Process for treating underground coal mine water by membrane method

Abstract

The invention relates to a process for treating underground coal mine water by a membrane method. The process comprises the following steps: S10, collecting raw water into a first circular sedimentation tank in a central raw water bin through a grating channel; s20, collecting large particles suspended on the surface of the raw water in the raw water in the first circular sedimentation tank through a first collection device arranged at the edge position of the first circular sedimentation tank; s30, sucking the raw water in the first circular sedimentation tank into a second circular sedimentation tank, and collecting fine suspended matters floating on the surface of the raw water in the second circular sedimentation tank through a second collecting device arranged at the edge position of the second circular sedimentation tank; s40, carrying out flocculation treatment on the raw water in the second circular sedimentation tank; s50, collecting flocculates suspended on the surface of the raw water through a second collecting device; and S60, drawing the raw water in the second circular sedimentation tank into a hollow nanofiltration fiber membrane for filtration treatment, and storing the filtered clean water into a clean water bin.

Description

Technical Field

[0001] The present invention relates to a sewage treatment process, and particularly to a process for treating underground mine water in coal mines by membrane method. Background Art

[0002] Coal mine sewage is wastewater generated during coal mine exploitation, processing, and the life in mining areas. The main sources include mine water, coal washing wastewater, and domestic sewage. Among them, mine water is the groundwater that gushes into the mine during the exploitation process, as well as the wastewater generated in links such as equipment cooling and dust suppression sprinkling. The main pollutants in it are suspended solids, minerals, oils, heavy metals, etc. The suspended solids mainly include particles such as coal powder, rock powder, and clay. The minerals mainly include calcium, magnesium, sulfates, and total dissolved solids. The oils are mainly composed of floating oils or emulsified oils formed by the leakage of equipment lubricating oil and hydraulic oil. The heavy metals include iron, manganese, mercury, cadmium, etc. Coal washing wastewater mainly includes the wastewater generated in processes such as screening, grading, and de-sludging during the coal washing process. Among them, the main pollutants in coal washing wastewater include high-concentration suspended solids, minerals, etc. The high-concentration suspended solids mainly include fine and difficult-to-settle coal slime, and the minerals mainly include dissolved salts. Domestic sewage mainly comes from the wastewater generated in the life in mining areas, including the drainage from canteens, dormitories, and bathrooms.

[0003] As described above, due to the large difference in water quality of coal mine sewage (such as high suspended solids, high salinity, oil or organic matter), the conventional treatment process for general underground mine water in coal mines is "primary sedimentation tank + regulating tank + flocculation reaction tank + mixed sedimentation + intermediate water tank + filtration + clear water tank", and the equipment cooling water and dust removal water underground need to be lifted to the ground for treatment.

[0004] It can be seen that the existing coal mine sewage treatment process is complex and the treatment time is long. At the same time, the above process cannot effectively treat the residual heavy metals, sulfates, calcium, magnesium and other divalent ions in the sewage. Summary of the Invention

[0005] The main object of the present invention is to provide a process for treating underground mine water in coal mines by membrane method, which has a simple process, less water treatment time, and can effectively treat heavy metal ions and the like in water.

[0006] To achieve the above object, the present invention provides a process for treating underground mine water in coal mines by membrane method, including the following steps: S10: Collect the raw water through the grid channel and enter the first circular sedimentation tank in the central raw water tank; S20: Collect the large particulate matters suspended on the surface of the raw water in the first circular sedimentation tank through the first collection device arranged at the edge position of the first circular sedimentation tank; S30: After the raw water in the first circular sedimentation tank has been statically sedimented for a preset period of time, draw the raw water in the first circular sedimentation tank into the second circular sedimentation tank, and collect the fine suspended matter floating on the surface of the raw water in the second circular sedimentation tank through a second collection device arranged at the edge position of the second circular sedimentation tank; S40: Carry out flocculation treatment on the raw water in the second circular sedimentation tank; S50: Collect and treat the flocs suspended on the surface of the raw water through the second collection device; S60: After the raw water in the second circular sedimentation tank has been statically sedimented for a preset period of time, draw the raw water in the second circular sedimentation tank into a hollow nanofiber membrane for filtration treatment, and store the filtered clean water in a clean water storage tank.

[0007] Preferably, the first collection device includes a first wave maker and a first floating device. The first wave maker is arranged at the middle position of the first circular sedimentation tank, and the first floating device is arranged at the edge of the first circular sedimentation tank. The first floating device rises as the liquid level of the raw water in the first sedimentation tank rises.

[0008] Further preferably, the first floating device includes a first enclosure, an inverted first trapezoidal trough and a plurality of first water tanks. The first enclosure is arranged along the inner edge of the first circular sedimentation tank. The first water tanks are located below the liquid level. These first water tanks are connected in series through a first water inlet pipe. The first trapezoidal trough is fixedly connected to the first enclosure, and the first trapezoidal trough can sink or rise as the water in the first water tank increases or decreases.

[0009] Even more preferably, the first trapezoidal trough is a right trapezoidal trough. The right-angled side of the first trapezoidal trough is fixedly connected to the first enclosure, and a plurality of leakage holes are provided at the bottom of the first trapezoidal trough.

[0010] Even more preferably, a first aeration pipe is provided on the outer side of the hypotenuse of the first trapezoidal trough.

[0011] Even more preferably, the usage method of the first collection device is as follows: S110: Set the first wave maker at the middle part of the first circular sedimentation tank. By controlling the water volume in the first water tank, make the top of the first trapezoidal trough be 1-2 cm below the liquid level. The first aeration pipe is always in the aeration state. Through the aeration of the first aeration pipe, prevent fine impurities from adhering to the outer side of the first trapezoidal trough; S120: Start the first wave maker to make the liquid level fluctuate, and push the large impurities floating on the liquid surface to the edge of the first circular sedimentation tank, so as to enter above the first trapezoidal trough; S130: After all the large impurities floating on the liquid surface are located above the first trapezoidal trough, pump out the water in the first water tank, so that the impurities are located above the first trapezoidal trough, and take the large impurities out of the first circular sedimentation tank; S140: Turn off the first wave maker; S150: Clean the impurities in the first trapezoidal groove. After cleaning, inject water into the first water tank to reset the first trapezoidal groove.

[0012] Preferably, the second collection device includes a second wave maker and a second suspension device. The second wave maker is arranged at the middle position of the second circular sedimentation tank, and the second suspension device is arranged at the edge of the second circular sedimentation tank. The second suspension device rises as the liquid level of the raw water in the second sedimentation tank rises.

[0013] Further preferably, the second suspension device includes a second enclosing plate, an inverted second trapezoidal groove, and a plurality of second water tanks. The second enclosing plate is arranged along the inner edge of the second circular sedimentation tank. The second water tanks are located below the liquid level. These second water tanks are connected in series through a second water inlet pipe. The second trapezoidal groove is fixedly connected to the second enclosing plate. The second trapezoidal groove can sink or rise as the water in the second water tank increases or decreases; the second trapezoidal groove is a right trapezoidal groove, and the right-angled side of the second trapezoidal groove is fixedly connected to the second enclosing plate.

[0014] Even more preferably, the usage method of the second collection device is as follows: S210: Set the second wave maker at the middle part of the second circular sedimentation tank. By controlling the water volume in the second water tank, make the top of the second trapezoidal groove be 1 - 2 cm below the liquid level. The second aeration pipe is always in the aeration state. Through the aeration of the second aeration pipe, prevent fine impurities from adhering to the outside of the second trapezoidal groove; S220: Start the second wave maker to make the liquid level fluctuate, and push the fine impurities floating on the liquid surface to the edge of the second circular sedimentation tank, so as to enter above the second trapezoidal groove; S230: After all the fine impurities floating on the liquid surface are located above the second trapezoidal groove, pump out the water in the second water tank to take out the fine impurities from the second circular sedimentation tank; S240: Turn off the second wave maker; S250: Clean the impurities in the second trapezoidal groove. After cleaning, inject water into the second water tank to reset the second trapezoidal groove.

[0015] Preferably, the hollow fiber nanofiltration membrane includes a brush filter and a membrane module. The raw water in the second circular sedimentation tank enters the membrane module for secondary filtration after being filtered by the brush filter.

[0016] The beneficial effects of the present invention are: The present invention realizes the targeted collection of suspended solids with different particle sizes through the setting of a first circular sedimentation tank and a second circular sedimentation tank. After two-stage sedimentation, heavy metals, sulfates, divalent ions such as calcium and magnesium in the raw water are filtered through a hollow fiber nanofiltration membrane, thereby completing the treatment of sewage. The entire treatment process is simple and time-saving, thus quickly completing the treatment of sewage. The wastewater in the mine does not need to be lifted to the ground for treatment and can directly enter the first circular sedimentation tank through the grid channel for treatment. At the same time, the wastewater treated by the hollow fiber nanofiltration membrane can be directly used for ground dust prevention, fire fighting, domestic water, etc., without worrying about the blockage of the water spray nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0018] Figure 1 is a process flow diagram of the membrane method for treating underground mine water of the present invention; Figure 2 is a top view structural schematic diagram of the first collection device of the present invention; Figure 3 is a side view structural schematic diagram of the first collection device of the present invention; Figure 4 is a top view structural schematic diagram of the first collection device of the present invention; Figure 5 is a side view structural schematic diagram of the first collection device of the present invention.

[0019] DESCRIPTION OF THE REFERENCE NUMERALS 1. First circular sedimentation tank; 2. First enclosure; 3. First trapezoidal trough; 4. First water tank; 5. First wave maker; 6. Second circular sedimentation tank; 7. Second enclosure; 8. Second trapezoidal trough; 9. Second water tank; 11. Second wave maker. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar promotions without departing from the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0021] As Figure 1 shown, this embodiment provides a process for treating underground mine water by the membrane method, including the following steps: S10: Collect the raw water through the grid channel and enter the first circular sedimentation tank 1 in the central raw water storage tank.

[0022] In this step, use the grid channel to intercept and remove large impurities in the raw water, such as cinder, sand, branches, plastic fragments, etc. Through the preliminary filtration of the grid channel, the load of the subsequent sedimentation tank is reduced, enabling the first circular sedimentation tank 1 to more efficiently treat large particulate matter suspended on the water surface. This step provides a pretreatment guarantee for the subsequent process and ensures the stable and efficient operation of the system.

[0023] S20: In the first circular sedimentation tank 1, collect the large particulate matter suspended on the surface of the raw water in the raw water through the first collection device arranged at the edge position of the first circular sedimentation tank 1.

[0024] Specifically, in this embodiment, as Figure 2 and Figure 3 shown, the first collection device includes a first wave maker 5 and a first suspension device. The first wave maker 5 is arranged at the middle position of the first circular sedimentation tank 1, and the first suspension device is arranged at the edge of the first circular sedimentation tank 1. The first suspension device rises as the liquid level of the raw water in the first sedimentation tank rises. Preferably, in this embodiment, the first suspension device includes a first enclosure 2, an inverted first trapezoidal trough 3, and a plurality of first water tanks 4. The first enclosure 2 is arranged along the inner edge of the first circular sedimentation tank 1. The first water tanks 4 are located below the liquid level. These first water tanks 4 are connected in series through a first water inlet pipe. The first trapezoidal trough 3 is fixedly connected to the first enclosure 2. The first trapezoidal trough 3 can sink or rise as the water in the first water tank 4 increases or decreases. The first trapezoidal trough 3 is a right trapezoidal trough. The right-angled side of the first trapezoidal trough 3 is fixedly connected to the first enclosure 2. The bottom of the first trapezoidal trough 3 is provided with a plurality of leakage holes. The other side of the first trapezoidal trough 3 faces the center position of the second circular sedimentation tank 1. The first trapezoidal trough 3 is horizontally arranged. The outer side of the hypotenuse of the first trapezoidal trough 3 is provided with a first aeration pipe.

[0025] In this step, through the first collection device arranged at the edge of the first circular sedimentation tank 1, use the liquid level fluctuation generated by the wave maker to push the floating large particulate impurities to the pool edge, and then collect and take them out of the sedimentation tank through a liftable device such as a trapezoidal trough. This step can separate larger floating objects in the raw water in advance, avoid them entering the subsequent treatment links, thereby reducing the treatment load of the subsequent process, and preventing large particulate impurities from blocking the equipment or affecting the treatment effect.

[0026] In this step, attention should be paid to the use frequency during the use of the first wave maker 5. At the same time, avoid agitating the sediment layer at the bottom of the pool during the use of the first wave maker 5.

[0027] In this embodiment, the usage method of the first collection device is: S110: Place the first wave maker 5 in the middle of the first circular sedimentation tank 1. By controlling the water volume in the first water tank 4, ensure that the top of the first trapezoidal trough 3 is 1 - 2 cm below the liquid level. The first aeration pipe is always in the aeration state. The aeration through the first aeration pipe prevents fine impurities from adhering to the outer side of the first trapezoidal trough 3. In this embodiment, the purpose of the first aeration pipe is to prevent impurities such as oil and coal ash floating on the liquid surface from adhering too much to the surface of the first trapezoidal trough 3.

[0028] S120: Start the first wave maker 5 to make the liquid level fluctuate, and push the large impurities floating on the liquid surface to the edge of the first circular sedimentation tank 1, so that they enter above the first trapezoidal trough 3.

[0029] S130: After all the large impurities floating on the liquid surface are located above the first trapezoidal trough 3, pump out the water in the first water tank 4, so that the impurities are located above the first trapezoidal trough 3 and take the large impurities out of the first circular sedimentation tank 1. In this step, the main impurities removed are some floating larger coal chips, coal powder particles, rock debris fragments, wood, plastics, fibrous or sheet - like floating objects, etc.

[0030] S140: Turn off the first wave maker 5.

[0031] S150: Clean the impurities in the first trapezoidal trough 3. After cleaning, inject water into the first water tank 4 to reset the first trapezoidal trough 3. In this step, a reciprocating slag scraper can be set on the first baffle 2, using a stainless - steel chain + elastic scraper, moving back and forth along the first trapezoidal trough 3 at an appropriate speed to hang the above - mentioned impurities into the collection hopper, thus completing the collection of impurities.

[0032] S30: After the raw water in the first circular sedimentation tank 1 has been statically precipitated for a preset time, draw the raw water in the first circular sedimentation tank 1 into the second circular sedimentation tank 6, and collect the fine suspended solids floating on the surface of the raw water in the second circular sedimentation tank 6 through the second collection device arranged at the edge of the second circular sedimentation tank 6.

[0033] The purpose of this step is to further remove the fine suspended solids in the raw water of the coal mine shaft bottom water. After the collection and treatment of large - particle suspended solids in step S20, there are still some impurities with smaller particle sizes and suspended on the water surface in the raw water. By drawing the raw water in the first circular sedimentation tank 1 into the second circular sedimentation tank 6 and using the second collection device arranged at the edge of the second circular sedimentation tank 6 to collect the fine suspended solids floating on the surface of the raw water, the cleanliness of the raw water is further improved, creating better conditions for subsequent treatment steps.

[0034] In addition, although primary static sedimentation has been carried out in the first circular sedimentation tank 1, due to the slow sedimentation rate of fine suspended solids, some fine particles may still not be completely sedimented within the preset time in the first circular sedimentation tank 1. Therefore, according to the actual situation, further static sedimentation can be carried out in the second circular sedimentation tank 6 to provide more time for these fine particles to gradually settle to the bottom under the action of gravity, facilitating the rise of lighter debris to the liquid surface for convenient collection by the second collection device. Meanwhile, the use of subsequent flocculants can be reduced.

[0035] In this step, the purpose and function of the second collection device are the same as those of the first collection device, except that the debris collected by the two is different.

[0036] Specifically, in this embodiment, as Figure 4 and Figure 5 shown, the second collection device includes a second wave maker 11 and a second suspension device. The second wave maker 11 is arranged at the middle position of the second circular sedimentation tank 6, and the second suspension device is arranged at the edge of the second circular sedimentation tank 6. The second suspension device rises as the liquid level of the raw water in the second sedimentation tank rises. Preferably, the second suspension device includes a second retaining plate 7, an inverted second trapezoidal trough 8, and a plurality of second water tanks 9. The second retaining plate 7 is arranged along the inner edge of the second circular sedimentation tank 6. The second water tanks 9 are located below the liquid level. These second water tanks 9 are connected in series through a second water inlet pipe. The second trapezoidal trough 8 is fixedly connected to the second retaining plate 7. The second trapezoidal trough 8 can sink or rise as the water in the second water tank 9 increases or decreases; the second trapezoidal trough 8 is a right trapezoidal trough. The right-angled side of the second trapezoidal trough 8 is fixedly connected to the second retaining plate 7, and the other side of the second trapezoidal trough 8 faces the center position of the second circular sedimentation tank 6. The second trapezoidal trough 8 is horizontally arranged.

[0037] In this step, the usage method of the second collection device is as follows: S210: Set the second wave maker 11 at the middle part of the second circular sedimentation tank 6. By controlling the water volume in the second water tank 9, make the top of the second trapezoidal trough 8 be 1 - 2 cm below the liquid surface. The second aeration pipe is always in the aeration state to prevent fine impurities from adhering to the outer side of the second trapezoidal trough 8 through the aeration of the second aeration pipe.

[0038] S220: Start the second wave maker 11 to make the liquid surface fluctuate, and push the fine impurities floating on the liquid surface to the edge of the second circular sedimentation tank 6, so as to enter above the second trapezoidal trough 8.

[0039] S230: After all the fine impurities floating on the liquid surface are located above the second trapezoidal trough 8, pump out the water in the second water tank 9 to take out the fine impurities from the second circular sedimentation tank 6.

[0040] S240: Turn off the second wave maker 11.

[0041] S250: Clean the impurities in the second trapezoidal groove 8. After cleaning, inject water into the second water tank 9 to reset the second trapezoidal groove 8. Similarly, in this step, a reciprocating slag scraper can be set on the second baffle 7, using a stainless steel chain + elastic scraper, moving back and forth along the first trapezoidal groove 3 at an appropriate speed to hang the above sundries into the collection hopper, thus completing the collection of sundries.

[0042] In this step, the mainly collected sundries are some other small sundries such as fine coal powder particles, fine rock debris, oil impurities, and microbial flocs.

[0043] S40: Carry out flocculation treatment on the raw water in the second circular sedimentation tank 6.

[0044] This step is a key link connecting physical sedimentation and membrane filtration. Its core purpose is to convert the colloids and fine particles that are difficult to settle naturally in water into separable flocs through chemical means, so as to improve the overall treatment efficiency, reduce the subsequent process load, and ensure the stable operation of membrane filtration.

[0045] S50: Collect and treat the flocs suspended on the surface of the raw water through the second collection device.

[0046] The main function of this step is to collect and treat the flocs suspended on the surface of the raw water after flocculation treatment.

[0047] After the flocculation treatment in step S40, the colloidal particles and fine suspended solids in the water aggregate into larger flocs. If these flocs are not removed in time, they will enter the subsequent hollow nanofiber membrane filtration link with the water flow, increasing the filtration burden of the membrane. At the same time, if the flocs enter the hollow nanofiber membrane, they may block the membrane pores, affect the normal operation of the membrane, and even cause membrane pollution, resulting in a shortened service life of the membrane and a reduced filtration efficiency. By collecting the flocs in this step, the impurity content in the water can be effectively reduced, creating good conditions for the subsequent membrane filtration treatment.

[0048] S60: After the raw water in the second circular sedimentation tank 6 stands for a preset time, draw the raw water in the second circular sedimentation tank 6 into the hollow nanofiber membrane for filtration treatment, and store the filtered clean water in the clean water storage tank.

[0049] The function of this step is to achieve the deep purification of mine water through the high-efficiency separation ability of the hollow nanofiber membrane, remove the remaining fine particles, dissolved organic matter, heavy metal ions and microorganisms, and ensure that the effluent quality meets the requirements for reuse or discharge.

[0050] Despite the precipitation in steps S20 and S30 and the flocculation collection in steps S40 and S50, a small amount of sub-micron particles (such as fine coal powder particles that have not completely settled and colloidal fragments) may still remain in the water. The pore size of the nanofiltration membrane is 0.001 - 0.1 μm, which can intercept these fine particles and prevent them from entering the final effluent, ensuring clear water quality.

[0051] At the same time, through the sieving effect and charge repulsion, the hollow fiber nanofiltration membrane can also effectively intercept dissolved organic matter (such as humic acid and petroleum derivatives), heavy metal ions (such as iron, manganese, and copper), hardness ions (calcium and magnesium ions), and inorganic salts (such as sulfates and chlorides) in mine water.

[0052] In this embodiment, the hollow fiber nanofiltration membrane includes a brush filter and a membrane module. The raw water in the second circular sedimentation tank 6 enters the membrane module for secondary filtration after passing through the brush filter. Optionally, in this embodiment, when the water flow passes through the brush filter, the mechanical impurities in the water are intercepted by the filter screen, and the impurities accumulate on the surface of the filter screen. When the impurities accumulated on the filter screen surface increase, causing the pressure difference between the inlet and outlet of the brush filter to reach the set value or the timer to reach the set time, the electric control box sends a signal. At this time, the drive motor in the brush filter starts, driving the brush to rotate, and the impurity particles adsorbed on the filter screen are brushed off by the wire brush. At the same time, the drain valve opens, and the impurities are discharged with the water flow from the drain valve, thereby realizing the cleaning of the filter screen. By intercepting impurities through the brush filter, these impurities are prevented from entering the subsequent treatment equipment, causing blockage or damage to the membrane system.

[0053] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

Claims

1. A process for treating underground water in coal mines by membrane method, characterized in that, It includes the following steps: S10: Collect raw water through a grille channel and enter the first circular sedimentation tank in the central raw water storage tank; S20: In the first circular sedimentation tank, collect large particulate matters suspended on the surface of the raw water through a first collection device arranged at the edge position of the first circular sedimentation tank; S30: After the raw water in the first circular sedimentation tank stands and precipitates for a preset time, draw the raw water in the first circular sedimentation tank into the second circular sedimentation tank, and collect the fine suspended matters floating on the surface of the raw water in the second circular sedimentation tank through a second collection device arranged at the edge position of the second circular sedimentation tank; S40: Perform flocculation treatment on the raw water in the second circular sedimentation tank; S50: Collect and treat the flocs suspended on the surface of the raw water through the second collection device; S60: After the raw water in the second circular sedimentation tank stands for a preset time, draw the raw water in the second circular sedimentation tank into a hollow nanofiber membrane for filtration treatment, and store the filtered clean water in a clean water storage tank.

2. The process for treating underground mine water in coal mines by membrane method according to claim 1, characterized in that, The first collection device includes a first wave maker and a first floating device. The first wave maker is arranged at the middle position of the first circular sedimentation tank, and the first floating device is arranged at the edge of the first circular sedimentation tank. The first floating device rises as the liquid level of the raw water in the first sedimentation tank rises.

3. The process for treating mine drainage of coal mines by membrane method according to claim 2, wherein, The first floating device includes a first enclosure, an inverted first trapezoidal trough, and a plurality of first water tanks. The first enclosure is arranged along the inner edge of the first circular sedimentation tank. The first water tanks are located below the liquid level. These first water tanks are connected in series through a first water inlet pipe. The first trapezoidal trough is fixedly connected to the first enclosure. The first trapezoidal trough can sink or rise as the water in the first water tank increases or decreases.

4. A process for treating mine drainage water by membrane method according to claim 3, characterized in that, The first trapezoidal trough is a right trapezoidal trough. The right-angled side of the first trapezoidal trough is fixedly connected to the first enclosure, and a plurality of leakage holes are provided at the bottom of the first trapezoidal trough.

5. A process for treating mine drainage water by membrane method according to claim 4, characterized in that, A first aeration pipe is arranged on the outer side of the hypotenuse of the first trapezoidal trough.

6. The process for treating mine drainage of coal mines by membrane method according to claim 5, characterized in that, The usage method of the first collection device is as follows: S110: Arrange the first wave maker at the middle part of the first circular sedimentation tank. By controlling the water volume in the first water tank, make the top of the first trapezoidal trough be 1 - 2 cm below the liquid level. The first aeration pipe is always in an aeration state. Through the aeration of the first aeration pipe, prevent fine impurities from adhering to the outer side of the first trapezoidal trough; S120: Start the first wave maker to make the liquid level fluctuate, and push the large impurities floating on the liquid surface to the edge of the first circular sedimentation tank, so as to enter above the first trapezoidal trough; S130: After all the large impurities floating on the liquid surface are above the first trapezoidal trough, pump out the water in the first water tank, so that the impurities are above the first trapezoidal trough, and take the large impurities out of the first circular sedimentation tank; S140: Turn off the first wave maker; S150: Clean the impurities in the first trapezoidal groove. After cleaning, inject water into the first water tank to reset the first trapezoidal groove.

7. The process for treating mine drainage water by membrane method according to claim 1, characterized in that The second collection device includes a second wave maker and a second suspension device. The second wave maker is arranged at the middle position of the second circular sedimentation tank, and the second suspension device is arranged at the edge of the second circular sedimentation tank. The second suspension device rises as the liquid level of the raw water in the second sedimentation tank rises.

8. A process for treating underground water in coal mines by membrane method according to claim 7, characterized in that, The second suspension device includes a second enclosing plate, an inverted second trapezoidal groove, and a plurality of second water tanks. The second enclosing plate is arranged along the inner edge of the second circular sedimentation tank. The second water tanks are located below the liquid level. These second water tanks are connected in series through a second water inlet pipe. The second trapezoidal groove is fixedly connected to the second enclosing plate. The second trapezoidal groove can sink or rise as the water in the second water tank increases or decreases. The second trapezoidal groove is a right trapezoidal groove, and the right-angled side of the second trapezoidal groove is fixedly connected to the second enclosing plate.

9. The process for treating mine drainage of coal mines by membrane method according to claim 8, characterized in that, The usage method of the second collection device is as follows: S210: Set the second wave maker at the middle part of the second circular sedimentation tank. By controlling the water volume in the second water tank, make the top of the second trapezoidal groove be 1-2 cm below the liquid level. The second aeration pipe is always in the aeration state. Through the aeration of the second aeration pipe, prevent fine impurities from adhering to the outside of the second trapezoidal groove. S220: Start the second wave maker to make the liquid level fluctuate, and push the fine impurities floating on the liquid surface to the edge of the second circular sedimentation tank, so as to enter above the second trapezoidal groove. S230: After all the fine impurities floating on the liquid surface are above the second trapezoidal groove, pump out the water in the second water tank to take out the fine impurities from the second circular sedimentation tank. S240: Turn off the second wave maker. S250: Clean the impurities in the second trapezoidal groove. After cleaning, inject water into the second water tank to reset the second trapezoidal groove.

10. The process for treating mine drainage of coal mines by membrane method according to claim 1, characterized in that, The hollow fiber nanofiltration membrane includes a brush filter and a membrane module. The raw water in the second circular sedimentation tank enters the membrane module for secondary filtration after being filtered by the brush filter.

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