Wastewater treatment device and method for simultaneously removing high-concentration heavy metals and sulfate radicals

Abstract

The present invention discloses a wastewater treatment device and method for synchronously removing high-concentration heavy metals and sulfate. The device is an MFC-MEC integrated configuration, comprising: a proton exchange membrane, which separates the anode chamber and the cathode chamber, the cathode chamber containing a first cathode chamber and a second cathode chamber; a partition, which separates the first cathode chamber and the second cathode chamber; a circular hole is opened at the upper end of the partition; a screen is contained inside the circular hole; the electrode of the anode chamber is a pre-cultured carbon fiber brush electrode containing electrochemically active microorganisms; the electrode of the first cathode chamber is a vortex mesh electrode sheet; the electrode of the second cathode chamber is a pre-cultured carbon fiber brush-shaped electrode; the anode chamber and the first cathode chamber are connected to form an MFC; the anode chamber and the second cathode chamber are connected to a power supply to form an MEC. The present invention can achieve synchronous and efficient removal of high-concentration heavy metals and sulfate.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial wastewater treatment, and in particular to a wastewater treatment device and method for simultaneously removing high-concentration heavy metals and sulfate radicals. Background Art

[0002] Mining, metal smelting, electroplating, and other fields often produce wastewater containing high concentrations of heavy metals and sulfates. This not only poses a threat to the ecological environment and human health, but also wastes resources. The simultaneous treatment of wastewater containing heavy metals and sulfate has become an urgent environmental and social issue. Achieving the efficient and simultaneous removal of heavy metals and sulfate has become a key focus. Biological methods offer promising results due to their low cost and environmental friendliness. However, microorganisms are susceptible to the toxic effects of heavy metals, which can affect their cell structure and growth, thereby compromising their performance. Biofilms, as microbial aggregates, can enhance intercellular connectivity and resistance to heavy metals. However, their ability to mitigate inhibitory effects is limited. Therefore, additional measures are needed to improve the ability of biological methods to simultaneously treat heavy metals and sulfates. The reduction process of heavy metals essentially involves the extraction of electrons. If a portion of heavy metal ions can be reduced to their elemental form, the concentration of heavy metals in wastewater can be substantially reduced, thereby improving the efficiency of biological methods for the simultaneous removal of heavy metals and sulfates.

[0003] Among the existing research on treating heavy metal sulfate wastewater with sulfate-reducing bacteria, Chinese patent document CN102276060A discloses a method for treating acidic heavy metal sulfate wastewater with sulfate-reducing bacteria. Fermented soybeans are used as a carbon source for the growth of sulfate-reducing bacteria. The wastewater and carbon source are mixed and then passed into an anaerobic moving bed bioreactor. This can reduce the sulfate concentration in the wastewater to 250 mg / L, and the effluent meets the national secondary sewage discharge standard. Chinese patent document CN102795739A discloses a comprehensive treatment device and method for acidic sulfate organic wastewater based on biological desulfurization. The device combines an anaerobic digestion reactor, a hydrogen sulfide stripping tower, and a sulfur oxidation reactor to remove sulfate from the sulfate organic wastewater in the form of elemental sulfur, achieving harmless and resource-based sulfate treatment.

[0004] However, the heavy metal content in the heavy metal-containing wastewater currently treated is relatively low, which is difficult to meet the treatment requirements of sulfate wastewater containing high concentrations of heavy metals. The treatment effect is not very ideal, and the treatment equipment is relatively complicated. Summary of the Invention

[0005] In view of this, in order to solve the above technical problems, the purpose of the present invention is to propose a wastewater treatment device and method for simultaneously removing high-concentration heavy metals and sulfate ions, which can achieve the simultaneous removal of heavy metals and sulfates.

[0006] The technical solutions adopted are:

[0007] The present invention provides a wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals, which is an MFC-MEC integrated configuration, comprising:

[0008] a proton exchange membrane separating the anode chamber from the cathode chamber, the cathode chamber comprising a first cathode chamber and a second cathode chamber;

[0009] a separator separating the first cathode chamber from the second cathode chamber;

[0010] A circular hole is formed at the upper end of the partition, and a screen is contained inside the circular hole; the electrode of the anode chamber is a pre-cultured carbon fiber brush electrode containing electrochemically active microorganisms; the electrode of the first cathode chamber is a vortex mesh electrode sheet; and the electrode of the second cathode chamber is a pre-cultured carbon fiber brush electrode;

[0011] The anode chamber and the first cathode chamber are connected to form an MFC, which is used for the preliminary treatment of heavy metals in high-concentration sulfate wastewater; the anode chamber and the second cathode chamber are connected to an external power supply to form an MEC, which is used for the simultaneous removal of sulfate and heavy metals in high-concentration sulfate wastewater.

[0012] Furthermore, the partition is movable, so that the volumes of the first cathode chamber and the second cathode chamber change with the movement of the partition, and the volumes of the first cathode chamber and the second cathode chamber can be adjusted and changed according to the concentration of heavy metals.

[0013] Furthermore, a scraper is provided on the partition to regularly clean the attachments on the partition from top to bottom.

[0014] Furthermore, the mesh size of the sieve inside the circular hole is 100-150 meshes.

[0015] Furthermore, the bottoms of the first cathode chamber and the second cathode chamber contain mud storage pools with triangular cross-sections.

[0016] Furthermore, the electrode of the anode chamber, the electrode of the first cathode chamber, and the electrode of the second cathode chamber are respectively connected to motors to form a stirring device, and the stirring speed is 500-800 rpm.

[0017] Furthermore, the wastewater treatment device is a rectangular parallelepiped as a whole.

[0018] The present invention provides a method for treating wastewater for simultaneously removing high-concentration heavy metals and sulfate radicals, which utilizes the above-mentioned wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals for treatment, and comprises the following steps:

[0019] The sludge and artificial water were mixed in a volume ratio of 1:1 as the influent of the anode chamber, and the influent was passed into the anode chamber by a peristaltic pump. The wastewater was passed into the first cathode chamber of the microbial electrolysis cell by a peristaltic pump. When the heavy metal concentration was <100 mg / L, the volume ratio of the first cathode chamber to the second cathode chamber was controlled to be 0.4-0.6:1 by moving the partition; when the heavy metal concentration was 100-200 mg / L, the volume ratio of the first cathode chamber to the second cathode chamber was controlled to be 0.7-0.8:1 by moving the partition; when the heavy metal concentration was >200 When the concentration of HgCl2 in the first cathode chamber is 0.1-1.1 mg / L, the volume ratio of the first cathode chamber and the second cathode chamber is controlled to be 0.9-1.1:1 by moving the partition; the initial reduction of heavy metals is achieved in the first cathode chamber, and the metal ions are reduced to metal elements; then the wastewater passes through the screen and enters the second cathode chamber of the microbial electrolysis cell, where sulfate is reduced to sulfide ions, forming metal sulfide precipitates with heavy metal ions, thereby achieving the simultaneous removal of heavy metals and sulfate.

[0020] Furthermore, artificial water was prepared with 1-5 g / L sodium acetate as substrate, and 50 mmol / L phosphate buffer solution, 12.5 mL / L trace element solution, and 5 mL / L vitamin solution were added.

[0021] Furthermore, domestic sewage was used instead of artificial water, and only 50 mmol / L phosphate buffer solution, 12.5 mL / L trace element solution, and 5 mL / L vitamin solution were added.

[0022] The beneficial effects of the present invention are:

[0023] Firstly, the present invention adopts the technology of combining microbial fuel cells (MFC) and microbial electrolysis cells (MEC) to pre-treat heavy metals in high-concentration sulfate wastewater. On this basis, low-concentration heavy metals and sulfates are further treated by microbial electrolysis cells (MEC). An integrated device can be used to achieve the simultaneous and efficient removal of high-concentration heavy metals and sulfates.

[0024] In a second aspect, as a preference, the present invention can pre-adjust the position of the partition according to the concentration of heavy metals, thereby controlling the areas of the first cathode chamber and the second cathode chamber, which can accelerate the treatment efficiency of wastewater.

[0025] Thirdly, as a preference, the present invention can collect sediment materials through the mud storage device carried by the device itself, thereby achieving continuous treatment of wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following is a brief description of the drawings involved in the embodiments, but the protection scope of the present invention is not limited thereto.

[0027] Figure 1 This is a schematic diagram of the overall structure of a wastewater treatment device that simultaneously removes high-concentration heavy metals and sulfate ions. Figure 1 In the figure, the names corresponding to the numbers are as follows: 1-electrode of the anode chamber; 2-electrode of the first cathode chamber; 3-electrode of the second cathode chamber; 4-power supply; 5-partition; 6-push rod; 7-scraper; 8-sludge storage tank; 9-motor; 10-anode chamber; 11-first cathode chamber; 12-second cathode chamber.

[0028] Figure 2 Schematic diagram of the structure of the partition.

[0029] Figure 3 Schematic diagram of the electrode structure of the first cathode chamber

[0030] Figure 4 This is a diagram showing the treatment effect of a wastewater treatment device that simultaneously removes high-concentration heavy metals and sulfate under different initial sulfate concentrations.

[0031] Figure 5 This is a diagram showing the treatment effect of a wastewater treatment device that simultaneously removes high-concentration heavy metals and sulfate ions under different initial metal concentrations.

[0032] Figure 6 Ultrastructural analysis of microorganisms under different heavy metal concentrations. Figure 4 a, b-copper ion concentration is 0 mg / L; c, d-copper ion concentration is 20 mg / L; e, f-copper ion concentration is 60 mg / L. Implementation Method

[0033] The present invention is described in detail below through specific examples, but the use and purpose of these exemplary embodiments are only used to illustrate the present invention and do not constitute any form of limitation on the actual protection scope of the present invention, nor do they limit the protection scope of the present invention to them.

[0034] It should be noted that the present invention is applicable to wastewater containing high concentrations of heavy metals and sulfates, such as one or more of Cr(VI), Au(III), V(V), Ag(I), and Cu(II). The specific embodiments of the present invention use copper as an example, but the present invention is not limited thereto. Example 1

[0035] See also Figure 1A wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate ions is shown, which is an MFC-MEC integrated configuration. As a specific embodiment, the overall configuration includes but is not limited to this, for example, a rectangular parallelepiped with a length of 400 mm, a width of 300 mm, and a height of 300 mm, specifically including an anode chamber 10 (with a size of 100*300*300 mm), a proton exchange membrane (with a size of 0.45*300*300 mm), a first cathode chamber 11, a separator 5 (with a size of 300*0.45*300 mm) and a second cathode chamber 12.

[0036] A proton exchange membrane separates the anode chamber 10 from the cathode chamber, and the cathode chamber includes a first cathode chamber 11 and a second cathode chamber 12 .

[0037] a separator 5 , which separates the first cathode chamber 11 from the second cathode chamber 12 ;

[0038] See also Figure 2 As shown, a circular hole is opened at the upper end of the partition 5, and a screen is contained inside the circular hole;

[0039] Electrode 1 in the anode chamber is a pre-cultured carbon fiber brush electrode containing electrochemically active microorganisms. The specific cultivation steps involve collecting sludge from a sewage treatment plant and mixing it with artificially prepared water (domestic sewage can also be substituted for artificial prepared water) in a 1:1 volume ratio as the influent for the air cathode microbial fuel cell, which contains the carbon fiber brush electrode. If artificial prepared water is used, the artificial prepared water contains 1-5 g / L sodium acetate as the substrate, along with 50 mmol / L phosphate buffer solution, 12.5 mL / L trace element solution, and 5 mL / L vitamin solution. If domestic sewage is substituted for artificial prepared water, only the same phosphate buffer solution, trace element solution, and vitamin solution need to be added. During the initial inoculation cycles, the influent solution is replaced with fresh water every 48 hours. After a significant increase in voltage, the influent water is replaced with fresh water when the voltage falls below 50 mV. Enrichment and acclimation of the electrochemically active microorganisms is considered complete when the output voltage curves for two consecutive cycles show the same shape. No domestic sewage is added to the influent during the stable operation phase.

[0040] See also Figure 3 As shown, the electrode 2 of the first cathode chamber is a vortex mesh electrode sheet;

[0041] The electrode 3 of the second cathode chamber is a pre-cultured carbon fiber brush-shaped electrode; the specific cultivation step is based on the dual cathode microbial electrolysis cell, and the carbon fiber brush of the enriched electrochemically active microorganisms is placed in the dual cathode microbial electrolysis cell system as the anode. The specific method is to input an external power supply of 0.8 V between the anode chamber and the second cathode chamber, and connect a resistor with an external resistance of 10 Ω, and use a data acquisition system to measure the voltage in real time. The anode water formula is 1g / L sodium acetate, 50 mmol / L phosphate buffer solution, 12.5 mL / L trace element solution, and 5 mL / L vitamin solution; the cathode water formula of the second chamber is 0.65 g L -1 KH2PO4, 0.06 g L -1 MgCl2·6H2O, 2.22 g L -1 Na2SO4, 0.04 g L -1 CaCl2·2H2O, 1 g L -1 NH4Cl, 1.0 g L -1 Yeast extract and 2.0 mL L -1 Sodium lactate; when the voltage data and sulfate reduction efficiency are stable, the sulfate-reducing bacteria biocathode is completed.

[0042] The anode chamber 10 and the first cathode chamber 11 are connected to form an MFC, which is used for the preliminary treatment of heavy metals in high-concentration sulfate wastewater;

[0043] The anode chamber 10 and the second cathode chamber 12 are connected to an external power supply 4 to form a MEC for the simultaneous removal of sulfate and heavy metals in high-concentration sulfate wastewater.

[0044] In one embodiment, the partition 5 is movable, allowing the volumes of the first and second cathode chambers to vary with the movement of the partition. A push rod 6 can be connected to the partition to move the partition. The volumes of the two chambers can be controlled based on the metal concentration in the wastewater. In other words, the volumes of the first and second cathode chambers can be adjusted based on the heavy metal concentration.

[0045] As a specific embodiment, a scraper 7 is provided on the partition 5 to regularly clean the attached matter on the partition from top to bottom. The attached matter includes sediment and microbial flocs.

[0046] As a specific embodiment, the mesh size of the screen in the circular hole on the partition 5 is 100-150 meshes. For example, it can be 100 meshes, 120 meshes or 150 meshes. In this embodiment, 100 meshes are selected.

[0047] As a specific embodiment, the bottom of the first cathode chamber 11 and the second cathode chamber 12 contains a triangular cross-section sludge reservoir 8. To avoid dead corners, the sludge reservoir is surrounded by a solid structure and is used to collect sediment cleaned from the filter, microbial flocs, and sediment generated by the cathode.

[0048] As a specific embodiment, the electrode 1 of the anode chamber, the electrode 2 of the first cathode chamber, and the electrode 3 of the second cathode chamber are connected to the motor 9 ( Figure 1 Three corresponding motors are shown in Figure 1 Only one of these is numbered) forms the stirring device. The stirring speed can be controlled between 500-800 rpm to achieve uniform solution consistency. This allows stirring to be achieved directly through the rotation of the motor. The stirring speed can be adjusted based on the influent conditions to achieve optimal mixing of the wastewater in each chamber. Example 2

[0049] A method for treating wastewater for simultaneously removing high-concentration heavy metals and sulfate radicals is provided, which utilizes the wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals of Example 1 for treatment, and comprises the following steps:

[0050] The sludge and artificial water were mixed in a volume ratio of 1:1 as the influent of the anode chamber, and the influent was passed into the anode chamber by a peristaltic pump. The wastewater was passed into the first cathode chamber of the microbial electrolysis cell by a peristaltic pump. When the heavy metal concentration was <100 mg / L, the volume ratio of the first cathode chamber to the second cathode chamber was controlled to be 0.4-0.6:1 by moving the partition; when the heavy metal concentration was 100-200 mg / L, the volume ratio of the first cathode chamber to the second cathode chamber was controlled to be 0.7-0.8:1 by moving the partition; when the heavy metal concentration was >200 mg / L, the volume ratio of the first cathode chamber and the second cathode chamber is controlled to be 0.9-1.1:1 by moving the partition; the initial reduction of heavy metals is achieved in the first cathode chamber, and the metal ions are reduced to metal elements; then the wastewater passes through the screen and enters the second cathode chamber of the microbial electrolysis cell, where sulfate is reduced to sulfur ions and forms metal sulfide precipitation with heavy metal ions, thereby achieving the simultaneous reduction of heavy metals and sulfates.

[0051] Step removal.

[0052] Specifically, perform the following experiments under the above steps:

[0053] Experiment 1:

[0054] When the volumes of the first cathode chamber and the second cathode chamber are 300*100*300 mm respectively,

[0055] 300*200*300 mm, the applied voltage is 0.8 V, the initial sulfate concentrations in the wastewater are 500, 1000, 1500, 2000 mg / L, and the copper concentration is 100 mg / L.

[0056] Evaluation conditions: Determine the heavy metal and sulfate content in the effluent from the second cathode chamber.

[0057] The results show: See Figure 4 As shown in the figure, under different initial sulfate concentrations, the sulfate removal efficiency in the effluent of the second cathode chamber was higher than 94.81%, and the residual content was far lower than the national secondary sewage discharge standard. The copper removal rate was higher than 99.69%, and the residual concentration was lower than 0.5 mg / L, which met the pollutant discharge standards for urban sewage treatment plants.

[0058] Experiment 2:

[0059] When the applied voltage is 0.8 V, the initial sulfate concentration in the wastewater is 1000 mg / L, the volumes of the first cathode chamber and the second cathode chamber are 300*100*300 mm and 300*200*300 mm, respectively, and the copper concentrations are 50, 75, and 100 mg / L, respectively. By moving the partition, the volumes of the first cathode chamber and the second cathode chamber are 300*150*300 mm and 300*150*300 mm, respectively, and the copper concentrations are 125 and 150 mg / L, respectively.

[0060] Evaluation conditions: Determine the heavy metal content in the effluent from the second cathode chamber.

[0061] The results show: See Figure 5 As shown in the figure, under different heavy metal concentrations, the removal rate of copper in the effluent of the second cathode chamber was higher than 94.81%, which met the pollutant discharge standards of urban sewage treatment plants.

[0062] Experiment 3:

[0063] When the anode chamber and the second cathode chamber (300*100*300 mm) form a loop, the applied voltage is 0.8 V, the initial sulfate concentration in the wastewater is 1500 mg / L, and the copper concentration is 0, 20, and 60 mg / L.

[0064] Evaluation conditions: The ultrastructure of the microorganisms in the second cathode chamber was measured.

[0065] The results show: See Figure 6As shown, at a heavy metal concentration of 0 mg / L, the microorganisms were regular rods and spherical, with intact cell walls and membranes. When exposed to 20 mg / L Cu, the cell walls and membranes remained relatively intact. However, when exposed to 60 mg / L Cu, the cells deformed, their cell walls and membranes were damaged, the cytoplasm became vacuolated, and the cell size decreased. This confirms that the presence of high heavy metal concentrations causes a range of damage to the morphology and ultrastructure of microbial cells.

[0066] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals, characterized in that: It is an MFC-MEC integrated configuration, including: a proton exchange membrane separating the anode chamber from the cathode chamber, the cathode chamber comprising a first cathode chamber and a second cathode chamber; A separator separating the first cathode chamber from the second cathode chamber; a circular hole is formed at the upper end of the separator, and a mesh is contained in the circular hole; The electrode of the anode chamber is a pre-cultured carbon fiber brush electrode containing electrochemically active microorganisms; the electrode of the first cathode chamber is a vortex mesh electrode sheet; the electrode of the second cathode chamber is a pre-cultured carbon fiber brush electrode; The anode chamber and the first cathode chamber are connected to form an MFC, which is used for the preliminary treatment of heavy metals in high-concentration sulfate wastewater. The anode chamber and the second cathode chamber are connected to an external power supply to form an MEC, which is used for the simultaneous removal of sulfate and heavy metals in high-concentration sulfate wastewater. The partition is movable, so that the volume of the first cathode chamber and the second cathode chamber changes with the movement of the partition, and the volume of the first cathode chamber and the second cathode chamber can be adjusted and changed according to the concentration of the heavy metal; when the heavy metal concentration is less than 100 mg / L, the volume ratio of the first cathode chamber and the second cathode chamber is controlled to be 0.4-0.6:1 by moving the partition; when the heavy metal concentration is 100-200 mg / L, the volume ratio of the first cathode chamber and the second cathode chamber is controlled to be 0.7-0.8:1 by moving the partition; when the heavy metal concentration is greater than 200 mg / L, the volume ratio of the first cathode chamber and the second cathode chamber is controlled to be 0.9-1.1:1 by moving the partition.

2. The wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals according to claim 1, characterized in that: The partition is provided with a scraper for regularly cleaning the attachments on the partition from top to bottom.

3. The wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals according to claim 1, characterized in that: The mesh number of the screen inside the circular hole is 100-150 meshes.

4. The wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals according to claim 1, characterized in that: The bottoms of the first cathode chamber and the second cathode chamber contain mud storage pools with triangular cross-sections.

5. The wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals according to claim 1, characterized in that: The electrode of the anode chamber, the electrode of the first cathode chamber, and the electrode of the second cathode chamber are respectively connected to motors to form a stirring device, and the stirring speed is 500-800 rpm.

6. The wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals according to claim 1, characterized in that: The wastewater treatment device is a rectangular parallelepiped as a whole.

7. A wastewater treatment method for simultaneously removing high-concentration heavy metals and sulfate radicals, characterized in that: The wastewater treatment device for simultaneously removing high-concentration heavy metals and sulfate radicals according to any one of claims 1 to 6 is used for treatment, and comprises the following steps: The sludge and artificial water were mixed in a volume ratio of 1:1 as the influent of the anode chamber. The influent was passed into the anode chamber by a peristaltic pump. The wastewater was passed into the first cathode chamber of the microbial electrolysis cell by a peristaltic pump. When the heavy metal concentration was less than 100 mg / L, the volume ratio of the first cathode chamber to the second cathode chamber was controlled to be 0.4-0.6:1 by moving the partition; when the heavy metal concentration was 100-200 mg / L, the volume ratio of the first cathode chamber to the second cathode chamber was controlled to be 0.7 -0.8:1; when the heavy metal concentration is >200 mg / L, the volume ratio of the first cathode chamber and the second cathode chamber is controlled to 0.9-1.1:1 by moving the partition; the initial reduction of heavy metals is achieved in the first cathode chamber, and the metal ions are reduced to metal elements; then the wastewater passes through the screen and enters the second cathode chamber of the microbial electrolysis cell, where sulfate is reduced to sulfide ions, forming metal sulfide precipitation with heavy metal ions, thereby achieving the simultaneous removal of heavy metals and sulfate.

8. The wastewater treatment method for simultaneously removing high-concentration heavy metals and sulfate radicals according to claim 7, characterized in that: Artificial water preparation uses 1-5 g / L sodium acetate as a substrate, and adds 50 mmol / L phosphate buffer solution, 12.5 mL / L trace element solution and 5 mL / L vitamin solution.

9. The wastewater treatment method for simultaneously removing high-concentration heavy metals and sulfate radicals according to claim 7, characterized in that: Domestic sewage was used instead of artificial water, and only 50 mmol / L phosphate buffer solution, 12.5 mL / L trace element solution and 5 mL / L vitamin solution were added.

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