A chromium-contaminated site soil and groundwater ecological remediation system and method

Abstract

The application discloses a kind of chromium pollution site soil and groundwater ecological restoration system and method, including the pretreatment structure, wetland main structure and end processing structure sequentially connected from upstream to downstream;The pretreatment structure includes pretreatment storage tank, and the filter interception structure is arranged and connected with the pretreatment storage tank;The wetland main structure includes the total area of wetland surrounded by annular wetland main peripheral wall, wetland input separation dam beam and wetland output separation dam beam are arranged in wetland main peripheral wall, and wetland input separation dam beam and wetland output separation dam beam divide the total area of wetland into wetland water distribution pool, wetland main area and wetland drainage pool;The ecological restoration system has high purification capacity, can remove chromium in soil and groundwater efficiently by physical, chemical and biological synergies, physical adsorption can quickly intercept chromium ion, chemical precipitation can convert chromium into low-solubility compound, plant absorption and microbial reduction can reduce the toxicity and mobility of chromium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil remediation, in particular to a chromium-polluted site soil and groundwater ecological remediation system and method. BACKGROUND

[0002] Chromium mainly exists in the form of hexavalent chromium and trivalent chromium in the environment, and the toxicity of hexavalent chromium is much greater than that of trivalent chromium. Soil chromium is easily oxidized into soluble complex anions under the action of leaching, and migrates to surface water or groundwater through hydraulic runoff. Under the influence of groundwater chemistry and hydrodynamic conditions, chromium is prone to migration, diffusion and transformation, resulting in potential pollution threat of Cr(Ⅵ) to soil and groundwater in a contaminated site for a long period of time and in a large spatial scale. Therefore, it is of great practical significance to carry out remediation of Cr(Ⅵ) pollution in site soil and groundwater.

[0003] At present, the main chromium-polluted soil and groundwater treatment technologies are as follows: (1) converting high-toxicity and high-migration hexavalent chromium into low-toxicity and low-migration trivalent chromium, and stabilizing trivalent chromium in soil; (2) reducing the chromium content in soil through leaching technology; (3) removing hexavalent chromium in groundwater by using chemical methods such as dosing, coagulation, flocculation and precipitation. With the rapid development of environmental protection, constructed wetlands have attracted more and more attention and development. As a new type of ecological sewage purification treatment method, the basic principle of constructed wetland system water purification technology is to plant specific wetland plants on the filler of the constructed wetland, so as to establish a constructed wetland ecosystem. When the sewage passes through the wetland system, the pollutants and nutrients in the sewage are absorbed or decomposed by the system, thereby realizing the purification function. However, the treatment technology for heavy chromium-polluted site soil and groundwater 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

[0004] The purpose of the present application is to provide a chromium-polluted site soil and groundwater ecological remediation system and method, which can effectively purify the soil and groundwater of a chromium-polluted site in an environmentally friendly manner.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] A chromium-polluted site soil and groundwater ecological remediation system, comprising a pretreatment structure, a wetland main structure and a terminal treatment structure connected in sequence from upstream to downstream;

[0007] The pretreatment structure comprises a pretreatment storage tank, and a filter interception structure is arranged in connection with the pretreatment storage tank;

[0008] The main structure of the wetland comprises a total wetland area surrounded by a ring-shaped wetland main peripheral wall, a wetland input separation dam beam and a wetland output separation dam beam are arranged in the wetland main peripheral wall, and the wetland input separation dam beam and the wetland output separation dam beam separate the total wetland area into a wetland water distribution pool, a wetland main area and a wetland drainage pool;

[0009] A plurality of flow partition dam beams are arranged in parallel in the wetland main area, and the flow partition dam beams separate the wetland main area into a plurality of wetland subareas;

[0010] A plurality of channel side dam beams are arranged in parallel in the wetland subarea, and the plurality of channel side dam beams jointly form a wetland water flow channel;

[0011] A channel substrate layer is arranged in the wetland water flow channel;

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

[0013] Chromium pollution purification microorganisms are scattered in the substrate in the wetland water flow channel;

[0014] The end treatment structure comprises an end purification treatment pool, and the end purification treatment pool is connected to the wetland drainage pool;

[0015] A plurality of end treatment filter dam bodies are arranged in parallel in the end purification treatment pool;

[0016] A plurality of end treatment discharge pipes are fixed to the downstream side of the end purification treatment pool and are connected to the inside of the end purification treatment pool, and the end treatment discharge pipes are provided with end discharge control valves;

[0017] Preferably, the filter interception structure comprises a filter interception pool, a plurality of filter partition plates are fixed in the filter interception pool and are arranged in parallel and vertically, and the filter partition plates separate the filter interception pool into a plurality of partition filter spaces;

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

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

[0020] The filter partition plates are fixed with partition filter screens on both sides;

[0021] The filter partitioning partition plate has a plurality of filter partitioning through holes penetrating both sides, the filter partitioning partition plate is hollow inside, and a partitioning on-off control plate is slidably connected to the filter partitioning partition plate along the horizontal direction, the partitioning on-off control plate has a plurality of filter partitioning matching holes penetrating both sides;

[0022] A plurality of on-off control accommodating shells are fixed outside the filter intercepting pool, the sidewall of the filter intercepting pool has on-off control perforations connecting the inside of the filter partitioning partition plate and the inside of the on-off control accommodating shell, an on-off control connecting rod is slidably connected in the on-off control perforation, and one end of the on-off control connecting rod in the inside of the filter partitioning partition plate is fixedly connected with the side end of the partitioning on-off control plate.

[0023] The on-off control accommodating shell is fixed with an on-off control driving rod for driving the on-off control connecting rod to move.

[0024] Description: The filter intercepting structure is used to control the specific flow mode of the contaminated groundwater in each filter partitioning space, and the flow is in the horizontal direction or the vertical direction.

[0025] Preferably, the channel matrix layer is sequentially filled and laid from bottom to top by a channel matrix bottom layer, a channel matrix middle layer and a channel matrix surface layer.

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

[0027] The channel matrix middle layer is composed of volcanic rock with a particle size of 10-20 mm, ceramic particles with a particle size of 5-15 mm and anthracite with a particle size of 5-10 mm.

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

[0029] Description: The channel matrix layer can play a good physical filtering and adsorption role, can adsorb chromium pollutants on the surface of the matrix, reduce the content of heavy metals in the wastewater, and at the same time, the channel matrix layer can provide a living environment for microorganisms and plants, and these microorganisms can convert and remove the chromium pollutants in the wastewater through metabolic action.

[0030] Preferably, the cross section of the channel side dam beam is in a trapezoidal structure, one seepage liquid discharge pipe is laid in the inner bottom of each channel side dam beam, a plurality of seepage liquid flow short pipes are fixed outside the seepage liquid discharge pipe and are in communication with the inside of the seepage liquid discharge pipe, a seepage liquid filter plate is fixed to the outer end of the seepage liquid flow short pipe, and a plurality of seepage liquid discharge pipes are jointly connected in communication to form a seepage liquid temporary storage pool.

[0031] Explanation: After the channel side dam beam absorbs water, the water inside will flow from top to bottom under the action of gravity, forming leachate. The chromium pollutants inside the channel side dam beam will be mixed into the leachate to form chromium contaminated leachate. Collecting these leachates together for delivery to the wetland water distribution pool can make the chromium contaminated leachate purify with the contaminated groundwater.

[0032] Preferably, the bottom of the total area of the wetland is an impermeable layer structure, which is sequentially composed of an impermeable bottom layer, an impermeable intermediate layer and an impermeable surface layer from bottom to top.

[0033] The impermeable bottom layer is clay, the impermeable intermediate layer is bentonite, and the impermeable surface layer is clay.

[0034] Explanation: The impermeable layer structure can confine the chromium pollutants inside the artificial wetland system, prevent them from penetrating downward through soil pores, and avoid the spread of pollution to deeper soil and groundwater, thereby expanding the pollution range.

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

[0036] An impermeable surface membrane is laid between the top of the impermeable intermediate layer and the bottom of the impermeable surface layer.

[0037] Explanation: The double bottom impermeable membrane can effectively prevent chromium pollutants from leaking due to damage to a single impermeable membrane.

[0038] Preferably, a plurality of plant planting tubes with openings facing upwards are fixed inside the top of the channel side dam beam, and the sidewalls of the plant planting tubes have a plurality of root system perforations that communicate between the inside and outside.

[0039] Explanation: The plant planting tubes facilitate the removal and replacement of the plants planted inside them, and the plants enriched with chromium pollutants can be easily treated harmlessly to avoid secondary pollution to the environment.

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

[0041] Explanation: The setting of the end treatment filter dam body can more thoroughly remove the small amount of chromium pollutants remaining in the groundwater, further improve the water quality after purification treatment, and make the purified groundwater safely flow into the surface runoff.

[0042] Preferably, a chromium contaminated site soil and groundwater ecological restoration method based on the above-mentioned chromium contaminated site soil and groundwater ecological restoration system, comprising the following steps:

[0043] S1, groundwater extraction:

[0044] The contaminated groundwater is pumped out and transported to a pretreatment storage pool and left for 6-12 hours;

[0045] The contaminated groundwater in the pretreatment storage pool is brought to the ambient temperature;

[0046] S2, adsorption pretreatment:

[0047] The contaminated groundwater after standing is then transported to a filter interception structure for physical adsorption and filtration treatment;

[0048] S3, wetland purification treatment:

[0049] The contaminated groundwater after adsorption pretreatment is transported to a wetland total area;

[0050] The contaminated groundwater flows through a wetland water distribution pool, a wetland main area and a wetland drainage pool in sequence;

[0051] In the wetland main area, the contaminated groundwater flows through the wetland water flow channel, and the contaminated groundwater flows horizontally in the substrate in the wetland water flow channel;

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

[0053] The flow partition dam beam and the channel side dam beam are made of the soil of the chromium pollution site, and the chromium pollutants in the flow partition dam beam and the channel side dam beam will diffuse into the contaminated groundwater and be adsorbed and purified together;

[0054] Meanwhile, plants capable of adsorbing and purifying chromium pollution are planted on the flow partition dam beam and the channel side dam beam, and the root system of the plants is used to purify the soil of the chromium pollution site;

[0055] S4, end treatment:

[0056] The contaminated groundwater after physical adsorption, microbial purification and plant purification finally enters an end purification treatment pool, and the contaminated groundwater flows through each end treatment filter dam body in sequence, and the adsorption of the end treatment filter dam body is used to remove the residual chromium pollutants in the contaminated groundwater;

[0057] Finally, clean groundwater is formed, which is discharged through each end treatment discharge pipe, so that the clean groundwater is merged into surface runoff, and the opening degree of the end discharge control valve can control the discharge speed of the clean groundwater.

[0058] Compared with the prior art, the beneficial effects of the present application are as follows:

[0059] 1、The ecological restoration system has reasonable structure design, high purification capacity, and can remove chromium in soil and groundwater through physical, chemical and biological synergistic effect; physical adsorption can quickly intercept chromium ions; chemical precipitation can convert chromium into low-solubility compounds; plant absorption and microbial reduction can reduce the toxicity and migration of chromium, so that different valence chromium can be effectively removed;

[0060] 2、The ecological restoration system can adapt to different pollution degrees, and can stably operate and reach a certain purification standard whether it is a light, medium or heavy chromium pollution site;

[0061] 3、The ecological restoration system has the ability to remove multiple pollutants, and can remove other heavy metals, organic matter and other pollutants that may exist in the site, has wide-range pollutant purification function, and can realize comprehensive restoration of soil and groundwater;

[0062] 4、The ecological restoration system has no secondary pollution, and will not produce secondary pollutants or harmful by-products in the purification process, will not convert chromium pollutants from one form to another more harmful form, and will not release other toxic and harmful substances to the environment, ensuring the environmental safety of the restoration process;

[0063] 5、The ecological restoration system has long-term stability and good impact load resistance, has strong adaptability to water quality and water quantity fluctuations, can maintain stable purification effect under certain impact load, has strong site adaptability, can adapt to various types of chromium pollution sites, including industrial wasteland, mine tailings, landfill, etc., and the entire ecological restoration system can be reasonably designed and adjusted according to the terrain, topography and soil type of the site to realize effective restoration. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 is the overall layout of the ecological restoration system of the present application;

[0065] Figure 2 is a structural schematic view of the filter interception structure of the present application;

[0066] Figure 3 is a structural schematic view of the filter partitioning plate of the present application;

[0067] Figure 4 is a top view of the filter partitioning plate of the present application;

[0068] Figure 5 is a structural schematic view of the wetland water flow channel of the present application;

[0069] Figure 6 is a structural schematic view of the leachate discharge pipe of the present application;

[0070] Figure 7 is a structural diagram of the plant growing cylinder of the present application;

[0071] Figure 8 is a structural diagram of the end purification treatment pool of the present application.

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

[0073] The following will be described in combination with Figures 1-8 The present application will be described in detail below, and for the convenience of description, the following directions are defined as follows: the up-down, left-right, front-back directions described below are consistent with the up-down, left-right, front-back directions of the projection relationship of the respective main view or structural diagram itself. Example 1

[0074] A chromium-contaminated site soil and groundwater ecological restoration system, as shown in Figure 1 Fig. 1, includes a pretreatment structure 10, a wetland main structure 20, and an end treatment structure 30 connected in sequence from upstream to downstream;

[0075] The pretreatment structure 10 includes a pretreatment storage pool 11, and a filter interception structure 12 connected to the pretreatment storage pool 11;

[0076] As Figure 1 shown, the wetland main structure 20 includes a total wetland area 200 surrounded by a ring-shaped wetland main peripheral wall 21, the wetland input partition dam beam 211 and the wetland output partition dam beam 212 are arranged in the wetland main peripheral wall 21, and the wetland input partition dam beam 211 and the wetland output partition dam beam 212 divide the total wetland area 200 into a wetland water distribution pool 201, a wetland main area 202 and a wetland drainage pool 203;

[0077] A plurality of pipes for connecting the wetland water distribution pool 201 and the wetland main area 202 are embedded in 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 embedded in the wetland output partition dam beam 212;

[0078] 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;

[0079] A plurality of flow partition dam beams 213 are arranged in parallel in the wetland main area 202, and the flow partition dam beams 213 divide the wetland main area 202 into a plurality of wetland sub-areas 2020;

[0080] A plurality of channel side dam beams 214 are arranged in parallel in the wetland sub-area 2020, and a plurality of channel side dam beams 214 together form a wetland water flow channel 2140;

[0081] As Figure 5 shown, a channel substrate layer 22 is laid in the wetland water flow channel 2140;

[0082] The wetland input partition dam beam 211 and the wetland output partition dam beam 212 are perpendicular to the upstream and downstream flow directions of the water flow, the flow partition dam beam 213 is parallel to the upstream and downstream flow directions of the water flow, and each channel side dam beam 214 is perpendicular to the upstream and downstream flow directions of the water flow;

[0083] The flow partition dam beam 213 and the channel side dam beam 214 are made of the soil of the chromium-polluted site;

[0084] Chromium-polluted purification plants are planted on the flow partition dam beam 213 and the channel side dam beam 214 in the wetland water flow channel 2140, and the chromium-polluted purification plants include reed, cattail, rush, leersia, yellow flag, canna, lycopus, wild rice, solanum nigrum and euphorbia humilis;

[0085] These plants have the ability to absorb chromium ions, absorb chromium through root systems, and then transport it to the aboveground part, and various ion channels and transport proteins exist on the cell membrane of the plant root system, which can recognize and absorb chromium ions;

[0086] After the plant absorbs the chromium, a certain degree of metabolism will be carried out in the body, part of the chromium will be fixed on the cell wall of the plant, and some will be combined with organic compounds in the cell. Chromium can be combined with organic acids in the plant body, such as citric acid, malic acid and the like, to reduce its toxicity. When the plant grows to a certain stage, the chromium can be removed from the wetland system by harvesting the plant to prevent the chromium from being released into the environment again;

[0087] The substrate in the water flow channel 2140 of the wetland is filled with chromium pollution purification microorganisms, which include denitrifying bacteria, anaerobic ammonia oxidation coupled iron-reducing bacteria, acetylmicrobacterium, and geobacillus;

[0088] These microorganisms have a strong ability to adsorb chromium in the constructed wetland. The surface of the microbial cells has a negative charge, which 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.

[0089] Microorganisms can also biotransform chromium, reducing Cr (VI) to Cr (III). Microorganisms can also change the form of chromium through methylation and other reactions. Microorganisms can convert chromium to organic chromium compounds, which have different properties and toxicity from inorganic chromium. To some extent, they can change the mobility and toxicity of chromium in the wetland ecosystem. At the same time, some enzymes and organic substances secreted by microorganisms during metabolism can also affect the chemical form and bioavailability of chromium.

[0090] As shown in Figure 5 , the channel substrate layer 22 is filled and laid from bottom to top by the channel substrate bottom layer 221, the channel substrate middle layer 222, and the channel substrate surface layer 223.

[0091] The channel substrate 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.

[0092] The channel substrate middle layer 222 is composed of volcanic rock with a particle size of 10 mm, ceramic particles with a particle size of 5 mm, and anthracite with a particle size of 5 mm in a volume ratio of 1:1:1.

[0093] The channel substrate surface layer 223 is composed of sand with a particle size of 0.5 mm, 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.

[0094] As shown in Figure 5 , the bottom of the total area of the wetland 200 is the impermeable layer structure 24, which is composed of the impermeable bottom layer 241, the impermeable middle layer 242, and the impermeable surface layer 243 from bottom to top.

[0095] The impermeable bottom layer 241 is clay, the impermeable middle layer 242 is bentonite, and the impermeable surface layer 243 is clay;

[0096] As shown in Figure 5 , a bottom impermeable film 2410 is laid between the top of the impermeable bottom layer 241 and the bottom of the impermeable middle layer 242, and the bottom impermeable film 2410 is a polyethylene geomembrane of the prior art;

[0097] An upper surface impermeable film 2430 is laid between the top of the impermeable middle layer 242 and the bottom of the impermeable surface layer 243, and the upper surface impermeable film 2430 is a polyethylene geomembrane of the prior art;

[0098] As shown in Figure 5 , a plurality of plant growing tubes 25 with openings facing upwards are fixed inside the top of the channel side dam beam 214, as shown in Figure 7 , the sidewall of the plant growing tube 25 has a plurality of root system perforations 251 that are in communication with the outside;

[0099] As shown in Figure 1 , the end treatment structure 30 includes an end purification treatment pool 31, which is in communication with the wetland drainage pool 203;

[0100] As shown in Figure 8 , a plurality of end treatment filter dam bodies 32 are arranged in the end purification treatment pool 31, and the extension direction of the end treatment filter dam bodies 32 is perpendicular to the water flow direction;

[0101] A plurality of end treatment discharge pipes 311 are fixed on the downstream side of the end purification treatment pool 31 and are in communication with the inside of the end purification treatment pool 31, and the end treatment discharge pipes 311 have end discharge control valves 3110;

[0102] As shown in Figure 8 , the end treatment filter dam bodies 32 are arranged in the end purification treatment pool 31 from upstream to downstream, and the end treatment filter dam bodies 32 are arranged in the end purification treatment pool 31 from upstream to downstream, and the end treatment filter dam bodies 32 are arranged in the end purification treatment pool 31 from upstream to downstream. Example 2

[0103] The present embodiment describes a method for ecological restoration of chromium-contaminated soil and groundwater, based on the chromium-contaminated soil and groundwater ecological restoration system of the above-mentioned embodiment 1, comprising the following steps:

[0104] S1, groundwater extraction:

[0105] The contaminated groundwater is extracted and transported to the pretreatment storage tank 11 and left for 6-12 hours;

[0106] The contaminated groundwater in the pretreatment storage tank 11 is brought to the same temperature as the outside environment;

[0107] S2, adsorption pretreatment:

[0108] The contaminated groundwater after standing is then transported into the filter interception structure 12 for physical adsorption filtering treatment;

[0109] The chromium-polluted purification plants are planted in each sub-area interception space 120, including reed, cattail, rush, leersia, yellow flag, canna, lycopus, wild rice, solanum nigrum, and pteridium aquilinum;

[0110] S3, wetland purification treatment:

[0111] The contaminated groundwater after adsorption pretreatment is transported into the wetland total area 200;

[0112] The contaminated groundwater flows through the wetland water distribution pool 201, the wetland main area 202, and the wetland drainage pool 203 in sequence;

[0113] In the wetland main area 202, the contaminated groundwater flows through the wetland water flow channel 2140, and the contaminated groundwater horizontally percolates in the substrate in the wetland water flow channel 2140;

[0114] The chromium pollution in the contaminated groundwater is purified by the adsorption of the substrate in the wetland water flow channel 2140;

[0115] The flow partition dam beam 213 and the channel side dam beam 214 are made of the soil of the chromium-polluted site, and the chromium pollutants in the flow partition dam beam 213 and the channel side dam beam 214 will diffuse into the contaminated groundwater and be adsorbed and purified together;

[0116] Meanwhile, the flow partition dam beam 213 and the channel side dam beam 214 are planted with plants capable of adsorbing and purifying chromium pollution, including reed, cattail, rush, leersia, yellow flag, canna, lycopus, wild rice, solanum nigrum, and pteridium aquilinum, which utilize the root absorption of these plants to purify the soil of the chromium-polluted site;

[0117] S4, end treatment:

[0118] The contaminated groundwater after physical adsorption, microbial purification, and plant purification finally enters the end purification treatment pool 31, and the contaminated groundwater flows through each end treatment interception dam body 32 in sequence, and the adsorption 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;

[0119] Finally, clean groundwater is formed, which is discharged through each end treatment discharge pipe 311, so that the clean groundwater is merged into surface runoff. The opening degree of the end discharge control valve 3110 can control the speed of clean groundwater discharge. Example 3:

[0120] On the basis of example 1,Figure 2 As shown, the filter interception structure 12 comprises a filter interception pool 121, a plurality of filter partition plates 122 are fixed in the filter interception pool 121 and arranged vertically and parallel to each other, and the filter partition plates 122 are perpendicular to the water flow direction, and the filter partition plates 122 divide the filter interception pool 121 into a plurality of partitioned filtration spaces 120;

[0121] From upstream to downstream, each partitioned filtration space 120 is filled with 20-30mm pebbles, 5-7mm pebbles, 1-2mm sand, and 0.5-0.7mm sand, respectively;

[0122] As shown, Figure 1 The upstream side of the filter interception pool 121 is connected to the downstream side of the pretreatment storage pool 11 through a plurality of filter interception input pipes 1201;

[0123] As shown, Figure 3 The filter partition plates 122 are fixed with partitioned filter screens 1221 on both sides, and the partitioned filter screens 1221 are prior art filter screens of the purpose of 20;

[0124] As shown, Figure 3 The filter partition plates 122 have a plurality of filtration partition through holes 1220 penetrating both sides, and the filter partition plates 122 are hollow structures, which are equivalent to being arranged in parallel by two plates, and the filter partition plates 122 are slidingly connected with a partitioned on-off control plate 123 in the horizontal direction, and the partitioned on-off control plate 123 has a plurality of filtration partition matching holes 1230 penetrating both sides;

[0125] The plurality of filtration partition through holes 1220 arranged in the horizontal direction form a group, and the filtration partition through holes 1220 are arranged in multiple groups in the vertical direction on the filter partition plates 122;

[0126] The sliding direction of the partitioned on-off control plate 123 is the direction of the filtration partition through holes 1220 arranged in the horizontal direction, and the partitioned on-off control plate 123 is arranged in multiple groups in the vertical direction inside the filter partition plates 122;

[0127] As shown, Figure 4 The filter interception pool 121 is fixed with a plurality of on-off control accommodating shells 124 outside, and the filter interception pool 121 has on-off control perforations 1240 connecting the inside of the filter partition plates 122 and the inside of the on-off control accommodating shells 124, and the on-off control perforations 1240 are slidingly connected with on-off control connecting rods 125, and one end of the on-off control connecting rods 125 inside the filter partition plates 122 is fixedly connected with the side end of the partitioned on-off control plate 123;

[0128] The on-off control accommodating shell 124 is fixed with an on-off control driving rod 126 for driving the on-off control connecting rod 125 to move, the on-off control driving rod 126 is an existing technology electric control telescopic rod driven by a servo motor, the outer rod end of the on-off control driving rod 126 is fixedly connected with the on-off control accommodating shell 124, and the inner rod end of the on-off control driving rod 126 is fixedly connected with one end of the on-off control connecting rod 125 in the on-off control accommodating shell 124. Embodiment 4:

[0129] The embodiment discloses a chromium-polluted site soil and groundwater ecological restoration method, and the chromium-polluted site soil and groundwater ecological restoration system based on the embodiment 3 is different from the embodiment 2, wherein in the step S1, the multiple partition on-off control plates 123 in each filter partition plate 122 can control whether the adjacent two partition filter spaces 120 are connected or not, the inner rod of the on-off control driving rod 126 can drive the on-off control connecting rod 125 and the partition on-off control plate 123 to move along the horizontal direction, and the on-off control connecting rod 125 can control the alignment and connection of the filter partition through hole 1220 and the filter partition fitting hole 1230 or the isolation of the filter partition through hole 1220 and the filter partition fitting hole 1230.

[0130] When the filter partition through hole 1220 and the filter partition fitting hole 1230 are aligned and connected, the adjacent two partition filter spaces 120 are connected at the partition on-off control plate 123, and vice versa, when the filter partition through hole 1220 and the filter partition fitting hole 1230 are isolated, the adjacent two partition filter spaces 120 are isolated at the partition on-off control plate 123.

[0131] The multiple partition on-off control plates 123 are arranged in the vertical direction in each filter partition plate 122, that is, each filter partition plate 122 can control the connection state of the adjacent two partition filter spaces 120 at multiple positions in the vertical direction.

[0132] Further, the specific flow mode of the contaminated groundwater in the partition filter space 120 is controlled, that is, the groundwater flows in the horizontal direction or the vertical direction.

[0133] When the connection states of the filter partition plates 122 at the upstream end and the filter partition plates 122 at the downstream end are consistent, the contaminated groundwater flows in the partition filter space 120 in the horizontal direction.

[0134] When the higher position of the filter partition plate 122 at the upstream end is set to be connected and the lower position of the filter partition plate 122 at the downstream end is set to be connected, the contaminated groundwater flows in the partition filter space 120 in the vertical direction from top to bottom. Embodiment 5:

[0135] On the basis of Embodiment 3, as shown in Figure 5 The channel side dam beam 214 is in a trapezoidal structure, and each channel side dam beam 214 is internally provided with a leachate discharge pipe 23, as shown in Figure 6 The leachate discharge pipe 23 is externally provided with a plurality of leachate flow short pipes 231 connected to the inside of the leachate discharge pipe 23, and the outer end of the leachate flow short pipe 231 is fixed with a leachate filter plate 232. The plurality of leachate discharge pipes 23 are connected in common to form a leachate temporary storage pool.

[0136] The leachate filter plate 232 is a filter plate of the prior art 100. Embodiment 6:

[0137] The embodiment describes a chromium-contaminated site soil and groundwater ecological restoration method, based on the chromium-contaminated site soil and groundwater ecological restoration system of Embodiment 5, and different from Embodiment 4, wherein in step S3, after the channel side dam beam 214 absorbs water, the water in the inside of the channel side dam beam 214 will flow downward under the action of gravity, forming leachate passing through the leachate flow short pipe 231 into the leachate discharge pipe 23, and the leachate in the leachate discharge pipe 23 is concentrated and flows into the leachate temporary storage pool. The leachate is transported to the wetland water distribution pool 201 by using a delivery pump, so that the leachate can be purified together with the contaminated groundwater. Embodiment 7:

[0138] Different from Embodiment 5, the channel substrate 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;

[0139] The channel substrate 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;

[0140] The channel substrate 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;

[0141] Each partitioned filtering space 120 is filled with 30-40 mm pebbles, 6-8 mm pebbles, 1-2 mm sand, and 0.6-0.8 mm sand in sequence. Embodiment 8:

[0142] Different from Embodiment 5, the channel substrate 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;

[0143] The intermediate layer 222 of the channel matrix is composed of volcanic rock with a particle size of 20 mm, ceramic particles with a particle size of 15 mm, and anthracite with a particle size of 10 mm, with a volume ratio of 3:2:1;

[0144] The surface layer 223 of the channel matrix 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, with a volume ratio of 3:2:1;

[0145] Each sub-area filtering space 120 is sequentially filled with 40-50 mm pebbles, 8-10 mm pebbles, 2-3 mm sand, and 0.8-1 mm sand. Example 9:

[0146] 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.

[0147] Example 10:

[0148] 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.

[0149] In the actual application process of the present application, the entire artificial wetland is built in a chromium-contaminated site, and the soil of the chromium-contaminated site is excavated for building the flow sub-area dam beam 213 and the channel side dam beam 214.

Claims

1. An ecological remediation system for soil and groundwater in chromium-contaminated sites, characterized in that, It includes a pretreatment structure (10), a wetland main structure (20), and an end-of-life treatment structure (30) that are connected sequentially from upstream to downstream. The preprocessing structure (10) includes a preprocessing storage pool (11), and a filtering and interception structure (12) is provided connected to the preprocessing storage pool (11). The filter interception structure (12) includes a filter interception pool (121), and a plurality of parallel and vertically placed filter partitions (122) are fixed inside the filter interception pool (121). The filter partitions (122) divide the interior of the filter interception pool (121) into a plurality of partitioned filter spaces (120). The upstream side of the filter interception pool (121) is connected to the downstream side of the pretreatment storage pool (11) through multiple filter interception input pipes (1201); The filter partition (122) has partitioned filter screens (1221) fixed on both sides. The filter partition (122) has multiple through holes (1220) that pass through both sides of the filter partition. The filter partition (122) has a hollow structure inside. A partition on / off control plate (123) is slidably connected inside the filter partition (122) in the horizontal direction. The partition on / off control plate (123) has multiple through holes (1230) that pass through both sides of the filter partition. Multiple on / off control housings (124) are fixed on the outside of the filter interception pool (121). The side wall of the filter interception pool (121) has an on / off control through hole (1240) that connects the inside of the filter partition plate (122) and the inside of the on / off control housing (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) inside the filter partition plate (122) is fixedly connected to the side end of the partition on / off control plate (123). The on / off control housing (124) contains a control rod (126) for driving the on / off control linkage (125) to move. The main wetland structure (20) includes a total wetland area (200) enclosed by a ring-shaped outer wall (21). The outer wall (21) contains a wetland input dividing dam (211) and a wetland output dividing dam (212). The wetland input dividing dam (211) and the wetland output dividing dam (212) divide the total wetland area (200) into a wetland water distribution pool (201), a wetland main area (202), and a wetland drainage pool (203). The main wetland area (202) is provided with multiple parallel circulation zone dams (213), which divide the main wetland area (202) into multiple wetland sub-areas (2020). The wetland subdivision area (2020) is provided with multiple parallel channel side dam beams (214), and the multiple channel side dam beams (214) together form a wetland water flow channel (2140). The wetland water flow channel (2140) is lined with a channel matrix layer (22); Chromium pollution purifying plants are planted in the wetland water flow channel (2140), on the flow zone dam beam (213), and on the channel side dam beam (214); Chromium-polluting purifying microorganisms are spread in the substrate within the wetland water flow channel (2140); The end-of-pipe treatment structure (30) includes an end-of-pipe purification treatment tank (31), which is connected to the wetland drainage tank (203); The terminal purification treatment pool (31) is equipped with multiple terminal treatment filter dams (32) arranged in parallel with each other. The downstream side of the terminal purification treatment tank (31) has a number of terminal treatment outflow pipes (311) that are connected to its interior, and the terminal treatment outflow pipes (311) have terminal outflow control valves (3110).

2. The ecological remediation system for soil and groundwater in a chromium-contaminated site according to claim 1, characterized in that, The channel matrix layer (22) is formed by filling and laying the channel matrix bottom layer (221), the channel matrix middle layer (222) and the channel matrix surface layer (223) from bottom to top; The bottom layer (221) of the channel matrix is ​​composed of pebbles with a particle size of 20-50 mm, gravel with a particle size of 20-40 mm, and zeolite with a particle size of 20-30 mm. The intermediate layer (222) of the channel matrix is ​​composed of volcanic rock with a particle size of 10-20 mm, ceramsite with a particle size of 5-15 mm, and anthracite with a particle size of 5-10 mm. The surface layer (223) of the channel matrix is ​​composed of sand with a particle size of 0.5~2mm, coconut shell activated carbon with a particle size of 0.5~2mm, and humus soil with a particle size of 0.05~0.2mm.

3. The ecological remediation system for soil and groundwater in a chromium-contaminated site according to claim 1, characterized in that, The cross-section of the channel side dam beam (214) is trapezoidal. A leachate drain pipe (23) is laid at the bottom of each channel side dam beam (214). Multiple leachate flow short pipes (231) connected to the outside of the leachate drain pipe (23) are fixed. A leachate filter plate (232) is fixed at the outer end of the leachate flow short pipe (231). Multiple leachate drain pipes (23) are connected together to form a leachate temporary storage tank.

4. The ecological remediation system for soil and groundwater in a chromium-contaminated site according to claim 1, characterized in that, The bottom of the wetland total area (200) is a seepage-proof layer structure (24), which consists of a seepage-proof bottom layer (241), a seepage-proof intermediate layer (242), and a seepage-proof top layer (243) from bottom to top. The impermeable bottom layer (241) is clay, the impermeable intermediate layer (242) is bentonite, and the impermeable surface layer (243) is clay.

5. The ecological remediation system for soil and groundwater in a chromium-contaminated site according to claim 4, characterized in that, A bottom impermeable membrane (2410) is laid between the top of the impermeable bottom layer (241) and the bottom of the impermeable intermediate layer (242). A surface geomembrane (2430) is laid between the top of the intermediate geomembrane (242) and the bottom of the surface geomembrane (243).

6. The ecological remediation system for soil and groundwater in a chromium-contaminated site according to claim 1, characterized in that, Multiple plant planting tubes (25) with upward openings are fixed inside the top of the side dam beam (214) of the channel. The side wall of the plant planting tube (25) has multiple root perforations (251) that are interconnected inside and out.

7. The ecological remediation system for soil and groundwater in a chromium-contaminated site according to claim 1, characterized in that, The end-of-line treatment filter dam (32) consists of a coal slag layer (321), a biological ceramsite layer (322), and a volcanic rock layer (323) from upstream to downstream.

8. A method for ecological remediation of soil and groundwater in chromium-contaminated sites, based on the ecological remediation system for soil and groundwater in chromium-contaminated sites as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Groundwater extraction: The contaminated groundwater was extracted and transported to a pretreatment storage tank (11) and left to stand for 6 to 12 hours. To bring the temperature of the contaminated groundwater in the pretreatment storage tank (11) into the same as that of the external environment; S2, Adsorption pretreatment: After settling, the polluted groundwater is then transported to the filtration and interception structure (12) for physical adsorption filtration treatment; S3. Wetland purification treatment: The pretreated polluted groundwater is then transported to the total wetland area (200); The polluted groundwater flows sequentially through the wetland water distribution pond (201), the main wetland area (202), and the wetland drainage pond (203). In the main wetland area (202), polluted groundwater flows along the wetland water flow channel (2140) and flows horizontally in the matrix within the wetland water flow channel (2140); Chromium pollution in contaminated groundwater is purified by the adsorption effect of the matrix in the wetland water flow channel (2140); Furthermore, the circulation zone dam beam (213) and the channel side dam beam (214) are constructed from the soil of the chromium-contaminated site. The chromium pollutants in the circulation zone dam beam (213) and the channel side dam beam (214) will diffuse into the contaminated groundwater and be adsorbed and purified together. Meanwhile, plants capable of absorbing and purifying chromium pollution are planted on both the circulation zone dam beam (213) and the side dam beam (214) of the passage. The soil of the chromium-polluted site is purified by the absorption of the plant roots. S4. End-of-pipe processing: After physical adsorption, microbial purification and plant purification, the polluted groundwater finally enters the end-of-pipe treatment pond (31). The polluted groundwater flows through each end-of-pipe treatment filter dam (32) in sequence, and the adsorption effect of the end-of-pipe treatment filter dam (32) is used to remove the residual chromium pollutants in the polluted groundwater. Finally, clean groundwater is formed and discharged through the terminal treatment outlet pipes (311) so that the clean groundwater can flow into the surface runoff. The speed of clean groundwater discharge can be controlled by adjusting the opening of the terminal outlet control valve (3110).

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