Constructed wetland and method for repairing heavy metal pollution by utilizing same

Abstract

The invention relates to the technical field of heavy metal treatment. The invention provides a constructed wetland and a method for repairing heavy metal pollution by using the constructed wetland, the constructed wetland comprises a heavy metal adsorption layer and heavy metal adsorption plants, and the heavy metal adsorption layer comprises the following components: modified zeolite, clay, attapulgite, sand and stones. According to the treatment method, the small constructed wetland is constructed near the natural wetland, water in the natural wetland is introduced into the constructed wetland to be purified, the content of heavy metal in the water body is reduced, and the purified water is introduced into the natural wetland again. The heavy metal in the wetland is transferred by using water, the treatment time is short, the efficiency is high, and the repair cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal treatment, and in particular to an artificial wetland and a method for repairing heavy metal pollution by using the artificial wetland. Background Art

[0002] As a transition zone between water and land, wetlands have great environmental regulation functions and ecological benefits. Together with forests and oceans, they are known as the world's three major ecosystems. They play an irreplaceable role in maintaining biodiversity, preventing floods and droughts, regulating climate, degrading pollutants, beautifying the environment, and providing production and living materials. They are one of the most important natural resources and living environments for mankind and are known as the "kidneys of the earth." In recent years, with the increasing prominence of environmental problems, wetland protection and sustainable use have become the focus and hotspot of common concern of governments and scientists around the world.

[0003] The sources of heavy metals in wetland sediments can be divided into two categories: natural sources and anthropogenic sources. Natural sources refer to various geological and geochemical processes, such as geological tectonic activities, rock weathering and soil formation processes. The natural sources of heavy metals form their natural abundance in a certain area, that is, the environmental background value. Anthropogenic sources mainly include industrial production pollution, traffic pollution, domestic waste, and unreasonable application of fertilizers, organic fertilizers, urban waste and pesticides containing heavy metals in agricultural production, as well as non-point source pollution caused by sewage irrigation. The heavy metals in these pollutants enter the sediments through surface runoff and atmospheric deposition, eventually leading to the accumulation of heavy metals in wetland sediments. In addition, the accumulation of heavy metals in sediments is not only controlled by the source of pollutants, but also affected by wetland environmental conditions and physical and chemical properties of sediments. It is generally believed that factors such as sediment organic matter content, mechanical composition, redox conditions, nutrient ion composition and vegetation coverage will affect the accumulation of heavy metals.

[0004] Therefore, how to repair the wetland system and reduce the level of heavy metal pollution has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide an artificial wetland and a method for repairing heavy metal pollution using the artificial wetland, so as to repair the wetland system and effectively reduce the heavy metal pollution level.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides an artificial wetland, which comprises a heavy metal adsorption layer and heavy metal adsorption plants. The heavy metal adsorption layer comprises the following components: modified zeolite, clay, attapulgite, sand and gravel.

[0008] Preferably, the thickness of the heavy metal adsorption layer is 20 to 100 cm;

[0009] The construction method of the heavy metal adsorption layer is:

[0010] (1) mixing modified zeolite, clay and attapulgite in a volume ratio of 7-11:10-20:1-1.4 to obtain a mixture;

[0011] (2) laying the mixed material on the bottom layer to obtain a mixed layer;

[0012] (3) A sand layer is laid on top of the mixed layer, and a gravel layer is laid on top of the sand layer.

[0013] Preferably, the thickness ratio of the mixed layer, the sand layer and the gravel layer is 5-10:4-8:3-6.

[0014] Preferably, the heavy metal adsorption plants include emergent plants and submerged plants; the density of the emergent plants is 15 to 25 plants / m 2 The density of submerged plants is 30 to 40 plants / m 2 .

[0015] Preferably, the emergent plants include lotus, cattail or reed; the submerged plants include duckweed, foxtail algae, pondweed or water chestnut.

[0016] The present invention also provides the use of the artificial wetland in repairing heavy metal pollution, and the object of the repair is a natural wetland polluted by heavy metals.

[0017] The present invention also provides a method for repairing heavy metal pollution using the artificial wetland, comprising the following steps: introducing water from a natural wetland into the artificial wetland, leaving it for 24 to 96 hours, testing the water quality, and discharging it back into the natural wetland after it meets the standards.

[0018] Preferably, the standard of the introduced water is: lead ion concentration of 50-400 mg / L, copper ion concentration of 25-250 mg / L, or zinc ion concentration of 90-800 mg / L.

[0019] Preferably, the water quality detection interval is 8 to 12 hours, and the compliance standards are: lead ion concentration <50 mg / L, copper ion concentration <25 mg / L and zinc ion concentration <90 mg / L.

[0020] The present invention provides an artificial wetland and a method for repairing heavy metal pollution using the artificial wetland. The artificial wetland includes a heavy metal adsorption layer and heavy metal adsorption plants. The heavy metal adsorption layer includes the following components: modified zeolite, clay, attapulgite, sand, and gravel. The treatment method of the present invention constructs a small artificial wetland near a natural wetland, introduces water from the natural wetland into the artificial wetland for purification, reduces the heavy metal content in the water body, and reintroduces the purified water into the natural wetland. The present invention uses water to achieve the transport of heavy metals in the wetland, with short processing time, high efficiency, and low repair cost. DETAILED DESCRIPTION

[0021] The invention provides an artificial wetland, which comprises a heavy metal adsorption layer and heavy metal adsorption plants. The heavy metal adsorption layer comprises the following components: modified zeolite, clay, attapulgite, sand and gravel.

[0022] In the present invention, the thickness of the heavy metal adsorption layer is preferably 20 to 100 cm, and more preferably 50 to 60 cm;

[0023] The construction method of the heavy metal adsorption layer is:

[0024] (1) mixing modified zeolite, clay and attapulgite in a volume ratio of 7-11:10-20:1-1.4 to obtain a mixture;

[0025] (2) laying the mixed material on the bottom layer to obtain a mixed layer;

[0026] (3) A sand layer is laid on top of the mixed layer, and a gravel layer is laid on top of the sand layer.

[0027] In the present invention, the volume ratio of the modified zeolite, clay and attapulgite is preferably 9:15:1.2.

[0028] In the present invention, the thickness ratio of the mixed layer, the sand layer and the gravel layer is preferably 5-10:4-8:3-6, and more preferably 7-8:6:4-5.

[0029] In the present invention, the heavy metal adsorbing plants include emergent plants and submerged plants; the density of the emergent plants is preferably 15 to 25 plants / m 2 , more preferably 20 plants / m 2 The density of the submerged plants is preferably 30 to 40 plants / m 2 , more preferably 35 plants / m 2 .

[0030] In the present invention, the emergent plants preferably include lotus, cattail or reed; the submerged plants preferably include hornwort, foxtail algae, pondweed or water chestnut.

[0031] The present invention also provides the use of the artificial wetland in repairing heavy metal pollution, and the object of the repair is a natural wetland polluted by heavy metals.

[0032] The present invention also provides a method for repairing heavy metal pollution using the artificial wetland, comprising the following steps: introducing water from a natural wetland into the artificial wetland, leaving it for 24 to 96 hours, testing the water quality, and discharging it back into the natural wetland after it meets the standards.

[0033] In the present invention, the residence time is preferably 48 to 72 hours.

[0034] In the present invention, the standard of the introduced water is preferably: a lead ion concentration of 50-400 mg / L, a copper ion concentration of 25-250 mg / L, or a zinc ion concentration of 90-800 mg / L, and more preferably: a lead ion concentration of 200-300 mg / L, a copper ion concentration of 100-150 mg / L, or a zinc ion concentration of 400-500 mg / L.

[0035] In the present invention, the interval for testing water quality is preferably 8 to 12 hours, and the standard for meeting the standard is preferably: lead ion concentration <50 mg / L, copper ion concentration <25 mg / L and zinc ion concentration <90 mg / L, and further preferably: lead ion concentration <30 mg / L, copper ion concentration <15 mg / L and zinc ion concentration <50 mg / L.

[0036] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0037] Example 1

[0038] A method for repairing a natural wetland polluted by heavy metals by using an artificial wetland comprises the following steps:

[0039] (1) According to the characteristics of the renovated site, the thickness of the heavy metal adsorption layer was determined to be 20 cm, and the mixed layer, sand layer, and gravel layer were constructed according to the thickness ratio of 5:4:3;

[0040] (2) mixing the modified zeolite, clay and attapulgite in a volume ratio of 7:10:1.4 to obtain a mixture;

[0041] (2) laying the mixed material on the bottom layer to obtain a mixed layer;

[0042] (3) laying a sand layer on the mixed layer, and laying a gravel layer on the sand layer to obtain a heavy metal adsorption layer;

[0043] (4) According to 15 plants / m 2 The standard for planting lotus is 40 plants / m 2Plant duckweed according to the standard and build artificial wetlands;

[0044] (5) Water from natural wetlands is introduced into artificial wetlands, and the water quality is tested every 8 hours. When the water meets the standards, it is discharged back into the natural wetlands.

[0045] Note: The standard of the introduced water is: lead ion concentration of 50-400 mg / L, copper ion concentration of 25-250 mg / L, or zinc ion concentration of 90-800 mg / L;

[0046] The standards for meeting the standards are: lead ion concentration <50 mg / L, copper ion concentration <25 mg / L and zinc ion concentration <90 mg / L.

[0047] Example 2

[0048] A method for repairing a natural wetland polluted by heavy metals by using an artificial wetland comprises the following steps:

[0049] (1) According to the characteristics of the renovated site, the thickness of the heavy metal adsorption layer was determined to be 100 cm, and the mixed layer, sand layer, and gravel layer were constructed according to the thickness ratio of 10:8:6;

[0050] (2) mixing the modified zeolite, clay and attapulgite in a volume ratio of 11:20:1 to obtain a mixture;

[0051] (2) laying the mixed material on the bottom layer to obtain a mixed layer;

[0052] (3) laying a sand layer on the mixed layer, and laying a gravel layer on the sand layer to obtain a heavy metal adsorption layer;

[0053] (4) According to 25 plants / m 2 The standard for planting cattail is 30 plants / m 2 Plant foxtail algae according to the standard and construct the artificial wetland;

[0054] (5) Water from natural wetlands is introduced into artificial wetlands, the water quality is tested every 12 hours, and it is discharged back into natural wetlands when it meets the standards.

[0055] Note: The standard of the introduced water is: lead ion concentration of 50-400 mg / L, copper ion concentration of 25-250 mg / L, or zinc ion concentration of 90-800 mg / L;

[0056] The standards for meeting the standards are: lead ion concentration <50 mg / L, copper ion concentration <25 mg / L and zinc ion concentration <90 mg / L.

[0057] Example 3

[0058] A method for repairing a natural wetland polluted by heavy metals by using an artificial wetland comprises the following steps:

[0059] (1) According to the characteristics of the renovated site, the thickness of the heavy metal adsorption layer was determined to be 60 cm, and the mixed layer, sand layer, and gravel layer were constructed according to the thickness ratio of 8:6:5;

[0060] (2) mixing the modified zeolite, clay and attapulgite in a volume ratio of 9:15:1.2 to obtain a mixture;

[0061] (2) laying the mixed material on the bottom layer to obtain a mixed layer;

[0062] (3) laying a sand layer on the mixed layer, and laying a gravel layer on the sand layer to obtain a heavy metal adsorption layer;

[0063] (4) According to 20 plants / m 2 The standard for planting reeds is 35 plants / m 2 Plant water chestnuts according to the standard and construct artificial wetlands;

[0064] (5) Water from natural wetlands is introduced into artificial wetlands, the water quality is tested every 10 hours, and it is discharged back into natural wetlands when it meets the standards.

[0065] Note: The standard of the introduced water is: lead ion concentration of 50-400 mg / L, copper ion concentration of 25-250 mg / L, or zinc ion concentration of 90-800 mg / L;

[0066] The standards for meeting the standards are: lead ion concentration <50 mg / L, copper ion concentration <25 mg / L and zinc ion concentration <90 mg / L.

[0067] Test example

[0068] The technical solutions of Examples 1 to 3 were used to conduct experiments in the same natural wetland contaminated by heavy metals. The water quality was detected before the experiment: the lead ion concentration was 387 mg / L, the copper ion concentration was 231 mg / L, or the zinc ion concentration was 604 mg / L.

[0069] After the test, the water quality of the artificial wetlands of Examples 1 to 3 was tested, and the results showed:

[0070] After 88 hours of treatment in the artificial wetland of Example 1, the lead ion concentration was 42 mg / L, the copper ion concentration was 21 mg / L, and the zinc ion concentration was 61 mg / L, meeting the emission standards;

[0071] After 72 hours of treatment in the artificial wetland of Example 2, the lead ion concentration was 37 mg / L, the copper ion concentration was 23 mg / L, and the zinc ion concentration was 75 mg / L, meeting the emission standards;

[0072] After 80 hours of treatment in the artificial wetland of Example 3, the lead ion concentration was 39 mg / L, the copper ion concentration was 17 mg / L, and the zinc ion concentration was 55 mg / L, which met the emission standards.

[0073] It can be seen from the above embodiments that the present invention provides an artificial wetland and a method for repairing heavy metal pollution using the artificial wetland, wherein the artificial wetland includes a heavy metal adsorption layer and heavy metal adsorption plants, and the heavy metal adsorption layer includes the following components: modified zeolite, clay, attapulgite, sand, and gravel. The treatment method of the present invention constructs a small artificial wetland near a natural wetland, introduces water from the natural wetland into the artificial wetland for purification, reduces the heavy metal content in the water body, and reintroduces the purified water into the natural wetland. The present invention utilizes water to achieve the transport of heavy metals in the wetland, with short processing time, high efficiency, and low repair cost.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An artificial wetland, characterized in that: The artificial wetland comprises a heavy metal adsorption layer and heavy metal adsorption plants, and the heavy metal adsorption layer comprises the following components: modified zeolite, clay, attapulgite, sand and stone.

2. The artificial wetland according to claim 1, characterized in that: The thickness of the heavy metal adsorption layer is 20 to 100 cm; The construction method of the heavy metal adsorption layer is: (1) mixing modified zeolite, clay and attapulgite in a volume ratio of 7-11:10-20:1-1.4 to obtain a mixture; (2) laying the mixed material on the bottom layer to obtain a mixed layer; (3) A sand layer is laid on top of the mixed layer, and a gravel layer is laid on top of the sand layer.

3. The artificial wetland according to claim 2, characterized in that: The thickness ratio of the mixed layer, the sand layer and the gravel layer is 5-10:4-8:3-6.

4. The artificial wetland according to claim 1, characterized in that: The heavy metal adsorption plants include emergent plants and submerged plants; the density of the emergent plants is 15 to 25 plants / m 2 The density of submerged plants is 30 to 40 plants / m 2 .

5. The artificial wetland according to claim 4, characterized in that: The emergent plants include lotus, cattail or reed; the submerged plants include duckweed, foxtail algae, pondweed or water chestnut.

6. Use of the artificial wetland according to any one of claims 1 to 5 in remediation of heavy metal pollution, characterized in that: The object of restoration is a natural wetland polluted by heavy metals.

7. A method for remediating heavy metal pollution using the artificial wetland according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: introducing water from a natural wetland into the artificial wetland described in any one of claims 1 to 5, leaving the water therein for 24 to 96 hours, testing the water quality, and discharging the water back to the natural wetland after the water meets the standards.

8. The method according to claim 7, characterized in that The standards of the introduced water are: lead ion concentration of 50-400 mg / L, copper ion concentration of 25-250 mg / L, or zinc ion concentration of 90-800 mg / L.

9. The method according to claim 8, characterized in that The water quality detection interval is 8 to 12 hours, and the compliance standards are: lead ion concentration <50 mg / L, copper ion concentration <25 mg / L and zinc ion concentration <90 mg / L.