Electric soil remediation method based on shewanella MR-1

Abstract

The invention relates to an electric soil remediation method based on shewanella MR-1, which is characterized by specifically comprising the following steps: S1, firstly cultivating a shewanella MR-1 bacterial liquid, and then concentrating the bacterial liquid; s2, a hopper in the feeding station is filled with soil to be remediated; s3, the hopper is conveyed to a remediation station, and then two electrodes are inserted into the soil of the hopper; s4, electrifying the two electrodes, and adjusting the current density; s5, concentrated shewanella MR-1 bacterial liquid is added, and the soil is repaired through combination of microorganisms and an electrochemical technology; s6, the hopper is turned over for soil discharging; and S7, cleaning the hopper for later use. Compared with pure electrokinetic remediation, the energy consumption cost can be saved, and soil hardening caused by high current or high voltage is avoided; and compared with a pure microbial technology, the time cost can be saved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and particularly to an electrokinetic soil remediation method based on Shewanella oneidensis MR-1. Background Art

[0002] Soil is complex in composition, and its components mainly include inorganic mineral particles (sand, silt and clay, gravel, stones and rocks), organic matter, air, moisture and living organisms. The presence of organic matter and living organisms endows the soil with the ability of self-cleaning and remediation, but the remediation process requires a high time cost. At present, advanced oxidation methods such as extraction and Fenton are mainly used in soil remediation, which are efficient but costly and prone to secondary pollution, and are likely to cause soil compaction and loss of organic matter. Therefore, it is urgent to find a low-cost, efficient and economical treatment technology. Summary of the Invention

[0003] In order to solve the above problems, the present invention designs an electrokinetic soil remediation method based on Shewanella oneidensis MR-1. The soil is remediated by a bioelectrochemical system combining microorganisms and electrochemistry technology. Microorganisms can be isolated from sediments, soil and water bodies, and some microorganisms can degrade pollutants by relying on their own growth and metabolism, and their biological activity and functionality can be enhanced under the stimulation of weak current.

[0004] To solve the above technical problems, the present invention provides an electrokinetic soil remediation method based on Shewanella oneidensis MR-1, which is characterized in that it specifically includes the following steps:

[0005] S1: First, cultivate the Shewanella oneidensis MR-1 bacterial solution, then use an amplification tank to amplify the cultivated Shewanella oneidensis MR-1 bacterial solution, then concentrate the amplified Shewanella oneidensis MR-1 bacterial solution, and transport the concentrated Shewanella oneidensis MR-1 bacterial solution into a storage tank for storage;

[0006] S2: Use a bucket elevator to transport the soil to be remediated into a hopper with an open upper end at the feeding station;

[0007] S3: Use a monorail conveying mechanism to transport the hopper to the remediation station. First, use a drilling mechanism to drill two electrode insertion holes in the soil of the hopper, and then insert two electrodes into the two electrode insertion holes;

[0008] S4: Energize the two electrodes, and adjust the current density in the soil in the hopper to 2 mA / cm 2 ;

[0009] S5: After the current density meets the requirements in step S4, while according to the volume of the soil in the hopper, use a rotary nozzle to add the Shewanella oneidensis MR-1 bacterial solution concentrated in step S1 into the hopper. The mass ratio of the added amount of the Shewanella oneidensis MR-1 bacterial solution to the soil in the hopper is 0.95 - 1:100. The Shewanella will gradually form a biofilm on the inner wall of the hopper, avoiding the leakage of microorganisms and accelerating the biodegradation ability. The soil in the hopper is mainly dominated by microbial degradation in the early stage and electrochemistry in the later stage until the repair is completed;

[0010] S6: After the soil repair in step S5 is completed, take out the electrodes, and use the monorail conveyor mechanism to transport the hopper to the blanking station. Pour the repaired soil onto the conveyor belt by flipping the hopper, and use the conveyor belt to transport the soil out;

[0011] S7: After the hopper is emptied, transport the inverted hopper into the cleaning room, and wash the inner wall of the hopper through the high-pressure nozzles set at the bottom of the cleaning room. After the washing is completed, the hopper is flipped back to its original position and waits for the next soil filling.

[0012] Furthermore: The cultivation of the Shewanella oneidensis MR-1 bacterial solution in step S1 specifically includes the following steps:

[0013] A1: Preparation of liquid Luria-Bertani medium: Add 5 g, 2.5 g, and 5 g of sodium chloride, yeast extract powder, and tryptone, which have been weighed on an electronic balance, into a 1 L beaker. After adding 500 ml of deionized water, stir with a glass rod and then put in a rotor. After completely dissolving on a magnetic stirrer at 500 rpm, divide it evenly into five portions and pour them into conical flasks. Then seal the five conical flasks with aluminum foil and sterilize them in an autoclave at 121 °C for 30 min;

[0014] A2: Preparation of Luria-Bertani solid medium: Add 7.5 g of agar on the basis of the Luria-Bertani liquid medium drugs. Place the prepared reagent in a wide-mouth conical flask with a capacity of 1 L, add an accurately measured 500 ml of deionized water, add a rotor to it before sealing with aluminum foil, and then place it on a stirrer at 99 °C and stir for about 1.5 h. When the reagent in the conical flask gradually dissolves completely and presents a semi-transparent jelly-like state, and the smell of yeast powder can also be smelled near the conical flask, sterilize it in an autoclave at 121 °C for 30 min. After the sterilization is completed, when the temperature on the autoclave display screen drops to 60 - 80 °C, take out the conical flask and immediately pour it into a 90 mm petri dish beside the alcohol lamp until it reaches the scale line. After the medium in the petri dish condenses, invert the petri dish and store it in the refrigerator freezer at 4 °C;

[0015] A3: Preservation of S. oneodensis MR-1: First, accurately pipette 30.3 ml of 99% glycerol and 29.7 ml of deionized water into a 100-ml beaker respectively to prepare 50% glycerol, and seal the beaker with aluminum foil; then put 200-μl and 1000-μl pipette tips and 1.5-ml brown centrifuge tubes needed for preserving the strain into a suitable beaker, seal it with aluminum foil and sterilize it together with the glycerol for 30 min; after sterilization, add the glycerol and the bacterial liquid with OD>1 into the centrifuge tube at a ratio of 2:8 beside the alcohol lamp, seal it with a sealing film and store it in a -80°C refrigerator;

[0016] A4: Cultivation of S. oneodensis MR-1: Take out the strain stored at -80°C, pick up 1-2 pieces of ice chips with an inoculation loop beside the alcohol lamp and smear them on the LB solid medium stored at 4°C, seal it with a sealing film and place it in a 30°C incubator for dark cultivation for 20 h, then take it out and store it in the refrigerator at 4°C;

[0017] A5: Preparation of S. oneodensis MR-1 bacterial liquid: Add 1-2 colonies picked from the solid medium with an inoculation loop into the sterilized LB medium beside the alcohol lamp, seal it with aluminum foil, and place it in a 30°C incubator at 220 rpm for dark cultivation for 16-19 h.

[0018] Furthermore: The electrode in step S3 is a cylindrical high-purity graphite electrode with a diameter of 1 cm and a height of 1.1 m, and the distance between the two electrodes is 10 cm.

[0019] Furthermore: The single-rail conveying mechanism includes a single-rail track and a track walking vehicle connected end to end. The cross-section of the single-rail track is in an I shape. The hopper is connected directly below the single-rail track through the track walking vehicle. A support frame is fixed at the bottom of the track walking vehicle. The hopper is connected to the support frame through a flipping and lifting mechanism. The hopper passes through the feeding station, the repair station, the discharging station and the cleaning station in turn driven by the track walking vehicle. A cleaning chamber is arranged in the cleaning station. The left and right ends of the cleaning chamber are open. The single-rail track passes through the cleaning chamber from left to right. A soil storage tank is arranged on one side of the feeding station. The bucket elevator is inclined. Its lower end extends into the bottom of the soil storage tank, and its upper end extends directly above the feeding station. A conveyor is arranged in the discharging station, and baffles are arranged on both the left and right sides of the conveyor.

[0020] Furthermore: The flipping and lifting mechanism includes side plates, lifting plates, a flipping motor, and a lifting electric cylinder that are vertically installed at the bottoms of the front and rear ends of the support frame. One lifting plate is connected to each of the opposite sides of the two side plates. On the outer wall of the side of the lifting plate connected to the side plate, there are vertically arranged trapezoidal ridges. On the side plate, at the position corresponding to the trapezoidal ridges, there are first chutes that match the trapezoidal ridges. The lifting plate is connected to the side plate through the cooperation of the trapezoidal ridges and the first chutes. On each of the opposite sides of the two side plates, two lifting electric cylinders are installed. The output shaft ends of the two lifting electric cylinders on the same side are each connected to the outer wall of the lower end of the lifting plate through a first connecting piece. On the side of the side plate facing the soil storage tank, there is a first notch for the upper end of the bucket elevator to pass through. The front and rear ends of the hopper are each connected between the two lifting plates through a rotating shaft, and one of the rotating shafts is connected to the flipping motor fixed on one of the lifting plates.

[0021] Furthermore: On the right side of the repair station, a first upper support plate is fixed through a first upright post. The first upper support plate is horizontally arranged. At the bottom of it, there is a first extension plate. On the top of the first extension plate, there is a first trapezoidal slide rail. At the bottom of the first upper support plate, there is a second chute that matches the first trapezoidal slide rail. The first extension plate is connected to the first upper support plate through the cooperation of the first trapezoidal slide rail and the second chute. On the top of the first upper support plate, a first translational telescopic electric cylinder is installed. The output shaft end of the first translational telescopic electric cylinder is connected to the first extension plate through a second connecting piece. At the bottom of the first extension plate, two rotating cylinders are rotatably connected. The two rotating cylinders are connected to a rotation driving mechanism. Inside each of the two rotating cylinders, there is a punching cylinder body. The lower end of the punching cylinder body is tooth-shaped, and the upper end of the punching cylinder body is sealed and there is a pushing electric cylinder installed on it. The output shaft end of the pushing electric cylinder extends into the punching cylinder body and is connected to a pushing plate. The pushing plate is driven by the pushing electric cylinder to slide up and down inside the punching cylinder body. On the outer wall of the punching cylinder body, there is an external thread. Between the upper and lower ends of the rotating cylinder, there is a threaded through hole that matches the external thread. The punching cylinder body passes through the rotating cylinder through the cooperation of the external thread and the threaded through hole. At the position corresponding to the punching cylinder body on the first extension plate, there is a through hole. At the position corresponding to the punching cylinder body on the first upper support plate, there is a first through slot. The left end of the first through slot is open. The punching cylinder body can move left and right along the first through slot under the drive of the first translational telescopic electric cylinder. The upper ends of the two punching cylinder bodies pass through the connecting plate and are both fixedly connected to it.

[0022] Furthermore: The rotation driving mechanism includes a driving sprocket, a servo motor, a chain, and a sprocket structure. The sprocket structure is sleeved and fixed on the outer wall of the rotating cylinder. The servo motor is installed at the bottom of the first extension plate. The driving sprocket is sleeved and fixed on the output shaft of the servo motor. The driving sprocket is connected to the sprocket structures on the two rotating cylinders through a chain.

[0023] Furthermore: A second upper support plate is fixed to the left side of the repair station by a second upright column. The second upper support plate is horizontally arranged. A second extension plate is connected to the bottom thereof. A second trapezoidal slide rail is arranged on the top of the first extension plate. A third chute matching the second trapezoidal slide rail is formed in the bottom of the second upper support plate. The second extension plate is connected to the second upper support plate through the cooperation of the second trapezoidal slide rail and the third chute. A second translational telescopic electric cylinder is installed on the top of the second upper support plate. The output shaft end of the second translational telescopic electric cylinder is connected to the second extension plate through a third connecting member. A telescopic electric cylinder is installed on the top of the second extension plate. The output shaft end of the telescopic electric cylinder passes through the second extension plate and is connected to a transmission plate. Two electrodes are fixed to the bottom of the transmission plate. The two electrodes are a positive electrode and a negative electrode respectively. A second through groove is formed in the second upper support plate at a position corresponding to the telescopic electric cylinder. The right end of the second through groove is open. The telescopic electric cylinder can move left and right along the second through groove under the action of the second translational telescopic electric cylinder.

[0024] Moreover: A storage tank is installed on the top of the second upper support plate. A pressure discharge pump connected thereto is installed on the outer wall of the storage tank. The pressure discharge pump is connected to a rotary spray head installed at the bottom right end of the transmission plate through a hose. A second through hole for the hose to pass through is formed in the second extension plate directly below the second through groove.

[0025] After adopting the above structure, the beneficial effects of the present invention are as follows:

[0026] 1. The present invention repairs the soil through a bioelectrochemical system combining microorganisms and electrochemistry technology. Microorganisms can be separated from sediments, soil and water bodies, and some microorganisms can rely on their own growth and metabolism to degrade pollutants and enhance their biological activity and functionality under the stimulation of weak current.

[0027] 2. The Shewanella oneidensis MR-1 adopted in the present invention will generate a biofilm on the inner wall of the hopper. Through this structure, the leakage of microorganisms can be avoided and the biodegradation ability can be accelerated.

[0028] 3. Compared with pure electrokinetic remediation, the present invention can save energy consumption costs and avoid soil compaction and hardening caused by high current or high voltage; compared with pure microorganism technology, it can save time costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0030] Figure 1 It is a top view structure diagram of a single-rail conveying mechanism.

[0031] Figure 2It is a top view structure diagram of the repair station.

[0032] Figure 3 It is a front view structure diagram of the repair station. Specific implementation manners

[0033] The present invention provides an electrokinetic soil remediation method based on Shewanella oneidensis MR-1, which specifically includes the following steps:

[0034] S1: First, cultivate the Shewanella oneidensis MR-1 bacterial liquid, then use an expansion tank to expand the cultivated Shewanella oneidensis MR-1 bacterial liquid, then concentrate the expanded Shewanella oneidensis MR-1 bacterial liquid, and transport the concentrated Shewanella oneidensis MR-1 bacterial liquid into a storage tank for storage;

[0035] S2: At the feeding station, use a bucket elevator to transport the soil to be repaired into a hopper with an open upper end;

[0036] S3: Use a monorail conveyor to transport the hopper to the repair station. First, use a punching mechanism to punch two electrode insertion holes in the soil of the hopper, and then insert two electrodes into the two electrode insertion holes;

[0037] S4: Energize the two electrodes, and adjust the current density in the soil in the hopper to 2 mA / cm 2 ;

[0038] S5: At the same time when the current density in step S4 meets the requirements, use a rotary spray head to add the Shewanella oneidensis MR-1 bacterial liquid concentrated in step S1 into the hopper according to the volume of the soil in the hopper. The mass ratio of the added amount of the Shewanella oneidensis MR-1 bacterial liquid to the soil in the hopper is 0.95-1:100. The Shewanella will gradually form a biofilm on the inner wall of the hopper, avoiding the leakage of microorganisms and accelerating the biodegradation ability. The soil in the hopper is mainly dominated by microbial degradation in the early stage and electrochemistry in the later stage until the repair is completed;

[0039] S6: After the soil repair in step S5 is completed, take out the electrodes, and use a monorail conveyor to transport the hopper to the discharging station. Pour the repaired soil onto a conveyor belt transporter by flipping the hopper, and use the conveyor belt transporter to transport the soil out;

[0040] S7: After the hopper is emptied, transport the inverted hopper into the cleaning room, and wash the inner wall of the hopper through a high-pressure spray head arranged at the bottom of the cleaning room. After the washing is completed, the hopper is flipped back to its original position and waits for the next filling of soil.

[0041] After filling the soil into the hopper, manually level the upper surface of the soil by hand and measure the distance from the upper surface of the soil in the hopper to the hopper inlet, so as to measure the volume of the poured soil.

[0042] The cultivation of Shewanella MR-1 bacterial solution in step S1 specifically includes the following steps:

[0043] A1: Preparation of liquid Luria-Bertani medium: add 5g, 2.5g and 5g of sodium chloride, yeast extract powder and tryptone weighed on an electronic balance into a 1L beaker, add 500ml of deionized water, stir with a glass rod and put into the rotor, dissolve completely on a magnetic stirrer at 500rpm, divide into five equal parts and pour into conical flasks, seal the five conical flasks with aluminum foil, and sterilize in an autoclave at 121℃ for 30min;

[0044] A2: Preparation of Luria-Bertani solid culture medium: Add 7.5g of agar to the Luria-Bertani liquid culture medium, place the prepared reagent in a wide-mouth conical flask with a capacity of 1L, add 500ml of deionized water accurately measured, add a rotor before sealing it with aluminum foil, and then place it on a 99℃ agitator and stir for about 1.5h. When the reagent in the conical flask gradually dissolves completely and presents a translucent gelatinous state, and the smell of yeast powder can be smelled near the conical flask, sterilize it in a 121℃ autoclave for 30min. After the sterilization is completed, when the temperature on the autoclave display drops to 60-80℃, take out the conical flask and immediately pour it into a 90mm culture dish next to the alcohol lamp to the scale line. After the culture medium in the culture dish condenses, turn the culture dish upside down and store it in a 4℃ refrigerator.

[0045] A3: Storage of S.oneodensis MR-1: First, use a pipette to accurately transfer 30.3ml of 99% glycerol and 29.7ml of deionized water into a 100ml beaker to prepare 50% glycerol, and seal the beaker with aluminum foil. Then, place the 200μl and 1000μl pipette tips and 1.5ml brown centrifuge tubes needed for preserving the strain into a suitable beaker, seal it with aluminum foil, and sterilize it with glycerol for 30 minutes. After sterilization, add glycerol and bacterial solution with OD>1 into the centrifuge tube at a ratio of 2:8 next to an alcohol lamp, seal it with a sealing film, and store it in a -80℃ refrigerator.

[0046] A4: Cultivation of S. oneodensis MR-1: Take out the strain stored at -80℃, pick up 1-2 pieces of ice chips with an inoculation loop next to an alcohol lamp and smear them on the LB solid medium stored at 4℃, seal it with a sealing film, place it in a 30℃ incubator in the dark for 20 hours, then take it out and store it in a refrigerator at 4℃;

[0047] A5: Preparation of S. oneodensis MR-1 bacterial suspension: Add 1-2 colonies picked from the solid culture medium with an inoculation loop to the sterilized LB medium next to an alcohol lamp, seal with aluminum foil, and place in an incubator at 30°C and 220 rpm in the dark for 16-19 hours.

[0048] The electrode in the above step S3 is a cylindrical high-purity graphite electrode with a diameter of 1 cm and a height of 1.1 m. The distance between the two electrodes is 10 cm.

[0049] The present invention repairs soil through a bioelectrochemical system combining microorganisms with electrochemical technology. Microorganisms can be separated from sediments, soil and water bodies, and some microorganisms can rely on their own growth metabolism to degrade pollutants, and enhance biological activity and functionality under the stimulation of weak current; and the Shewanella MR-1 used in the present invention will form a layer of biofilm on the inner wall of the hopper, and this structure can prevent the leakage of microorganisms and accelerate the biodegradation ability; and compared with simple electric repair, the present invention can save energy consumption costs and avoid soil compaction and hardening caused by high current or high voltage; compared with simple microbial technology, it can save time costs.

[0050] like Figure 1 The monorail conveying mechanism shown includes a monorail track 1 and a track traveler 2 connected end to end, the cross-section of the monorail track is I-shaped, the hopper 4 is connected to the bottom of the monorail track through the track traveler, a support frame 3 is fixed to the bottom of the track traveler, the hopper is connected to the support frame through a flip lifting mechanism, and the hopper passes through the loading station, the repair station, the unloading station and the cleaning station in sequence under the drive of the track traveler, a cleaning chamber 11 is provided in the cleaning station, the left and right ends of the cleaning chamber are open, the monorail track passes through the cleaning chamber on the left and right, a soil storage tank 5 is provided on one side of the loading station, and the bucket elevator 6 is inclined, its lower end extends into the bottom of the soil storage tank, and its upper end extends to the top of the loading station, a conveyor belt conveyor 9 is provided in the unloading station, and baffles 10 are provided on both sides of the conveyor belt conveyor. The present invention can automatically complete the loading, repairing and unloading of soil by adopting the above-mentioned design, thereby greatly improving the repair efficiency. Moreover, after the repair is completed, the hopper can be automatically cleaned to prevent adverse effects on the next use, thereby increasing the practical performance.

[0051] like Figure 2The shown tipping and lifting mechanism includes side plates 21, lifting plates 22, tipping motors 25 and lifting electric cylinders 24 vertically installed at the bottoms of the front and rear ends of the support frame. One lifting plate is connected to each side of the two side plates. A trapezoidal rib 23 is provided on the outer wall of the lifting plate on the side connected to the side plate. The trapezoidal rib is vertically arranged. A first chute matching the trapezoidal rib is provided on the side plate at the position corresponding to the trapezoidal rib. The lifting plate is connected to the side plate through the cooperation of the trapezoidal rib and the first chute. Two lifting electric cylinders are installed on each of the opposite sides of the two side plates. The output shaft ends of the two lifting electric cylinders on the same side are each connected to the outer wall of the lower end of the lifting plate through a first connecting piece. A first notch for the upper end of the bucket elevator to pass through is provided on the side of the side plate facing the soil storage tank. The front and rear ends of the hopper are each connected between the two lifting plates through a rotating shaft. One of the rotating shafts is connected to the tipping motor fixed on one of the lifting plates. When drilling holes and inserting electrodes are required, start the lifting electric cylinder to adjust the distance between the hopper and the support frame, so as to facilitate drilling holes in the soil in the hopper and inserting electrodes. When discharging materials is required, start the tipping motor to drive the hopper to tip with the rotating shafts on the front and rear sides, and pour the repaired soil onto the conveyor belt conveyor.

[0052] As Figure 2 and Figure 3On the right side of the shown repair station, a first upper support plate 8 is fixed by a first upright column. The first upper support plate is horizontally arranged. A first extension plate 18 is connected to the bottom thereof. A first trapezoidal slide rail 20 is arranged on the top of the first extension plate. A second chute matching the first trapezoidal slide rail is opened at the bottom of the first upper support plate. The first extension plate is connected to the first upper support plate through the cooperation of the first trapezoidal slide rail and the second chute. A first translation telescopic cylinder 19 is installed on the top of the first upper support plate. The output shaft end of the first translation telescopic cylinder is connected to the first extension plate through a second connecting member. Two rotating cylinders 28 are rotatably connected to the bottom of the first extension plate. The two rotating cylinders are connected to a rotation driving mechanism. A drilling cylinder is connected to the inside of each of the two rotating cylinders. The lower end of the drilling cylinder is in a toothed shape. The upper end of the drilling cylinder is sealed and a pushing cylinder 27 is installed thereon. The output shaft end of the pushing cylinder extends into the drilling cylinder and is connected to a pushing plate. The pushing plate is connected to slide up and down in the drilling cylinder through the driving of the pushing cylinder. An external thread is arranged on the outer wall of the drilling cylinder. A threaded through hole matching the external thread is opened between the upper and lower ends of the rotating cylinder. The drilling cylinder passes through the rotating cylinder through the cooperation of the external thread and the threaded through hole. A through hole is opened on the first extension plate at a position corresponding to the drilling cylinder. A first through groove is opened on the first upper support plate at a position corresponding to the drilling cylinder. The left end of the first through groove is open. The drilling cylinder can move left and right along the first through groove under the driving of the first translation telescopic cylinder. The upper ends of the two drilling cylinders pass through the connecting plate and are both fixedly connected thereto. During operation, start the first translation telescopic cylinder to transport the two drilling cylinders directly above the soil in the hopper. Start the rotation driving mechanism to rotate the rotating cylinders. The drilling cylinders will automatically drill downward under the cooperation of the external thread and the threaded through hole. When the drilling cylinders leave the drilling position, start the pushing cylinder to push the soil in the drilling cylinders back into the hopper again.

[0053] As Figure 3 The rotation driving mechanism shown includes a driving sprocket, a servo motor 29, a chain and a sprocket structure. The sprocket structure is sleeved and fixed on the outer wall of the rotating cylinder. The servo motor is installed at the bottom of the first extension plate. The driving sprocket is sleeved and fixed on the output shaft of the servo motor. The driving sprocket is connected to the sprocket structures on the two rotating cylinders through a chain.

[0054] As Figure 2 and Figure 3On the left side of the shown repair station, a second upper support plate 7 is fixed by a second upright post. The second upper support plate is horizontally arranged. A second extension plate 12 is connected to the bottom thereof. A second trapezoidal slide rail 17 is arranged on the top of the first extension plate. A third chute matching the second trapezoidal slide rail is opened at the bottom of the second upper support plate. The second extension plate is connected to the second upper support plate through the cooperation of the second trapezoidal slide rail and the third chute. A second translational telescopic electric cylinder 16 is installed on the top of the second upper support plate. The output shaft end of the second translational telescopic electric cylinder is connected to the second extension plate through a third connecting piece. A telescopic electric cylinder 15 is installed on the top of the second extension plate. The output shaft end of the telescopic electric cylinder passes through the second extension plate and is connected to a transmission plate 31. Two electrodes 33 are fixed to the bottom of the transmission plate. The two electrodes are a positive electrode and a negative electrode respectively. A second through groove is opened on the second upper support plate at a position corresponding to the telescopic electric cylinder. The right end of the second through groove is open. The telescopic electric cylinder can move left and right along the second through groove under the action of the second translational telescopic electric cylinder. After drilling, start the second translational telescopic electric cylinder to convey the two electrodes to directly above the electrode insertion holes, and then start the telescopic electric cylinder to insert the two electrodes into the electrode insertion holes.

[0055] As Figure 2 and Figure 3 shown, a storage tank 30 is installed on the top of the second upper support plate. A pressure discharge pump connected to the storage tank is installed on the outer wall of the storage tank. The pressure discharge pump is connected to a rotary spray head 32 installed at the bottom right end of the transmission plate through a hose. A second through hole for the hose to pass through is opened on the second extension plate directly below the second through groove. Before inserting the electrodes, add an appropriate amount of concentrated bacterial solution into the hopper through the rotary spray head.

[0056] During actual repair, 500 kg of soil to be repaired is poured into each hopper. The contents of benzo[a]pyrene and petroleum hydrocarbons in the soil to be repaired are 7.8 mg / kg and 1560 mg / kg respectively. After 1 hour of repair, the contents of benzo[a]pyrene and petroleum hydrocarbons can be reduced to 0.12 mg / kg and 3.8 mg / kg. However, in conventional ordinary electro-repair, they can only be reduced to 1.8 mg / kg and 360 mg / kg in 1 hour. Through comparison, it can be proved that the repair method provided by the present invention is much better than the existing methods, not only accelerating the repair efficiency, but also greatly reducing the energy consumption.

[0057] The above is only the preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. An electrokinetic soil remediation method based on Shewanella MR-1, characterized in that: The specific steps include: S1: firstly, cultivating Shewanella MR-1 bacterial solution, then using a culture expansion tank to expand the cultivated Shewanella MR-1 bacterial solution, then concentrating the expanded Shewanella MR-1 bacterial solution, and transporting the concentrated Shewanella MR-1 bacterial solution into a storage tank for storage; S2: At the loading station, the soil to be repaired is transported into the hopper with an open top by using a bucket elevator; S3: Use a monorail conveying mechanism to transport the hopper to the repair station, first use a punching mechanism to punch two electrode insertion holes in the soil of the hopper, and then insert two electrodes into the two electrode insertion holes; S4: Power the two electrodes and adjust the current density in the soil in the hopper to 2 mA / cm according to the current meter display. 2 ; S5: After the current density in step S4 reaches the requirement, the Shewanella MR-1 bacterial solution concentrated in step S1 is added into the hopper using a rotary nozzle according to the volume of the soil in the hopper. The mass ratio of the Shewanella MR-1 bacterial solution added to the soil in the hopper is 0.95-1:

100. Shewanella will gradually form a biofilm on the inner wall of the hopper to prevent microbial leakage and accelerate biodegradation. The soil in the hopper is mainly degraded by microorganisms in the early stage and by electrochemistry in the later stage until the restoration is completed; S6 : After the soil remediation is completed in step S5, the electrode is taken out, and the hopper is transported to the unloading station by using a monorail conveying mechanism, and the remediated soil is dumped onto the conveyor belt by turning the hopper over, and the soil is transported out by using the conveyor belt conveyor; S7: After the hopper is unloaded, the inverted hopper is transported into the cleaning chamber, and the inner wall of the hopper is washed by a high-pressure nozzle arranged at the bottom of the cleaning chamber. After the washing, the hopper is turned over and reset to wait for the next filling of soil.

2. The electrokinetic soil remediation method based on Shewanella MR-1 according to claim 1, characterized in that: The cultivation of Shewanella MR-1 bacterial solution in step S1 specifically includes the following steps: A1: Preparation of liquid Luria-Bertani medium: add 5g, 2.5g and 5g of sodium chloride, yeast extract powder and tryptone weighed on an electronic balance into a 1L beaker, add 500ml of deionized water, stir with a glass rod and put into the rotor, dissolve completely on a magnetic stirrer at 500rpm, divide into five equal parts and pour into conical flasks, seal the five conical flasks with aluminum foil, and sterilize in an autoclave at 121℃ for 30min; A2: Preparation of Luria-Bertani solid culture medium: Add 7.5g of agar to the Luria-Bertani liquid culture medium, place the prepared reagent in a wide-mouth conical flask with a capacity of 1L, add 500ml of deionized water accurately measured, add a rotor before sealing it with aluminum foil, and then place it on a 99℃ agitator and stir for about 1.5h. When the reagent in the conical flask gradually dissolves completely and presents a translucent gelatinous state, and the smell of yeast powder can be smelled near the conical flask, sterilize it in a 121℃ autoclave for 30min. After the sterilization is completed, when the temperature on the autoclave display drops to 60-80℃, take out the conical flask and immediately pour it into a 90mm culture dish next to the alcohol lamp to the scale line. After the culture medium in the culture dish condenses, turn the culture dish upside down and store it in a 4℃ refrigerator. A3: Storage of S.oneodensis MR-1: First, use a pipette to accurately transfer 30.3ml of 99% glycerol and 29.7ml of deionized water into a 100ml beaker to prepare 50% glycerol, and seal the beaker with aluminum foil. Then, place the 200μl and 1000μl pipette tips and 1.5ml brown centrifuge tubes needed for preserving the strain into a suitable beaker, seal it with aluminum foil, and sterilize it with glycerol for 30 minutes. After sterilization, add glycerol and bacterial solution with OD>1 into the centrifuge tube at a ratio of 2:8 next to an alcohol lamp, seal it with a sealing film, and store it in a -80℃ refrigerator. A4: Cultivation of S. oneodensis MR-1: Take out the strain stored at -80℃, pick up 1-2 pieces of ice chips with an inoculation loop next to an alcohol lamp and smear them on the LB solid medium stored at 4℃, seal it with a sealing film, place it in a 30℃ incubator in the dark for 20 hours, then take it out and store it in a refrigerator at 4℃; A5: Preparation of S. oneodensis MR-1 bacterial suspension: Add 1-2 colonies picked from the solid culture medium with an inoculation loop to the sterilized LB medium next to an alcohol lamp, seal with aluminum foil, and place in an incubator at 30°C and 220 rpm in the dark for 16-19 hours.

3. The electrokinetic soil remediation method based on Shewanella MR-1 according to claim 1, characterized in that: The electrode in step S3 is a cylindrical high-purity graphite electrode with a diameter of 1 cm and a height of 1.1 m. The distance between the two electrodes is 10 cm.

4. The electrokinetic soil remediation method based on Shewanella MR-1 according to claim 1, characterized in that: The monorail conveying mechanism comprises a monorail track (1) and a track traveler (2) connected end to end, the cross section of the monorail track is in an I-shape, the hopper (4) is connected to the bottom of the monorail track through the track traveler, a support frame (3) is fixed at the bottom of the track traveler, the hopper is connected to the support frame through a flip lifting mechanism, the hopper passes through the loading station, the repair station, the unloading station and the cleaning station in sequence under the drive of the track traveler, a cleaning chamber (11) is arranged in the cleaning station, the left and right ends of the cleaning chamber are open, the monorail track passes through the cleaning chamber on the left and right, a soil storage tank (5) is arranged on one side of the loading station, the bucket elevator (6) is arranged in an inclined manner, its lower end extends into the bottom of the soil storage tank, and its upper end extends to the top of the loading station, a conveyor belt conveyor (9) is arranged in the unloading station, and baffles (10) are arranged on both sides of the conveyor belt conveyor.

5. The electrokinetic soil remediation method based on Shewanella MR-1 according to claim 4, characterized in that: The overturning and lifting mechanism comprises a side plate (21) vertically mounted at the bottom of the front and rear ends of the support frame, a lifting plate (22), a overturning motor (25) and a lifting electric cylinder (24), wherein a lifting plate is connected to each side plate on the opposite side of the two side plates, and a trapezoidal convex strip (23) is arranged on the outer wall of the side where the lifting plate is connected to the side plate, the trapezoidal convex strip is arranged vertically, a first slide groove matching the trapezoidal convex strip is provided on the side plate at a position relative to the trapezoidal convex strip, and the lifting plate is connected to the side plate through the cooperation of the trapezoidal convex strip and the first slide groove, two lifting electric cylinders are respectively mounted on the side plate on the opposite side of the two side plates, and the output shaft ends of the two lifting electric cylinders on the same side are respectively connected to the outer wall of the lower end of the lifting plate through a first connecting piece, and a first notch for the upper end of the bucket elevator to pass through is provided on the side of the side plate facing the soil storage tank, and the front and rear ends of the hopper are respectively connected between the two lifting plates through a rotating shaft, and one of the rotating shafts is connected to the overturning motor fixed on one lifting plate.

6. The electrokinetic soil remediation method based on Shewanella MR-1 according to claim 4, characterized in that: A first upper support plate (8) is fixed to the right side of the repair station through a first column. The first upper support plate is horizontally arranged, and its bottom is connected to a first extension plate (18). A first trapezoidal slide rail (20) is arranged on the top of the first extension plate. A second slide groove matching the first trapezoidal slide rail is opened at the bottom of the first upper support plate. The first extension plate is connected to the first upper support plate through the cooperation of the first trapezoidal slide rail and the second slide groove. A first translation telescopic electric cylinder (19) is installed on the top of the first upper support plate. The output shaft end of the first translation telescopic electric cylinder is connected to the first extension plate through a second connecting piece. The bottom of the first extension plate is rotatably connected to two rotating cylinders (28). The two rotating cylinders are connected to a rotating drive mechanism. A punching cylinder is connected to the inside of each of the two rotating cylinders. The lower end of the punching cylinder is gear-shaped. The punching cylinder is tooth-shaped, the upper end of the punching cylinder is sealed and a pushing electric cylinder (27) is installed thereon, the output shaft end of the pushing electric cylinder extends into the punching cylinder and is connected to the pushing plate, the pushing plate is connected to the punching cylinder by sliding up and down through the driving of the pushing electric cylinder, an external thread is arranged on the outer wall of the punching cylinder, a threaded through hole matching the external thread is arranged between the upper and lower ends of the rotating cylinder, the punching cylinder passes through the rotating cylinder through the cooperation of the external thread and the threaded through hole, a through hole is arranged on the first extension plate relative to the position of the punching cylinder, a first through groove is arranged on the first upper support plate relative to the position of the punching cylinder, the left end of the first through groove is open, the punching cylinder can move left and right along the first through groove under the driving of the first translation telescopic electric cylinder, the upper ends of the two punching cylinders pass through the connecting plate and are fixedly connected to it.

7. The electrokinetic soil remediation method based on Shewanella MR-1 according to claim 6, characterized in that: The rotary drive mechanism comprises a driving sprocket, a servo motor (29), a chain and a sprocket structure, wherein the sprocket structure is fixedly mounted on the outer wall of the rotating drum, the servo motor is mounted on the bottom of the first extension plate, the driving sprocket is fixedly mounted on the output shaft of the servo motor, and the driving sprocket is connected to the sprocket structures on the two rotating drums via a chain.

8. The electrokinetic soil remediation method based on Shewanella MR-1 according to claim 4, characterized in that: A second upper support plate (7) is fixed to the left side of the repair station through a second column. The second upper support plate is horizontally arranged and connected to a second extension plate (12) at its bottom. A second trapezoidal slide rail (17) is arranged on the top of the first extension plate. A third slide groove matching the second trapezoidal slide rail is provided at the bottom of the second upper support plate. The second extension plate is connected to the second upper support plate through the cooperation of the second trapezoidal slide rail and the third slide groove. A second translation telescopic electric cylinder (16) is installed on the top of the second upper support plate. The output shaft end of the second translation telescopic electric cylinder is connected to the second extension plate through a third connecting member. A telescopic electric cylinder (15) is installed on the top of the second extension plate. The output shaft end of the telescopic electric cylinder passes through the second extension plate and is connected to a transmission plate (31). Two electrodes (33) are fixed to the bottom of the transmission plate. The two electrodes are respectively a positive electrode and a negative electrode. A second through groove is provided on the second upper support plate relative to the position of the telescopic electric cylinder. The right end of the second through groove is open. The telescopic electric cylinder can move left and right along the second through groove under the action of the second translation telescopic electric cylinder.

9. The electrokinetic soil remediation method based on Shewanella MR-1 according to claim 8, characterized in that: A storage tank (30) is installed on the top of the second upper support plate, and a pressure discharge pump connected to the storage tank is installed on the outer wall of the storage tank. The pressure discharge pump is connected to a rotating nozzle (32) installed at the bottom of the right end of the transmission plate through a hose, and a second through hole for the hose to pass through is opened on the second extension plate directly below the second through groove.

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