Chromium-polluted site soil and underground water ecological restoration system and method

Abstract

The invention discloses an ecological restoration system and method for chromium-polluted site soil and underground water. The ecological restoration system comprises a pretreatment structure, a wetland main body structure and a tail end treatment structure which are sequentially connected from upstream to downstream, the pretreatment structure comprises a pretreatment storage pool, and a filtering and intercepting structure is connected with the pretreatment storage pool; the wetland main body structure comprises a wetland total area defined by an annular wetland main body outer wall, a wetland input separation dam beam and a wetland output separation dam beam are arranged in the wetland main body outer wall, and the interior of the wetland total area is divided into wetland water distribution tanks by the wetland input separation dam beam and the wetland output separation dam beam; a wetland main body area and a wetland drain tank; the ecological restoration system has the efficient purification capacity, chromium in soil and underground water can be efficiently removed through the physical, chemical and biological synergistic effect, chromium ions can be rapidly intercepted through physical adsorption, chromium can be converted into low-solubility compounds through chemical precipitation, and the toxicity and mobility of chromium can be reduced through plant absorption and microbial reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a soil and groundwater ecological remediation system and method for a chromium-contaminated site. Background Art

[0002] With the development of industrial activities such as chromate production, electroplating and leather tanning, chromium enters the environmental medium through industrial wastewater, waste gas and solid waste. In recent years, excessive chromium has often been detected in soil and groundwater. Chromium mainly exists in the environment in the form of hexavalent chromium and trivalent chromium, of which hexavalent chromium is much more toxic than trivalent chromium. Soil chromium is easily oxidized into soluble complex anions under leaching and migrates to surface water or groundwater through hydraulic runoff. Under the influence of groundwater chemistry and hydrodynamic conditions, chromium is very easy to migrate, diffuse and transform, resulting in the soil and groundwater of contaminated plots being threatened by potential Cr(VI) contamination over a long period of time and over a large area. Therefore, it is of great practical significance to carry out site soil and groundwater Cr(VI) contamination remediation.

[0003] At present, the mainstream technologies for treating chromium-contaminated soil and groundwater are: (1) converting highly toxic and highly mobile hexavalent chromium into low-toxic and low-mobility trivalent chromium, and solidifying and stabilizing the trivalent chromium in the soil; (2) reducing the chromium content in the soil through leaching technology; (3) removing hexavalent chromium from groundwater by chemical methods such as dosing-coagulation-flocculation-precipitation. With the rapid development of environmental protection, artificial wetlands have received more and more attention and development. As a new type of ecological sewage purification method, artificial wetland system water purification technology has the basic principle of planting specific wetland plants on artificial wetland fillers to establish an artificial wetland ecosystem. When sewage passes through the wetland system, the pollutants and nutrients in it are absorbed or decomposed by the system, thereby achieving the purification function. However, the soil and groundwater treatment technology specifically for heavily chromium-contaminated sites is very traditional and limited, and an efficient chromium pollution remediation technology is urgently needed to solve such soil and underground chromium pollution problems. Summary of the invention

[0004] The purpose of the present invention is to provide a system and method for ecological restoration of soil and groundwater in chromium-contaminated sites, which can effectively purify the soil and groundwater in chromium-contaminated sites in an environmentally friendly manner.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A soil and groundwater ecological restoration system for a chromium-contaminated site, comprising a pretreatment structure, a wetland main structure and a terminal treatment structure which are sequentially connected from upstream to downstream;

[0007] The pre-processing structure includes a pre-processing storage pool, and a filtering and intercepting structure is connected to the pre-processing storage pool;

[0008] The main structure of the wetland includes a wetland total area surrounded by a circular wetland main body outer wall, and a wetland input dividing dam beam and a wetland output dividing dam beam are arranged inside the wetland main body outer wall. The wetland input dividing dam beam and the wetland output dividing dam beam divide the interior of the wetland total area into a wetland water distribution pool, a wetland main area and a wetland drainage pool;

[0009] There are multiple parallel circulation partition dams in the main wetland area, which divide the main wetland area into multiple wetland subdivision areas;

[0010] There are multiple channel side dam beams arranged in parallel in the wetland subdivision area, and the multiple channel side dam beams together form a wetland water flow channel;

[0011] A channel matrix layer is laid in the wetland water flow channel;

[0012] Chromium pollution purification plants are planted in the wetland water flow channel, on the circulation partition dam beams and the channel side dam beams;

[0013] Chromium pollution-purifying microorganisms are spread in the matrix within the wetland water flow channel;

[0014] The terminal treatment structure includes a terminal purification treatment pool, which is connected to the wetland drainage pool;

[0015] The terminal purification treatment pool is provided with a plurality of terminal treatment filter dams arranged in parallel with each other;

[0016] A plurality of terminal treatment external discharge pipes connected with the interior of the terminal purification treatment pool are fixed on the downstream side thereof, and a terminal treatment external discharge pipe is provided with a terminal external discharge control valve.

[0017] Preferably, the filtering and intercepting structure comprises a filtering and intercepting pool, in which a plurality of filtering partition baffles which are parallel to each other and placed vertically are fixed, and the filtering partition baffles divide the interior of the filtering and intercepting pool into a plurality of partitioned filtering spaces;

[0018] From upstream to downstream, each partitioned filter space is filled with 20-50 mm pebbles, 5-10 mm pebbles, 1-3 mm gravel, and 0.5-1 mm sand respectively;

[0019] The upstream side of the filter interception tank is connected to the downstream side of the pretreatment storage tank through a plurality of filter interception input pipes;

[0020] Partition filter screens are fixed on both sides of the filter partition plate;

[0021] The filter partition partition has a plurality of filter partition through holes that pass through both sides. The filter partition partition has a hollow structure inside. The filter partition partition is horizontally slidably connected with a partition on-off control board inside. The partition on-off control board has a plurality of filter partition matching holes that pass through both sides.

[0022] A plurality of on-off control accommodating shells are fixed on the outside of the filter interception pool, and an on-off control through hole is provided on the side wall of the filter interception pool, which connects the inside of the filter partition partition and the inside of the on-off control accommodating shell. An on-off control connecting rod is slidably connected in the on-off control through hole, and one end of the on-off control connecting rod is located inside the filter partition partition and is fixedly connected to the side end of the partition on-off control board;

[0023] An on-off control driving rod for driving the on-off control connecting rod to move is fixed in the on-off control accommodating shell.

[0024] Description: The use of filtering and intercepting structures facilitates the control of the specific flow mode of contaminated groundwater in each partitioned filtering space, and allows for underground flow in the horizontal direction or in the vertical direction.

[0025] Preferably, the channel matrix layer is formed by filling and paving a channel matrix bottom layer, a channel matrix middle layer and a channel matrix surface layer in sequence from bottom to top;

[0026] The bottom layer of the channel matrix is ​​composed of pebbles with a particle size of 20 to 50 mm, gravel with a particle size of 20 to 40 mm, and zeolite with a particle size of 20 to 30 mm;

[0027] The middle layer of the channel matrix is ​​composed of volcanic rock with a particle size of 10 to 20 mm, ceramsite with a particle size of 5 to 15 mm, and anthracite with a particle size of 5 to 10 mm;

[0028] The surface layer of the channel matrix is ​​composed of sand with a particle size of 0.5 to 2 mm, coconut shell activated carbon with a particle size of 0.5 to 2 mm, and humus soil with a particle size of 0.05 to 0.2 mm.

[0029] Description: The channel matrix layer can play a good role in physical filtration and adsorption. It can adsorb chromium pollutants on the surface of the matrix and reduce the content of heavy metals in sewage. At the same time, the channel matrix layer can provide a living environment for microorganisms and plants. These microorganisms transform and remove chromium pollutants in sewage through metabolism.

[0030] Preferably, the cross-section of the channel side dam beam is a trapezoidal structure, and a leachate discharge pipe is laid at the bottom of each channel side dam beam. A plurality of leachate flow short pipes connected to the interior are fixed to the outside of the leachate discharge pipe, and a leachate filter plate is fixed to the outer end of the leachate flow short pipe. Multiple leachate discharge pipes are connected together to form a leachate temporary storage tank.

[0031] Note: After the dam beams on the side of the channel absorb water, the moisture inside them will flow from top to bottom under the action of gravity to form leachate. The chromium pollutants inside the dam beams on the side of the channel will be mixed into the leachate to form chromium-contaminated leachate. These leachates will be collected together for easy transportation to the wetland water distribution pool, so that the chromium-contaminated leachate can be purified together with the contaminated groundwater.

[0032] Preferably, the bottom of the wetland total area is an impermeable layer structure, and the impermeable layer structure is an impermeable bottom layer, an impermeable middle layer and an impermeable surface layer from bottom to top;

[0033] The anti-seepage bottom layer is clay, the anti-seepage middle layer is bentonite, and the anti-seepage surface layer is clay.

[0034] Note: The anti-seepage layer structure can confine chromium pollutants within the artificial wetland system, preventing them from penetrating downward through the soil pores and spreading to deeper soil and groundwater, thereby expanding the scope of pollution.

[0035] Preferably, a bottom layer impermeable membrane is laid between the top of the impermeable bottom layer and the bottom of the impermeable middle layer;

[0036] A surface anti-seepage membrane is laid between the top of the anti-seepage middle layer and the bottom of the anti-seepage surface layer.

[0037] Note: The double bottom anti-seepage membrane can effectively prevent the leakage of chromium pollutants caused by damage to a single anti-seepage membrane.

[0038] Preferably, a plurality of plant planting tubes with openings facing upward are fixed inside the top of the channel side dam beam, and a plurality of root through holes communicating with the inside and outside are provided on the side walls of the plant planting tubes.

[0039] Note: The plant planting tube is convenient for taking out the plants planted inside for replacement. Plants enriched with chromium pollutants are also convenient for harmless treatment to avoid secondary pollution to the environment.

[0040] Preferably, the terminal treatment filter dam body is composed of a coal slag layer, a bioceramsite layer, and a volcanic rock layer from upstream to downstream.

[0041] Note: Setting up a terminal treatment filter dam can more thoroughly remove the small amount of chromium pollutants remaining in the groundwater, further improve the quality of the purified water, and allow the purified groundwater to safely flow into the surface runoff.

[0042] Preferably, a method for ecological restoration of soil and groundwater in a chromium-contaminated site is based on a system for ecological restoration of soil and groundwater in a chromium-contaminated site according to any one of claims 1 to 8, comprising the following steps:

[0043] S1. Groundwater extraction:

[0044] The contaminated groundwater is pumped out and transported to a pre-treatment storage tank, where it is left to stand for 6 to 12 hours;

[0045] Make the contaminated groundwater in the pre-treatment storage tank consistent with the external environment temperature;

[0046] S2. Adsorption pretreatment:

[0047] After standing, the polluted groundwater is then transported to the filtration and interception structure for physical adsorption and filtration treatment;

[0048] S3, Wetland purification treatment:

[0049] The contaminated groundwater after adsorption pretreatment is then transported to the wetland area;

[0050] The contaminated groundwater flows sequentially through the wetland distribution pool, the main wetland area, and the wetland drainage pool;

[0051] In the main area of ​​the wetland, the contaminated groundwater circulates along the wetland water flow channel, and the contaminated groundwater flows horizontally in the matrix of the wetland water flow channel;

[0052] The chromium pollution in the contaminated groundwater is purified by the adsorption effect of the matrix in the wetland water flow channel;

[0053] The circulation partition dam beam and the channel side dam beam are constructed of soil from the chromium-contaminated site. The chromium pollutants in the circulation partition dam beam and the channel side dam beam will diffuse into the contaminated groundwater and be adsorbed and purified together;

[0054] At the same time, plants that can absorb and purify chromium pollution are planted on the dam beams of the circulation partitions and the dam beams on the sides of the channel. The soil of the chromium-contaminated site is purified by the absorption function of the plant roots.

[0055] S4, terminal processing:

[0056] After physical adsorption, microbial purification and plant purification, the contaminated groundwater finally enters the terminal purification treatment pool. The contaminated groundwater flows through each terminal treatment filter dam in turn, and the adsorption effect of the terminal treatment filter dam is used to remove the residual chromium pollutants in the contaminated groundwater.

[0057] Finally, clean groundwater is formed and discharged through the external discharge pipes of each terminal treatment unit, so that the clean groundwater merges into the surface runoff. By adjusting the opening of the terminal external discharge control valve, the discharge speed of the clean groundwater can be controlled.

[0058] Compared with the prior art, the beneficial effects of the present invention are embodied in the following aspects:

[0059] 1. The structural design of the present invention is reasonable. The ecological restoration system has high-efficiency purification ability and can efficiently remove chromium in soil and groundwater through physical, chemical and biological synergistic effects. Physical adsorption can quickly intercept chromium ions, chemical precipitation can convert chromium into low-soluble compounds, and plant absorption and microbial reduction can reduce the toxicity and mobility of chromium, thereby achieving effective removal of chromium in different valence states.

[0060] 2. The ecological restoration system of the present invention can adapt to different pollution levels. Whether it is a light, medium or heavy chromium-contaminated site, it can operate stably and reach a certain purification standard;

[0061] 3. The ecological restoration system of the present invention has the ability to remove a variety of pollutants. In addition to chromium pollutants, it can also remove other heavy metals, organic matter and other pollutants that may exist in the site. It has a wide range of pollutant purification functions and can achieve comprehensive restoration of soil and groundwater;

[0062] 4. The ecological restoration system of the present invention has no secondary pollution. During the purification process, no secondary pollutants or harmful by-products will be generated, chromium pollutants will not be converted from one form to another more harmful form, and other toxic and harmful substances will not be released into the environment, thus ensuring the environmental safety of the restoration process;

[0063] 5. The ecological restoration system of the present invention has long-term stability, good resistance to shock loads, strong adaptability to fluctuations in water quality and water volume, and can maintain a stable purification effect under a certain degree of shock load. It also has strong site adaptability and can adapt to various types of chromium-contaminated sites, including industrial wastelands, mine tailings ponds, landfills, etc. The entire ecological restoration system can be reasonably designed and adjusted according to the terrain, landform, and soil type of the site to achieve effective restoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a top view of the overall layout of the ecological restoration system of the present invention;

[0065] Figure 2 It is a structural schematic diagram of the filtering and intercepting structure of the present invention;

[0066] Figure 3 It is a schematic diagram of the structure of the filter partition baffle of the present invention;

[0067] Figure 4 is a top view of the filter partition baffle of the present invention;

[0068] Figure 5 It is a schematic diagram of the structure of the wetland water flow channel of the present invention;

[0069] Figure 6 It is a schematic diagram of the structure of the leachate external discharge pipe of the present invention;

[0070] Figure 7 It is a structural schematic diagram of the plant planting tube of the present invention;

[0071] Figure 8 It is a schematic diagram of the structure of the terminal purification treatment pool of the present invention.

[0072] In the figure, 10-pretreatment structure, 11-pretreatment storage pool, 12-filtration interception structure, 120-partitioned filtration space, 1201-filtration interception input pipe, 1202-filtration interception output pipe, 121-filtration interception pool, 122-filtration partition partition, 1220-filtration partition through hole, 1221-partition filter screen, 123-partition on-off control board, 1230-filtration partition matching hole, 124-on-off control housing shell, 1240-on-off control perforation, 125-on-off control connecting rod, 126-on-off control driving rod, 20-wetland main structure, 200-wetland total area, 201-wetland water distribution pool, 202-wetland main area, 2020-wetland subdivision area, 203-wetland drainage pool, 21-wetland main outer wall, 211-wetland input Separation dam beam, 212-wetland output separation dam beam, 213-circulation partition dam beam, 214-channel side dam beam, 2140-wetland water flow channel, 22-channel matrix layer, 221-channel matrix bottom layer, 222-channel matrix middle layer, 223-channel matrix surface layer, 23-leachate external discharge pipe, 231-leachate circulation short pipe, 232-leachate filter plate, 24-anti-seepage layer structure, 241-anti-seepage bottom layer, 242-anti-seepage middle layer, 243-anti-seepage surface layer, 25-plant planting tube, 251-root perforation, 30-terminal treatment structure, 31-terminal purification treatment pool, 311-terminal treatment external discharge pipe, 3110-terminal external discharge control valve, 32-terminal treatment filter dam body, 321-coal slag layer, 322-biological ceramsite layer, 323-volcanic rock layer. DETAILED DESCRIPTION

[0073] Combine the following Figures 1 to 8 The present invention is described in detail. For the convenience of description, the directions mentioned below are defined as follows: the up, down, left, right, front, and back directions mentioned below are consistent with the up, down, left, right, front, and back directions of the projection relationship of the respective main views or structural schematic diagrams themselves.

[0074] Embodiment 1:

[0075] A soil and groundwater ecological restoration system for chromium contaminated sites, such as Figure 1 As shown, it includes a pre-treatment structure 10, a wetland main structure 20 and a terminal treatment structure 30 which are sequentially connected from upstream to downstream;

[0076] The pre-processing structure 10 includes a pre-processing storage tank 11, and a filtering and intercepting structure 12 is connected to the pre-processing storage tank 11;

[0077] like Figure 1 As shown, the wetland main structure 20 includes a wetland total area 200 surrounded by a circular wetland main body peripheral wall 21, and a wetland input partition dam beam 211 and a wetland output partition dam beam 212 are arranged inside the wetland main body peripheral wall 21. The wetland input partition dam beam 211 and the wetland output partition dam beam 212 divide the interior of the wetland total area 200 into a wetland water distribution pool 201, a wetland main area 202 and a wetland drainage pool 203;

[0078] A plurality of pipes for connecting the wetland water distribution pool 201 and the wetland main area 202 are buried inside the wetland input partition dam beam 211, and a plurality of pipes for connecting the wetland main area 202 and the wetland drainage pool 203 are buried inside the wetland output partition dam beam 212;

[0079] The downstream side of the filter interception pool 121 is connected to the wetland water distribution pool 201 through a plurality of filter interception output pipes 1202;

[0080] A plurality of circulation partition dam beams 213 arranged in parallel with each other are provided in the main wetland area 202, and the circulation partition dam beams 213 divide the main wetland area 202 into a plurality of wetland subdivision areas 220;

[0081] A plurality of channel side dam beams 214 arranged in parallel with each other are provided in the wetland subdivision area 220, and a wetland water flow channel 2140 is formed by the plurality of channel side dam beams 214;

[0082] like Figure 5 As shown, a channel matrix layer 22 is laid in the wetland water flow channel 2140;

[0083] The wetland input partition dam beam 211 and the wetland output partition dam beam 212 are both perpendicular to the upstream and downstream flow direction of the water flow, the flow partition dam beam 213 is parallel to the upstream and downstream flow direction of the water flow, and the side dam beams 214 of each channel are both perpendicular to the upstream and downstream flow direction of the water flow;

[0084] The circulation partition dam beam 213 and the channel side dam beam 214 are constructed from soil from the chromium contaminated site;

[0085] Chromium pollution purification plants are planted in the wetland water flow channel 2140, on the circulation partition dam beam 213 and the channel side dam beam 214. The chromium pollution purification plants include reed, cattail, rush, Li's grass, yellow iris, canna, lily flower, wild rice, nightshade, centipede grass;

[0086] These plants have the ability to absorb chromium ions, absorb chromium through the root system, and then transport it to the aboveground parts. There are various ion channels and transport proteins on the cell membrane of the plant root system, which can recognize and absorb chromium ions;

[0087] After plants absorb chromium, they will undergo a certain degree of metabolism in their bodies. Some of the chromium will be fixed on the plant cell walls, and some will combine with organic compounds in the cells. Chromium can combine with organic acids in the plant body, such as citric acid and malic acid, to reduce its toxicity. When the plants grow to a certain stage, the chromium can be removed from the wetland system by harvesting the plants to prevent it from being released into the environment again.

[0088] Chromium pollution purification microorganisms are spread in the matrix in the wetland water flow channel 2140, and the chromium pollution purification microorganisms include denitrifying bacteria, anaerobic ammonia oxidation coupled iron-reducing bacteria, acetyl bacteria, and Geobacter;

[0089] These microorganisms have a strong ability to adsorb chromium in artificial wetlands. The surface of microbial cells is negatively charged and can adsorb positively charged chromium ions. This adsorption can cause chromium ions to accumulate on the surface of microbial cells, thereby reducing their free concentration in soil and groundwater.

[0090] Microorganisms can also biotransform chromium, reducing Cr(VI) to Cr(III). Microorganisms can also change the form of chromium through reactions such as methylation. Microorganisms can convert chromium into organic chromium compounds. The properties and toxicity of these compounds are different from those of inorganic chromium. To a certain extent, they can change the mobility and toxicity of chromium in wetland ecosystems. At the same time, some enzymes and organic substances secreted by microorganisms during metabolism can also affect the chemical form and bioavailability of chromium.

[0091] like Figure 5 As shown, the channel matrix layer 22 is formed by filling and paving a channel matrix bottom layer 221, a channel matrix middle layer 222 and a channel matrix surface layer 223 in sequence from bottom to top;

[0092] The channel matrix bottom layer 221 is composed of pebbles with a particle size of 20 mm, gravel with a particle size of 20 mm, and zeolite with a particle size of 20 mm in a volume ratio of 1:1:1;

[0093] The channel matrix middle layer 222 is composed of volcanic rock with a particle size of 10 mm, ceramsite with a particle size of 5 mm, and anthracite with a particle size of 5 mm in a volume ratio of 1:1:1;

[0094] The channel matrix surface layer 223 is composed of sand with a particle size of 0.5 mm, coconut shell activated carbon with a particle size of 0.5 mm, and humus soil with a particle size of 0.05 mm in a volume ratio of 1:1:1;

[0095] like Figure 5 As shown, the bottom of the wetland total area 200 is an impermeable layer structure 24, and the impermeable layer structure 24 is composed of an impermeable bottom layer 241, an impermeable middle layer 242 and an impermeable surface layer 243 from bottom to top;

[0096] The anti-seepage bottom layer 241 is clay, the anti-seepage middle layer 242 is bentonite, and the anti-seepage surface layer 243 is clay;

[0097] like Figure 5 As shown, a bottom anti-seepage membrane 2410 is laid between the top of the anti-seepage bottom layer 221 and the bottom of the anti-seepage middle layer 222, and the bottom anti-seepage membrane 2410 is a polyethylene geomembrane in the prior art;

[0098] A surface anti-seepage membrane 2430 is laid between the top of the anti-seepage middle layer 222 and the bottom of the anti-seepage surface layer 223. The surface anti-seepage membrane 2430 is a polyethylene geomembrane in the prior art.

[0099] like Figure 5 As shown, a plurality of plant planting tubes 25 with openings facing upward are fixed inside the top of the channel side dam beam 214, such as Figure 7 As shown, the side wall of the plant planting tube 25 has a plurality of root through holes 251 communicating with each other inside and outside;

[0100] like Figure 1 As shown, the terminal treatment structure 30 includes a terminal purification treatment pool 31, and the terminal purification treatment pool 31 is connected to the wetland drainage pool 203;

[0101] like Figure 8 As shown, a plurality of terminal treatment filter dams 32 arranged in parallel with each other are provided in the terminal purification treatment pool 31, and the extension direction of the terminal treatment filter dams 32 is perpendicular to the water flow direction;

[0102] A plurality of terminal treatment external discharge pipes 311 connected to the interior of the terminal purification treatment tank 31 are fixed to the downstream side thereof, and a terminal treatment external discharge pipe 311 is provided with a terminal external discharge control valve 3110;

[0103] like Figure 8 As shown, the terminal treatment filter dam body 32 comprises a coal slag layer 321, a biological ceramsite layer 322, and a volcanic rock layer 323 from upstream to downstream.

[0104] Embodiment 2:

[0105] This embodiment describes a method for ecological restoration of soil and groundwater in a chromium-contaminated site, and a system for ecological restoration of soil and groundwater in a chromium-contaminated site based on the above-mentioned embodiment 1, comprising the following steps:

[0106] S1. Groundwater extraction:

[0107] The contaminated groundwater is pumped out and transported to the pretreatment storage tank 11, and allowed to stand for 6 to 12 hours;

[0108] Make the contaminated groundwater in the pre-treatment storage tank 11 consistent with the external environment temperature;

[0109] S2. Adsorption pretreatment:

[0110] The polluted groundwater after standing is then transported to the filtering and intercepting structure 12 for physical adsorption and filtering treatment;

[0111] Chromium pollution purification plants are planted in the interception and filtration space 120 of each partition, including reed, cattail, rush, Li's grass, yellow iris, canna, lily flower, zizyphus, nightshade, centipede grass;

[0112] S3, Wetland purification treatment:

[0113] The contaminated groundwater after adsorption pretreatment is then transported to the wetland total area 200;

[0114] The contaminated groundwater flows sequentially through the wetland water distribution pool 201, the wetland main area 202 and the wetland drainage pool 203;

[0115] In the wetland main area 202, the contaminated groundwater flows along the wetland water flow channel 2140, and the contaminated groundwater flows horizontally in the matrix within the wetland water flow channel 2140;

[0116] Purify chromium pollution in contaminated groundwater by using the adsorption effect of the matrix in the wetland water flow channel 2140;

[0117] The circulation partition dam beam 213 and the channel side dam beam 214 are constructed of soil from the chromium-contaminated site. The chromium pollutants in the circulation partition dam beam 213 and the channel side dam beam 214 will diffuse into the contaminated groundwater and be adsorbed and purified together.

[0118] At the same time, plants capable of absorbing and purifying chromium pollution are planted on the circulation partition dam beam 213 and the channel side dam beam 214, including reeds, cattails, rushes, Li's grass, yellow iris, canna, lily flower, zizyphus, nightshade, and centipede grass. The soil of the chromium-contaminated site is purified by the root absorption of these plants;

[0119] S4, terminal processing:

[0120] After physical adsorption, microbial purification and plant purification, the contaminated groundwater finally enters the terminal purification treatment pool 31, and the contaminated groundwater flows through each terminal treatment filter dam 32 in sequence, and the adsorption effect of the coal slag layer 321, the biological ceramsite layer 322 and the volcanic rock layer 323 is used to remove the residual chromium pollutants in the contaminated groundwater;

[0121] Finally, clean groundwater is formed and discharged through each terminal treatment external discharge pipe 311, so that the clean groundwater merges into the surface runoff. The opening of the terminal external discharge control valve 3110 can be adjusted to control the discharge speed of the clean groundwater.

[0122] Embodiment 3:

[0123] On the basis of Example 1, Figure 2 As shown, the filtering and intercepting structure 12 includes a filtering and intercepting pool 121, in which a plurality of filtering partition baffles 122 which are parallel to each other and placed vertically are fixed, and the plane of the filtering partition baffles 122 is perpendicular to the water flow direction, and the filtering partition baffles 122 divide the inside of the filtering and intercepting pool 121 into a plurality of partitioned filtering spaces 120;

[0124] From upstream to downstream, each partitioned filter space 120 is filled with 20-30 mm pebbles, 5-7 mm pebbles, 1-2 mm gravel, and 0.5-0.7 mm sand respectively;

[0125] like Figure 1 As shown, the upstream side of the filter interception tank 121 is connected to the downstream side of the pretreatment storage tank 11 through a plurality of filter interception input pipes 1201;

[0126] like Figure 3 As shown, partition filter screens 1221 are fixed on both sides of the filter partition partition 122, and the partition filter screen 1221 is a 20-mesh filter screen of the prior art;

[0127] like Figure 3 As shown, the filter partition partition plate 122 has a plurality of filter partition through holes 1220 that pass through both sides. The filter partition partition plate 122 has a hollow structure inside, which is equivalent to being formed by two plates arranged in parallel. The filter partition partition plate 122 is slidably connected to a partition on-off control plate 123 in the horizontal direction. The partition on-off control plate 123 has a plurality of filter partition matching holes 1230 that pass through both sides.

[0128] A plurality of filtering partition through holes 1220 arranged in the horizontal direction form a group, and a plurality of filtering partition through holes 1220 are arranged in the vertical direction on the filtering partition partition plate 122;

[0129] The sliding direction of the partition on-off control plate 123 is the direction in which the filter partition through holes 1220 are arranged horizontally. A plurality of partition on-off control plates 123 are arranged vertically inside the filter partition baffle 122.

[0130] like Figure 4 As shown, a plurality of on-off control accommodating shells 124 are fixed to the outside of the filter interception pool 121, and an on-off control through hole 1240 is provided on the side wall of the filter interception pool 121 to connect the inside of the filter partition partition 122 and the inside of the on-off control accommodating shell 124, and an on-off control connecting rod 125 is slidably connected in the on-off control through hole 1240, and one end of the on-off control connecting rod 125 is located inside the filter partition partition 122 and is fixedly connected to the side end of the partition on-off control board 123;

[0131] An on-off control driving rod 126 for driving the on-off control connecting rod 125 to move is fixed inside the on-off control accommodating shell 124. The on-off control driving rod 126 is an electrically controlled telescopic rod driven by a servo motor in the prior art. The outer rod end of the on-off control driving rod 126 is fixedly connected to the on-off control accommodating shell 124, and the inner rod end of the on-off control driving rod 126 is fixedly connected to one end of the on-off control connecting rod 125 inside the on-off control accommodating shell 124.

[0132] Embodiment 4:

[0133] This embodiment records a method for ecological restoration of soil and groundwater in a chromium-contaminated site, and a system for ecological restoration of soil and groundwater in a chromium-contaminated site based on the above-mentioned embodiment 3, which is different from embodiment 2 in that, in step S1, a plurality of partition on-off control panels 123 in each filtering partition partition 122 can control the connectivity of two adjacent partitioned filter spaces 120, and the extension and retraction of the inner rod of the on-off control driving rod 126 can drive the on-off control connecting rod 125 together with the partition on-off control panel 123 to move in the horizontal direction, so as to control the alignment and connection of each filter partition through hole 1220 with the filter partition matching hole 1230, and to isolate the misaligned phases;

[0134] When the through holes 1220 of each filtering partition are aligned and connected with the matching holes 1230 of the filtering partition, the two adjacent partition filtering spaces 120 are in a connected state at the partition on-off control plate 123; on the contrary, when the through holes 1220 of each filtering partition are misaligned and isolated with the matching holes 1230 of the filtering partition, the two adjacent partition filtering spaces 120 are in an isolated state at the partition on-off control plate 123;

[0135] Multiple partition on-off control panels 123 are arranged in each filtering partition partition 122 along the vertical direction, that is, each filtering partition partition 122 can independently control the connectivity between two adjacent partition filtering spaces 120 at multiple positions in the vertical direction;

[0136] Finally, the specific flow mode of the contaminated groundwater in each partitioned filter space 120 is controlled, and the contaminated groundwater flows horizontally or vertically.

[0137] When the connection states of the filter partition baffle 122 at the upstream end and the filter partition baffle 122 at the downstream end are consistent, the contaminated groundwater is in a horizontal undercurrent state in the partitioned filter space 120;

[0138] When the higher position of the filter partition baffle 122 at the upstream end is set to a connected state, and the lower position of the filter partition baffle 122 at the downstream end is set to a connected state, the contaminated groundwater is in a vertical underflow state from top to bottom in the partition filtration space 120.

[0139] Embodiment 5:

[0140] On the basis of Example 3, Figure 5 As shown, the cross section of the channel side dam beam 214 is a trapezoidal structure, and a leachate discharge pipe 23 is laid at the bottom of each channel side dam beam 214. Figure 6 As shown, multiple leachate flow short tubes 231 connected to the inside of the leachate discharge pipe 23 are fixed to the outside, and a leachate filter plate 232 is fixed to the outer end of the leachate flow short tube 231. Multiple leachate discharge pipes 23 are connected together to form a leachate temporary storage tank.

[0141] The leachate filter plate 232 is a 100-mesh filter plate of the prior art.

[0142] Embodiment 6:

[0143] This embodiment records a method for ecological restoration of soil and groundwater in a chromium-contaminated site, and a system for ecological restoration of soil and groundwater in a chromium-contaminated site based on the above-mentioned embodiment 5. The difference from embodiment 4 is that in step S3, after the channel side dam beam 214 absorbs water, the water inside it will flow from top to bottom under the action of gravity, forming leachate that enters the leachate external discharge pipe 23 through the leachate circulation short pipe 231. The leachate in the leachate external discharge pipe 23 then flows into the leachate temporary storage tank, and the leachate is transported to the wetland water distribution pool 201 by a delivery pump, so that the leachate can be purified together with the contaminated groundwater.

[0144] Embodiment 7:

[0145] The difference from Example 5 is that the channel matrix bottom layer 221 is composed of pebbles with a particle size of 35 mm, gravel with a particle size of 30 mm, and zeolite with a particle size of 25 mm in a volume ratio of 1:2:1;

[0146] The channel matrix middle layer 222 is composed of volcanic rock with a particle size of 15 mm, ceramsite with a particle size of 10 mm, and anthracite with a particle size of 8 mm in a volume ratio of 1:2:1;

[0147] The channel matrix surface layer 223 is composed of sand with a particle size of 1 mm, coconut shell activated carbon with a particle size of 1 mm, and humus soil with a particle size of 0.1 mm in a volume ratio of 1:2:1;

[0148] Each partitioned filtering space 120 is filled with 30-40 mm pebbles, 6-8 mm pebbles, 1-2 mm gravel, and 0.6-0.8 mm sand in sequence.

[0149] Embodiment 8:

[0150] The difference from Example 5 is that the channel matrix bottom layer 221 is composed of pebbles with a particle size of 50 mm, gravel with a particle size of 40 mm, and zeolite with a particle size of 30 mm in a volume ratio of 3:2:1;

[0151] The channel matrix middle layer 222 is composed of volcanic rock with a particle size of 20 mm, ceramsite with a particle size of 15 mm, and anthracite with a particle size of 10 mm in a volume ratio of 3:2:1;

[0152] The channel matrix surface layer 223 is composed of sand with a particle size of 2 mm, coconut shell activated carbon with a particle size of 2 mm, and humus soil with a particle size of 0.2 mm in a volume ratio of 3:2:1;

[0153] Each partitioned filtering space 120 is filled with 40-50 mm pebbles, 8-10 mm pebbles, 2-3 mm gravel, and 0.8-1 mm sand in sequence.

[0154] Embodiment 9:

[0155] The difference from Example 6 is that in step S1, the contaminated groundwater is left to stand in the pretreatment storage tank 11 for 9 hours.

[0156] Embodiment 10:

[0157] The difference from Example 6 is that in step S1, the contaminated groundwater is left to stand in the pretreatment storage tank 11 for 12 hours.

[0158] In the actual application process of the present invention, the entire artificial wetland is constructed in a chromium-contaminated site, and the soil of the chromium-contaminated site is dug out to construct the circulation partition dam beam 213 and the channel side dam beam 214.

Claims

1. A soil and groundwater ecological restoration system for chromium-contaminated sites, characterized in that: It comprises a pre-treatment structure (10), a wetland main structure (20) and a terminal treatment structure (30) which are sequentially connected from upstream to downstream; The pre-processing structure (10) comprises a pre-processing storage pool (11), and a filtering interception structure (12) is connected to the pre-processing storage pool (11); The wetland main structure (20) comprises a wetland total area (200) surrounded by an annular wetland main body peripheral wall (21), wherein a wetland input partition dam beam (211) and a wetland output partition dam beam (212) are arranged inside the wetland main body peripheral wall (21), and the wetland input partition dam beam (211) and the wetland output partition dam beam (212) divide the interior of the wetland total area (200) into a wetland water distribution pool (201), a wetland main body area (202) and a wetland drainage pool (203); A plurality of circulation partitioning dam beams (213) arranged in parallel with each other are provided in the main wetland area (202), and the circulation partitioning dam beams (213) divide the main wetland area (202) into a plurality of wetland subdivision areas (2020); A plurality of channel side dam beams (214) arranged in parallel with each other are provided in the wetland subdivision area (220), and the plurality of channel side dam beams (214) together form a wetland water flow channel (2140); A channel matrix layer (22) is laid in the wetland water flow channel (2140); Chromium pollution purification plants are planted in the wetland water flow channel (2140), on the circulation partition dam beam (213) and the channel side dam beam (214); Chromium pollution purification microorganisms are spread in the matrix in the wetland water flow channel (2140); The terminal treatment structure (30) comprises a terminal purification treatment pool (31), and the terminal purification treatment pool (31) is connected to the wetland drainage pool (203); The terminal purification treatment pool (31) is provided with a plurality of terminal treatment filter dams (32) arranged in parallel with each other; A plurality of terminal treatment external discharge pipes (311) connected to the interior of the terminal purification treatment pool (31) are fixed to the downstream side thereof, and the terminal treatment external discharge pipes (311) are provided with terminal external discharge control valves (3110).

2. The chromium contaminated site soil and groundwater ecological restoration system according to claim 1, characterized in that: The filtering and intercepting structure (12) comprises a filtering and intercepting pool (121), wherein a plurality of filtering partition baffles (122) which are parallel to each other and placed vertically are fixed in the filtering and intercepting pool (121), and the filtering partition baffles (122) divide the interior of the filtering and intercepting pool (121) into a plurality of partitioned filtering spaces (120); The upstream side of the filtering and intercepting pool (121) is connected to the downstream side of the pretreatment storage pool (11) via a plurality of filtering and intercepting input pipes (1201); Partition filter screens (1221) are fixed on both sides of the filtering partition plate (122); The filtering partition partition (122) has a plurality of filtering partition through holes (1220) penetrating both sides, the filtering partition partition (122) has a hollow structure inside, the filtering partition partition (122) is slidably connected with a partition on-off control board (123) in a horizontal direction inside, and the partition on-off control board (123) has a plurality of filtering partition matching holes (1230) penetrating both sides; A plurality of on-off control accommodating shells (124) are fixed on the outside of the filtering interception pool (121); an on-off control through hole (1240) is provided on the side wall of the filtering interception pool (121) for communicating the interior of the filtering partition partition (122) and the interior of the on-off control accommodating shell (124); an on-off control connecting rod (125) is slidably connected in the on-off control through hole (1240); one end of the on-off control connecting rod (125) is located inside the filtering partition partition (122) and is fixedly connected to the side end of the partition on-off control board (123); An on-off control driving rod (126) for driving the on-off control connecting rod (125) to move is fixed in the on-off control accommodating shell (124).

3. The chromium contaminated site soil and groundwater ecological restoration system according to claim 1, characterized in that: The channel matrix layer (22) is formed by filling and paving a channel matrix bottom layer (221), a channel matrix middle layer (222) and a channel matrix surface layer (223) in sequence from bottom to top; The channel matrix bottom layer (221) is composed of pebbles with a particle size of 20 to 50 mm, gravels with a particle size of 20 to 40 mm, and zeolites with a particle size of 20 to 30 mm; The channel matrix middle layer (222) is composed of volcanic rock with a particle size of 10 to 20 mm, ceramsite with a particle size of 5 to 15 mm, and anthracite with a particle size of 5 to 10 mm; The channel matrix surface layer (223) is composed of sand with a particle size of 0.5 to 2 mm, coconut shell activated carbon with a particle size of 0.5 to 2 mm, and humus with a particle size of 0.05 to 0.2 mm.

4. The chromium contaminated site soil and groundwater ecological restoration system according to claim 1, characterized in that: The cross section of the channel side dam beam (214) is a trapezoidal structure. A leachate external discharge pipe (23) is laid at the bottom of each channel side dam beam (214). A plurality of leachate circulation short pipes (231) connected to the inside of the leachate external discharge pipe (23) are fixed to the outside of the leachate external discharge pipe (23). A leachate filter plate (232) is fixed to the outer end of the leachate circulation short pipe (231). A plurality of the leachate external discharge pipes (23) are connected together to form a leachate temporary storage tank.

5. The chromium contaminated site soil and groundwater ecological restoration system according to claim 1, characterized in that: The bottom of the wetland total area (200) is an anti-seepage layer structure (24), and the anti-seepage layer structure (24) comprises, from bottom to top, an anti-seepage bottom layer (241), an anti-seepage middle layer (242) and an anti-seepage surface layer (243); The anti-seepage bottom layer (241) is clay, the anti-seepage middle layer (242) is bentonite, and the anti-seepage surface layer (243) is clay.

6. The chromium contaminated site soil and groundwater ecological restoration system according to claim 1, characterized in that: A bottom layer impermeable membrane (2410) is laid between the top of the impermeable bottom layer (221) and the bottom of the impermeable middle layer (222); A surface anti-seepage membrane (2430) is laid between the top of the anti-seepage middle layer (222) and the bottom of the anti-seepage surface layer (223).

7. The chromium contaminated site soil and groundwater ecological restoration system according to claim 1, characterized in that: A plurality of plant planting tubes (25) with openings facing upward are fixed inside the top of the channel side dam beam (214), and a plurality of root system through holes (251) communicating with each other are provided on the side walls of the plant planting tubes (25).

8. The chromium contaminated site soil and groundwater ecological restoration system according to claim 1, characterized in that: The terminal treatment filter dam body (32) comprises, from upstream to downstream, a coal slag layer (321), a biological ceramsite layer (322), and a volcanic rock layer (323).

9. A method for ecological restoration of soil and groundwater in a chromium-contaminated site, based on a system for ecological restoration of soil and groundwater in a chromium-contaminated site according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Groundwater extraction: The contaminated groundwater is pumped out and transported to a pre-treatment storage tank (11) and allowed to stand for 6 to 12 hours; Making the contaminated groundwater in the pre-treatment storage tank (11) consistent with the external environment temperature; S2. Adsorption pretreatment: The contaminated groundwater after standing is then transported to the filtering and intercepting structure (12) for physical adsorption and filtration treatment; S3, Wetland purification treatment: The contaminated groundwater after adsorption pretreatment is then transported to the wetland area (200); The contaminated groundwater flows sequentially through the wetland distribution pool (201), the wetland main area (202) and the wetland drainage pool (203); In the main wetland area (202), the contaminated groundwater flows along the wetland water flow channel (2140), and the contaminated groundwater flows horizontally in the matrix within the wetland water flow channel (2140); Purifying chromium pollution in contaminated groundwater by utilizing the adsorption effect of the matrix in the wetland water flow channel (2140); The circulation partition dam beam (213) and the channel side dam beam (214) are constructed from soil from a chromium-contaminated site, and the chromium pollutants in the circulation partition dam beam (213) and the channel side dam beam (214) will diffuse into the contaminated groundwater and be adsorbed and purified together; At the same time, plants capable of absorbing and purifying chromium pollution are planted on the circulation partition dam beam (213) and the channel side dam beam (214), and the soil of the chromium-contaminated site is purified by utilizing the absorption function of the plant roots; S4, terminal processing: After physical adsorption, microbial purification and plant purification, the contaminated groundwater finally enters the terminal purification treatment pool (31), and the contaminated groundwater flows through each terminal treatment filter dam body (32) in sequence, and the adsorption effect of the terminal treatment filter dam body (32) is used to remove the residual chromium pollutants in the contaminated groundwater; Finally, clean groundwater is formed and discharged through each terminal treatment external discharge pipe (311), so that the clean groundwater merges into the surface runoff. By adjusting the opening of the terminal external discharge control valve (3110), the discharge speed of the clean groundwater can be controlled.

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