CN103878171A - Ecological treatment bed of chromium contaminated soil - Google Patents

Abstract

The invention relates to an ecological treatment bed of chromium contaminated soil. Coal gangue as a filling material directly fills the lower part of to-be-treated contaminated soil; plants are selected to be planted on the ecological treatment bed; the treatment bed is irrigated regularly to maintain the survival of the plants on the bed; a chromium element in soil is absorbed by plants, and part of chromium is removed by harvesting the plants; the contaminated soil is leached by pouring water or rainwater; leachate permeates into a gangue layer at the lower part of the ecological treatment bed and reacts with acidic coal gangue, and hexavalent chromium is reduced to form low-toxicity low-harm substances such as trivalent chromium; the land occupation problem of coal gangue storage is also solved. The ecological treatment bed of chromium contaminated soil is simple and convenient to operate, low in investment, and low in running cost.

Description

A kind of ecological treatment bed for chromium polluted soil

technical field

The invention relates to the technical field of contaminated soil treatment, in particular to an ecological treatment bed for chromium-contaminated soil.

Background technique

Chromium and its compounds are widely used in various fields of industrial production, and are essential raw materials for industries such as metallurgy, electroplating, tanning, printing and dyeing, etc. These enterprises pollute the soil during the production process. The toxicity of chromium mainly comes from hexavalent chromium, which is extremely harmful to the human body and the environment. Treatment of chromium-contaminated soil is a hot spot in environmental science and technology research.

Coal mines and other mining enterprises produce a large amount of coal gangue and other wastes in the production process, and a certain amount of land is required to stack these coal gangues. Miner's lamp houses and machinery factories of coal mining enterprises will produce a certain amount of waste acid. How to reasonably and economically Utilizing these abandoned coal gangue and waste acid has become a difficult problem for major coal mining enterprises.

Contents of the invention

The technical problem to be solved by the present invention is: in order to solve the problem of chromium removal in polluted soil and the disposal and utilization of land occupied by coal gangue and the waste acid produced by miner's lamp house, to provide a chromium-contaminated soil with simple operation and low investment Treatment method and ecological treatment bed, using coal gangue after acid treatment as reducing material, in-situ treatment of polluted soil, combining the treatment and utilization of coal gangue and waste acid with the treatment of polluted soil, and taking the road of treating waste by waste .

The technical solution adopted by the present invention to solve its technical problems is: the ecological treatment bed of a kind of chromium-contaminated soil of the present invention is built and implemented according to the following steps:

(1) Investigate, experiment and analyze to determine the scope, area and depth of polluted soil.

(2) According to the survey results, plan and determine the location and area of contaminated soil treatment, and calculate the filling thickness and earth volume; plan the treatment target area into a grid structure, and plan it into a rectangular block with a side length of 5-10 meters .

(3) The contaminated soil layer is stripped, and part of the stripped soil is piled up around the ecological treatment bed to form a cofferdam for the ecological treatment bed.

(4) The bottom of the ecological treatment bed is designed with a water flow gradient of 1-3%.

(5) The anti-seepage treatment at the bottom of the ecological treatment bed adopts the laying of anti-seepage film, and the anti-seepage film can adopt a plastic film with a thickness of 1.5-2 millimeters, and the lap joint will be handled well to improve the anti-seepage effect; further, in order to prevent If the anti-seepage film is damaged, it is necessary to lay fine sand on the lower soil layer of the anti-seepage film and the upper surface of the anti-seepage film, or use geotextile plus fine sand as a protective layer.

(6) Crushing the gangue and passing through a 100-300 mesh sieve.

(7) Immerse the sieved coal gangue in the waste acid solution, keep the pH value at 2-5, let it dry naturally after soaking for 2-4 hours, and the waste acid solution comes from miner lamp houses and machinery factories of coal mining enterprises.

(8) Fill the air-dried coal gangue on the protective layer of the anti-seepage film, and the filling thickness of the coal gangue is 0.5-0.8 meters.

(9) Cover the stripped polluted soil on the coal gangue again, and the covering thickness of the polluted soil is 1-1.5 meters.

(10) Select plants on the ecological treatment bed, and the selected plants should meet the following requirements: ① strong absorption capacity for chromium; ② use native species, plant according to soil, and adapt measures to local conditions; ③ strong disease resistance; ④ easy to harvest , easy to handle; ⑤ strong waterlogging tolerance; ⑥ well-developed root system, dense stems and leaves. Commonly used plants include Lishihe, reed, bermudagrass, gray green quinoa, goosegrass and so on.

(11) Water the ecological treatment bed regularly. On the one hand, to maintain the survival of the plants on the bed, the plants absorb the chromium element in the soil, and part of the chromium can be removed through the harvest of the plants. On the other hand, irrigation water or natural rainwater leaches the polluted soil, the leachate contains a certain amount of hexavalent chromium, the leachate penetrates into the gangue layer at the bottom of the ecological treatment bed, reacts with the acidic coal gangue, and the hexavalent chromium is reduced into low-toxic and low-harm substances such as trivalent chromium.

(12) A leachate collection pond is designed downstream of the ecological treatment bed to collect treated irrigation water or natural rainwater to achieve standard discharge.

(13) Keep the ecological treatment bed running for 6-12 months. The harmless ecological treatment bed can be used for landscaping, ecological planting, or as construction land.

The beneficial effect of the present invention is that the present invention uses coal gangue as filling material to directly fill the lower part of the polluted soil to be treated, and uses acid-treated coal gangue as a reducing material, so that the hexavalent chromium in the soil is reduced to trivalent chromium and other low Toxic and low-hazardous substances, in-situ treatment of chromium-contaminated soil; also solves the problem of land occupation for coal gangue storage; the invention is easy to operate, less investment, and low operating cost.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a sectional view of a specific embodiment of an ecological treatment bed of the present invention, and Fig. 2 is a plan view of a specific embodiment of an ecological treatment bed of the present invention.

In the figure: 1. anti-seepage layer, 2. gangue layer, 3. polluted soil layer, 4. plants, 5. cofferdam, 6. gangue and soil filling area, 7. leachate discharge port, 8. leachate collection pond .

Detailed ways

The present invention is described in further detail now in conjunction with accompanying drawing. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, so they only show the configurations related to the present invention.

Example 1

After the relocation of an enterprise in southern Jiangsu, the industrial plant site was investigated, tested, and analyzed, and the soil was determined to be heavily polluted by chromium. According to the investigation results, the location and area of contaminated soil treatment were determined and planned into a rectangular square with a side length of 8 meters.

Strip the polluted soil layer, and pile up part of the stripped soil around the ecological treatment bed to form the cofferdam of the ecological treatment bed. The bottom of the ecological treatment bed is designed with a 2% water flow gradient, and the bottom of the ecological treatment bed is laid with 1.5 mm thick plastic For the anti-seepage membrane, fine sand is laid on the lower soil layer of the anti-seepage membrane and the upper surface of the anti-seepage membrane as a protective layer.

Crush the coal gangue and pass it through a 200-mesh sieve. Immerse the screened coal gangue in the waste acid solution, keep the pH value at 3, soak for 2 hours and then dry it naturally. .

Fill the air-dried coal gangue on the protective layer of the anti-seepage film. The filling thickness of the coal gangue is 0.6 meters, and then cover the stripped polluted soil on the coal gangue. The covering thickness of the polluted soil is 1.2 meters. Plants are selected on the ecological treatment bed Li Shihe.

Regularly water the ecological treatment bed to maintain the normal growth of the plants on the bed. The plants absorb the chromium in the soil, and a part of the chromium can be removed through the harvest of Li Shihe; on the other hand, the polluted soil is leached by irrigation water or natural rainwater , The leachate contains a certain amount of hexavalent chromium, the leachate penetrates into the gangue layer at the bottom of the ecological treatment bed, reacts with the acidic gangue, and the hexavalent chromium is reduced to trivalent chromium and other low-toxic and low-harm substances.

A leachate collection pond is designed downstream of the ecological treatment bed to collect treated irrigation water or natural rainwater to achieve standard discharge.

Keep the ecological treatment bed running for 8 months, and the harmless ecological treatment bed is used for landscaping.

Example 2

After the relocation of an enterprise in northern Jiangsu, the industrial factory site was determined to be severely polluted by chromium in the soil after investigation, experimentation, and analysis. According to the investigation results, the location and area of contaminated soil treatment were determined, and the plan was made into a rectangular square with a side length of 10 meters.

Strip the polluted soil layer, and pile up part of the stripped soil around the ecological treatment bed to form the cofferdam of the ecological treatment bed. The bottom of the ecological treatment bed is designed with a 3% water flow gradient, and the bottom of the ecological treatment bed is laid with 2 mm thick plastic For the anti-seepage membrane, fine sand is laid on the lower soil layer of the anti-seepage membrane and the upper surface of the anti-seepage membrane as a protective layer.

Crush the coal gangue and pass it through a 300-mesh sieve. Immerse the screened coal gangue in the waste acid solution to keep the pH value at 4. After soaking for 4 hours, let it dry naturally. The waste acid solution comes from miner lamp houses and machinery factories of coal mining enterprises. .

Fill the air-dried coal gangue on the protective layer of the anti-seepage film. The filling thickness of the coal gangue is 0.8 meters, and then cover the peeled polluted soil on the coal gangue. The covering thickness of the polluted soil is 1.5 meters. Plants are selected on the ecological treatment bed reed.

Regularly water the ecological treatment bed to maintain the normal growth of the reeds on the bed. The reeds absorb the chromium in the soil and remove the chromium through the harvesting of the reeds. On the other hand, the irrigation water or natural rainwater leaches the polluted soil, and the leachate contains a certain amount The hexavalent chromium, the leachate penetrates into the gangue layer at the lower part of the ecological treatment bed, reacts with the acidic gangue, and the hexavalent chromium is reduced to trivalent chromium and other low-toxic and low-harm substances.

A leachate collection pond is designed downstream of the ecological treatment bed to collect treated irrigation water or natural rainwater to achieve standard discharge.

Keep the ecological treatment bed running for 12 months, and the harmless ecological treatment bed is used for construction land.

Inspired by the above-mentioned ideal embodiment according to the present invention, through the above-mentioned description content, relevant workers can make various changes and modifications within the scope of not departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, but must be determined according to the scope of the claims.

Claims (3)

1. an Ecological Disposal bed for chromium-polluted soil, is characterized in that, it builds enforcement in accordance with the following steps:

(1) investigate, test, analyze, determine scope, area and the degree of depth of contaminated soil.

(2) according to investigation result, plan, determine position, area that contaminated soil is administered, calculate thickness, the earth volume of filling; Management goal section planning is become to square grid shape structure, be formulated for the rectangular block that the length of side is 5-10 rice.

(3) peel off contaminated soil layer, part is peeled off to soil and is deposited in the surrounding of Ecological Disposal bed, form the cofferdam of Ecological Disposal bed.

(4) bottom design of Ecological Disposal bed has the current gradient of 1-3%.

(5) the bottom antiseepage processing of Ecological Disposal bed, adopts and lays barrier film, and barrier film can adopt the plastic foil of 1.5-2 millimeters thick, and lap-joint will handle well, to improve anti-seepage effect; Further, destroyed for preventing barrier film, need lay fine sand at barrier film bottom soil layer and barrier film upper surface, or add fine sand as protective layer using geotextiles.

(6) gangue fragmentation, mistake 100-300 mesh sieve.

(7) gangue after screening is immersed in waste acid liquor, keeps pH value 2-5, soak natural air drying after 2-4 hour, waste acid liquor is from the unit such as lamp house, machinery plant of coal mining enterprise.

(8) the air-dry gangue of filling on the protective layer of barrier film, the filling thickness of gangue is 0.5-0.8 rice.

(9) on gangue, cover the contaminated soil of peeling off, the cladding thickness of contaminated soil is 1-1.5 rice again.

(10) plant of choosing seeds on Ecological Disposal bed.

(11) Ecological Disposal bed is regularly watered.Maintain on the one hand surviving of a upper plant, plant absorbs the chromium element in soil, is removed by the harvesting part chromium of plant.Water on the other hand and pour water or natural rainwater carries out leaching to contaminated soil, leachate contains a certain amount of Cr VI, leachate is penetrated into the spoil layer of Ecological Disposal bed bottom, reacts with acid gangue, and Cr VI is reduced into the low harmful substances of the low toxicities such as trivalent chromium.

(12) be designed with the collection pool of leachate in the downstream of Ecological Disposal bed, be used for that watering after collection and treatment poured water or natural rainwater, realize qualified discharge.

(13) keep Ecological Disposal bed operating 6-12 month, the Ecological Disposal bed after innoxious can be used for afforestation, ecologic planting, or as construction land etc.

2. the Ecological Disposal bed of a kind of chromium-polluted soil as claimed in claim 1, is characterized in that: described waste acid liquor is from the unit such as lamp house, machinery plant of coal mining enterprise.

3. the Ecological Disposal bed of a kind of chromium-polluted soil as claimed in claim 1, is characterized in that: the plant of seed selection should meet the following requirements: 1. strong to the absorbability of chromium; 2. adopt Native species, because of soil plantation, suit measures to local conditions; 3. resistance against diseases is strong; 4. be easy to results, be convenient to dispose; 5. waterlogging ability is strong; 6. well developed root system, cauline leaf is dense.Conventional plant has Li Shi standing grain, reed, Bermuda grass, chenopodium glaucum linn, eleusine indica etc.

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