end wall 108 left side wall 109 right side wall 110 bottom wall 111 side groove 112 washing wastewater supply device 113 washing wastewater return path 114 water level holding device 120 ground , 121 bottom groove, 122 communicating hole, 123 convex portion, 124 perforated plate, 125 sand layer, 130 water tank, 131 tank, 132 washing wastewater supply pump, 133 washing wastewater supply pipe, 126 frame structure, 137 roof.

Claims (3)

A soil remediation system for remediating a soil that is polluted with harmful metals or compounds thereof, which contains moss, sand and soil.
The soil remediation system cleans the soil classification part which classifies the soil into cocoons, sand and soil, and the sand and cocoon separated by the soil classification part with a chelating cleaning solution containing a chelating agent and water. It is equipped with sand and soot purification department to purify,
The soil classification section
A mixing device for mixing the soil and wash water supplied to the soil classification unit;
A trommel for separating straw from a mixture of soil and wash water discharged from the mixing device;
A hydrocyclone separating sand from the mixture of sand, soil and wash water discharged from the trommel;
A thickener which separates a mixture of soil and wash water discharged from the hydrocyclone into supernatant water and sludge containing soil by sedimentation.
A filter press for filtering the sludge discharged from the thickener to separate the soil;
The sand and soot purification unit is
A sand washing unit for washing sand discharged from the hydrocyclone with a chelate washing solution and removing harmful metals or compounds thereof from the sand;
An eyebrow washing unit for washing the weir discharged from the trommel with a chelating washing solution and removing harmful metals or compounds thereof from the weir;
The chelating agent is regenerated by removing harmful metals or compounds thereof from the chelating agent in the chelate cleaning solution discharged from the sand cleaning unit and the tub cleaning unit, and the chelating agent is regenerated to be returned to the sand cleaning unit and the tub cleaning unit. Department,
A sand rinsing unit that rinses sand discharged from the sand washing unit with rinsing water to remove a chelating agent;
A rinsing section that rinses the sputum discharged from the sputum washing section with rinsing water to remove a chelating agent;
And a chelating agent recovery unit for recovering the chelating agent from the cleaning wastewater containing the chelating agent discharged from the sand rinsing unit and the crucible rinsing unit,
The sand washing unit is
A flow type mixing stirrer which mixes and stirs sand discharged from the hydrocyclone and a chelate washing solution, and captures a harmful metal or a compound thereof adhering to or bound to the sand in a chelating agent;
A vibrating screen for removing the chelate washing solution from the mixture of sand and the chelate washing solution discharged from the mixing stirrer;
It has an upper belt mechanism and a lower belt mechanism facing each other with a porous endless belt which is wound around a plurality of rollers and receives sand wetted with a chelate cleaning solution discharged from the vibrating screen. A belt press device for conveying the sheet between the upper belt mechanism and the lower belt mechanism;
Pressurized air is supplied to the upper surface of the endless belt of the upper belt mechanism at a portion facing the lower belt mechanism, and the pressurized air is supplied to the endless belt of the upper belt mechanism; Pressurized air that is allowed to flow downward through the sand layer sandwiched between the upper belt mechanism and the lower belt mechanism and the endless belt of the lower belt mechanism to reduce the content of the sand cleaning solution A feeding device is provided,
The crucible cleaning unit includes a chelate cleaning solution tank for holding a chelate cleaning solution, and a crucible transfer device for moving a crucible container storing crucibles in a chelate cleaning solution in the chelate cleaning solution tank in a horizontal direction. And the bottom and sides of the crucible container are formed of a screen having an eye dimension not to allow passage of the crucible,
The chelating agent regeneration unit has a higher complexing power than the chelating agent and the chelate washing solution discharged from the sand washing unit and the tub washing unit, and the harmful metal or the compound thereof in the chelate washing solution A solid solution adsorbing material, and a chelating solution cleaning device for removing harmful metals or compounds thereof from the chelating agent in the chelating solution to regenerate the chelating solution,
The sand rinsing unit has a sand rinsing device that sprays or jets rinse water on the sand discharged from the sand washing unit to remove a chelating agent held in the sand,
The wrinkle rinsing unit has a wrinkle rinsing device that sprays or sprays rinse water on the wrinkles discharged from the wrinkle washing unit to remove the chelating agent held in the wrinkles.
The chelating agent recovery unit
A cleaning wastewater storage tank for receiving and storing cleaning wastewater including the sand rinsing unit and the chelating agent discharged from the crucible rinsing unit;
A porous plate disposed in the ground and disposed in the space formed by the peripheral wall, the bottom wall coupled to the lower end of the peripheral wall, the peripheral wall and the bottom wall, and passing cleaning wastewater but not sand And a container-like sand containing portion opened on the upper side, containing sand for water evaporation on the perforated plate in its inner space;
A roof disposed above the sand storage unit to prevent rainwater from falling to the sand storage unit;
The inner space is disposed adjacent to the outer surface of the peripheral wall of the sand storage portion, and the internal space thereof communicates with the internal space of the sand storage portion via the communication hole formed in the peripheral wall below the porous plate. Side groove,
A washing wastewater supply device for feeding washing wastewater stored in the washing wastewater storage tank to the gutter;
A washing wastewater return path for refluxing washing wastewater in the gutter to the washing wastewater storage tank;
And a water level holding device for holding the water level of the cleaning wastewater in the gutter at a preset sand immersion upper end position,
The water evaporation sand, which is located between the sand immersion upper end position and the position of the upper surface of the water evaporation sand contained in the inner space of the sand container, forms a capillary water zone. Set as
In the soil remediation system, washing wastewater is supplied from the gutter to the water evaporation sand contained in the sand storage unit over a predetermined period, and the water of the washing wastewater supplied to the water evaporation sand evaporates in the air. Water evaporation sand transfer means for transferring the water evaporation sand accumulated in the sand storage unit to the sand cleaning unit when the chelating agent is accumulated in the water evaporation sand;
A soil purification system, comprising: water evaporation sand supply means for supplying a part of the sand discharged from the sand rinse unit to the sand storage unit as water evaporation sand. A method for soil remediation in a soil remediation facility, comprising soil, sand, sand and soil, wherein the soil is cleaned with a harmful metal or a compound thereof,
The soil remediation facility cleans the soil classification part which classifies the soil into cocoon, sand and soil, and the sand and cocoon separated by the soil classification part with a chelating cleaning solution containing a chelating agent and water. We have sand, agate purification department to purify,
The soil classification section
A mixing device for mixing the soil and wash water supplied to the soil classification unit;
A trommel for separating straw from a mixture of soil and wash water discharged from the mixing device;
A hydrocyclone separating sand from the mixture of sand, soil and wash water discharged from the trommel;
A thickener which separates a mixture of soil and wash water discharged from the hydrocyclone into supernatant water and sludge containing soil by sedimentation.
A filter press for filtering the sludge discharged from the thickener to separate the soil;
The sand and soot purification unit is
A sand washing unit for washing sand discharged from the hydrocyclone with a chelate washing solution and removing harmful metals or compounds thereof from the sand;
An eyebrow washing unit for washing the weir discharged from the trommel with a chelating washing solution and removing harmful metals or compounds thereof from the weir;
The chelating agent is regenerated by removing harmful metals or compounds thereof from the chelating agent in the chelate cleaning solution discharged from the sand cleaning unit and the tub cleaning unit, and the chelating agent is regenerated to be returned to the sand cleaning unit and the tub cleaning unit. Department,
A sand rinsing unit that rinses sand discharged from the sand washing unit with rinsing water to remove a chelating agent;
A rinsing section that rinses the sputum discharged from the sputum washing section with rinsing water to remove a chelating agent;
And a chelating agent recovery unit for recovering the chelating agent from the cleaning wastewater containing the chelating agent discharged from the sand rinsing unit and the crucible rinsing unit,
The sand washing unit is
A flow type mixing stirrer which mixes and stirs sand discharged from the hydrocyclone and a chelate washing solution, and captures a harmful metal or a compound thereof adhering to or bound to the sand in a chelating agent;
A vibrating screen for removing the chelate washing solution from the mixture of sand and the chelate washing solution discharged from the mixing stirrer;
It has an upper belt mechanism and a lower belt mechanism facing each other with a porous endless belt which is wound around a plurality of rollers and receives sand wetted with a chelate cleaning solution discharged from the vibrating screen. A belt press device for conveying the sheet between the upper belt mechanism and the lower belt mechanism;
Pressurized air is supplied to the upper surface of the endless belt of the upper belt mechanism at a portion facing the lower belt mechanism, and the pressurized air is supplied to the endless belt of the upper belt mechanism; Pressurized air that is allowed to flow downward through the sand layer sandwiched between the upper belt mechanism and the lower belt mechanism and the endless belt of the lower belt mechanism to reduce the content of the sand cleaning solution A feeding device is provided,
The crucible cleaning unit includes a chelate cleaning solution tank for holding a chelate cleaning solution, and a crucible transfer device for moving a crucible container storing crucibles in a chelate cleaning solution in the chelate cleaning solution tank in a horizontal direction. And the bottom and sides of the crucible container are formed of a screen having an eye dimension not to allow passage of the crucible,
The chelating agent regeneration unit has a higher complexing power than the chelating agent and the chelate washing solution discharged from the sand washing unit and the tub washing unit, and the harmful metal or the compound thereof in the chelate washing solution A solid solution adsorbing material, and a chelating solution cleaning device for removing harmful metals or compounds thereof from the chelating agent in the chelating solution to regenerate the chelating solution,
The sand rinsing unit has a sand rinsing device that sprays or jets rinse water on the sand discharged from the sand washing unit to remove a chelating agent held in the sand,
The wrinkle rinsing unit has a wrinkle rinsing device that sprays or sprays rinse water on the wrinkles discharged from the wrinkle washing unit to remove the chelating agent held in the wrinkles.
The chelating agent recovery unit
A cleaning wastewater storage tank for receiving and storing cleaning wastewater including the sand rinsing unit and the chelating agent discharged from the crucible rinsing unit;
A porous plate disposed in the ground and disposed in the space formed by the peripheral wall, the bottom wall coupled to the lower end of the peripheral wall, the peripheral wall and the bottom wall, and passing cleaning wastewater but not sand And a container-like sand containing portion opened on the upper side, containing sand for water evaporation on the perforated plate in its inner space;
A roof disposed above the sand storage unit to prevent rainwater from falling to the sand storage unit;
The inner space is disposed adjacent to the outer surface of the peripheral wall of the sand storage portion, and the internal space thereof communicates with the internal space of the sand storage portion via the communication hole formed in the peripheral wall below the porous plate. Side groove,
A washing wastewater supply device for feeding washing wastewater stored in the washing wastewater storage tank to the gutter;
A washing wastewater return path for refluxing washing wastewater in the gutter to the washing wastewater storage tank;
And a water level holding device for holding the water level of the cleaning wastewater in the gutter at a preset sand immersion upper end position,
The water evaporation sand, which is located between the sand immersion upper end position and the position of the upper surface of the water evaporation sand contained in the inner space of the sand container, forms a capillary water zone. Set as
The soil remediation method is
With the water level holding device, the water level of the cleaning wastewater in the gutter is held at the sand immersion upper end position to form a capillary water zone in the sand layer above the sand immersion upper end position, for water evaporation in the capillary water zone The water of the cleaning wastewater adhering to the sand is evaporated in the air and removed from the sand storage section,
The sand for water evaporation which has been used in the sand storage unit for a predetermined period and in which the chelating agent is accumulated is introduced into the sand washing unit to recover the chelating agent accumulated in the sand for water evaporation,
A soil remediation method characterized by using a part of sand discharged from said sand rinse part as sand for water evaporation stored in said sand storage part.   The soil remediation method according to claim 2, characterized in that fine sand is separated from sand discharged from the sand rinsing unit, and the fine sand is used as water evaporation sand stored in the sand storage unit.

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