Device and method for treating groundwater pollution in metal mining areas by pumping and infiltration

Abstract

The present invention provides a device for treating groundwater pollution in metal mining areas by pumping, injection and filtration, and a sewage treatment method. The device for treating groundwater pollution in metal mining areas by pumping, injection and filtration comprises an extraction well, a reaction tank and an injection well, wherein the reaction tank is located between the extraction well and the injection well; an electrode is arranged in the extraction well, the electrode is connected to the positive electrode of the power supply, forming an anode; an electrode is arranged in the injection well, the electrode is connected to the negative electrode of the power supply, forming a cathode, and a bulk iron-loaded biochar is placed in the injection well. The present invention adopts a composite system of electrochemistry, microorganisms, and iron-rich biochar, and synergizes and enhances efficiency by extraction and sequential reaction, thereby greatly improving the treatment efficiency and treatment effect of contaminated groundwater. At the same time, the treatment device has a small footprint, low energy consumption, and stable treatment effect. The pollutant removal efficiency of the device is high, and the device is particularly suitable for the repair of contaminated groundwater in metal mining areas, and has good application prospects in the field of contaminated groundwater repair.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater pollution treatment, and in particular to a device and method for treating groundwater pollution in metal mining areas by pumping, injection and infiltration. Background Art

[0002] Pollutants that enter groundwater come from both human activities and natural processes. Domestic sewage and domestic waste can increase the total mineralization, total hardness, nitrate, and chloride content of groundwater, and sometimes cause pathogen contamination. Industrial wastewater and industrial waste can increase the concentration of organic and inorganic compounds in groundwater. Fertilizers and manure applied in agriculture can cause large-scale increases in groundwater nitrate levels. Pesticide contamination of groundwater is relatively minor and limited to shallow layers. Agricultural farming activities can promote the oxidation of soil organic matter, such as the oxidation of organic nitrogen to inorganic nitrogen (primarily nitrate nitrogen), which enters groundwater with seepage water.

[0003] Groundwater pollution also stems from mining pollution, which refers to the environmental impacts and hazards caused by various factors during the mining process. These include mine drainage, leachate from ore and waste rock piles, industrial and domestic wastewater, ore dust, smoke and SO2 emissions from coal combustion, and radiation from radioactive substances. These pollutants contain a large number of harmful substances, severely harming the mining environment and human health.

[0004] Regarding water pollution caused by mining, there is an urgent need to treat high-salinity heavy metal and organic contaminated wastewater. Studies have shown that heavy metal forms can be modified through release, complexation, and co-precipitation. However, studies have found that the reduction and oxidation of pollutants, the formation and transport of colloids, the dissolution and recrystallization of sediments, and the growth and aggregation of microorganisms are crucial for regulating the stability of reclaimed water stored underground.

[0005] In particular, for metal mining areas, the content of heavy metals and organic pollutants in their underground contaminated water is very high, making it difficult to treat. Summary of the Invention

[0006] Based on the above technical background, the inventors have conducted intensive research and provided a device for treating groundwater pollution in metal mining areas by pumping, injection and filtration, and a sewage treatment method. The device includes an extraction well, an injection well and a reaction tank. The reaction tank is located between the extraction well and the injection well. An anode and a cathode are respectively provided in the extraction well and the injection well. Iron-rich biochar is loaded on the cathode of the injection well, and microorganisms are also loaded on the cathode. The iron-rich biochar loaded with microorganisms promotes the removal of metal ions in groundwater through the active substances produced by the primary cell and the bioelectrochemical effect, and further mineralizes organic pollutants into carbon dioxide and water. The present invention uses a composite system of electrochemistry, microorganisms, and iron-rich biochar, and plays a synergistic role through extraction and sequential reaction, which greatly improves the treatment effect and efficiency of contaminated groundwater. In addition, the device occupies a small area and has low energy consumption, and is extremely suitable for the repair of contaminated groundwater in metal mining areas, thereby completing the present invention.

[0007] The first aspect of the present invention is to provide a device for treating groundwater pollution in metal mining areas by pumping, injection and filtration. The device for treating groundwater pollution in metal mining areas by pumping, injection and filtration comprises an extraction well 1, an injection well 2 and a reaction tank 5. The reaction tank 5 is located between the extraction well 1 and the injection well 2.

[0008] An electrode is provided in the extraction well 1 , and the electrode is connected to the positive electrode of the power supply to form an anode 3 ; an electrode is provided in the water injection well 2 , and the electrode is connected to the negative electrode of the power supply to form a cathode 4 .

[0009] The second aspect of the present invention is to provide a method for sewage treatment using the device described in the first aspect of the present invention, the method comprising extracting the underground sewage in the metal mining area to be treated from the extraction well 1 to the reaction tank 5 through a centrifugal pump, and discharging it from the reaction tank 5 into the water injection well 2. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic diagram showing the structure of a pumping and filtration device for treating water pollution in metal mining areas according to a preferred embodiment of the present invention;

[0011] Explanation of Figure Numbers

[0012] 1-Extraction well;

[0013] 2-water injection wells;

[0014] 3- anode;

[0015] 4- cathode;

[0016] 5- reaction tank;

[0017] 6-water inlet pipe;

[0018] 7-Water outlet pipe. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below, and the characteristics and advantages of the present invention will become clearer and more distinct with the following description.

[0020] The first aspect of the present invention is to provide a device for treating groundwater pollution in metal mining areas by pumping and infiltration. The device for treating groundwater pollution in metal mining areas by pumping and infiltration includes an extraction well 1, an injection well 2 and a reaction tank 5, and the reaction tank 5 is located between the extraction well 1 and the injection well 2.

[0021] The extraction well 1 is used to extract the sewage to be treated into the device, and the groundwater is extracted into the reaction tank 5 by a centrifugal pump, and is discharged from the reaction tank 5 to the injection well 2 by gravity.

[0022] The water injection well and extraction well provided in the present invention can enable the device to treat the contaminated groundwater to be treated by extraction and sequential reaction, thereby greatly improving the treatment efficiency and treatment effect of the contaminated groundwater.

[0023] According to a preferred embodiment of the present invention, an electrode is provided in the extraction well 1 , and the electrode is connected to the positive electrode of the power supply to form the anode 3 .

[0024] An electrode is provided in the water injection well 2 and is connected to the negative electrode of the power supply to form a cathode 4 .

[0025] The inventors have discovered that the cathode and anode configuration improves the treatment of contaminated groundwater through galvanic cells and bioelectrochemical effects, while also promoting the production of active substances by microorganisms and iron-rich biochar, thereby facilitating the removal of metal ions and organic pollutants.

[0026] According to a further preferred embodiment of the present invention, the anode 3 is at least partially located below the groundwater level in the extraction well 1, preferably entirely below the groundwater level; the cathode 4 is at least partially located below the groundwater level in the injection well 2, preferably entirely below the groundwater level.

[0027] The anode 3 is selected from laser titanium carbide or plastic electrode, preferably laser titanium carbide electrode.

[0028] The cathode 4 is selected from a graphite electrode or a cast iron electrode, preferably a cast iron electrode.

[0029] The voltage set on the anode 3 and the cathode 4 is 2-8V, preferably 5V.

[0030] A water inlet pipe 6 is provided between the extraction well 1 and the reaction tank 5. One end of the water inlet pipe 6 is located above the reaction tank 5, and the other end of the water inlet pipe 6 leads to the extraction well 1. A centrifugal pump is provided on the water inlet pipe 6 to pump the contaminated groundwater to be treated from the extraction well 1 into the reaction tank 5. A valve is installed on the water inlet pipe 6, located between the centrifugal pump and the reaction tank 5, to control whether water enters.

[0031] A water outlet pipe 7 is provided between the reaction tank 5 and the water injection well 2. One end of the water outlet pipe 7 is located at the bottom of the reaction tank 5, and the other end of the water outlet pipe 7 leads to the water injection well 2. A water outlet valve is installed on the water outlet pipe 7 to control whether water is discharged.

[0032] In the device, chloroaluminate gel material is used as filler in the extraction well 1, and iron-rich biochar or molecular sieve layering is put into the water injection well 2 as filler, both of which can be used for a long time.

[0033] In the extraction well 1, chloroaluminate gel material is used as filler, which has good stability and support. In the present invention, there is no particular limitation on the chloroaluminate gel, but chloroaluminate gel prepared by the sol-gel method is preferred, which has good performance and can be used for a long time.

[0034] As another embodiment, molecular sieves may be packed in layers as fillers in the extraction well.

[0035] According to a preferred embodiment of the present invention, microorganisms are also introduced into the water injection well 2, and the microorganisms are preferably loaded in iron-rich biochar.

[0036] The microorganism is selected from one or more of nitrifying bacteria, denitrifying bacteria, and sulfate-reducing bacteria, preferably sulfate-reducing bacteria.

[0037] Among them, denitrifying bacteria can convert ammonia nitrogen into nitrate; denitrifying bacteria can reduce nitrate into nitrogen gas under anoxic conditions, thereby removing nitrogen from sewage; sulfate-reducing bacteria can convert heavy metal ions into insoluble sulfide precipitates through reduction.

[0038] The iron-rich biochar loaded with microorganisms promotes the removal of metal ions in the treated groundwater through the active substances produced by the galvanic cell and bioelectrochemical effect, while further mineralizing organic pollutants into carbon dioxide and water.

[0039] A packing layer is provided in the reaction tank 5 , and the packing layer is preferably a limestone packing layer, including an upper limestone packing layer, a middle limestone packing layer and a lower limestone packing layer arranged in sequence from top to bottom.

[0040] The present invention creates an alkaline environment by setting a limestone filler layer, which can promote the flocculation and sedimentation of heavy metal pollutants and some organic pollutants in the sewage to be treated, thereby improving the sewage treatment effect.

[0041] Preferably, the particle size of the upper limestone filler layer is larger than that of the middle limestone filler layer, and the particle size of the lower limestone filler layer is larger than that of the middle limestone filler layer.

[0042] More preferably, the particle size of the upper limestone filler layer is 15 to 30 mm, the particle size of the middle limestone filler layer is 8 to 15 mm, and the particle size of the lower limestone filler layer is 15 to 30 mm.

[0043] The device further comprises a planting layer, which is located on the upper part of the reaction tank 5 and is used to plant aquatic plants.

[0044] Reaction tank 5 also contains iron-rich biochar. This iron-rich biochar is obtained by anaerobic pyrolysis of plants grown in iron-rich soil. It has the highest loading of zero-valent iron and is loaded in bulk form, allowing for long-term use. The iron-rich biochar can be any iron-rich biochar disclosed in the art, without particular limitation.

[0045] The device of the present invention may also include other parts, such as pipe caps, sedimentation pipes, filter materials, 2m UPVC high-efficiency slotted water pipes, filter screen filter pipes, clay seals, well chambers, etc. Figure 1 As shown in , these parts can adopt common technical contents in this field and are not particularly limited.

[0046] The device of the present invention has a small footprint and low energy consumption, and is suitable for repairing contaminated groundwater in metal mining areas.

[0047] The second aspect of the present invention is to provide a method for sewage treatment using the device described in the first aspect of the present invention, the method comprising extracting the underground sewage in the metal mining area to be treated from the extraction well 1 to the reaction tank 5 through a centrifugal pump, and discharging it from the reaction tank 5 into the water injection well 2 by gravity.

[0048] Through electrochemical treatment of the anode 3 in the extraction well 1 and the cathode 4 in the injection well 2, metal ions and organic pollutants are reacted and removed, and the electrochemical removal is promoted by the iron-rich biochar loaded with microorganisms in the groundwater injection well 2.

[0049] The voltage set on the anode 3 and the cathode 4 is 2-8V, preferably 5V.

[0050] Experiments have found that using the voltage within the above range on the anode 3 and the cathode 4 can promote the iron-rich biochar of the microorganisms loaded on the cathode to produce active substances, which is beneficial to the removal of metal ions and the further mineralization of organic pollutants, and effectively improves the treatment effect and efficiency of contaminated groundwater.

[0051] The flow rate of the contaminated groundwater to be treated in the device is 5-15 L / min, preferably 10 L / min.

[0052] The residence time of the contaminated groundwater to be treated in the device is 8 to 12 minutes, preferably 10 minutes per 100L of sewage volume in the device.

[0053] The device for treating contaminated groundwater described in the present invention adopts electrochemistry, iron-rich biochar and microorganisms, and simultaneously sets up extraction wells and injection wells. Through the synergistic effect of extraction and sequential reaction, the treatment effect and efficiency of contaminated groundwater are greatly improved, and the energy consumption is low.

[0054] In the method of the present invention, the problem of pollutants easily bypassing each other laterally can be solved by controlling the pumping rate and filler particle size to ensure hydraulic retention time. If the pollutant concentration is too high, one pumping well and multiple injection wells can be set up to ensure the flow rate of the pumping well while reducing the flow rate of the injection well to increase the reaction time. If the pollution source shifts, the pumping well and injection well can be replaced, that is, the injection well can be used as a pumping well and the pumping well can be used as an injection well to flexibly treat contaminated groundwater.

[0055] The beneficial effects of the present invention are:

[0056] (1) The present invention adopts a composite system of electrochemistry + microorganisms + iron-rich biochar, which greatly improves the treatment efficiency of contaminated groundwater through extraction / sequential reaction;

[0057] (2) Reactive oxygen free radicals such as superoxide radicals generated by anode self-reaction can reduce pollutants to small molecules;

[0058] (3) The limestone filler in the present invention can create an alkaline environment, promoting the flocculation and sedimentation of heavy metal pollutants, as well as the sedimentation of some organic pollutants;

[0059] (4) Iron-rich biochar loaded with microorganisms promotes the removal of metal ions in groundwater through active substances produced by galvanic cells and bioelectrochemical effects, while further mineralizing organic pollutants into carbon dioxide and water;

[0060] (5) The treatment method of the present invention has high pollutant removal efficiency, stable treatment effect, small treatment device footprint, and low energy consumption, and is particularly suitable for the remediation of contaminated groundwater in metal mining areas. Example

[0061] The present invention is further described below through specific examples. These examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0062] Example 1

[0063] Use Figure 1The device shown in the figure for treating groundwater pollution in metal mining areas by extraction, injection and filtration treats underground sewage. The device includes an extraction well 1, an injection well 2 and a reaction tank 5. The reaction tank 5 is located between the extraction well 1 and the injection well 2. An electrode is set in the extraction well 1, and the electrode is connected to the positive pole of the power supply to form an anode 3. An electrode is set in the injection well 2, and the electrode is connected to the negative pole of the power supply to form a cathode 4. The anode 3 is a laser titanium carbide electrode, and the cathode 4 is a cast iron electrode. A water inlet pipe 6 is set between the extraction well 1 and the reaction tank 5. One end of the water inlet pipe 6 is located at the upper part of the reaction tank 5, and the other end of the water inlet pipe 6 is connected to the extraction well 2. Chloroaluminate gel material is used as a filler in the extraction well 1.

[0064] A centrifugal pump is provided on the water inlet pipe 6, a valve is installed between the centrifugal pump and the reaction tank 5 on the water inlet pipe 6, a water outlet pipe 7 is provided between the reaction tank 5 and the water injection well 2, one end of the water outlet pipe 7 is installed at the bottom of the reaction tank 5, and the other end of the water outlet pipe 7 is connected to the water injection well 2, a valve is installed on the water outlet pipe 7, iron-rich biochar is used as filler in the water injection well 2, and sulfate-reducing bacteria Desulfovibrio ferrophilus is also loaded on the iron-rich biochar, a filler layer is provided in the reaction tank 5, including an upper limestone filler layer, a middle limestone filler layer and a lower limestone filler layer arranged in sequence from top to bottom, the particle size of the upper limestone filler layer is 15 to 30 mm, the particle size of the middle limestone filler layer is 8 to 15 mm, and the particle size of the lower limestone filler layer is 15 to 30 mm, a planting layer is provided on the upper part of the reaction tank 5, and aquatic plants are planted in the planting layer.

[0065] The voltage set on the anode 3 and the cathode 4 in the device is 5V, the flow rate of the contaminated groundwater to be treated in the device is 10L / min, and the residence time of the contaminated groundwater to be treated in the device is 10 min / 100L sewage volume.

[0066] Before treatment, the heavy metal content was 0.11 mg / L and the organic pollutant content was 25 mg / L. After treatment with this device, the heavy metal content of the groundwater was 0.009 mg / L and the organic pollutant content was 0.51 mg / L.

[0067] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear" and the like, indicating positions or locations, are based on the operating state of the present invention and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0068] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific contexts.

[0069] The present invention has been described above with reference to preferred embodiments, but these embodiments are merely exemplary and serve only as illustrations. On this basis, various replacements and improvements can be made to the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A device for treating groundwater pollution in metal mining areas by pumping and filtration, characterized in that: The device for treating groundwater pollution in a metal mining area by pumping and infiltration comprises an extraction well (1), an injection well (2), and a reaction tank (5), wherein the reaction tank (5) is located between the extraction well (1) and the injection well (2); An electrode is provided in the extraction well (1), the electrode being connected to the positive electrode of the power supply to form an anode (3); an electrode is provided in the water injection well (2), the electrode being connected to the negative electrode of the power supply to form a cathode (4); A chloroaluminate gel material is provided as a filler in an extraction well (1); Placing iron-rich biochar or molecular sieve as filler in the water injection well (2); Microorganisms are also placed in the water injection well (2), and the microorganisms are loaded in the iron-rich biochar. The microorganism is selected from one or more of nitrifying bacteria, denitrifying bacteria and sulfate-reducing bacteria.

2. The device for treating groundwater pollution in metal mining areas by pumping and infiltration according to claim 1 is characterized in that: The anode (3) is at least partially located below the groundwater level in the extraction well (1), and the cathode (4) is at least partially located below the groundwater level in the injection well (2).

3. The device for treating groundwater pollution in metal mining areas by pumping and infiltration according to claim 1 is characterized in that: The anode (3) is selected from laser titanium carbide or plastic electrode; The cathode (4) is selected from a graphite electrode or a cast iron electrode.

4. The device for treating groundwater pollution in metal mining areas by pumping and infiltration according to claim 1 is characterized in that: A water inlet pipe (6) is provided between the extraction well (1) and the reaction tank (5), one end of the water inlet pipe (6) is located at the upper part of the reaction tank (5), and the other end of the water inlet pipe (6) is connected to the extraction well (1). A centrifugal pump is provided on the water inlet pipe (6); A water outlet pipe (7) is provided between the reaction tank (5) and the water injection well (2), one end of the water outlet pipe (7) is located at the bottom of the reaction tank (5), and the other end of the water outlet pipe (7) is connected to the water injection well (2).

5. The device for treating groundwater pollution in metal mining areas by pumping and infiltration according to claim 1 is characterized in that: The microorganisms are sulfate-reducing bacteria.

6. The device for treating groundwater pollution in metal mining areas by pumping and infiltration according to claim 1 is characterized in that: A packing layer is provided in the reaction tank (5), and the packing layer is a limestone packing layer, comprising an upper limestone packing layer, a middle limestone packing layer and a lower limestone packing layer, which are arranged in sequence from top to bottom.

7. The device for treating groundwater pollution in metal mining areas by pumping and infiltration according to claim 1, characterized in that: The device further comprises a planting layer, which is located on the upper part of the reaction tank (5) and is used to plant aquatic plants; The reaction tank (5) also includes iron-rich biochar.

8. A method for treating sewage using the device according to any one of claims 1 to 7, the method comprising extracting underground sewage from a metal mining area to be treated from an extraction well (1) into a reaction tank (5) using a centrifugal pump, and discharging the sewage from the reaction tank (5) into an injection well (2).

9. The sewage treatment method according to claim 8, characterized in that: The voltage set on the anode (3) and cathode (4) is 5V; The flow rate of the contaminated groundwater to be treated in the device is 10L / min; The residence time of the contaminated groundwater to be treated in the device is 10 min / 100 L volume.

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