A system for treating acid mine drainage water

Abstract

The application discloses a system for treating acid mine wastewater, comprising a treatment structure, wherein a water inlet area, a reaction area, a precipitation area and a water outlet area are sequentially arranged in the water flow direction; the water inlet area and the reaction area are both provided with an aeration device; the reaction area is filled with an alkaline reaction medium to form a filler area; after the acid mine wastewater sequentially flows through the water inlet area, the reaction area, the precipitation area and the water outlet area, the acid mine wastewater is discharged or enters a next-stage treatment structure. A plurality of treatment structures are connected in series through pipelines, so that the acid mine wastewater can be efficiently treated.

Description

Technical Field

[0001] This utility model relates to the field of acidic mine wastewater treatment, specifically to a system for treating acidic mine wastewater. Background Technology

[0002] Acid mine wastewater (AMD) is a highly hazardous type of wastewater generated during mining operations. It primarily forms after sulfide minerals are exposed to the surface, where they interact complexly with water, the atmosphere, and microorganisms, leading to oxidation and gradual dissolution to form an acidic liquid containing large amounts of sulfate and various heavy metal ions. These wastewaters originate from a wide range of sources, including direct wastewater from mining operations, surface runoff from natural rainfall, and underground sewage generated from seepage in mine pits and tunnels. Traditionally, the treatment of acidic wastewater from abandoned mines primarily employs adsorption and neutralization precipitation methods. While adsorption can remove some pollutants from wastewater to a certain extent, it suffers from drawbacks such as easy saturation of the adsorbent, difficulty in regeneration, and high treatment costs. Neutralization precipitation involves adding alkaline substances to acidic mine wastewater to raise its pH value, causing metal ions to be removed as hydroxide precipitates. However, this method has revealed several drawbacks in practical applications. On the one hand, it generates large amounts of sludge containing heavy metals, the subsequent treatment of which is extremely challenging and can easily lead to secondary pollution if not handled properly. On the other hand, for some complex acidic mine wastewaters, simple neutralization precipitation is insufficient to achieve efficient removal of multiple heavy metal ions, and the treated water quality often fails to meet discharge standards.

[0003] Existing treatment processes are easy to implement for effluent treatment projects with large outflow rates and readily available sites to meet construction requirements. However, for some effluents with relatively small outflow rates and no available sites nearby, treatment is difficult due to technological and site limitations. This results in pollution control projects being delayed and causing these effluents to continue to have an adverse impact on the surrounding environment.

[0004] Referring to a treatment scheme provided by the inventor, this method involves simple modification of natural streams or artificial ditches. Specifically, the drainage ditch is divided into a non-polluted water channel and a wastewater treatment channel. Each wastewater treatment channel contains at least one treatment unit, and each treatment unit includes a multi-stage reaction wall constructed from carbonate rock particles, a sedimentation tank, and an aeration device. The carbonate rock reacts with sulfuric acid and other substances in acidic wastewater to produce CO2 and H2O, thereby reducing the acidity of the wastewater and increasing its pH value. The aeration device continuously replenishes O2 to the water; when natural reoxygenation is insufficient, additional O2 can be added to ensure Fe... 2+ To Fe 3+ The process is accelerated through conversion; sludge is separated in a sedimentation tank. Two methods are employed. However, this solution has the following drawbacks: The main problems are: (1) When the length of the ditch does not meet the treatment requirements, the treated effluent may not achieve the treatment target; (2) When there are many outlets along the ditch, all of them will flow into the wastewater ditch, which will gradually increase the amount of treated water in the ditch and may cause the water quality to deteriorate. It is necessary to treat the dispersed outlets first so that the water quality and quantity entering the ditch will not affect the ditch system. If possible, the effluent from the dispersed treatment points can directly achieve the treatment target and be discharged directly into the non-polluted water ditch as non-polluted water.

[0005] Therefore, in some special scenarios (such as ecological protection areas around mining areas, narrow valleys, underground tunnels, etc.), when only short ditches can be used or small, decentralized treatment units need to be built manually, the above treatment solutions are obviously not applicable. Utility Model Content

[0006] This invention aims to provide a system for treating acidic mine wastewater, which uses pipelines to connect short ditches or small, decentralized treatment units that need to be constructed manually to achieve the treatment of acidic mine wastewater.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A system for treating acidic mine wastewater includes at least one treatment structure, wherein an inlet zone, a reaction zone, a sedimentation zone, and an outlet zone are sequentially arranged along the water flow direction; both the inlet zone and the reaction zone are equipped with aeration devices; the reaction zone is filled with an alkaline reaction medium; and the acidic wastewater flows sequentially through the inlet zone, the reaction zone, the sedimentation zone, and the outlet zone before being discharged or entering the next stage of treatment structure.

[0008] The working principle and effects of this utility model: The aeration device in the influent zone oxygenates the wastewater, thereby reducing Fe content. 2+ Oxidized to Fe 3+ The alkaline medium (such as carbonate rock) in the reaction zone neutralizes acidic substances, raises the pH value, and promotes Fe production. 3+ Hydrolysis produces Fe(OH)3 flocs; the flocs are separated by gravity in the sedimentation zone; the purified wastewater is discharged through the effluent zone or enters the next stage of treatment.

[0009] The integrated and compact structure eliminates the need for long trenches, and a single processing unit can complete the entire process, making it suitable for scenarios with "no continuous space" such as narrow valleys and alleys; it is also suitable for short trenches or small, decentralized processing units that need to be built manually.

[0010] In the optimized system, multiple treatment structures are connected in parallel or series via effluent pipes. When connected in series, the effluent from the previous stage serves as the influent for the next stage, enhancing the treatment effect through multi-stage purification.

[0011] In an optimized multi-stage series arrangement, the height difference between each treatment stage should be no less than 0.1m. Wastewater flows by gravity, eliminating the need for pumps or other power equipment.

[0012] The optimized single treatment structure has a total length of 1.5m to 3.0m, a width of 0.5m to 0.8m, an effective water depth of 0.5m to 1.0m, a reaction zone filling depth of 0.2m to 0.4m, a sedimentation zone depth of 0.2m to 0.4m, and a water level of 0.15m to 0.4m above the packing zone.

[0013] Each treatment structure adopts a compact size of 1.5–3.0m in total length and 0.5–0.8m in width. The depth of each functional zone (reaction zone 0.2–0.4m, sedimentation zone 0.2–0.4m) is matched to the hydraulic retention time of low-flow wastewater (0.5–1h per stage) to ensure sufficient reaction. Width ≤0.8m allows passage through narrow underground tunnels (usually 2–3m wide), and total length ≤3.0m is suitable for fragmented spaces such as valley corners.

[0014] In the optimized configuration, the reaction zone is located above the precipitation zone, and the two are separated by a support mesh with a pore size of 0.5–2 mm. The support mesh supports the alkaline medium while allowing Fe(OH)3 flocs to enter the precipitation zone.

[0015] In the optimized configuration, the upper part of the support mesh is filled with carbonate rock reaction medium, and the filling thickness of the filler is 0.2 to 0.4 m.

[0016] The optimized carbonate rock reaction medium uses carbonate rock particles with a diameter of 1-2 cm. The 1-2 cm carbonate rock particles form uniform pores, which not only ensures smooth wastewater infiltration but also increases the contact area between the medium and the wastewater.

[0017] The optimized method involves setting up guide channels along the water flow direction at the bottom of the sedimentation zone. The guide channels are 5-10cm wide and the channel walls are 3cm high.

[0018] In an optimized configuration, an overflow weir is installed between the reaction zone and the effluent zone, with the overflow weir being 0.15m higher than the upper edge of the packing material. The overflow weir is 0.15m higher than the water surface at the top of the packing area, ensuring that if the wastewater volume is too large, the wastewater will overflow directly from the overflow weir and be led to the next stage via the effluent pipe, preventing wastewater from overflowing from the upper part of the reaction structure and affecting the surrounding environment.

[0019] In the optimized configuration, the bottom of the effluent pipe is aligned with the upper edge of the packing zone. This flush alignment ensures that the water level in the reaction zone matches the effluent level, resulting in uniform wastewater distribution within the reaction zone and ensuring all media participate in the reaction. Attached Figure Description

[0020] Figure 1This is a cross-sectional view of a system for treating acidic mine wastewater; Figure 2 for Figure 1 Top view of the processing structure; Figure 3 This is a schematic diagram of the internal structure. Detailed Implementation

[0021] The following detailed description illustrates the specific implementation method: Example: Figure 1 , Figure 2 and Figure 3 As shown, a system for treating acidic mine wastewater includes multiple treatment structures connected in series via effluent pipes, so that the effluent from the previous stage serves as the influent for the next stage, thereby enhancing the treatment effect through multi-stage purification.

[0022] Each treatment structure is arranged sequentially along the water flow direction, including an inlet zone, a reaction zone, a sedimentation zone, and an outlet zone. Both the inlet zone and the reaction zone are equipped with aeration devices, which are aeration pipes or aeration discs. The reaction zone is filled with an alkaline reaction medium to form a packing zone. The alkaline reaction medium consists of 1-2 cm carbonate rock particles. Alternatively, the carbonate rock particles can be placed in a bag with a pore size of 2-5 mm and then the bag can be filled into the reaction zone.

[0023] The total length of a single treatment structure is 1.5m to 3.0m, the width is 0.5m to 0.8m, the effective water depth is 0.5m to 1.0m, the filling depth of the reaction zone is 0.2m to 0.4m, the depth of the sedimentation zone is 0.2m to 0.4m, and the water level above the filling material is 0.15m to 0.4m higher than the surface of the filling material.

[0024] The reaction zone is located above the sedimentation zone, and the two are separated by a support mesh with a pore size of 0.5–2 mm. The bottom of the sedimentation zone is equipped with guide channels along the water flow direction, each channel being 5 cm wide and 3 cm high. An overflow weir is installed between the reaction zone and the effluent zone, with the overflow weir being 0.15 m higher than the upper edge of the packing material. The bottom of the effluent pipe is at the same height as the upper edge of the packing area.

[0025] The treatment system comprises an inlet zone, a reaction zone, a sedimentation zone, and an effluent zone. Acidic wastewater is introduced into the treatment system through an inlet pipe connected to the inlet zone. An aeration device is installed in the inlet zone to aerate and oxygenate the incoming wastewater, reducing the amount of Fe in the wastewater. 2+ Oxidized to Fe 3+ Oxygen is provided, and the reoxygenated wastewater overflows into the upper part of the reaction zone, passing through the carbonate rock packing layer in an upward-in, downward-out manner. Within the packing zone, the pH is increased, promoting Fe... 3+ Hydrolyzes to Fe(OH)3 solid, reducing the Fe content in the water. 2+ / 3+ It can be separated from the aqueous phase, and the wastewater can be purified.

[0026] An aeration device is also arranged above the support net in the reaction zone, where dissolved oxygen in the water cannot meet the Fe... 2+ Oxidized to Fe 3 + At this time, oxygen can continue to be supplied to the reaction zone to promote Fe. 2+ Oxidized to Fe 3+ After passing through the reaction zone, the wastewater enters the sedimentation zone. The Fe(OH)3 solid generated in the reaction zone can precipitate in the sedimentation zone, achieving solid-liquid separation and reducing the suspended solids content in the effluent. A guide tank is set at the bottom of the sedimentation zone. When sludge is discharged from the bottom of the sedimentation zone, it is pumped out and discharged through the sludge discharge pipe.

[0027] During sludge removal from the sedimentation zone, the rapid drop in water level increases the water flow velocity between the packing pores, carrying away some of the sediment. If the packing zone is severely clogged, two methods are mainly used for adjustment: Method 1: Sludge is pumped from the sedimentation zone and sent upwards to the upper part of the packing zone. High-speed water flow is used to continuously flush the pores. After a certain period of time, the sludge in the sedimentation zone is directly pumped out for discharge. Method 2: If Method 1 still does not meet the requirements, the packing can be removed and flushed during the flushing process to completely empty the sludge from the pores between the packing, thus restoring the system.

[0028] Wastewater flowing out of the sedimentation zone enters the effluent zone, which is connected to an effluent pipe to allow the wastewater to enter the next stage of treatment or be discharged. The bottom of the effluent pipe must be flush with the upper edge of the packing layer in the reaction zone to improve the uniformity of water distribution in the reaction zone.

[0029] Because the carbonate rock reaction layer in the reaction zone continuously increases the pH of the wastewater, a large amount of newly generated Fe(OH)3 will form flocculent deposits on the surface of the carbonate rock, gradually filling the voids in the carbonate rock packing layer and increasing the resistance of the wastewater through the packing layer. When the resistance is too high, it is necessary to clean it in time to prevent the water level in the reaction zone from exceeding the overflow weir, so that the wastewater is discharged directly to the downstream stage without being treated in the reaction zone.

[0030] To address the sedimentation on the surface of carbonate rock particles, this structure utilizes a water pump to draw water from the outlet area, pressurize it, and then flush the carbonate rock packing layer. The high-speed water flow carries away the sediment from the pores of the carbonate rock. Finally, the wastewater from the entire structure is discharged into a sludge tank, achieving sludge removal and treatment. If the sedimentation is high and difficult to remove from the pores, the carbonate rock packing bags can be manually removed one by one and rinsed individually with water to clean the entire packing layer.

[0031] The integrated, compact structure eliminates the need for long trenches; a single treatment unit can complete the entire process, making it suitable for scenarios with "discontinuous spaces" such as narrow valleys and alleyways. It is applicable to short trenches or decentralized small-scale treatment units requiring manual construction, or decentralized treatment systems with small water volumes and low pollutant concentrations. The treatment results for five different wastewater groups with varying pollutant concentrations using this method are shown in the table below:

[0032] pH adjustment: The influent pH is 4.2~6.2 (acidic to slightly acidic), and the effluent pH is stable at 6.7~6.8 (close to neutral, which meets the pH range of Class III surface water standard (6~9), indicating stable neutralization capacity).

[0033] Iron ion removal: The influent Fe concentration is 22.5~102.6mg / L (medium to high concentration of pollution), and the effluent Fe concentration is 0.2~0.5mg / L, with an average removal rate of 99%, far exceeding the traditional neutralization method (removal rate of about 80%).

[0034] The above descriptions are merely embodiments of this utility model. Commonly known technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this utility model. These modifications and improvements should also be considered within the scope of protection of this utility model, and will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A system for treating acidic mine wastewater, characterized in that: The system includes a treatment structure, which is provided with an inlet zone, a reaction zone, a sedimentation zone, and an outlet zone in sequence along the water flow direction. Both the inlet zone and the reaction zone are equipped with aeration devices. The reaction zone is filled with an alkaline reaction medium to form a packing zone. Acidic wastewater flows through the inlet zone, reaction zone, sedimentation zone, and outlet zone in sequence before being discharged or entering the next stage of the treatment structure. The processing structure is multiple, and the processing structures are connected in parallel or in series through water outlet pipes; When using a multi-stage series arrangement, the height difference between each stage of the treatment structure should not be less than 0.1m; The total length of a single treatment structure is 1.5m to 3.0m, the width is 0.5m to 0.8m, the effective water depth is 0.5m to 1.0m, the filling depth of the reaction zone is 0.2m to 0.4m, the sedimentation zone depth is 0.2m to 0.4m, and the water depth above the packing zone is 0.1m to 0.4m. The reaction zone is located above the precipitation zone, and the two are separated by a support mesh with a pore size of 0.5 to 2 mm.

2. The system for treating acidic mine wastewater according to claim 1, characterized in that: The upper part of the support mesh is filled with carbonate rock reaction medium, and the filling thickness is 0.2 to 0.4 m.

3. The system for treating acidic mine wastewater according to claim 2, characterized in that: At the bottom of the sedimentation zone, guide channels are set up along the direction of water flow. The width of the guide channels is 5-10cm and the height of the channel walls is 3cm.

4. The system for treating acidic mine wastewater according to claim 3, characterized in that: An overflow weir is provided between the reaction zone and the effluent zone, and the overflow weir is 0.15m higher than the water surface above the filler zone.

5. The system for treating acidic mine wastewater according to claim 4, characterized in that: The bottom of the outlet pipe is at the same height as the upper edge of the packing area.

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