An acidic mine wastewater treatment system

Abstract

This application discloses an acidic mine wastewater treatment system, including a drainage ditch for separate treatment, wherein the drainage ditch is divided into a non-polluting water channel and a wastewater treatment channel; non-polluting water is directly discharged through the non-polluting water channel, while acidic wastewater is purified through the wastewater treatment channel before being discharged; the wastewater treatment channel includes at least one treatment unit, each treatment unit including an oxidation aid device for promoting the oxidation of reducing substances in the wastewater, an alkaline reaction component for neutralizing acidic substances, and a precipitation component for solid-liquid separation. By setting up the non-polluting water channel and the wastewater treatment channel, the non-polluting water and acidic wastewater are treated and discharged separately, reducing the interference of non-polluting water on the acidic wastewater treatment system and ensuring treatment efficiency.

Description

Technical Field

[0001] This utility model relates to the field of acidic mine wastewater treatment, specifically to an acidic mine wastewater treatment system. 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. AMD contains very low levels of organic matter but is rich in high concentrations of sulfates, and its pH value is usually at a very low level. If this highly acidic wastewater, which is rich in heavy metal ions, is discharged directly without proper treatment, it will have a catastrophic impact on the ecological environment and biological systems. In particular, the harmful heavy metals in it will accumulate through the food chain and eventually seriously threaten human health.

[0003] 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.

[0004] 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. Utility Model Content

[0005] This utility model aims to provide an acidic mine wastewater treatment system. By setting up a non-polluting water channel and a wastewater treatment channel, the non-polluting water and acidic wastewater are treated and discharged separately, reducing the interference of non-polluting water on the acidic wastewater treatment system and ensuring treatment efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: An acidic mine wastewater treatment system includes a drainage ditch for diversion treatment, wherein the drainage ditch is divided into a non-polluting water channel and a wastewater treatment channel; the non-polluting water is directly discharged through the non-polluting water channel, and the acidic wastewater is discharged after being purified through the wastewater treatment channel; the wastewater treatment channel includes at least one treatment unit, each treatment unit including an oxidation aid device for promoting the oxidation of reducing substances in the wastewater, an alkaline reaction component for neutralizing acidic substances, and a precipitation component for solid-liquid separation.

[0007] In an optimized configuration, the wastewater treatment channel is located on one side of the drainage ditch, with its sidewall height higher than the surrounding ground level; the drainage ditch is equipped with a connecting channel for introducing non-polluted water into the non-polluted channel, thereby achieving separation of clean and polluted water.

[0008] The optimized alkaline reaction assembly is a multi-level reaction wall constructed with alkaline mineral materials. The reaction wall has a height of 30-60cm, a thickness of 10-20cm, a width of 30-60cm, and a spacing of 10-20cm between adjacent reaction walls.

[0009] The optimized wastewater treatment channel has a slope at the bottom, with a slope greater than 0.5%.

[0010] The optimized alkaline mineral material is carbonate rock particles with a particle size of 1-2 cm.

[0011] Optimized, the outer side of the reaction wall has a porous support structure, and the carbonate rock particles are encapsulated in mesh bags with a pore size of 2-5 mm. Multiple mesh bags are then placed inside the reaction wall. For example, using mesh bags with a porous structure, after the carbonate rock is placed in the mesh bags, when the backwashing effect is poor or additional cleaning is needed, the mesh bags can be directly lifted for cleaning, reducing operational difficulty. Optimized, the oxidation aid device is an aeration structure, set in the interval area between the multi-stage reaction walls. The aeration structure consists of aeration discs or aeration pipes and matching gas delivery pipelines.

[0012] The optimized sedimentation assembly includes a water inlet pipe, a sedimentation tank, and a sludge hopper located at the bottom of the sedimentation tank. The water inlet pipe directs acidic wastewater to the lower middle part of the sedimentation tank.

[0013] Ideally, the volume of the sedimentation tank in each treatment unit should be no less than five times the volume of the water treatment area of ​​the reaction wall in that treatment unit.

[0014] The working principle of this utility model: This system relies on naturally formed or man-made drainage ditches in mountainous areas, constructing wastewater treatment channels and non-polluting channels within these ditches. Non-polluting water is collected in the non-polluting channels and discharged directly downstream, while acidic wastewater enters the wastewater treatment channels for purification.

[0015] The treatment channel consists of multiple treatment and purification units. Each unit includes multi-stage carbonate rock reaction walls, sedimentation tanks, and effluent weirs, with aeration devices installed in the intervals between the reaction walls. The carbonate rocks can react 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.

[0016] The aeration devices installed in the intervals between the reaction walls can continuously replenish O2 to the water. When the natural reoxygenation is insufficient, additional O2 can be added to ensure Fe... 2+ To Fe 3+ The conversion accelerates the oxidation process. The Fe(OH)3 solid generated by subsequent hydrolysis and conversion easily forms a precipitate on the surface of carbonate rock particles when passing through the carbonate rock reaction wall, while the solid particles that pass through the carbonate rock wall can be removed by sedimentation in the settling tank.

[0017] When excessive Fe(OH)3 solids are deposited on the surface of carbonate rocks, causing a significant rise in the liquid level in the channel, the sludge in the bottom sludge zone of the sedimentation tank can be discharged to the sludge tank to lower the liquid level in the treatment channel. Then, the supernatant in the sedimentation tank can be pumped out to flush the reaction wall. The washed sludge flows into the sedimentation tank with the water flow for sedimentation and separation. After the sludge is removed, the water level in the ditch returns to normal.

[0018] The liquid level in the treatment channel is controlled by the effluent weir of the sedimentation tank, so that each sedimentation tank, together with the reaction wall between it and the previous sedimentation tank, forms a complete treatment and purification unit. Meanwhile, the treatment channel is located on one side of the drainage ditch, with its sidewalls raised above ground level. A connecting ditch is installed at the top of the channel, which directs uncontaminated drainage into the non-contaminated water channel, reducing the increase in system treatment load caused by the mixing of non-contaminated water with acidic wastewater.

[0019] The beneficial effects of this utility model are: (1) By setting up non-polluting water channels and wastewater treatment channels, non-polluting water and acidic wastewater are treated and discharged separately, which reduces the interference of non-polluting water on the acidic wastewater treatment system and ensures treatment efficiency.

[0020] (2) The system is constructed by simply modifying natural streams or artificial ditches, eliminating the need for reaction tanks and other structures commonly used in existing technologies, thus saving on infrastructure costs. The carbonate rocks used are inexpensive and readily available, which greatly reduces the cost of wastewater treatment. Furthermore, the system does not require complex equipment or high energy consumption during operation, resulting in low operating costs.

[0021] (3) The acidic wastewater treated by the technical solution of this application has a high alkalinity, and the average pH value after multi-stage treatment can reach about 7. It also has a good effect on iron removal. When the influent concentration is about 30 mg / L, the iron removal rate can reach more than 90%. If the influent pH is low and the Fe content is high, the wastewater can be treated by increasing the number of treatment units.

[0022] In summary, the technical solution of this application has strong acid neutralization ability, low investment, short construction period, low operating cost, convenient management, good iron removal effect, and can effectively improve the ecological environment of the mining area. It has good application prospects in carbonate rock areas. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of an acidic mine wastewater treatment system. Figure 2 for Figure 1 Schematic diagram of the connecting channel Figure 3 for Figure 1 Cross-sectional view of the connecting channel. Detailed Implementation

[0024] The following detailed description illustrates the specific implementation method: Example: Refer to Figures 1-3 An acidic mine wastewater treatment system utilizes naturally formed or man-made drainage ditches in mountainous areas. Within these ditches, wastewater treatment channels and non-polluting channels are constructed. Each wastewater treatment channel contains n treatment and purification units, including a multi-stage carbonate rock reaction wall, an effluent weir, and a sedimentation tank. Aeration devices, such as aeration discs and aeration pipes, are installed in the intervals between the reaction walls.

[0025] Carbonate rocks refer to the general term for rocks composed of carbonate minerals. They can react with sulfuric acid to produce CO2 and H2O, reducing wastewater acidity and increasing the pH value of acidic wastewater. Aeration devices are added at the intervals between the reaction walls. When natural reoxygenation is insufficient, aeration is performed through these devices, while airflow agitation ensures more complete vertical mixing of the wastewater. This process allows Fe2+ to be mixed more thoroughly during the wastewater flow. 2+ To Fe 3+ The process involves conversion to generate Fe(OH)3 solid particles. When these Fe(OH)3 solid particles pass through the carbonate rock reaction wall, they tend to precipitate on the surface of the carbonate rock particles. The solid particles that pass through the carbonate rock wall are removed by sedimentation in the settling tank.

[0026] When excessive Fe(OH)3 solid particles deposit on the carbonate rock surface, causing a significant rise in the water level within a certain stage of the wastewater treatment channel, the sludge from the bottom sludge zone of the sedimentation tank can be discharged to an externally constructed sludge thickening or drying tank. This lowers the water level within the wastewater treatment channel. The supernatant from the sedimentation tank is then pumped out to flush the reaction wall, thus cleaning the carbonate rock surface. The washed-out sludge flows with the water into the sedimentation tank for sedimentation and separation. Once the sludge between the carbonate rock particles is removed, the water level in the channel returns to normal. The water level depth within the wastewater treatment channel is controlled by the effluent weir of the sedimentation tank, ensuring that each sedimentation tank, along with the reaction wall between it and the preceding sedimentation tank, forms a complete treatment and purification unit.

[0027] When the drainage in the catchment area is non-polluted water, the side wall of the drainage ditch near the treatment ditch is higher than the ground. According to the water volume, a connecting ditch is set at regular intervals to introduce the non-polluted water on the side of the treatment ditch into the non-polluted water ditch for collection and discharge, thereby reducing the significant increase in the system's treatment load caused by the mixing of non-polluted water with acidic wastewater.

[0028] Through multi-stage treatment, the mine wastewater undergoes multiple pH-raising, reoxygenation, and Fe treatment processes. 2+ To Fe 3+ The process involves stages such as transformation and precipitation to treat the mine's wastewater. The carbonate rock used is limestone, which is easy to obtain and inexpensive.

[0029] The following table shows the results of treating five groups of wastewater under different conditions using this method:

[0030] Note: "-" indicates not detected. The results shown in the table above demonstrate that the pH value of the effluent can be increased to a certain extent after treatment with the technical solution of this application. The conclusions are as follows: (1) Significant pH adjustment effect Influent pH range: 4.5-6.6 (acidic to weakly acidic), covering the typical range of low to moderately acidic wastewater.

[0031] The pH range of the effluent is 6.6-6.8 (close to neutral; 6.5-7.5 is the normal pH range for water bodies in nature).

[0032] Conclusion: Regardless of the acidity of the influent, the pH value was steadily increased to near neutral after treatment by the system. This indicates that the system has a strong and stable acid neutralization capacity through the neutralization effect of the carbonate rock reaction wall, which can effectively solve the low pH problem of acidic wastewater.

[0033] (2) Excellent iron ion removal efficiency Influent Fe concentration range: 14.2-89.2 mg / L (including scenarios with medium to high concentrations of iron ion pollution).

[0034] The Fe concentration range in the effluent is 0.3-0.8 mg / L, and iron ions were not detected in the effluent of group 4.

[0035] Removal rate calculation: Group 1: (89.2 - 0.3) / 89.2 × 100% ≈ 99.7% Group 2: (78.3 - 0.4) / 78.3 × 100% ≈ 99.5% Group 3: (75.5 - 0.8) / 75.5 × 100% ≈ 98.9% Group 5: (45.2 - 0.5) / 45.2 × 100% ≈ 98.9% The overall removal rate exceeds 98%, and even when the influent iron ion concentration is as high as 89.2 mg / L, it can still be reduced to below 1 mg / L.

[0036] 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. An acidic mine wastewater treatment system, comprising drainage ditches for diverting wastewater, wherein the drainage ditches are divided into non-polluted water channels and wastewater treatment channels; characterized in that: Non-polluted water is discharged directly through a non-polluted water channel, while acidic wastewater is discharged after being purified through a wastewater treatment channel. The wastewater treatment channel includes at least one treatment unit, and each treatment unit includes an oxidation aid device for promoting the oxidation of reducing substances in the wastewater, an alkaline reaction component for neutralizing acidic substances, and a precipitation component for solid-liquid separation.

2. The acidic mine wastewater treatment system according to claim 1, characterized in that: The wastewater treatment channel is located on one side of the drainage ditch, and its sidewall is higher than the surrounding ground. The drainage ditch is equipped with a connecting channel to introduce non-polluted water into the non-polluted channel, so as to achieve separation of clean and polluted water.

3. The acidic mine wastewater treatment system according to claim 2, characterized in that: The alkaline reaction assembly is a multi-level reaction wall constructed with alkaline mineral materials. The reaction wall has a height of 30-60cm, a thickness of 10-20cm, a width of 30-60cm, and a spacing of 10-20cm between adjacent reaction walls.

4. The acidic mine wastewater treatment system according to claim 3, characterized in that: The bottom of the wastewater treatment channel has a slope greater than 0.5%.

5. The acidic mine wastewater treatment system according to claim 4, characterized in that: The alkaline mineral material is carbonate rock particles with a particle size of 1-2 cm.

6. The acidic mine wastewater treatment system according to claim 5, characterized in that: The outer side of the reaction wall has a porous support structure; the carbonate rock particles are placed in mesh bags with a pore size of 2~5mm, and then multiple mesh bags are placed inside the reaction wall.

7. The acidic mine wastewater treatment system according to claim 6, characterized in that: The oxidation aid device is an aeration structure, located in the interval area between multi-stage reaction walls. The aeration structure consists of an aeration disc or aeration pipe and a matching gas delivery pipeline.

8. The acidic mine wastewater treatment system according to claim 7, characterized in that: The sedimentation assembly includes a water inlet pipe, a sedimentation tank, and a sludge hopper located at the bottom of the sedimentation tank. The water inlet pipe directs acidic wastewater to the lower middle part of the sedimentation tank.

9. The acidic mine wastewater treatment system according to claim 8, characterized in that: The volume of the sedimentation tank in each treatment unit shall not be less than 5 times the volume of the water treatment area of ​​the reaction wall in that treatment unit.

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