Coal mine wharf sewage treatment uses multilayer filtration clean water pool

Abstract

The utility model relates to the technical field of sewage treatment, and disclose a coal mine wharf sewage treatment is with multilayer filtration's clean water pool, including clean water pool body, clean water pool body includes the aeration tank for treating coal mine wharf sewage, is located the collecting piece for collecting gas in aeration tank top, is used for treating the gas after collection's purification device and gas recycling device, and purification device includes dust removal dehydration unit, desulfurization deodorization unit and oxygen enrichment unit, and dust removal dehydration unit, desulfurization deodorization unit and oxygen enrichment unit are sequentially connected and set up. The clean water pool of the application has realized the whole process collaborative treatment of sewage pretreatment, aeration reaction, gas recovery purification and recycling, can effectively remove coal dust, water vapor, hydrogen sulfide, volatile organic compounds and other pollutants in gas, and improve oxygen concentration, both avoid secondary pollution, and realize the resource recovery of coal dust.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically to a multi-layer filtration clear water tank for wastewater treatment at a coal mine wharf. Background Technology

[0002] During coal mining and transportation, coal mine terminals, as crucial hubs for coal transshipment, storage, and loading, generate large amounts of wastewater. This wastewater is complex in composition, containing not only solid particles such as coal dust and rock dust carried during mining, but also various harmful substances such as grease, heavy metal ions, and organic pollutants introduced during coal's inherent properties and transportation. Direct discharge of this wastewater without effective treatment will severely pollute surrounding water bodies, soil, and the ecological environment, damaging aquatic habitats, affecting soil fertility, and even jeopardizing human health through the food chain.

[0003] In the wastewater treatment process at coal mine wharves, to ensure effective purification, various treatment facilities are typically set up according to the process flow, including anoxic tanks, aeration tanks, sedimentation tanks, and clear water tanks for advanced treatment. Among them, the aeration tank, as one of the core treatment units, mainly functions to increase the dissolved oxygen content in the wastewater by injecting air into it, providing sufficient oxygen for the metabolic activities of aerobic microorganisms to degrade organic pollutants in the wastewater.

[0004] However, the current operation of aeration tanks presents significant problems of resource waste and environmental pollution. The air injected into the aeration tank contains approximately 21% oxygen, but during actual aeration, due to limited contact efficiency between the gas and wastewater, about 60%–80% of the gas fails to be absorbed by the water and escapes directly into the air. These escaped gases are complex in composition, mainly containing large amounts of nitrogen, undissolved oxygen (with a residual oxygen content of approximately 15%–18%), a small amount of water vapor, and volatile pollutants unique to coal mine wastewater, such as hydrogen sulfide and coal dust volatiles.

[0005] If these escaping gases are directly emitted, on the one hand, unused oxygen in the air will be wasted, requiring the aeration system to continuously draw in large amounts of fresh air, leading to high energy consumption of equipment such as blowers; on the other hand, volatile pollutants in the escaping gases will cause secondary pollution to the surrounding environment, affecting air quality and even endangering the health of workers. Therefore, we propose a multi-layer filtration clear water tank for coal mine dock wastewater treatment to solve the aforementioned problems. Utility Model Content

[0006] The purpose of this invention is to provide a multi-layer filtration clear water tank for coal mine dock sewage treatment, in order to solve the problems mentioned in the background art, such as low air-water contact efficiency in the aeration tank, large amount of gas not being absorbed by the water and escaping, containing a large amount of nitrogen, undissolved oxygen, a small amount of water vapor, and volatile pollutants unique to coal mine sewage, such as hydrogen sulfide and coal dust volatiles. Direct discharge of these gases leads to the waste of unused oxygen, and the volatile pollutants in the escaped gases will pollute the surrounding environment, affect air quality, and endanger the health of workers.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A multi-layer filtration clear water tank for treating coal mine dock wastewater includes a clear water tank body, which includes an aeration tank for treating coal mine dock wastewater, a collection device located at the top of the aeration tank for collecting gas, a purification device for treating the collected gas, and a gas recycling device. The purification device includes a dust removal and dehydration unit, a desulfurization and deodorization unit, and an oxygen enrichment unit, which are connected in sequence.

[0009] The collection device includes a transparent cover plate covering the top of the aeration tank. The cover plate is arranged in an inverted V-shape with a higher center and lower sides. Guide plates are evenly distributed on the inner walls of both sides of the cover plate. An air guide plate is arranged on the inner wall of the top of the cover plate. The air guide plate and the guide plate are connected through each other. An air collection port is connected through the top center of the cover plate. An air collection pipe is connected to the top of the air collection port. An induced draft fan is connected to the air collection pipe.

[0010] Preferably, the dust removal and dewatering unit includes a cyclone separator and a gas-liquid separator. The air inlet of the cyclone separator is connected to the outlet of the gas collecting pipe, and the outlet of the cyclone separator is connected to the gas-liquid separator through a pipeline. A ash discharge valve is provided at the bottom of the cyclone separator. The gas-liquid separator is equipped with stainless steel wire mesh packing for removing moisture from the gas. The liquid outlet of the gas-liquid separator is connected to the aeration tank through a one-way reflux valve.

[0011] Preferably, the desulfurization and deodorization unit includes a biological filter and an activated carbon adsorption tower. The biological filter is located on one side of the aeration tank, and the air inlet of the biological filter is connected to the gas outlet of the gas-liquid separator. The biological filter is filled with volcanic rock and inoculated with sulfur-oxidizing bacteria. The activated carbon adsorption tower is located on the side of the biological filter away from the aeration tank. The biological filter and the activated carbon adsorption tower are connected by a pipeline. The activated carbon adsorption tower is filled with potassium permanganate activated carbon impregnated for removing volatile organic compounds from the gas.

[0012] Preferably, the oxygen enrichment unit includes an oxygen enrichment membrane, and the inlet of the oxygen enrichment membrane is connected to the outlet of the activated carbon adsorption tower.

[0013] Preferably, the gas recycling device includes a mixing tank and a Roots blower. The air inlet of the mixing tank is connected to the air outlet of the oxygen-enriched membrane. An oxygen content sensor is connected to the mixing tank. The mixing tank is connected to the Roots blower. The air outlet of the mixing tank is connected to the air inlet pipe of the aeration tank through a pipeline.

[0014] Preferably, the clear water tank body further includes a multi-layer filtration tank, the outlet of which is connected to the inlet of the aeration tank via a pipeline. The multi-layer filtration tank contains a coarse filtration layer, a medium filtration layer, and a fine filtration layer arranged sequentially along the sewage flow direction. The coarse filtration layer uses a grid with a pore size of 5-10 mm, the medium filtration layer is filled with quartz sand with a particle size of 2-5 mm, and the fine filtration layer uses an ultrafiltration membrane module with a pore size of 0.1-0.5 μm. A drain valve is provided at the bottom of the fine filtration layer.

[0015] Compared with the prior art, the beneficial effects of this utility model are:

[0016] 1. This application boasts a high resource recycling rate. It efficiently collects escaping gas from the aeration tank using a collection device. After dust removal, dehydration, desulfurization, deodorization, and oxygen enrichment treatment by a purification device, the enriched oxygen is reintroduced into the aeration tank via a gas recycling device. This process effectively recovers the originally escaping undissolved oxygen, significantly reduces the amount of fresh air intake, lowers the energy consumption of equipment such as blowers, achieves efficient energy utilization, and solves the problem of severe oxygen waste in traditional aeration tanks.

[0017] 2. The purification device can specifically remove volatile pollutants such as hydrogen sulfide and coal dust volatiles from the emitted gas. Among them, the sulfur-oxidizing bacteria in the biological filter can decompose hydrogen sulfide, and the potassium permanganate activated carbon in the activated carbon adsorption tower can adsorb volatile organic compounds, avoiding the secondary pollution to the surrounding environment caused by the direct emission of these pollutants, improving air quality, and protecting the health of the staff.

[0018] 3. High wastewater treatment efficiency: The multi-layer filtration system pre-treats the wastewater entering the aeration tank. The coarse filtration layer removes large particulate impurities, the quartz sand in the medium filtration layer filters fine particles, and the ultrafiltration membrane module in the fine filtration layer further purifies the wastewater. This effectively reduces the pollutant load in the wastewater, creates a more favorable environment for the metabolic activities of aerobic microorganisms in the aeration tank, improves the degradation efficiency of organic pollutants, and ensures a more stable and reliable wastewater purification effect.

[0019] 4. The collection unit adopts an inverted V-shaped transparent cover plate, combined with the design of the flow guide plate and the air guide plate, which can efficiently guide the escaping gas to converge towards the gas collection port, thereby improving the gas collection efficiency; the sequential connection of each purification unit and circulation device forms a complete closed-loop treatment system. The structure is compact and operates smoothly, making it easy to operate and maintain, and it has strong practicality and promotional value. Attached Figure Description

[0020] Figure 1 This is an overall isometric view of the present invention;

[0021] Figure 2 This is a schematic diagram of the collecting component structure of this utility model;

[0022] Figure 3 This is the overall filtration process diagram of this utility model.

[0023] In the diagram: 1. Aeration tank; 2. Collection component; 21. Transparent cover; 211. Guide plate; 212. Air guide plate; 213. Air collection port; 214. Air collection pipe; 215. Exhaust fan; 3. Purification device; 31. Cyclone separator; 32. Gas-liquid separator; 33. Biological filter; 34. Activated carbon adsorption tower; 35. Oxygen-enriched membrane; 4. Gas recycling device; 41. Mixing tank; 42. Roots blower; 5. Multi-layer filter; 51. Coarse filtration layer; 52. Medium filtration layer; 53. Fine filtration layer. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Please see Figure 1 and Figure 2As shown, a multi-layer filtration clear water tank for treating coal mine dock wastewater includes a clear water tank body. The clear water tank body includes an aeration tank 1 for treating coal mine dock wastewater, a collection unit 2 located at the top of the aeration tank 1 for collecting gas, a purification device 3 for treating the collected gas, and a gas recycling device 4. The inlet of the aeration tank 1 is connected to a multi-layer filtration tank 5 via a pipeline, and the outlet of the multi-layer filtration tank 5 is connected to the inlet of the aeration tank 1 via a pipeline. This multi-layer filtration clear water tank for treating coal mine dock wastewater integrates functions such as wastewater pretreatment, aeration reaction, gas recovery and purification, and recycling to form a highly efficient closed-loop treatment system. Each unit is connected in an orderly manner via pipelines. The system connects to achieve full-process treatment of wastewater, from primary filtration to deep purification, and from gas collection to recycling. The multi-layer filtration tank 5 contains a coarse filtration layer 51, a medium filtration layer 52, and a fine filtration layer 53 arranged sequentially along the wastewater flow direction. The coarse filtration layer 51 uses a grid with a pore size of 5–10 mm to intercept larger particles such as coal and stones in the wastewater. The medium filtration layer 52 is filled with quartz sand with a particle size of 2–5 mm to further filter medium-sized coal dust particles and suspended solids. The fine filtration layer 53 uses an ultrafiltration membrane module with a pore size of 0.1–0.5 μm to remove fine colloidal and small molecule pollutants. A drain valve is installed at the bottom of the fine filtration layer 53 for easy periodic cleaning of the filter residue.

[0026] The collecting component 2 includes a transparent cover plate 21 covering the top of the aeration tank 1. The cover plate 21 has an inverted V-shaped structure, higher in the middle and lower on both sides. Guide plates 211 are evenly distributed on the inner walls of both sides of the cover plate 21, and an air guide plate 212 is provided on the inner wall of the top of the cover plate 21. The air guide plate 212 is connected to the guide plate 211. An air collecting port 213 is connected to the top of the center of the cover plate 21, and an air collecting pipe 214 is connected to the top of the air collecting port 213. An induced draft fan 215 is connected to the air collecting pipe 214. The transparent cover plate 21 covers the top of the aeration tank 1 to prevent gas from escaping. The cover plate has an inverted V-shaped structure, higher in the middle and lower on both sides, with guide plates 211 evenly distributed on the inner walls of both sides, and an air guide plate 212 connected to the guide plate 211 on the inner wall of the top. The through-type air guide plate 212 and flow guide plate 211 are used to guide the gas flow and facilitate collection. The high-low structure on both sides facilitates the return of water covering the inner wall into the aeration tank 1. The aeration tank 1 injects air into the sewage through the aeration system to provide oxygen for aerobic microorganisms and degrade organic pollutants. During the aeration process, the gas that escapes is guided by the flow guide plate 211 and air guide plate 212 under the constraint of the inverted V-shaped transparent cover plate 21 and converges to the air collection port 213. Under the negative pressure of the blower 215, it enters the purification device 3 through the air collection pipe 214. The inverted V-shaped design of the transparent cover plate can promote the return of condensate to the aeration tank and reduce water loss. The through-type structure of the flow guide plate and air guide plate greatly improves the gas collection efficiency.

[0027] Please see Figure 1 and Figure 3As shown, the purification device 3 includes a dust removal and dehydration unit, a desulfurization and deodorization unit, and an oxygen enrichment unit, which are connected in sequence. The dust removal and dehydration unit includes a cyclone separator 31 and a gas-liquid separator 32. The inlet of the cyclone separator 31 is connected to the outlet of the gas collecting pipe 214, and the outlet of the cyclone separator 31 is connected to the gas-liquid separator 32 through a pipeline. A ash discharge valve is provided at the bottom of the cyclone separator 31. The gas-liquid separator 32 is equipped with stainless steel wire mesh packing for removing moisture from the gas. The outlet is connected to the aeration tank 1 via a one-way reflux valve. The gas transported from the gas collection pipe 214 first enters the cyclone separator 31. Under the action of the high-speed rotating airflow, the centrifugal force throws coal dust particles with a diameter ≥10μm entrained in the gas toward the wall of the separator, and finally discharges them through the bottom ash discharge valve. This process can remove solid impurities and avoid the subsequent equipment from being reduced in efficiency due to dust blockage. By intercepting coal dust in advance through the cyclone separator 31, not only is the subsequent purification unit protected, but the recovered coal dust can also be returned to the coal mine raw material system, realizing the secondary utilization of resources and reducing the cost of solid waste treatment.

[0028] After dust removal, the gas enters the gas-liquid separator 32. The stainless steel wire mesh packing inside provides a large gas-liquid contact area. Water vapor in the gas condenses into droplets on the surface of the packing, flows down along the packing and collects through the bottom liquid outlet, and finally returns to the aeration tank 1 through the one-way return valve. This effectively removes moisture from the gas, preventing water vapor from entering the biological filter and causing the packing to become damp and caking, or entering the oxygen-enriched membrane and causing the membrane module to age. At the same time, the returned condensate reduces the water loss in the aeration tank and saves water resources.

[0029] The desulfurization and deodorization unit includes a biological filter 33 and an activated carbon adsorption tower 34. The biological filter 33 is located on one side of the aeration tank 1. The air inlet of the biological filter 33 is connected to the gas outlet of the gas-liquid separator 32. The biological filter 33 is filled with volcanic rock and inoculated with sulfur-oxidizing bacteria. The activated carbon adsorption tower 34 is located on the side of the biological filter 33 away from the aeration tank 1. The biological filter 33 and the activated carbon adsorption tower 34 are connected by a pipeline. The activated carbon adsorption tower 34 is filled with potassium permanganate activated carbon impregnated for removing volatile organic compounds from the gas. The oxygen enrichment unit includes an oxygen enrichment membrane 35. The air inlet of the oxygen enrichment membrane 35 is connected to the air outlet of the activated carbon adsorption tower 34.

[0030] After dehydration, the gas enters the biological filter 33. The volcanic rock packing material inside the filter provides an attachment carrier for sulfur-oxidizing bacteria (thiobacillus thiooxidans). Under aerobic conditions, the bacteria oxidize hydrogen sulfide (H2S) in the gas into harmless sulfate (H2SO4) through metabolism. Biological desulfurization is highly efficient, more environmentally friendly and less expensive than chemical desulfurization. In addition, the volcanic rock packing material has good air permeability and a long service life, reducing the maintenance cost of frequent replacement.

[0031] When gas passes through the oxygen-enriched membrane at 35°C, the selective permeability of the membrane to oxygen and nitrogen (the oxygen permeation rate is 3-5 times that of nitrogen) increases the oxygen concentration in the gas. The oxygen-enriched gas then enters the aeration tank, significantly improving the dissolved oxygen transfer efficiency in wastewater, reducing the aeration volume required per unit time, and laying an energy-saving foundation for subsequent recycling.

[0032] The gas recycling device 4 includes a mixing tank 41 and a Roots blower 42. The air inlet of the mixing tank 41 is connected to the air outlet of the oxygen enrichment membrane 35. An oxygen content sensor is connected to the mixing tank 41. The mixing tank 41 is connected to the Roots blower 42. The air outlet of the mixing tank 41 is connected to the air inlet pipe of the aeration tank 1 through a pipeline.

[0033] Gas treated by the biological filter enters the activated carbon adsorption tower 34. The activated carbon, impregnated with potassium permanganate, removes residual volatile organic compounds and small amounts of undegraded odor substances through a combination of physical adsorption and chemical oxidation. Potassium permanganate, acting as an oxidant, oxidizes organic matter into harmless CO2 and H2O, extending the adsorption cycle of the activated carbon; further reducing gas odor, increasing VOCs removal rate, avoiding the inhibition of microbial activity in the aeration tank by reused gas, and minimizing the impact of exhaust emissions on the surrounding environment.

[0034] The oxygen-enriched gas enters the mixing tank 41. An oxygen sensor on the tank monitors the oxygen concentration in real time. If the concentration is too high, a small amount of fresh air is automatically added; if the concentration is insufficient, the proportion of oxygen-enriched gas is increased, ultimately stabilizing the oxygen concentration of the mixed gas. This precisely matches the aerobic microorganisms' needs in the aeration tank, avoiding energy waste due to excessively high oxygen concentrations or degradation efficiency issues caused by excessively low oxygen concentrations.

[0035] Workflow: Wastewater from the coal mine wharf first enters the multi-layer filtration tank 5, where it undergoes three stages of filtration along the water flow direction. The coarse filtration layer 51 intercepts larger particles of coal, stones, and other impurities in the wastewater, preventing large particles from entering subsequent systems and causing equipment damage. The medium filtration layer 52 further filters medium-sized coal dust particles and suspended solids, using the adsorption properties of quartz sand to reduce wastewater turbidity. The fine filtration layer 53 deeply removes fine colloids, small molecular pollutants, and some bacteria. The pretreated wastewater then enters the aeration tank 1 through pipelines, while the fine filtration layer is periodically activated. The drain valve at the bottom of 53 discharges accumulated filter residue, maintaining filtration efficiency. After entering the aeration tank 1, air is injected into the wastewater through the aeration system to provide oxygen for aerobic microorganisms and degrade organic pollutants in the wastewater. During the aeration process, the gas that escapes is guided by the guide plates 211 on both sides of the transparent cover to the air guide plate 212 at the top, and finally converges to the air collection port 213. Under the negative pressure of the blower 215, it enters the purification device 3 through the air collection pipe 214. The inverted V-shaped design of the cover also allows condensation on the inner wall. Water naturally flows back to aeration tank 1, reducing water loss. After entering purification device 3, the gas first enters cyclone separator 31, where the centrifugal force generated by high-speed rotation separates coal dust particles, which are then discharged and recycled through the bottom ash discharge valve. Next, the dust-removed gas enters gas-liquid separator 32, where water vapor is removed by stainless steel wire mesh packing. The condensate returns to aeration tank 1 via a one-way return valve. Subsequently, the dehydrated gas enters biological filter 33, where sulfur-oxidizing bacteria on the volcanic rock packing oxidize hydrogen sulfide (H2S) into harmless sulfate (H2SO4). The gas enters the activated carbon adsorption tower 34, where it is impregnated with potassium permanganate to remove residual volatile organic compounds and odor substances. The potassium permanganate oxidizes the organic compounds into CO2 and H2O. The purified gas then passes through the oxygen-enriched membrane 35, where the oxygen concentration is increased by utilizing the membrane's selective permeability to oxygen. Finally, the oxygen-enriched gas enters the mixing tank 41, where it is mixed with an appropriate amount of fresh air under real-time monitoring by an oxygen content sensor. The mixed gas is then pressurized by the Roots blower 42 and reinjected into the air inlet pipe of the aeration tank 1 through pipelines, completing the gas circulation.

[0036] This application achieves a synergistic treatment process encompassing wastewater pretreatment, aeration reaction, gas recovery and purification, and recycling. It effectively removes pollutants such as coal dust, water vapor, hydrogen sulfide, and volatile organic compounds from the gas while increasing oxygen concentration. This avoids secondary pollution and enables the recovery of coal dust resources. The purified, oxygen-enriched gas is reused in the aeration tank, significantly improving oxygen utilization, reducing energy consumption of the aeration system, and saving operating costs. The overall system has a compact structure and well-connected units, saving floor space and possessing good stability and adaptability. It comprehensively achieves multiple benefits, including high-efficiency purification, resource recovery, energy conservation, and environmental emission reduction.

[0037] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0038] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-layer filtration clear water tank for treating coal mine dock wastewater, comprising a clear water tank body, the clear water tank body including an aeration tank (1) for treating coal mine dock wastewater, a collection device (2) located at the top of the aeration tank (1) for collecting gas, a purification device (3) for treating the collected gas, and a gas recycling device (4), characterized in that: The purification device (3) includes a dust removal and dehydration unit, a desulfurization and deodorization unit and an oxygen enrichment unit, which are connected in sequence. The collecting component (2) includes a transparent cover plate (21) covering the top of the aeration tank (1). The cover plate (21) is arranged in an inverted V-shape with a high center and low sides. Guide plates (211) are evenly distributed on the inner walls of both sides of the cover plate (21). An air guide plate (212) is arranged on the inner wall of the top of the cover plate (21). The air guide plate (212) is connected to the guide plate (211). An air collection port (213) is connected to the top of the center of the cover plate (21). An air collection pipe (214) is connected to the top of the air collection port (213). An induced draft fan (215) is connected to the air collection pipe (214).

2. The multi-layer filtration clear water tank for coal mine wharf wastewater treatment according to claim 1, characterized in that: The dust removal and dehydration unit includes a cyclone separator (31) and a gas-liquid separator (32). The air inlet of the cyclone separator (31) is connected to the outlet of the gas collecting pipe (214). The outlet of the cyclone separator (31) is connected to the gas-liquid separator (32) through a pipeline. A ash discharge valve is provided at the bottom of the cyclone separator (31). The gas-liquid separator (32) is filled with stainless steel wire mesh packing for removing moisture from the gas. The liquid outlet of the gas-liquid separator (32) is connected to the aeration tank (1) through a one-way reflux valve.

3. The multi-layer filtration clear water tank for coal mine dock wastewater treatment according to claim 2, characterized in that: The desulfurization and deodorization unit includes a biological filter (33) and an activated carbon adsorption tower (34). The biological filter (33) is located on one side of the aeration tank (1). The air inlet of the biological filter (33) is connected to the gas outlet of the gas-liquid separator (32). The biological filter (33) is filled with volcanic rock and inoculated with sulfur-oxidizing bacteria. The activated carbon adsorption tower (34) is located on the side of the biological filter (33) away from the aeration tank (1). The biological filter (33) and the activated carbon adsorption tower (34) are connected by a pipeline. The activated carbon adsorption tower (34) is filled with potassium permanganate activated carbon impregnated for removing volatile organic compounds from the gas.

4. A multi-layer filtration clear water tank for coal mine dock wastewater treatment according to claim 3, characterized in that: The oxygen enrichment unit includes an oxygen enrichment membrane (35), the inlet of which is connected to the outlet of the activated carbon adsorption tower (34).

5. A multi-layer filtration clear water tank for coal mine dock wastewater treatment according to claim 4, characterized in that: The gas recycling device (4) includes a mixing tank (41) and a Roots blower (42). The air inlet of the mixing tank (41) is connected to the air outlet of the oxygen-enriched membrane (35). An oxygen content sensor is connected to the mixing tank (41). The mixing tank (41) is connected to the Roots blower (42). The air outlet of the mixing tank (41) is connected to the air inlet pipe of the aeration tank (1) through a pipeline.

6. A multi-layer filtration clear water tank for coal mine wharf wastewater treatment according to claim 1, characterized in that: The main body of the clear water tank also includes a multi-layer filter tank (5). The outlet of the multi-layer filter tank (5) is connected to the inlet of the aeration tank (1) through a pipeline. The multi-layer filter tank (5) is provided with a coarse filter layer (51), a medium filter layer (52) and a fine filter layer (53) in sequence along the sewage flow direction. The coarse filter layer (51) adopts a grid with a pore size of 5-10 mm. The medium filter layer (52) is filled with quartz sand with a particle size of 2-5 mm. The fine filter layer (53) adopts an ultrafiltration membrane module with a pore size of 0.1-0.5 μm. A drain valve is provided at the bottom of the fine filter layer (53).

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