A dynamic plate density electrochemical water treatment device and a method for treating chromium-containing wastewater.

Abstract

This invention discloses a dynamic electrode density electrochemical water treatment device and a method for treating chromium-containing wastewater. The device includes a reaction tank and an electrolytic adsorption module. The reaction tank has an inlet and an outlet at its two ends. The electrolytic adsorption module is installed inside the reaction tank, located between the inlet and outlet. The electrolytic adsorption module includes an adjustment component and an electrolytic reaction module. The adjustment component includes a fixed baffle plate, a sliding baffle plate, a first connector, and a second connector. The fixed baffle plate is fixed to the middle of one side wall of the reaction tank. The sliding baffle plate and the fixed baffle plate form a sliding pair that slides along the width of the flow channel. The electrolytic reaction module includes multiple electrode plates, an X-shaped telescopic unit, and a driving mechanism. An X-shaped telescopic unit is provided between any two adjacent electrode plates. This invention can dynamically adjust the electrode density according to the concentration of the input wastewater, thereby maximizing treatment efficiency while ensuring treatment effectiveness.

Description

Technical Field

[0001] This invention belongs to the field of wastewater purification technology, specifically relating to a dynamic plate density electrochemical water treatment device and method. Background Technology

[0002] Electroplating and other processes generate wastewater containing heavy metal ions, including a large amount of hexavalent chromium ions. Currently, electrolysis is mainly used to convert hexavalent chromium ions into trivalent chromium ions, which are then separated from the wastewater through flocculation and precipitation. Existing electrolysis devices typically involve immersing several energized electrode plates in the wastewater, which is then electrolyzed as it flows through them. However, in actual use, the concentration of chromium ions in the wastewater varies, while the specifications of the electrolysis device are usually fixed. When the amount of heavy metal ions to be electrolyzed in the wastewater is large, a strong electric field is required between the electrode plates to adsorb the chromium ions and facilitate the reaction. Simultaneously, the flow rate between the electrode plates needs to be reduced to ensure a more complete reaction, and vice versa.

[0003] With prolonged use, impurities or polarization products accumulate on the electrode plates submerged in wastewater, leading to passivation and decreased electrode efficiency. Regular removal and surface cleaning are typically required. When the distance between electrode plates decreases and the plate area becomes larger, laminar flow occurs naturally between the plates. This hinders thorough mixing and flocculant formation, and also reduces the uniformity of liquid composition. Inhomogeneous liquid composition results in varying electrolysis effects at different points on the electrode plates, leading to uneven reaction on the iron plates, impacting electrode lifespan and electrolysis efficiency. Furthermore, stable laminar flow also impedes sufficient contact between the liquid and the electrode plates. Summary of the Invention

[0004] The purpose of this invention is to provide a dynamic plate density electrochemical water treatment device.

[0005] In a first aspect, the present invention provides a dynamic plate density electrochemical water treatment device, which includes a reaction tank and an electrolytic adsorption module, characterized in that: an inlet and an outlet are respectively provided at both ends of the reaction tank; the electrolytic adsorption module is installed in the reaction tank and located between the inlet and the outlet.

[0006] The electrolytic adsorption module includes an adjustment component and an electrolytic reaction module. The adjustment component includes a fixed baffle plate, a sliding baffle plate, a first connector, and a second connector. The fixed baffle plate is fixed to the middle of one side wall of the reaction tank. The sliding baffle plate and the fixed baffle plate form a sliding pair that slides along the width of the flow channel. The width of the flow channel is perpendicular to the direction from the inlet to the outlet, which is the water flow direction. Both the fixed baffle plate and the sliding baffle plate can block the water flow. The location of the fixed baffle plate and the sliding baffle plate is the blocking area. The area between the sliding baffle plate and the other side wall of the reaction tank is the flow passage area. By adjusting the position of the sliding baffle plate, the width of the flow passage area can be changed, thereby changing the flow rate of the reaction tank under the same hydraulic residence time.

[0007] The first connector is fixed to another side wall; the second connector is fixed to the sliding baffle plate; the first connector and the second connector are directly opposite each other; the electrolysis reaction module is installed between the first connector and the second connector.

[0008] The electrolysis reaction module includes multiple electrode plates, an X-shaped telescopic unit, and a drive mechanism; the multiple electrode plates are arranged sequentially along the width of the flow channel; each electrode plate forms a sliding pair with the bottom surface of the reaction tank that slides along the width of the flow channel; each electrode plate is slidably connected to a slider; the electrode plates arranged at both ends are fixed to the first connecting member and the second connecting member, respectively.

[0009] An X-shaped telescopic unit is provided between any two adjacent electrode plates; the X-shaped telescopic unit includes two driving rods; the middle part of the two driving rods forms a revolute joint; one end of the two driving rods and the corresponding two electrode plates respectively form a revolute joint; the sliders on the corresponding two electrode plates at the other end of the two driving rods respectively form a revolute joint; the driving mechanism is used to drive two adjacent electrode plates to move closer to each other or further away from each other.

[0010] Preferably, all electrode plates are vertically arranged; the slider is slidably connected to the top edge of the electrode plate.

[0011] Preferably, the drive mechanism includes a transmission component, a hydraulic cylinder, and two pins; the drive mechanism corresponds to two adjacent electrode plates; the two pins are respectively fixed to the two electrode plates corresponding to the drive mechanism; a first sliding groove is provided on the transmission component; both pins are slidably connected in the first sliding groove; the hydraulic cylinder is fixed to the reaction tank; the transmission component is fixed to the output push rod of the hydraulic cylinder.

[0012] Preferably, two scrapers are fixed on the slider. The two scrapers abut against the two sides of the electrode plate respectively; thus, during the width adjustment of the electrolysis reaction module, the scrapers automatically clean the two sides of the electrode plate.

[0013] Preferably, each X-shaped telescopic unit corresponds to one aeration pipe. The two drive rods in the same X-shaped telescopic unit are hinged at the middle by a hollow pin. The bottom opening of the hollow pin is fixed to the air inlet at the top of the aeration pipe. The air inlet at the top of each hollow pin is connected to an air source. Each aeration pipe can be adjusted closer to or further away from each other according to the width of the electrolysis reaction module.

[0014] Preferably, each electrode plate consists of multiple anode plates and multiple cathode plates arranged alternately in sequence; the anode plates are all connected to the positive terminal interface of the power supply; and the cathode plates are all connected to the negative terminal interface of the power supply.

[0015] Preferably, the inlet of the reaction tank is equipped with a water quality detection device.

[0016] Preferably, the electrolysis reaction module further includes a support beam frame and multiple stirring modules corresponding one-to-one with the X-shaped telescopic units; the middle parts of the two drive rods in the same X-shaped telescopic unit are hinged by a pin. The two ends of the support beam frame and the two sides of the top of the reaction tank respectively form sliding pairs that slide along the water flow direction; the stirring module includes a sliding motor base, a stirring rod, a rotating shaft, and a stirring drive motor; the sliding motor base is slidably connected to the support beam frame; the sliding motor base is fixed on the sliding motor base, and the output shaft is fixed to the top end of the pin. The bottom end of the pin is fixed to the top end of the vertically arranged stirring rod. Each stirring module can be adjusted to move closer to or further away from each other according to the width of the electrolysis reaction module.

[0017] Secondly, the present invention provides a method for treating chromium-containing wastewater, which employs the aforementioned dynamic electrode density electrochemical water treatment device; the process of the chromium-containing wastewater treatment method is as follows: electricity is supplied to the electrode plates in the electrolysis reaction module; an iron plate is fixed on the electrode plates; wastewater containing hexavalent chromium ions is input into the reaction tank from the inlet; when the wastewater passes through the electrolysis reaction module, an electrochemical reaction occurs, producing chromium-containing precipitate.

[0018] The concentration of chromium ions in the input wastewater is continuously monitored, and the spacing between adjacent electrode plates in the electrolytic adsorption module and the wastewater input flow rate in the reaction tank are dynamically adjusted based on the chromium ion concentration. A higher chromium ion concentration results in a smaller spacing between the electrode plates in the electrolytic adsorption module, a smaller flow area in the reaction tank at the electrolytic adsorption module, and a smaller wastewater input flow rate in the reaction tank. Therefore, as the chromium ion concentration increases, the treatment speed decreases, and the treatment effect improves. Conversely, as the chromium ion concentration decreases, the treatment speed increases, and the treatment effect decreases, thus maximizing the overall treatment efficiency.

[0019] Preferably, the wastewater input flow rate of the reaction tank is Q = v0·H·L; v0 is the wastewater flow velocity in the flow zone; H is the height difference between the outlet and the bottom of the reaction tank; L is the width of the flow zone of the reaction tank at the electrolytic adsorption module; the wastewater flow velocity v0 in the flow zone remains constant throughout the entire treatment process.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention utilizes an X-shaped telescopic unit on two electrode plates. During the movement of the two electrode plates, the distance between them decreases due to the action of two driving rods, increasing the electric field strength between the plates and enhancing their adsorption capacity for heavy metal ions in wastewater. This allows the invention to dynamically adjust the electrode plate density based on the concentration of the input wastewater, thereby maximizing treatment efficiency while maintaining treatment effectiveness.

[0022] 2. The present invention controls the distance between two electrode plates by using an X-shaped telescopic unit, thereby controlling the flow rate of sewage flowing between the electrode plates, so that heavy metal ions in the sewage can be fully reacted.

[0023] 3. This invention, by incorporating aeration pipes, allows the gas output from these pipes to push the flocculent precipitates generated in the wastewater to the surface, while simultaneously preventing these precipitates from affecting the reaction on the electrode plates. Furthermore, the aeration pipes stir the wastewater during gas output, ensuring a more complete reaction of heavy metal ions in the wastewater. Attached Figure Description

[0024] Figure 1 This is a top view schematic diagram of Embodiment 1 of the present invention.

[0025] Figure 2 This is a cross-sectional view along the AA direction in Embodiment 1 of the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of the X-type telescopic unit in Embodiment 1 of the present invention. Figure 1 (A magnified view of part C in the middle).

[0027] Figure 4 This is a schematic diagram of the drive mechanism in Embodiment 1 of the present invention. Figure 1 (A magnified view of part D in the middle).

[0028] Figure 5 This is a schematic diagram of the overall structure in Embodiment 2 of the present invention.

[0029] Figure 6 This is a cross-sectional view along the BB direction in Embodiment 2 of the present invention.

[0030] The components include: 1. Reaction tank; 2. Inlet; 3. Outlet; 4. Fixed baffle plate; 5. First connecting piece; 6. Second connecting piece; 7. Sliding baffle plate; 8. Anode plate; 9. Cathode plate; 10. X-type telescopic unit; 11. Scraper; 12. Aeration pipe; 13. Support beam frame; 14. Stirring rod; 15. Motor; 16. Mounting plate; 17. Transmission component; 18. Hydraulic cylinder; 19. Sliding block. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] Example 1

[0033] like Figure 1 and 2 As shown, a dynamic plate density electrochemical water treatment device includes a reaction tank 1 and an electrolytic adsorption module. An outlet 3 and an inlet 2 are respectively provided at both ends of the reaction tank 1. A water quality detection device is installed at the inlet of the reaction tank. The electrolytic adsorption module is installed inside the reaction tank 1, located between the inlet 2 and the outlet 3. The water flow direction within the reaction tank 1 is from the inlet 2 to the outlet 3. The water quality detection device is used to detect the concentration of chromium ions in the water. The direction of the flow channel width is defined as perpendicular to the direction from the inlet to the outlet as the water flow direction.

[0034] The electrolytic adsorption module includes an adjustment component and an electrolytic reaction module. The adjustment component includes a sliding baffle 7, two fixed baffles 4, and two parallel first connecting parts 5 and second connecting parts 6. The two fixed baffles 4 are fixed at intervals in the middle of one side wall of the reaction tank 1. The sliding baffle 7 is disposed between the two fixed baffles 4, forming a sliding pair with the sliding direction perpendicular to the water flow direction. The bottom edges of both the sliding baffle 7 and the fixed baffles 4 are in contact with the reaction tank 1, which can block water flow from passing through the sliding baffle 7 and the fixed baffles 4. The location of the fixed baffles and the sliding baffles is the blocking area; the area between the sliding baffle and the other side wall of the reaction tank is the flow passage area; by adjusting the position of the sliding baffle, the width of the flow passage area can be changed, thereby changing the flow rate of the reaction tank under the same hydraulic residence time.

[0035] The first connector 5 and the second connector 6 are arranged at intervals along the width of the flow channel; the first connector 5 is fixedly connected to the side wall of the reaction tank 1 without a fixed baffle 4; the second connector 6 is fixed to the outer edge of the sliding baffle 7. The electrolysis reaction module is installed between the two connectors. The sliding baffle 7 is used to provide support force in the direction of water flow for the second connector 6 when it slides, preventing the second connector 6 from shaking due to the impact of the water flow.

[0036] The electrolysis reaction module includes a slide rail, an X-shaped telescopic unit 10, a drive mechanism, multiple anode plates 8 and multiple cathode plates 9, and a telescopic frame mounted on the positive cathode plate 9. The slide rail is fixedly installed within the reaction tank 1 along the width of the flow channel. The anode plates 8 and cathode plates 9 are alternately arranged on the slide rail, with a gap between them. Both the anode plates 8 and cathode plates 9 are slidably connected to the slide rail. Iron plates are fixed to both sides of the anode plate 8. Two connecting pieces are fixedly connected to one anode plate 8 and one cathode plate 9, respectively. The iron plates are used to provide ferrous ions in the electrolysis reaction.

[0037] The X-shaped telescopic unit 10 is disposed between any two electrode plates. The X-shaped telescopic unit 10 includes two cross-hinged drive rods, an aeration pipe 12, and two scrapers 11. One end of each of the two drive rods is rotatably connected to the corresponding two electrode plates. The other end of each of the two drive rods is slidably connected to the two electrode plates.

[0038] The drive mechanism includes a mounting plate 16, a transmission component 17, two pins, and a hydraulic cylinder 18 fixedly mounted on the mounting plate 16. The mounting plate 16 is fixedly mounted on the side wall of the reaction tank 1 and is on the same side wall as the first connecting component 5. The two pins are respectively fixedly connected to the sliding ends of the two drive rods. The transmission component 17 is fixedly connected to the output shaft of the hydraulic cylinder 18. The transmission component 17 has a first sliding groove, and both pins extend into the first sliding groove. By pushing the moving ends of the two drive rods in one of the X-shaped telescopic units 10, the scissor structure amplifies the stroke, causing each X-shaped telescopic unit 10 to move synchronously, thereby gradually changing the distance between the anode plate 8 and the cathode plate 9 in each electrode plate group, achieving the purpose of changing the electric field strength.

[0039] A slider 19, shaped like an inverted U, is fixed to the displacement end of the driving rod. Two scrapers 11 are fixed to both ends of the slider 19. The scrapers 11 are used to remove dirt adhering to both sides of the electrode plate. An aeration pipe 12 is fixedly installed on the lower surface of one of the driving rods. The gas output from the aeration pipe 12 causes the flocculent precipitate produced by the reaction to float to the surface; this does not affect the reaction of other heavy metal ions, thereby improving the overall reaction efficiency.

[0040] Working principle of this invention:

[0041] Industrial wastewater containing chromium ions is fed into the reaction tank through the inlet. Electricity is applied to the anode and cathode plates. After energization, Fe is generated on the iron anode plate. 2+ Fe 2+ Hexavalent chromium is reduced to trivalent chromium. Hydrogen gas is released at the cathode as part of the reduction reaction. The reaction equation is as follows:

[0042] The reaction that occurs at the anode:

[0043] Fe-2e- →Fe 2+

[0044] Fe 2＋ The ions then undergo the following surface transformation reaction

[0045] Cr2O7 2- +6Fe 2+ +14H + →2Cr 3+ +6Fe 3+ +7H2O

[0046] CrO4 2- +3Fe 2+ +8H + →Cr 3+ +3Fe 3+ +4H2O

[0047] Furthermore, when the anode is passivated, H2O discharge will occur, releasing oxygen.

[0048] 2H2O-4e - =O2+4H +

[0049] Cathode reaction:

[0050] 2H + +2e - →H2↑

[0051] Cr2O7 2+ +6e - +14H + →2Cr 3+ +7H2O

[0052] CrO4 2- +3e - +8H + →Cr 3+ +4H2O

[0053] The amount of hexavalent chromium directly reduced in the cathode region is very small, only 4% in the anode region. The reduction of hexavalent chromium is mainly due to the ferrous ions dissolved from the anode. As the electrolysis reaction proceeds, hydrogen ions in the wastewater are continuously consumed, and the pH value continuously increases. When the pH value is >5, chromium hydroxide, ferrous oxide, and ferric hydroxide precipitate out.

[0054] Cr 3+ +3OH - →Cr(OH)3↓

[0055] Fe 2+ +2OH - →Fe(OH)2↓

[0056] Fe3+ +3OH - →Fe(OH)3↓

[0057] When precipitation occurs during the reaction, aeration pipe 12 is activated. The gas output from aeration pipe 12 causes the flocculent precipitate to float to the surface, without affecting the reaction of the remaining chromium ions, thus improving the reaction efficiency. At the same time, the gas output from aeration pipe 12 agitates the wastewater, allowing the chromium ions flowing between the two electrode plates to come into contact with the iron plate and react more fully.

[0058] When the concentration of hexavalent chromium ions in the wastewater increases, the electric telescopic rod is activated, and the output shaft of the hydraulic cylinder 18 drives the transmission component 17 to move. During the movement of the transmission component 17, two pins slide within the first groove. These two pins cause the displacement ends of the two drive rods in the reference module to move. Utilizing the principle of amplified stroke inherent in the scissor mechanism, the entire telescopic frame moves synchronously, gradually reducing the distance between the anode plate 8 and the cathode plate 9 in each electrode group. This strengthens the electric field between the anode plate 8 and the cathode plate 9, increasing the attraction to chromium ions. Consequently, the reaction of chromium ions in the wastewater becomes more complete.

[0059] During the dynamic adjustment of the electrode spacing, the wastewater input flow rate Q of reaction tank 1 is dynamically adjusted according to the following relationship:

[0060] Q=v0·H·L

[0061] Wherein, v0 is the wastewater flow velocity; H is the height difference between the outlet (3) and the bottom of the reaction tank (1); L is the width of the flow area of ​​the reaction tank (1) at the electrolytic adsorption module; so that the wastewater flow velocity v0 remains unchanged in the flow area throughout the entire treatment process.

[0062] Example 2

[0063] A dynamic plate density electrochemical water treatment device is disclosed. The difference between this embodiment and Embodiment 1 is that the multiple aeration pipes 12 in the electrolysis reaction module are replaced with a stirring module. The stirring module includes a support beam 13, a stirring rod 14, a rotating shaft, a sliding motor base, and a stirring drive motor 15 fixedly connected to the sliding motor base. Both ends of the support beam 13 are fixedly connected to two connecting pieces, and a second sliding groove is provided on the support beam 13, within which the sliding motor base is slidably disposed. The rotating shaft passes through the hinge point of the two driving rods, and both ends of the rotating shaft are fixedly connected to the stirring rod 14 and the output shaft of the stirring drive motor 15, respectively. The stirring rod 14 is driven by the stirring drive motor 15 to agitate the flowing liquid, causing laminar flow to be eliminated during natural liquid flow, thereby preventing uneven reaction of the iron plates on the stirring drive motor 15 plate.

Claims

1. A dynamic plate density electrochemical water treatment device, comprising a reaction tank (1) and an electrolytic adsorption module, characterized in that: The reaction tank (1) is provided with an inlet (2) and an outlet (3) at both ends respectively; the electrolytic adsorption module is installed in the reaction tank (1) and is located between the inlet (2) and the outlet (3); The electrolytic adsorption module includes an adjustment component and an electrolytic reaction module; the adjustment component includes a fixed baffle (4), a sliding baffle (7), a first connector (5), and a second connector (6); the fixed baffle (4) is fixed in the middle of one side wall of the reaction tank (1); the sliding baffle (7) and the fixed baffle (4) form a sliding pair that slides along the width of the flow channel; the fixed baffle and the sliding baffle are located in a blocking area that blocks the water flow; the area between the sliding baffle and the other side wall of the reaction tank is a flow passage area; the width of the flow passage area is changed by adjusting the position of the sliding baffle; The first connector (5) is fixed to another side wall; the second connector (6) is fixed to the sliding baffle (7); the first connector (5) and the second connector (6) are directly opposite each other; the electrolysis reaction module is installed between the first connector (5) and the second connector (6); The electrolysis reaction module includes multiple electrode plates, an X-shaped telescopic unit (10), and a driving mechanism; the multiple electrode plates are arranged sequentially along the width of the flow channel; each electrode plate forms a sliding pair with the bottom surface of the reaction tank (1) that slides along the width of the flow channel; each electrode plate is slidably connected to a slider; the electrode plates arranged at both ends are fixed to the first connecting piece (5) and the second connecting piece (6), respectively; An X-shaped telescopic unit (10) is provided between any two adjacent electrode plates; the X-shaped telescopic unit (10) includes two driving rods; the middle part of the two driving rods forms a rotating pair; one end of the two driving rods and the corresponding two electrode plates respectively form a rotating pair; the sliders on the two electrode plates corresponding to the other ends of the two driving rods respectively form a rotating pair; the driving mechanism is used to drive two adjacent electrode plates to move closer to each other or further away from each other. Two scrapers (11) are fixed on the slider; the two scrapers (11) respectively abut against the two sides of the electrode plate; Each X-type telescopic unit (10) corresponds to an aeration pipe (12); the middle of the two drive rods in the same X-type telescopic unit (10) is hinged by a hollow pin; the bottom opening of the hollow pin is fixed to the air inlet at the top of the aeration pipe (12); the air inlet at the top of each hollow pin is connected to an air source.

2. The dynamic electrode density electrochemical water treatment device according to claim 1, characterized in that: All electrode plates are set vertically; the slider is slidably connected to the top edge of the electrode plate.

3. The dynamic plate density electrochemical water treatment device according to claim 1, characterized in that: The drive mechanism includes a transmission component (17), a hydraulic cylinder (18), and two pins; the drive mechanism corresponds to two adjacent electrode plates; the two pins are fixed to the two electrode plates corresponding to the drive mechanism respectively; a first sliding groove is provided on the transmission component (17); both pins are slidably connected in the first sliding groove; the hydraulic cylinder (18) is fixed to the reaction tank (1); the transmission component (17) is fixed to the output push rod of the hydraulic cylinder (18).

4. The dynamic plate density electrochemical water treatment device according to claim 1, characterized in that: Each electrode plate is divided into multiple anode plates (8) and multiple cathode plates (9) arranged alternately in sequence; the anode plates (8) are all connected to the positive terminal interface of the power supply; the cathode plates (9) are all connected to the negative terminal interface of the power supply.

5. The dynamic electrode density electrochemical water treatment device according to claim 1, characterized in that: The inlet (2) of the reaction tank (1) is equipped with a water quality detection device.

6. A method for treating chromium-containing wastewater, characterized in that: The method of treating chromium-containing wastewater using a dynamic plate density electrochemical water treatment device as described in claim 1 is as follows: electricity is supplied to the electrode plates in the electrolysis reaction module; wastewater containing hexavalent chromium ions is input into the reaction tank (1) from the inlet (2); when the wastewater passes through the electrolysis reaction module, an electrochemical reaction occurs, producing chromium-containing precipitate; The concentration of chromium ions in the input wastewater is continuously monitored, and the spacing between adjacent electrode plates in the electrolytic adsorption module and the wastewater input flow rate of the reaction tank (1) are dynamically adjusted according to the concentration of chromium ions. The higher the chromium ion concentration, the smaller the spacing between the electrode plates in the electrolytic adsorption module, the smaller the width of the flow area of ​​the reaction tank (1) at the electrolytic adsorption module, and the smaller the wastewater input flow rate of the reaction tank (1).

7. The method for treating chromium-containing wastewater according to claim 6, characterized in that: The wastewater input flow rate Q of the reaction tank (1) is... v 0· H · L ; v 0 represents the wastewater flow velocity in the flow path area; H The height difference between the outlet (3) and the bottom of the reaction tank (1); L The width of the flow zone in the reaction tank (1) at the electrolysis adsorption module; the wastewater flow velocity in the flow zone. v 0 remains unchanged throughout the entire process.

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