CN110842018A - Leaching system and method suitable for high-water-content heavy metal polluted clay - Google Patents
Leaching system and method suitable for high-water-content heavy metal polluted clay Download PDFInfo
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- 239000004927 clay Substances 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000002386 leaching Methods 0.000 title claims description 166
- 229910001385 heavy metal Inorganic materials 0.000 title claims description 33
- 239000002689 soil Substances 0.000 claims abstract description 87
- 238000010828 elution Methods 0.000 claims abstract description 28
- 238000004065 wastewater treatment Methods 0.000 claims abstract description 28
- 239000004576 sand Substances 0.000 claims abstract description 25
- 238000002360 preparation method Methods 0.000 claims abstract description 18
- 239000003814 drug Substances 0.000 claims abstract description 9
- 238000012216 screening Methods 0.000 claims abstract description 7
- 239000002245 particle Substances 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 49
- 239000010802 sludge Substances 0.000 claims description 32
- 239000003795 chemical substances by application Substances 0.000 claims description 28
- 238000003756 stirring Methods 0.000 claims description 15
- 230000009471 action Effects 0.000 claims description 12
- 230000005484 gravity Effects 0.000 claims description 12
- 239000002920 hazardous waste Substances 0.000 claims description 8
- 238000012545 processing Methods 0.000 claims description 6
- 239000002351 wastewater Substances 0.000 claims description 5
- 238000012797 qualification Methods 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 2
- 230000001376 precipitating effect Effects 0.000 claims 1
- 238000005516 engineering process Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 9
- 230000008569 process Effects 0.000 description 7
- 239000003344 environmental pollutant Substances 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 5
- 231100000719 pollutant Toxicity 0.000 description 5
- 238000005067 remediation Methods 0.000 description 5
- 238000010276 construction Methods 0.000 description 4
- 229910052785 arsenic Inorganic materials 0.000 description 3
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000008439 repair process Effects 0.000 description 3
- 238000004062 sedimentation Methods 0.000 description 3
- 239000010963 304 stainless steel Substances 0.000 description 2
- 229920002430 Fibre-reinforced plastic Polymers 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 2
- 230000001112 coagulating effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000003480 eluent Substances 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000011151 fibre-reinforced plastic Substances 0.000 description 2
- 239000004800 polyvinyl chloride Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000009388 chemical precipitation Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 230000008635 plant growth Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000009287 sand filtration Methods 0.000 description 1
- 238000012163 sequencing technique Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/02—Extraction using liquids, e.g. washing, leaching, flotation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
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- Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Processing Of Solid Wastes (AREA)
- Treatment Of Sludge (AREA)
Abstract
The invention relates to an elution system suitable for high-water-content polluted clay and an elution method thereof, which sequentially comprise a first-stage elution grading system (1), a second-stage elution grading system (2), a third-stage elution grading system (3), a wastewater treatment system (4) and a medicament preparation system (5); after being screened by a screening machine, the polluted soil with the particle size not larger than 5cm is directly fed into a first-stage elution grading system, then is sequentially pumped into a second-stage elution grading system and a third-stage elution grading system by a self-priming pump, finally, the upper-layer effluent enters wastewater treatment equipment and is recycled, and the polluted soil is divided into coarse sand, medium sand and fine sand by the third-stage elution grading system.
Description
Technical Field
The invention belongs to the field of ecological environment restoration, and particularly relates to a leaching system and method suitable for high-water-content heavy metal polluted clay.
Background
Because heavy metals have concealment and biological degradability, once the heavy metals enter the soil, the heavy metal contaminated soil is difficult to remove, and the current heavy metal contaminated soil remediation ideas commonly used in the field of ecological remediation are mainly divided into two categories, namely, the heavy metals in the soil are converted into a more stable state, and the migration is reduced; the other is to extract heavy metals from the soil. The currently common ecological restoration engineering application technologies include a solidification/stabilization technology, a passivation technology, a plant enrichment and extraction technology, a soil leaching technology and the like. With the discovery of engineering application practices, the first idea of converting heavy metals in soil into a more stable state has great uncertainty in the actual application process, and the main reason is that the heavy metals are not removed from the soil, and the change of the surrounding environment can be converted back to an unstable state again along with the lapse of time when the heavy metals converted into the stable state are converted into the stable state; the second concept of removing heavy metals from soil is gradually receiving attention from people. The technology for removing heavy metals from soil mainly comprises a plant extraction technology and a soil leaching technology, and the former technology depends on plant growth and has the disadvantages of slow effect, large climate influence and the like, so the soil leaching technology is considered to be a quick and effective method for removing the heavy metals from the soil.
The invention patent of the publication No. CN 104610973B provides an eluent for repairing chromium-contaminated soil and a method thereof, and the patent provides an eluent with better repairing effect on total chromium in clay under the condition of ultrasonic enhanced elution, but does not provide a whole set of applicable elution system. The invention patent of the publication number CN 104889150B provides a chemical leaching process for heavy metal contaminated soil, which is realized by the steps of crushing, stirring, screening, leaching, cyclone separation, chemical precipitation and the like, and the process has a good leaching effect on sandy soil with low water content, but the crushing and stirring at the front end of the process cannot achieve the preset effect on contaminated soil with high water content and high soil viscosity. The invention patent of the patent publication No. CN 105772497B provides an ectopic leaching complete equipment which can be suitable for the remediation of soil with different pollutant types and different particle size grades aiming at the defect of the remediation of the soil polluted by the soil with different particle size grades, and the equipment mainly comprises a wet-type screening mechanism, a spiral grading mechanism, a leaching remediation mechanism, a wastewater treatment mechanism and a wastewater recycling mechanism. The invention patent with application publication number CN 109794500A discloses a sequencing batch leaching device for heavy metal contaminated soil. The two inventions are improved and upgraded in some aspects, so that some practical problems encountered on site are solved, but the clay with high water content is still difficult to exert a good leaching effect.
China has broad breadth, the difference of soil in south and north is very large, the north is mainly sandy soil, the south is mainly clay, and the climate difference in south and north causes that underground water in south is much richer than that in north. Based on the reasons, the same technology in actual repair engineering has different requirements on repair equipment for different types of soil, for example, in a polluted site in south China, the common water level of underground water is about 0.5-1.5m, and when the remote leaching repair technology is adopted, the excavated polluted soil is often found to have high water content and high viscosity, and the common soil leaching equipment is difficult to effectively play a role. Therefore, the invention is very necessary to provide a leaching system and a leaching method suitable for the high-water-content polluted clay.
Disclosure of Invention
The invention aims to provide an efficient and feasible leaching system and method for polluted soil with high water content and high viscosity in the polluted site repairing process. The invention is inspired by the technology of a grit chamber in an urban domestic sewage treatment plant: pollutants in the high-water-content polluted clay are difficult to remove in conventional leaching equipment, and if a secondary sedimentation tank process is adopted, the high-water-content clay is directly placed in a water tank filled with a leaching agent, and the pollutants in the soil are removed in a manner of graded leaching and mud-water separation of the soil through external power.
The purpose of the invention is realized by the following technical scheme:
the leaching system suitable for the high-water-content polluted clay sequentially comprises a first-stage leaching grading system 1, a second-stage leaching grading system 2, a third-stage leaching grading system 3, a wastewater treatment system 4 and a medicament preparation system 5; after being screened by a screening machine, the polluted soil with the particle size not larger than 5cm is directly fed into a first-stage elution grading system, then is sequentially pumped into a second-stage elution grading system and a third-stage elution grading system by a self-priming pump, finally, the upper-layer effluent enters wastewater treatment equipment and is recycled, and the polluted soil 9 is separated into coarse sand 16, medium sand 17 and fine sand 18 through the third-stage elution grading system.
The primary leaching grading system 1 sequentially comprises a primary leaching tank using a first leaching agent 10, primary feeding equipment, a primary stirring motor and a primary sludge discharge equipment dewatering screen;
the secondary leaching grading system 2 sequentially comprises a secondary leaching tank using a second leaching agent 11, secondary feeding equipment, a secondary stirring motor and a secondary sludge discharge equipment plate-and-frame filter press;
the three-stage leaching grading system 3 sequentially comprises a three-stage leaching tank using a third leaching agent 12, three-stage feeding equipment, a three-stage stirring motor and a three-stage sludge discharge equipment plate-and-frame filter press;
the wastewater treatment system 4 is a typical heavy metal wastewater treatment system;
the agent preparation system 5 comprises rinsing agent preparation and water treatment agent preparation.
The invention also provides a leaching method suitable for the high-water-content heavy metal polluted clay, which comprises the following steps: (1) pretreatment of contaminated soil: after the polluted soil is excavated, large-size building rubbish is screened out. (2) Primary leaching: the polluted soil is fed by the excavator, enters a first-stage leaching system, is precipitated under the action of gravity and centrifugal force, coarse sand with the water content of less than 25% is discharged through a sludge discharge system, and the rest components enter a second-stage leaching system. (3) Secondary leaching: after the first-stage leaching of the polluted soil, the polluted soil enters a second-stage leaching system, the polluted soil is precipitated under the action of gravity and centrifugal force, the middlings with the water content not higher than 65% are discharged through a sludge discharge system, and the rest components enter a third-stage leaching system. (3) Third-stage leaching: after the first-stage leaching and the second-stage leaching of the polluted soil, the polluted soil enters a third-stage leaching system, is precipitated under the action of gravity and centrifugal force, fine sand with the water content not higher than 65% is discharged through a sludge discharge system, and the rest components enter a wastewater treatment system. (4) And (3) terminal processing: and after the polluted soil passes through the three-stage leaching system, the residual wastewater enters the wastewater treatment system to be treated and recycled after reaching the standard, and the sludge discharged by the wastewater treatment system is treated by a unit with hazardous waste treatment qualification according to the hazardous waste commission.
The leaching system and the leaching method suitable for the high-water-content polluted clay have the obvious advantages of simple process, sufficient leaching, graded reduction, energy conservation, emission reduction and the like, and are the most different from the existing leaching device.
Drawings
Fig. 1 is a leaching system suitable for high water content contaminated clay according to the present invention.
Numbering system equipment: 1, first-level leaching equipment; 2, secondary leaching equipment; 3, three-stage leaching equipment; 4, adjusting the reaction zone; 5 a coagulating sedimentation area; 6, a sand filtering area; 7, a clean water tank; 8 sludge dewatering equipment.
Material numbering: 9, polluted soil; 10 a first elution reagent; 11 a second elution reagent; 12 a third elution reagent; 13 a first water treatment agent; 14 a second water treatment agent; 15 a third water treatment agent; 16 coarse sand; 17, medium sand; 18 fine sand.
Fig. 2 is a leaching method suitable for the high water content contaminated clay provided by the invention.
Detailed Description
For the purpose of making the present invention more apparent in view of its objects, summary and advantages, the present invention will be described in further detail with reference to the following examples.
Fig. 1 is a leaching system suitable for high water content contaminated clay according to the present invention.
The leaching system suitable for the high-water-content polluted clay sequentially comprises a first-stage leaching grading system 1, a second-stage leaching grading system 2, a third-stage leaching grading system 3, a wastewater treatment system 4 and a medicament preparation system 5; after being screened by a screening machine, the polluted soil with the particle size not larger than 5cm is directly fed into a first-stage elution grading system, then is sequentially pumped into a second-stage elution grading system and a third-stage elution grading system by a self-priming pump, finally, the upper-layer effluent enters wastewater treatment equipment and is recycled, and the polluted soil 9 is separated into coarse sand 16, medium sand 17 and fine sand 18 through the third-stage elution grading system.
The primary leaching grading system 1 sequentially comprises a primary leaching tank using a first leaching agent 10, primary feeding equipment, a primary stirring motor and a primary sludge discharge equipment dewatering screen;
the secondary leaching grading system 2 sequentially comprises a secondary leaching tank using a second leaching agent 11, secondary feeding equipment, a secondary stirring motor and a secondary sludge discharge equipment plate-and-frame filter press;
the three-stage leaching grading system 3 sequentially comprises a three-stage leaching tank using a third leaching agent 12, three-stage feeding equipment, a three-stage stirring motor and a three-stage sludge discharge equipment plate-and-frame filter press;
the wastewater treatment system 4 is a typical heavy metal wastewater treatment system;
the agent preparation system 5 comprises a leaching agent preparation pool and a water treatment agent preparation pool.
Further, the air conditioner is provided with a fan,
(1) the first-stage leaching pond in the first-stage leaching grading system is made of Fiber Reinforced Plastic (FRP), is cylindrical, and is conical at the bottom, and the specific size is determined according to the processing capacity of the whole system. Preferably, the whole set of the leaching equipment has the treatment capacity Q of 5-20m3In the h range, the height of the first-level leaching tankThe degree is 2.3-3 times of the diameter of the cylinder, and the size of the primary leaching tank is determined according to the following formula:
wherein:
a: total area of the first-stage shower bath, m2；
Q: the entire leaching system is designed with processing capacity, m3/d；
C: designing a solid-liquid ratio of the slurry, g/L;
m: the mud output of the first-stage leaching tank is kg/(m)2/d)；
D: diameter of the first-stage leaching tank, m.
(2) The power of a first-stage stirring motor in the first-stage leaching grading system is within the range of 2.2-5.5 kw, and a stirring rotor is made of 304 stainless steel.
(3) The first-stage sludge discharge equipment in the first-stage leaching and grading system requires the discharged sludge to have the water content lower than 25%.
Further, the air conditioner is provided with a fan,
and (3) determining the material and the size of a second-stage leaching pool and a second stirring motor in the second-stage leaching grading system by referring to the step (1) and the step (2).
The secondary feeding equipment in the secondary leaching grading system comprises a feeding pump and a feeding pipeline, wherein the feeding pump is a self-suction type vortex non-blocking slurry pump, and the flow rate is 5-20m3The speed is 2900r/min, the power of the motor is 1.5-2.2kW, and the pressure control range is 0.1-0.5 Mpa. The material of the feeding pipeline is 304 stainless steel, and the flow rate is 5-20m3/h。
And the secondary sludge discharge equipment in the secondary leaching and grading system requires that the water content of the discharged sludge is not higher than 65%.
Further, the air conditioner is provided with a fan,
and the specification and model of a three-level leaching tower, a three-level feeding device, a three-level stirring motor and a three-level sludge discharging device in the three-level leaching and grading system are determined by referring to the two-level leaching and grading system.
Further, the air conditioner is provided with a fan,
the wastewater treatment system comprises functional modules, wherein the functional modules comprise an adjusting reaction area 4 for introducing a first water treatment medicament 13, a coagulating sedimentation area 5 for introducing a second water treatment medicament 14, a sand filtration area 6 for introducing a third water treatment medicament 15 and a clean water tank 7; and a sludge dewatering device 8.
Further, the air conditioner is provided with a fan,
the leaching agent preparation in the agent preparation system comprises two cylindrical barrels with the volume of 5 cubic meters and made of polyvinyl chloride (PVC), the concentration range of the leaching agent preparation in the system is 1% -50%, and the adding capacity of the leaching agent is 1-2000 kg/h.
The medicament preparation system is used for preparing water treatment medicaments. The system comprises three cylindrical cylinders with the volume of 5 cubic meters and made of polyvinyl chloride (PVC), the water treatment agent of the system has the preparation concentration range of 0.1-30%, and the adding capacity of the leaching agent is 1-1000 kg/h.
The invention also provides a leaching method suitable for the high-water-content heavy metal polluted clay, which comprises the following steps: (1) pretreatment of contaminated soil: after the polluted soil is excavated, large-size building rubbish is screened out. (2) Primary leaching: the polluted soil is fed by the excavator, enters a first-stage leaching system, is precipitated under the action of gravity and centrifugal force, coarse sand with the water content of less than 25% is discharged through a sludge discharge system, and the rest components enter a second-stage leaching system. (3) Secondary leaching: after the first-stage leaching of the polluted soil, the polluted soil enters a second-stage leaching system, the polluted soil is precipitated under the action of gravity and centrifugal force, the middlings with the water content not higher than 65% are discharged through a sludge discharge system, and the rest components enter a third-stage leaching system. (3) Third-stage leaching: after the first-stage leaching and the second-stage leaching of the polluted soil, the polluted soil enters a third-stage leaching system, is precipitated under the action of gravity and centrifugal force, fine sand with the water content not higher than 65% is discharged through a sludge discharge system, and the rest components enter a wastewater treatment system. (4) And (3) terminal processing: and after the polluted soil passes through the three-stage leaching system, the residual wastewater enters the wastewater treatment system to be treated and recycled after reaching the standard, and the sludge discharged by the wastewater treatment system is treated by a unit with hazardous waste treatment qualification according to the hazardous waste commission.
Fig. 2 is a leaching method suitable for the high water content contaminated clay provided by the invention.
The method comprises the following steps: (1) pretreatment of contaminated soil: after the polluted soil is excavated, large-size building rubbish is screened out. (2) Primary leaching: the polluted soil is fed by the excavator, enters a first-stage leaching system, is precipitated under the action of gravity and centrifugal force, coarse sand with the water content of less than 25% is discharged through a sludge discharge system, and the rest components enter a second-stage leaching system. (3) Secondary leaching: after the first-stage leaching of the polluted soil, the polluted soil enters a second-stage leaching system, the polluted soil is precipitated under the action of gravity and centrifugal force, the middlings with the water content not higher than 65% are discharged through a sludge discharge system, and the rest components enter a third-stage leaching system. (3) Third-stage leaching: after the first-stage leaching and the second-stage leaching of the polluted soil, the polluted soil enters a third-stage leaching system, is precipitated under the action of gravity and centrifugal force, fine sand with the water content not higher than 65% is discharged through a sludge discharge system, and the rest components enter a wastewater treatment system. (4) And (3) terminal processing: and after the polluted soil passes through the three-stage leaching system, the residual wastewater enters the wastewater treatment system to be treated and recycled after reaching the standard, and the sludge discharged by the wastewater treatment system is treated by a unit with hazardous waste treatment qualification according to the hazardous waste commission.
Example 1
In a heavy metal polluted site, the common water level of underground water is 1.2m, the upper layer is 0-0.7m of miscellaneous fill, and the lower layer is 0.7-6.0m of silty clay. The concentration ranges of the heavy metal pollution nickel and arsenic in the land parcel soil are 1250.42-3376.81mg/kg and 89.33-179.16mg/kg respectively, and the maximum pollution depth is 4.3 m. The amount of pollution is 5894m3And the original water content of the soil is about 44 percent. After the polluted soil is excavated and screened, the leaching system provided by the invention is adopted, and the design and disposal amount is 5m3And h, sequentially carrying out leaching according to the leaching method provided by the invention, and finally smoothly completing the repairing and disposing work of all the polluted soil of the project through on-site tension construction for 62 days, comparing the heavy metal concentrations in the soil before and after leaching with the following table, and displaying according to the result that the system has a more effective leaching effect on the high-water-content polluted clay.
TABLE 1 comparison of heavy metal concentrations in soil before and after leaching
| Heavy metals | Concentration Range before Leaching (mg/kg) | Concentration range after elution (mg/kg) |
| Arsenic (As) | 89.33-179.16 | 10.14-22.37 |
| Nickel (II) | 1250.42-3376.81 | 307.19-643.45 |
Example 2
In a heavy metal polluted site in a certain city, the common water level of underground water is 0.6m, and the site is mainly silty clay. The post-stage planning of the site is residential and commercial sites, the concentration ranges of main pollutants are 31.08-102.6mg/kg, 468.13-1258.71mg/kg and 9.2-25.53mg/kg, and the maximum pollution depth of the site is 6.1 m. The amount of pollution is 18043m3And the original water content of the soil is about 53 percent. The leaching system provided by the invention is adopted in field construction, and the design and disposal amount is 10m3And/h, sequentially carrying out the leaching according to the leaching method provided by the invention, and finally successfully completing the project and detecting the project qualified at one time. The heavy metal concentrations of the project polluted soil before and after leaching are compared in the following table, and according to the detection result, the system and the method provided by the invention have a good leaching effect on the polluted clay of the project.
TABLE 2 comparison of heavy metal concentrations in soil before and after leaching
| Heavy metals | Concentration Range before Leaching (mg/kg) | Concentration range after elution (mg/kg) |
| Cadmium (Cd) | 31.08-102.6 | 2.46-10.53 |
| Lead (II) | 468.13-1258.71 | 93.22-261.74 |
| Hexavalent chromium | 9.2-25.53 | 0.33-1.06 |
Example 3
In a polluted site of a certain commercial power plating old site, the underground water level of the site is buried for about 1.0m, the upper layer is 0-0.6m of cement terrace and miscellaneous filling soil, and the lower layer is silty clay. The characteristic pollutants are hexavalent chromium and arsenic, the concentration ranges are 7.22-31.43 and 49.63-97.70mg/kg respectively, and the maximum pollution depth is 5.1 m. The amount of the pollution is 24894m3And the original water content of the soil is about 49 percent. After the polluted soil is excavated and screened, the leaching system in the embodiment 2 is adopted, the leaching method provided by the invention is used for on-site construction, and all the work contents of the project are smoothly completed through the tense construction of nearly 6 months. According to sampling and submitting before and after the leaching, the result shows that the system has a relatively effective leaching effect on the high-water-content polluted clay.
TABLE 3 comparison of heavy metal concentrations in soil before and after washing
In conclusion, the embodiments show that when the device and the method provided by the patent are used for leaching and repairing the high-moisture-content polluted clay, the problems that the device is difficult to normally operate, the leaching effect is poor and the like in the existing repairing industry can be effectively solved.
Claims (2)
1. The leaching system suitable for the high-water-content polluted clay sequentially comprises a first-stage leaching grading system (1), a second-stage leaching grading system (2), a third-stage leaching grading system (3), a wastewater treatment system (4) and a medicament preparation system (5); after being screened by a screening machine, the polluted soil with the particle size not larger than 5cm is directly fed into a first-stage elution grading system, then is sequentially pumped into a second-stage elution grading system and a third-stage elution grading system by a self-priming pump, finally, the upper-layer effluent enters wastewater treatment equipment and is recycled, and the polluted soil is divided into coarse sand, medium sand and fine sand by the third-stage elution grading system.
The primary leaching grading system (1) sequentially comprises a primary leaching tank using a first leaching agent, primary feeding equipment, a primary stirring motor and a primary sludge discharge equipment dewatering screen;
the secondary leaching grading system (2) sequentially comprises a secondary leaching tank using a second leaching agent, secondary feeding equipment, a secondary stirring motor and a secondary sludge discharge equipment plate-and-frame filter press;
the three-stage leaching grading system (3) sequentially comprises a three-stage leaching tank using a third leaching agent, three-stage feeding equipment, a three-stage stirring motor and a three-stage sludge discharge equipment plate-and-frame filter press;
the wastewater treatment system (4) is a typical heavy metal wastewater treatment system;
the agent preparation system (5) comprises a leaching agent preparation pool and a water treatment agent preparation pool.
2. The leaching method of the leaching system for the high-water-content heavy metal contaminated clay according to claim 1, comprising the following steps: (1) pretreatment of contaminated soil: after the polluted soil is excavated, screening large-size building rubbish; (2) primary leaching: feeding the polluted soil by an excavator, feeding the polluted soil into a first-stage leaching system, precipitating under the action of gravity and centrifugal force, discharging coarse sand with the water content of less than 25% through a sludge discharge system, and feeding the rest components into a second-stage leaching system; (3) secondary leaching: after primary leaching, the contaminated soil enters a secondary leaching system, is precipitated under the action of gravity and centrifugal force, medium sand with the water content not higher than 65% is discharged through a sludge discharge system, and the rest components enter a tertiary leaching system; (3) third-stage leaching: after primary leaching and secondary leaching of the polluted soil, the polluted soil enters a third leaching system, is precipitated under the action of gravity and centrifugal force, fine sand with the water content not higher than 65% is discharged through a sludge discharge system, and the rest components enter a wastewater treatment system; (4) and (3) terminal processing: and after the polluted soil passes through the three-stage leaching system, the residual wastewater enters the wastewater treatment system to be treated and recycled after reaching the standard, and the sludge discharged by the wastewater treatment system is treated by a unit with hazardous waste treatment qualification according to the hazardous waste commission.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911217960.2A CN110842018A (en) | 2019-12-03 | 2019-12-03 | Leaching system and method suitable for high-water-content heavy metal polluted clay |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911217960.2A CN110842018A (en) | 2019-12-03 | 2019-12-03 | Leaching system and method suitable for high-water-content heavy metal polluted clay |
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| CN113210417A (en) * | 2021-05-26 | 2021-08-06 | 中国地质环境监测院(自然资源部地质灾害技术指导中心) | Intelligent soil heavy metal pollution prosthetic devices |
| CN113732034A (en) * | 2021-09-09 | 2021-12-03 | 上海环境保护有限公司 | Heavy metal contaminated soil device is handled in drip washing of increasing benefit |
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