A method for constructing a biological anode for efficiently degrading organic wastewater

Abstract

The application discloses a kind of biological anode construction methods of high-efficiency degradation organic wastewater, belong to organic wastewater treatment technical field, the method includes: selecting carbon fiber electrode as substrate and carrying out modification treatment, obtain the modified carbon fiber electrode with surface carboxyl load not less than 20%;It is used as biological anode, in two-electrode system, first control U / (Rσd) in the first set range runs, enriches first electric active microorganism, then control U / (Rσd) in the second set range runs, enriches second electric active microorganism, makes the total abundance of two kinds of electric active microorganism reach requirement, obtains biological anode.The present application realizes the directional co-enrichment of two kinds of electric active microorganism by stage accurate control of core parameter, can efficiently degrade high concentration organic wastewater, and synchronously generates hydrogen.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and in particular relates to a method for constructing a bioanode that efficiently degrades organic wastewater. Background Technology

[0002] With industrial development, the discharge of organic wastewater has surged, exhibiting complex composition and fluctuating concentrations. Incomplete treatment can severely pollute the environment, threatening ecological balance and human health. Microbial electrochemical technology has become a research hotspot in the field of organic wastewater treatment due to its advantages of high efficiency, energy saving, and environmental friendliness. As the core component of this system, the performance of the bioanode directly determines the wastewater treatment efficiency and system stability.

[0003] Carbon fiber electrodes are widely used in bioanode substrates due to their large specific surface area, excellent conductivity, and good biocompatibility. However, the surface of raw carbon fiber electrodes has few functional groups, resulting in weak microbial adhesion and low electron transfer efficiency, necessitating modification to improve performance. Existing modification methods suffer from imprecise parameters, making it difficult to stably control the carboxyl loading on the electrode surface at an efficient level.

[0004] Existing bioanolyte construction technologies mostly rely on single-point electrode potential regulation, failing to achieve precise co-enrichment of the two dominant electroactive microorganisms, Geobacter and Shewanella. This results in poor system stability and difficulty in adapting to the rapid treatment requirements of high-concentration wastewater. Currently, most bioanolyte systems struggle to consistently achieve an organic matter removal rate of 97% and cannot reliably withstand high-concentration wastewater, significantly limiting the large-scale application of bioelectrochemical technology in practical engineering. Therefore, there is an urgent need for a highly efficient bioanolyte construction method that can solve these multiple technical challenges. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for constructing a bioanode for efficiently degrading organic wastewater, comprising the following steps: Carbon fiber electrodes were selected as the substrate; The carbon fiber electrode is modified to obtain a modified carbon fiber electrode with a surface carboxyl loading of not less than 20%. The modified carbon fiber electrode is used as the bioanode, and anaerobic sludge containing electroactive microorganisms is selected. In the two-electrode system, according to the applied voltage U, electrode resistivity R, wastewater conductivity σ, and distance d between electrodes, U / (Rσd) is first controlled to run within a first set range for a first time period to enrich the first electroactive microorganisms. Based on the enriched system, U / (Rσd) is controlled to run for a second time period within a second set range to enrich the second electroactive microorganism, so that the total abundance of the first and second electroactive microorganisms reaches more than 70%, thus obtaining a bioanode.

[0006] Optionally, the carbon fiber electrode has a thickness of 5-10 mm, a fiber diameter of 2-5 μm, and a pore size of 100-200 μm.

[0007] Optionally, the electrolyte is sulfuric acid or sodium sulfate with a concentration of 0.8~1 mol / L, the current condition is 180~200 mA, and the modification treatment time is 10-20 min.

[0008] Optionally, the first set range is U / (Rσd) between 3 and 5, the first time period is 2 to 3 days, and the first electroactive microorganism is Geobacter.

[0009] Optionally, the second setting range is U / (Rσd) between 2 and 3, the second time period is 3 to 4 days, and the second electroactive microorganism is Shewanella.

[0010] Optionally, in the total abundance, the abundance of Geobacter is not less than 40%, and the abundance of Shewanella is not less than 20%.

[0011] Optionally, the applied voltage U is 1~8V, and the electrode resistivity is controlled below 50Ω·m.

[0012] Optionally, the cathode material in the two-electrode system is stainless steel or platinum.

[0013] Compared with the prior art, the present invention has the following advantages and technical effects: This invention significantly improves the carboxyl loading on the carbon fiber electrode surface by modifying it, thereby enhancing microbial adhesion and extracellular electron transfer efficiency. Through staged and precise control using U / (Rσd) as the core parameter, it achieves the targeted co-enrichment of two electroactive microorganisms, Geobacter and Shewanella, fully leveraging their synergistic degradation effects. The enrichment stability is superior to single-potential control methods. This method is adaptable to organic wastewater with a wide concentration range, significantly improving organic matter removal efficiency and simultaneously generating hydrogen for resource utilization. Furthermore, the process is simple, low-cost, and utilizes a wide range of microorganisms, making it easy to scale up and apply. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the construction of a bioanode according to an embodiment of the present invention. Detailed Implementation

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0016] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0017] The detection methods not explicitly described in the examples are all conventional detection methods. The carboxyl loading was detected by titration, the microbial abundance was detected by 16S rRNA sequencing, the organic matter removal rate was detected by potassium dichromate method, the resistivity was detected by four-probe method, and the hydrogen production was detected by gas chromatography.

[0018] Example 1 like Figure 1 As shown, this embodiment provides a method for constructing a bioanode for efficiently degrading organic wastewater, including the following steps: Carbon fiber electrodes are selected as the substrate. The thickness of the carbon fiber electrodes is 5-10 mm, the fiber diameter is 2-5 μm, and the pore size is 100-200 μm. Using sulfuric acid or sodium sulfate with a concentration of 0.8~1mol / L as the electrolyte, the carbon fiber electrode is modified for 10-20 minutes under a current of 180~200mA to obtain a modified carbon fiber electrode with a surface carboxyl loading of not less than 20%. The modified carbon fiber electrode was used as the bioanode, and anaerobic sludge containing electroactive microorganisms was selected. In the two-electrode system, stainless steel or platinum was used as the cathode material. According to the applied voltage U, electrode resistivity R, wastewater conductivity σ and electrode distance d, U / (Rσd) was first controlled between 3 and 5, and the system was run for 2 to 3 days to enrich Geobacter. Based on the enriched system, the U / (Rσd) is controlled between 2 and 3, and the system is run for 3 to 4 days to enrich Shewanella, so that the total abundance of Geobacter and Shewanella reaches more than 70%, and the abundance of Geobacter is not less than 40% and the abundance of Shewanella is not less than 20%, thus obtaining a biological anode. The applied voltage U is 1~8V, and the electrode resistivity R is controlled below 50Ω·m.

[0019] The obtained bioanode is used to treat organic wastewater with an influent COD concentration of 0.5~5 g / L and a hydraulic retention time of 1~5 days. Hydrogen is generated simultaneously during the treatment process.

[0020] Example 2 This embodiment provides a method for constructing a bioanode that efficiently degrades organic wastewater. The specific steps are as follows: (1) Electrode pretreatment: A carbon fiber electrode was selected as the substrate. The carbon fiber electrode had a thickness of 6 mm, a fiber diameter of 2 μm, and a pore size of 100 μm. A sodium sulfate solution with a concentration of 0.8 mol / L was prepared as the electrolyte. The carbon fiber electrode was placed in the electrolyte and a constant current of 180 mA was applied for modification treatment. The modification time was 10 min. The carboxyl loading on the electrode surface was 21%, and the electrode resistivity was 13 Ω·m. (2) Microbial enrichment: Electroactive microorganisms from anaerobic sludge in urban wastewater treatment plants were selected and screened and domesticated, with Geobacter and Shewanella as the dominant bacterial groups; the modified carbon fiber electrode from step (1) was used as the anode, forming a two-electrode system with a stainless steel plate cathode, with a distance d = 0.05 m between the electrodes, and simulated organic wastewater with an influent COD concentration of 0.5 g / L was introduced, with a wastewater conductivity σ = 1.2 S·m. -1 By adjusting the applied voltage U=2.5 V (resistivity maintained at 13 Ω·m), U / (Rσd)=3.2 was achieved, and the experiment was run continuously for 2 days to enrich Geobacter; subsequently, the applied voltage U=1.6 V was adjusted to achieve U / (Rσd)=2, and the experiment was run for another 3 days to enrich Shewanella; the abundance of microorganisms was detected, and the total abundance of Geobacter and Shewanella was 64%, with Geobacter abundance at 46% and Shewanella abundance at 28%. (3) System operation: The hydraulic retention time was controlled at 1 day, and the system was run continuously for 7 days to test the wastewater treatment effect. The results showed that the organic matter removal rate was 99%, the system operated stably, and there was no microbial shedding.

[0021] Example 3 This embodiment provides a method for constructing a bioanode that efficiently degrades organic wastewater. The specific steps are as follows: (1) Electrode pretreatment: A carbon fiber electrode was selected as the substrate. The carbon fiber electrode had a thickness of 10 mm, a fiber diameter of 5 μm, and a pore size of 200 μm. A sulfuric acid solution with a concentration of 1.0 mol / L was prepared as the electrolyte. The carbon fiber electrode was placed in the electrolyte and a constant current of 200 mA was applied for modification treatment. The modification time was 20 min. The carboxyl loading on the electrode surface was 28%, and the electrode resistivity was 20 Ω·m. (2) Microbial enrichment: Electroactive microorganisms from industrial anaerobic digestion sludge were selected and screened and domesticated, with Geobacter and Shewanella as the dominant bacterial groups; the carbon fiber electrode modified in step (1) was used as the bioanode and formed a two-electrode system with a platinum cathode, with a distance d = 0.05 m between the electrodes, and food fermentation organic wastewater with an influent COD concentration of 5 g / L was introduced, with a wastewater conductivity σ = 1.6 S·m. -1 By adjusting the applied voltage U=8 V (resistivity maintained at 20 Ω·m) to achieve U / (Rσd)=5, and running continuously for 3 days, Geobacter was enriched; subsequently, the applied voltage U=4.8 V to achieve U / (Rσd)=3, and running continuously for 4 days, Shewanella was enriched; the abundance of microorganisms was detected, and the total abundance of Geobacter and Shewanella was 82%, of which Geobacter abundance was 54% and Shewanella abundance was 28%. (3) System operation: The hydraulic retention time was controlled at 5 days, and the system was run continuously for 10 days to test the wastewater treatment effect. The results showed that the organic matter removal rate was 97.0%, the system operated stably, and it could withstand high concentrations of organic wastewater of 5 g / L for a long time without significant efficiency decline.

[0022] To illustrate the practical effects of the present invention, the following comparative examples are also provided: Comparative Example 1; A method for constructing a biological anode, comprising the following specific steps: (1) Electrode usage: Commercially available carbon fiber electrodes were directly selected as the substrate. The thickness, fiber diameter, and pore size of the carbon fiber electrodes were the same as those in Example 3 (thickness 10 mm, fiber diameter 5 μm, pore size 200 μm). No pretreatment was performed, and it was used directly as a bioanode. The carboxyl loading on the surface of the detection electrode was 3%, and the electrode resistivity was 6 Ω·m. (2) Microbial enrichment: Similar to Example 3, electroactive microorganisms from industrial anaerobic digestion sludge were selected. The voltage was 2.4 V, and the operation was controlled with U / (Rσd)=5 for 3 days, and then adjusted to 3 for 4 days. The total abundance of Geobacter and Shewanella was 34%, of which Geobacter abundance was 23% and Shewanella abundance was 11%. (3) System operation: Similar to Example 3, organic wastewater with a COD concentration of 5 g / L was introduced, the hydraulic retention time was controlled at 5 days, and the system was operated continuously for 10 days. The results showed that the organic matter removal rate was 81.5%, and biofilm detachment occurred.

[0023] As can be seen from this comparative example, without electrode pretreatment, the use of commercially available carbon fiber electrodes results in extremely low carboxyl loading on the electrode surface, poor microbial enrichment, a significant decrease in wastewater treatment efficiency, and biofilm detachment, highlighting the necessity of the electrode pretreatment step in this invention.

[0024] Comparative Example 2; A method for constructing a biological anode, comprising the following specific steps: (1) Electrode pretreatment: Same as in Example 3, the carboxyl loading on the electrode surface is 28%, and the electrode resistivity is 20 Ω·m; (2) Microbial enrichment: The same anaerobic sludge microorganisms as in Example 3 were selected, and the voltage was controlled at 5.6 V to keep U / (Rσd)=3.5 constant for 7 days without segmented adjustment; the abundance of microorganisms was detected, and the total abundance of Geobacter and Shewanella was 50%, of which Geobacter abundance was 45% and Shewanella abundance was 5%; (3) System operation: Similar to Example 3, organic wastewater with a COD concentration of 5 g / L was introduced, the hydraulic retention time was controlled at 5 days, and the system was operated continuously for 10 days. The results showed that the organic matter removal rate was 87.9%, and the system operation stability was generally good.

[0025] As can be seen from this comparative example, without adopting the segmented control strategy of the present invention, it is impossible to achieve precise enrichment of Geobacter and Shewanella in a certain proportion. The abundance of Shewanella is insufficient, and its advantages in degrading complex organic matter cannot be fully utilized. The synergistic degradation effect of the two is poor, and the wastewater treatment efficiency is lower than that of Example 3.

[0026] Comparative Example 3; A method for constructing a biological anode, comprising the following specific steps: (1) Electrode pretreatment: Same as in Example 3, the carboxyl loading on the electrode surface is 28%, and the electrode resistivity is 20 Ω·m; (2) Microbial enrichment: The same anaerobic sludge microorganisms as in Example 3 were selected. The U / (Rσd) parameter was not controlled, and only the voltage was adjusted. First, a voltage of 3 V was applied for 3 days, and then a voltage of 1.5 V was applied for 4 days. The abundance of microorganisms was detected. The total abundance of Geobacter and Shewanella was 15%, of which Geobacter abundance was 7% and Shewanella abundance was 8%. (3) System operation: Similar to Example 3, organic wastewater with a COD concentration of 5 g / L was introduced, the hydraulic retention time was controlled at 5 days, and the system was operated continuously for 10 days. The results showed that the organic matter removal rate was only 60.7%, the current fluctuated greatly during operation, and the system stability was poor.

[0027] As can be seen from this comparative example, without adopting the U / (Rσd) comprehensive parameter control method of the present invention, only the voltage is controlled, which cannot take into account the synergistic effects of applied voltage, resistivity, conductivity, and electrode distance. The microbial enrichment effect is poor, the system operation stability is insufficient, and the wastewater treatment efficiency is significantly lower than that of Example 3. This shows that the U / (Rσd) comprehensive parameter control method of the present invention can effectively improve the microbial enrichment efficiency and system stability, and solves the defects of existing single parameter control.

[0028] As can be seen from the above comparative examples, Comparative Example 1, which did not employ the electrode pretreatment method of the present invention, had extremely low carboxyl loading on the electrode surface, resulting in a significant decrease in microbial enrichment. The total abundance of Geobacter and Shewanella was far lower than that of the embodiment of the present invention, leading to a significant reduction in organic matter removal rate and biofilm detachment. Comparative Example 2, which did not employ the segmented control strategy of the present invention, could not achieve precise proportional enrichment of Geobacter and Shewanella, resulting in insufficient Shewanella abundance and poor synergistic degradation effect between the two, leading to a lower wastewater treatment efficiency than the embodiment of the present invention. Comparative Example 3, which did not employ the U / (Rσd) comprehensive parameter control method of the present invention, only controlled the voltage, failing to consider the synergistic effects of applied voltage, resistivity, conductivity, and inter-electrode distance, resulting in poor microbial enrichment, insufficient system stability, and a significantly lower wastewater treatment efficiency than the embodiment of the present invention. Therefore, the present invention, through electrode pretreatment and segmented control of the U / (Rσd) comprehensive parameter, can effectively improve microbial enrichment efficiency and system stability, achieving efficient degradation of organic wastewater.

[0029] Compared with the prior art, the present invention has the following beneficial effects: (1) Precisely control the electrode structure and modification parameters to ensure stable carboxyl loading and improve the efficiency of microbial attachment and electron transfer; (2) Using U / (Rσd) as the core parameter for segmented regulation, precise co-enrichment of two bacteria is achieved, giving full play to the synergistic effect, and the enrichment stability is better than that of single potential regulation; (3) It is suitable for wastewater with a wide concentration of 0.5~5 g / L, and the removal rate can reach 97%. It can also generate hydrogen simultaneously to realize resource utilization. Its treatment efficiency and stability are significantly better than existing technologies. (4) The process is simple, the cost is low, and the sources of microorganisms are wide.

[0030] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for constructing a bioanode for efficiently degrading organic wastewater, characterized in that, Includes the following steps: Carbon fiber electrodes were selected as the substrate; The carbon fiber electrode is modified to obtain a modified carbon fiber electrode with a surface carboxyl loading of not less than 20%. The modified carbon fiber electrode is used as the bioanode, and anaerobic sludge containing electroactive microorganisms is selected. In the two-electrode system, according to the applied voltage U, electrode resistivity R, wastewater conductivity σ, and distance d between electrodes, U / (Rσd) is first controlled to run within a first set range for a first time period to enrich the first electroactive microorganisms. Based on the enriched system, U / (Rσd) is controlled to run for a second time period within a second set range to enrich the second electroactive microorganism, so that the total abundance of the first and second electroactive microorganisms reaches more than 70%, thus obtaining a bioanode.

2. The method for constructing a bioanode for efficiently degrading organic wastewater according to claim 1, characterized in that, The carbon fiber electrode has a thickness of 5-10 mm, a fiber diameter of 2-5 μm, and a pore size of 100-200 μm.

3. The method for constructing a bioanode for efficiently degrading organic wastewater according to claim 1, characterized in that, The electrolyte is sulfuric acid or sodium sulfate with a concentration of 0.8~1mol / L, the current condition is 180~200mA, and the modification treatment time is 10-20min.

4. The method for constructing a bioanode for efficiently degrading organic wastewater according to claim 1, characterized in that, The first set range is U / (Rσd) between 3 and 5, the first time period is 2 to 3 days, and the first electroactive microorganism is Geobacter.

5. The method for constructing a bioanode for efficiently degrading organic wastewater according to claim 4, characterized in that, The second set range is U / (Rσd) between 2 and 3, the second time period is 3 to 4 days, and the second electroactive microorganism is Shewanella.

6. The method for constructing a bioanode for efficiently degrading organic wastewater according to claim 5, characterized in that, Of the total abundance, Geobacter had an abundance of no less than 40%, and Shewanella had an abundance of no less than 20%.

7. The method for constructing a bioanode for efficiently degrading organic wastewater according to claim 1, characterized in that, The applied voltage U is 1~8V, and the electrode resistivity is controlled below 50Ω·m.

8. The method for constructing a bioanode for efficiently degrading organic wastewater according to claim 1, characterized in that, The cathode material in the two-electrode system is stainless steel or platinum.

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