KR20100077479A - Soil washing system for pops and heavy metals contaminated soils - Google Patents

Abstract

PURPOSE: A method for washing and restoring soil contaminated with heavy metal and residual organic compounds is provided to wash soil without effects of conditions of the soil to be washed by adjusting reaction time of the soil. CONSTITUTION: A method for washing and restoring soil contaminated with heavy metal and residual organic compounds includes the following steps: supplying soil(S10); screening the soil which is 30mm or more(S20); washing soil and foreign materials by friction, separation, mixing, and pulverizing(S30); restoring the soil and separating foreign materials by dehydrating the separated soil with a first dehydrating vibration screen(S40); collecting water and soil of 1 mm or less in a cyclone(S50); separating contaminants(S60); and restoring the soil by dehydrating soil of 0.075 mm or more(S70).

Description

Restorative cleaning method for soil contaminated with persistent organic compounds and heavy metals. {Soil Washing System for POPs and heavy metals contaminated soils}

The present invention relates to a method for restoring and cleaning soils contaminated with persistent organic compounds and heavy metals, and more particularly, to a system for unifying soil washing process comprising three steps of separation / concentration, desorption / washing and dissolution / extraction. By implementing it, it can be applied to a variety of pollutants, it is possible to adjust the reaction time according to the concentration of the pollutants to be able to wash without being affected by the properties of the soil to be washed.

Since the Industrial Revolution, today's industries have been developed almost entirely based on petroleum energy, and today's living standards have improved to a level comparable to before the Industrial Revolution. It is a serious problem that threatens life.

Environmental pollution can be classified into air pollution, water pollution, and soil pollution. Among them, soil pollution can be a very serious threat to food production, and it can cause pollution of drinking water sources through surface water and groundwater pollution. Therefore, contaminated soil must be cleaned up quickly.

However, today's industry is based on the mechanical industry, and almost all machines need oil directly, such as lubricating oils and fuels, and in particular, oil consumed by various vehicles, one of the most essential in modern life. The amount of oil is consumed so much that it cannot be measured, and due to the carelessness and inevitability of oil during transportation, storage and use, a large amount of oil is leaked to the outside and polluting the soil.

In addition to the above oils, Persistent Organic Pollutants (POPs) are introduced into the environment according to industrial production processes, product use, waste disposal, leakage accidents, and fuel and garbage combustion. These persistent organic compounds have a volatility, which not only diffuses into large areas through the atmosphere, but also have very low half-lives in the environment and are also detected in the Antarctic and Arctic, especially since they do not degrade in the body and accumulate in animal and human adipose tissue. High levels are found in animals and humans, the highest levels of The persistent organic compounds include pesticides such as DDT and Aldrin, industrial chemicals such as PCB and hexachlorobenzene, dioxins, and furans.

In addition, the soil is contaminated by heavy metals such as arsenic, cadmium, copper, lead, mercury, chromium, etc. contained in the tailings flowing out from the mine, especially arsenic is a highly toxic carcinogenic substance that greatly pollutes the surrounding environment. Soil or water-based foods containing arsenic contaminants, direct inhalation of arsenic mixtures, and skin exposure can lead to fatal toxicity across various organs, including the human skin, respiratory system, digestive system, and nervous system. Indicates.

Thus, as described above, methods for restoring contaminated soils include physicochemical methods such as soil washing, incineration, solidification, stabilization and solvent extraction, soil cultivation, composting, bioventing, and plant restoration. It can be classified into biological methods such as, bar, etc. Among the various methods as described above, because the treatment time is short, it is the soil washing that can quickly restore the contaminated soil.

The above-mentioned soil washing is a technique of weakening the surface tension of harmful organic pollutants bound to soil particles by using an appropriate cleaning agent or separating heavy metals from liquid particles and removing them from soil particles to remove a wide range of organic and inorganic pollutants. It can be applied regardless of the type of pollutants.

The soil cleaning technique was first developed in the United States in the late 1970s, but is now more developed and used in Europe than the United States, and is one of the most widely used methods for restoring contaminated soil. It is suitable for the current situation in which a large amount of various organic and inorganic pollutants are discharged, and is recognized as one of the methods of purifying relatively economically and efficiently.

The soil washing method can be divided into field treatment (In-situ method) and off-site treatment (Ex-situ method), the field treatment method does not excavate contaminated soil, washing solution injection well, washing solution discharge well, washing Effluent treatment facility, pump and instrumentation facility, and volatile material treatment facility are installed in the contaminated site to circulate the wash water in the contaminated soil to be treated, which directly washes the contaminated soil. If you want to wash the soil because of the disadvantages mainly the off-site treatment method is applied.

The off-site treatment method detects the distribution of contaminants in soil and physical / chemical characteristics of the soil, excavates the contaminated soil in the range to be treated, and then removes the contaminated soil excavated using an appropriate cleaning solution in the place where the washing device is located. As a method of washing, generally referred to as soil washing.

However, the conventional soil washing has only a selective separation function, so when the soil with high pollution concentration is introduced, it has to be rewashed, and there is a limitation on the properties of the soil to be washed, which has a lot of influences and constraints on site conditions. However, there was a problem that the processing cost is high.

Therefore, an object of the present invention is to solve all the problems of the conventional soil washing method described above, the process of washing the contaminated soil consisting of three steps of separation / concentration, desorption / washing and dissolution / extraction as a unified system By implementing, it can be applied to a variety of pollutants, it is possible to adjust the reaction time according to the concentration of the pollutant so that it can be washed without being affected by the properties of the soil to be washed.

In addition, by automatically classifying the washed soil by particle size, it is easy to recycle the washed soil, and by recycling the polluted washing water generated after washing the polluted soil as it is, secondary environmental pollution Is to prevent this from happening.

Restoration and cleaning method of the soil contaminated with the residual organic compound and heavy metals according to the present invention for achieving the above object, the soil supply step of supplying the soil into the hopper through the belt feeder, and through the screen 30mm in diameter The screen step of filtering out the above soil, and the washing step of washing the soil less than 30mm diameter passed through the screen with a log washer to separate the soil and foreign matter, and dewatering the separated foreign matter with a foreign material dehydration vibration screen Separating and separating the soil with a first dehydration vibration screen to restore the soil having a diameter of 1 mm or more and restoring the first soil recovery step, and the diameter discharged through the foreign matter dehydration vibration screen and the first dehydration vibration screen. A collecting step of collecting less than 1 mm of soil and washing water and supplying it to the cyclone, The contaminant separation step of separating the contaminants attached to the soil by centrifuging the soil with less than 1mm diameter and the washing water at high speed, and supplying the soil having a diameter of 0.075mm or more to the second dehydration vibration screen, and the second dehydration vibration screen. It is characterized in that it comprises a secondary soil restoration step of dehydration and restoration of the supplied soil more than 0.075mm in diameter.

In addition, after supplying the micro soil and the washing water of less than 0.075mm diameter discharged through the cyclone and the second dehydration vibration screen to the sedimentation tank, the fine soil precipitated in the lower part of the sedimentation tank again the foreign matter dehydration vibration screen and the first dehydration vibration The sedimentation step of collecting together with the soil and washing water discharged through the screen and supplying it to the cyclone, and supplying the remaining non-sedimented ultrafine soil and washing water to the sedimentation tank, and coagulating and sedimenting the microscopic soil by administering a flocculant to the sedimentation tank. The ultra-fine soil precipitated is supplied to the filter press through a concentration tank to separate the sludge and water, and the wash water from which the ultra-fine soil discharged through the sedimentation tank is removed using an oil / water separator. It further comprises a washing water treatment step of removing and making it reusable as washing water And a gong.

According to the present invention, it can be applied to various contaminants, and the reaction time can be adjusted according to the pollution concentration so that the washing can be performed without being affected by the properties of the soil to be washed, and the soil is cleaned and sorted by particle size automatically. By doing so, it provides an effect of facilitating the recycling of the washed soil.

In addition, the polluted washing water generated after washing the contaminated soil is recycled without being discharged as it is, thereby providing an effect of preventing secondary environmental pollution.

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 3.

As can be seen in Figures 1 to 3, the present invention is a soil supply step (S10), screen step (S20), washing step (S30), foreign matter separation and primary soil recovery step (S40), collecting step (S50) ), Pollutant separation step (S60), secondary soil recovery step (S70), sedimentation separation step (S80), ultra fine soil separation step (S90) and washing water treatment step (S100).

First, the contaminated soil supplied to the hopper 1 is supplied to the screen 4 through a belt feeder 2 (S10). At this time, the contaminated soil does not distinguish the characteristics, but determine the time according to the degree of contamination during the cleaning process (S30) to determine the degree of contamination.

The soil supplied to the screen 4 is screened and discharged through the screen 4, the soil having a diameter of 30mm or more, that is, aggregates such as gravel, and discharged (S20), the remaining soil to the log washer (5). Transfer.

At this time, the sprinkling device 41 is mounted on the upper portion of the screen 4 to spray the washing water so that the polluted soil can be first washed. Therefore, the soil having a diameter of 30 mm or more selected and discharged through the screen 4 can be washed with washing water at one time.

And the remaining soil that is not screened through the screen (4) is transferred to the log washer (5) with the wash water, in the log washer (5) by mixing, crushing (S30) to separate the soil and foreign matter.

The log washer 5 may be applied to a double log washer, the washing water is sprayed through the spray nozzles installed on the log washer (20). That is, when the rotary shaft of the log washer 5 is transported by the paddle while the soil is rotated, aggregates in the soil are rubbed, peeled, crushed, and mixed with each other, thereby washing and separating contaminants in the aggregate from the soil. Spray nozzles are installed in the log washer 5, and the washing water is sprayed from the nozzle to easily clean and separate the contaminants.

At this time, a washing agent may be added to the log washer 5 together with the washing water, and as the washing agent, various kinds of surfactants used in the related art may be added thereto, and the type of the washing agent is not limited.

And to determine the degree of contamination of the soil introduced into the initial hopper (1), to determine the reaction time, that is, the washing time in the log washer (5).

Next, the foreign matter separated through the log washer (5) is transferred to the foreign matter dehydration vibration screen (6) to dehydrate and separate, and the soil separated through the log washer (5) is the first dehydration vibration screen (7) By dehydration to soil 1mm diameter or more to complete the first restoration (S40).

At this time, the first dehydration vibration screen 7 is crushed and washed by the washing water and vibrating screen sprayed at a high pressure, the soil of diameter 1mm or more is discharged by reducing the water to a predetermined level or less by the screen. The vibrating screen 6 is also discharged to reduce the moisture of the foreign matter below a certain level. That is, the restored soil discharged through the first dehydration vibration screen 7 is soil of 1 to 30 mm in diameter, that is, aggregate. The foreign matter dehydration vibration screen 6 and the first dehydration vibration screen 7 are conventionally used in the art, and a separate description thereof will be omitted.

Soil and the washing water of less than 1mm in diameter discharged through the foreign matter dehydration vibration screen 6 and the first dehydration vibration screen 7 are collected together and supplied to the cyclone (Cyclone) (8) (S50). The cyclone (8) is a device for separating and settling the particles having a high specific gravity by centrifugal force by giving a pivoting motion to the mixed soil and the washing water, the high-speed centrifugation of soil and water of less than 1mm diameter supplied to the cyclone (8) Separating to separate the contaminants attached to the soil, and supplies the soil more than 0.075mm in diameter to the second dehydration vibration screen (9) (S60).

 The soil having a diameter of 0.075 mm or more supplied to the second dehydration vibration screen 9 is discharged after the soil restoration is completed in the same manner as the first dehydration vibration screen 7 (S70). Therefore, the soil has a size of 0.075 ~ 1mm.

In addition, the micro soil and the washing water having a diameter less than 0.075 mm discharged through the cyclone 8 and the second dehydration vibration screen 9 are supplied to the immersion tank 10, and 0.075 supplied to the immersion tank 10. The micro soil and the washing water of less than mm stays in the sedimentation tank 10 for 5 to 10 minutes and the soil is precipitated and separated from the washing water.

Therefore, the fine soil precipitated in the lower part of the sedimentation tank 10 is collected together with the soil and washing water discharged through the foreign matter dehydration vibration screen 6 and the first dehydration vibration screen 7 and supplied to the cyclone 8. (S50) to be repeatedly centrifuged, the remaining fine soil and fine water not precipitated is supplied to the settling tank 11 (S80).

And the ultra-fine soil and washing water supplied to the sedimentation tank (11), by administering a flocculant to the sedimentation tank (11) to agglomerate and precipitate the ultra-fine soil, and the precipitated ultra-fine soil is filter press 13 through the concentration tank (12) Sludge is discharged by being supplied to the sludge and water (S90), and the water is supplied to the settling tank 11 or reused as washing water.

At this time, the flocculant is supplied through a separate drug supply device 20, the drug and the fresh water supplied through the chemical tank 21 and the fresh water tank 22 is mixed with each other in the chemical mixing tank 23, the settling tank (11) Will be added to The flocculant uses an inorganic electrolyte or an organic polymer compound as a material which causes the solid particles suspended in the liquid to aggregate and precipitate.

In addition, the washing water from which the ultra-fine soil discharged through the sedimentation tank 11 is removed is used to remove oil using the oil / water separator 14 (S100) and reusable as the washing water.

The oil-water separation device 14 is an electrolytic levitation incorporating a pressurized floatation device. The oil component is separated and removed from the wash water by bubbles generated by generating an air bubble and discharging an electric current in the wash water containing the oil component. The wash water passing through the oil / water separator 14 is again stored in the fresh water tank through air stripping and an active adsorption tank, and the stored wash water is the screen 4, the first dehydration vibration screen 7, and It is supplied to the second dehydration vibration screen 9 and can be reused.

On the other hand, although not added to the description in the present invention, it is natural that it is further provided with a compressor and an air storage tank, and can be smoothly washed by continuously supplying raw water as needed.

In addition, the transport, discharge, etc. of the contaminated soil is made by a conveyor, it is natural that the discharged reconstructed soil can be selected by size and used respectively.

As described above, according to the present invention, the washing and sorting operations of the soil are performed as a single continuous system without being limited to the properties of the contaminated soil. The sorting work of is unnecessary.

1 is a schematic flowchart according to the restoration cleaning method of the soil of the present invention.

Figure 2 is a flow chart of the process according to the restoration cleaning method of the soil of the present invention.

Figure 3 is a block diagram of a restoration system of the soil of the present invention.

* Description of the major symbols in the drawings *

1: hopper 2: belt feeder

4: screen 5: log washer

6: Foreign body dehydration vibration screen

7: 1st dehydration vibration screen 8: cyclone

9: second dehydration vibration screen 10: tide tank

11: settling tank 12: thickening tank

13: filter press 14: oil / water separator

Claims (5)

Soil supply step (S10) for supplying the soil introduced into the hopper (1) to the screen (4) through the belt feeder (2), A screen step (S20) for filtering out soil having a diameter of 30 mm or more through the screen (4); A washing step (S30) of separating soil and foreign matter by rubbing, peeling, crushing, mixing and washing the soil having a diameter of less than 30 mm passing through the screen 4 with a log washer 5; The separated foreign matter is dewatered with a foreign matter dehydration vibration screen (6) to separate foreign matters, and the separated soil is dehydrated with the first dehydration vibration screen (7) to separate soils having a diameter of 1 mm or more, and to separate the primary soil. Restoration step (S40), Collecting step (S50) of collecting the soil and washing water of less than 1mm diameter discharged through the foreign matter dehydration vibration screen (6) and the first dehydration vibration screen (7), and supplies to the cyclone (8), High-speed centrifugation of the soil and washing water of less than 1mm in diameter supplied to the cyclone (8) to separate the contaminants attached to the soil, and contaminants for supplying a soil diameter of 0.075mm or more to the second dehydration vibration screen (9) Separation step (S60), Restoration of the soil contaminated with the residual organic compounds and heavy metals, characterized in that it comprises a second soil recovery step (S70) for dehydrating and restoring the soil more than 0.075mm diameter supplied to the second dehydration vibration screen (9) How to wash. The method of claim 1, After supplying the micro soil and the washing water of less than 0.075mm in diameter discharged through the cyclone (8) and the second dehydration vibration screen (9) to the sedimentation tank (10), the sedimentation in the lower part of the sedimentation tank (10) The fine soil is collected together with the soil and washing water discharged through the foreign matter dehydration vibration screen (6) and the first dehydration vibration screen (7) and supplied to the cyclone (8). Sedimentation step (S80) and the washing water is supplied to the settling tank (11), By administering a flocculant to the sedimentation tank (11), the micro-fine soil is aggregated and precipitated, and the precipitated micro-fine soil is supplied to the filter press 13 through the concentration tank 12 so as to be separated into sludge and water. (S90), It further comprises a washing water treatment step (S100) to remove the oil using the oil and water separator (14) to remove the ultra-fine soil discharged through the sedimentation tank 11 and reusable as washing water (S100). Method for restoring and cleaning soil contaminated with persistent organic compounds and heavy metals. 3. The method of claim 2, Restoring washing method of the soil contaminated with the residual organic compound and heavy metals, characterized in that the soil is first washed by mounting the sprinkling device (41) on the upper portion of the screen (4). The method of claim 3, wherein Soil contaminated with residual organic compounds and heavy metals, characterized in that the washing water passed through the washing water treatment step (S100) is supplied to the screen (4), the first dewatering vibration screen (7) and the second dewatering vibration screen (9). How to restore. 5. The method according to any one of claims 1 to 4, The log washer (5) to the washing method for restoring the soil contaminated with residual organic compounds and heavy metals, characterized in that the cleaning agent is added.

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