Double-anode-based single-chamber electro-Fenton antibiotic mineralization device and method

Abstract

The invention discloses a single-chamber electro-Fenton antibiotic mineralization device and method based on double anodes, in the device, an air cathode, a first anode and a second anode are sequentially arranged in a single chamber, an electrolyte contains antibiotics, the first anode comprises an electrogenesis biological membrane and in-situ synthesized nano FeS, and the second anode comprises an electrogenesis biological membrane and in-situ synthesized nano FeS; the second anode comprises a degradation biological membrane of a typical antibiotic degradation intermediate, and the surface of the air cathode is coated with an aerobic reduction catalyst. The first anode is used for driving Fe (III) / Fe (II) circulation, generation of OH is accelerated, meanwhile, nano FeS is used for protecting cells from being damaged, and therefore the antibiotic degradation efficiency is improved, and generation of intermediates is promoted; the second anode is used for promoting anode biodegradation to be coupled with cathode chemical oxidation, the intermediate is rapidly mineralized, electrons are released to drive the cathode electro-Fenton reaction, and finally thorough mineralization of the antibiotics is achieved. The device and the method provided by the invention can realize high-efficiency green low-carbon treatment of antibiotic wastewater, and have important application prospects in the aspects of environmental protection and resource utilization.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical wastewater treatment, and particularly relates to a device and method for mineralizing antibiotics in a single-chamber electro-Fenton driven by a dual-anode synthetic biofilm in a synergistic manner. Background Art

[0002] The discharge of a large amount of antibiotic wastewater causes more than 50,000 tons of antibiotics to enter the environment every year and accumulate for a long time, seriously threatening the ecosystem and human health. The detected concentration of antibiotics in water bodies can reach 3 - 47,400 ng / L, and even up to the mg / L level in pharmaceutical wastewater. Antibiotics have a stable chemical structure, strong antibacterial activity, and the risk of carcinogenesis and teratogenesis, and it is difficult to remove them in wastewater treatment. Although traditional treatment methods (such as physical adsorption, chemical oxidation, and biodegradation) can remove antibiotics to a certain extent, they generally have the following problems: (1) consuming a large amount of energy or chemicals, with high operating costs; (2) complex treatment processes, prone to secondary pollution; (3) difficult to achieve complete mineralization, and easily generating toxic intermediates. Therefore, the development of green and low-carbon antibiotic wastewater treatment technologies has become an urgent need.

[0003] Bio-electro-Fenton (BEF) technology combines bioelectrochemistry and electro-Fenton technology. It uses the anodic biofilm to oxidize organic matter to generate electrons, which are transferred to the cathode to drive the reduction of O2 to generate H2O2, and then react with Fe(II) to generate highly oxidizing •OH to degrade pollutants. Compared with traditional electro-Fenton technology, BEF powers through microorganisms, reducing power consumption and showing unique advantages in the treatment of antibiotic wastewater. The current mainstream dual-chamber BEF system uses a diaphragm to separate the anode (anaerobic electricity-generating environment) from the cathode (oxygen-rich electro-Fenton environment), and antibiotics are mainly degraded by electro-Fenton at the cathode. However, this indirect coupling of the anode and cathode makes the functions of the two poles unable to cooperate, resulting in limited antibiotic degradation and mineralization effects. The single-chamber BEF eliminates the diaphragm to achieve direct coupling of the anode and cathode, showing significant advantages in degrading antibiotics such as carbamazepine (efficiency increased by 38%) and sulfamethoxazole (degradation rate up to 96%), but still faces two major bottlenecks: insufficient Fe(III) / Fe(II) cycle and •OH damage to the biofilm. Summary of the Invention

[0004] Considering the disadvantages and deficiencies of the existing technology, the purpose of the present invention is to provide a device and method for mineralizing antibiotics in a single-chamber electro-Fenton driven by a dual-anode synthetic biofilm in a synergistic manner, which realizes the complete mineralization of various refractory antibiotics and can provide a new method for solving antibiotic pollution in the environment.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: An apparatus for mineralizing antibiotics based on a dual anode in a single chamber, comprising a first anode, a second anode, an air cathode and an electrolyte disposed in the same single chamber. The first anode is arranged between the air cathode and the second anode, and an oxygen reduction catalyst is coated on the surface of the air cathode. The electrolyte contains the antibiotic. The first anode includes a first conductive matrix, and an electricity-producing biofilm and in-situ synthesized nano-FeS are provided on the surface of the first conductive matrix. The second anode includes a second conductive matrix, and a degradation biofilm of typical antibiotic degradation intermediates is provided on the surface of the second conductive matrix.

[0006] Preferably, the material of the first conductive matrix or the second conductive matrix is carbon felt, and the material of the air cathode is selected from carbon materials, stainless steel materials or titanium mesh materials.

[0007] Preferably, the oxygen reduction catalyst is carbon black.

[0008] To further improve the degradation effect on antibiotics, as a more preferred technical solution, a Fenton catalyst is also coated on the surface of the air cathode. The Fenton catalyst is γ-FeOOH.

[0009] Preferably, the electricity-producing biofilm is obtained by domestication or artificial screening.

[0010] Preferably, the degradation biofilm of the typical antibiotic degradation intermediates is obtained by domestication or artificial screening.

[0011] Preferably, the first anode is obtained by the following steps: (1-1) In a dual-chamber microbial fuel cell (MFC), using the first conductive matrix as the anode and activated sludge as the inoculation source, carry out domestication and enrichment of the electricity-producing biofilm to obtain a first conductive matrix with an electricity-producing biofilm on its surface; (1-2) In a dual-chamber microbial fuel cell (MFC), using the first conductive matrix with an electricity-producing biofilm on its surface obtained in step (1-1) as the anode and a solution containing an iron source and a sulfur source as the anolyte, carry out in-situ synthesis under dark light conditions to obtain the first anode.

[0012] Preferably, the anolyte in step (1-1) is wastewater or simulated wastewater. More preferably, the COD of the anolyte in step (1-1) is 1000 mg / L. More preferably, the composition of the anolyte in step (1-1) is: 0.31 g / L NH4Cl, 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, 1 g / L C6H 12 O6·H2O, and the pH is 7.

[0013] Preferably, the organic carbon in the anolyte is derived from one or more of glucose, sodium acetate, sodium lactate, or sodium propionate.

[0014] Preferably, the catholyte in step (1-1) is a phosphate buffer solution containing potassium ferricyanide. More preferably, the concentration of potassium ferricyanide in the catholyte in step (1-1) is 50 mM. More preferably, the composition of the catholyte in step (1-1) is: 16.472 g / L K3[Fe(CN)6], 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, and the pH is 7.

[0015] Preferably, the method for acclimation and enrichment in step (1-1) is as follows: in an environment of 30 °C, the catholyte and anolyte are replaced every 3 days, and when the power generation of the battery is stable for 2 consecutive cycles, the electrogenic biofilm is successfully acclimated and enriched.

[0016] Preferably, the anolyte in step (1-2) is wastewater or simulated wastewater added with an iron source and a sulfur source. More preferably, the COD of the anolyte in step (1-2) is 1000 mg / L. More preferably, the composition of the anolyte in step (1-2) is: 5 mM iron source, 5 mM sulfur source, 0.31 g / L NH4Cl, 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, 1 g / L C6H 12 O6·H2O, and the pH is 7.

[0017] Preferably, the iron source is one or more of ferric chloride, ferric citrate, or ferric sulfate.

[0018] Preferably, the sulfur source is one or two of sodium thiosulfate or sodium sulfate.

[0019] Preferably, the method for in-situ synthesis in step (1-2) is as follows: in an environment of 30 °C, the catholyte and anolyte are replaced every 3 days, and in-situ synthesis is carried out for 4 cycles to obtain.

[0020] Preferably, the second anode is obtained by the following steps: (2) In a dual-chamber microbial fuel cell (MFC), using the second conductive matrix as the anode, anaerobic activated sludge as the inoculum source, and wastewater or simulated wastewater containing typical antibiotic degradation intermediates and glucose as the anolyte for domestication. During the domestication process, the catholyte and anolyte are replaced every 3 days. Each time the anolyte is replaced, the concentration of the typical antibiotic degradation intermediate is higher than the corresponding concentration in the anolyte replaced last time, and the concentration of glucose is lower than the corresponding concentration in the anolyte replaced last time, until the mineralization rate of the typical antibiotic degradation intermediate reaches 100%.

[0021] Preferably, the anaerobic activated sludge is used as the activated sludge. Preferably, the activated sludge is derived from lake bottom sediments, soil, wastewater, biogas residue or biogas slurry.

[0022] Preferably, the typical antibiotic degradation intermediate is selected from the degradation intermediates of chloramphenicol, tetracycline, sulfamethoxazole, penicillin, metronidazole or nitrofurazone. The specific degradation intermediates can be obtained by referring to the literature or by detecting after degrading antibiotics through building a simple electro-Fenton device.

[0023] The present invention also provides the method for mineralizing antibiotics based on a dual-anode single-chamber electro-Fenton, including: using the liquid to be treated containing antibiotics as the electrolyte and operating the device for mineralizing antibiotics based on a dual-anode single-chamber electro-Fenton.

[0024] The present invention adopts a single-chamber bioelectro-Fenton (BEF) system design and uses the "dual-anode functional division" strategy of "nano-FeS hybrid bioanode driving Fe(III) / Fe(II) cycle + intermediate degradation bioanode for directional mineralization of accumulated intermediates", having the following advantages and beneficial effects: (1) Aiming at the two core problems of low Fe(III) / Fe(II) cycle efficiency and •OH damaging the anode biofilm in the single-chamber BEF system, the present invention innovatively proposes the "dual-anode functional division" strategy to strengthen the mineralization of antibiotics in the single-chamber BEF system.

[0025] (2) The "dual-anode functional division" strategy of the single-chamber BEF system provided by the present invention strengthens the Fe(III) / Fe(II) cycle through the construction of a nano-FeS hybrid bioanode and the synergistic effect of microorganisms and nanomaterials, solving the technical bottleneck of low iron cycle efficiency in traditional electro-Fenton; by designing an intermediate degradation bioanode, it realizes the near-field coupling of biodegradation-chemical oxidation and breaks through the governance problem of incomplete antibiotic mineralization.

[0026] (3) The process of the present invention has strong universality, is applicable to wastewater of various refractory antibiotics (chloramphenicol, tetracycline, sulfamethoxazole, penicillin, metronidazole, nitrofurazone) and has excellent treatment efficiency (both the degradation rate and the mineralization rate can reach 100%).

[0027] (4) The present invention has prominent green and low-carbon features and great potential for engineering. The diaphragm-free single-chamber design simplifies the reactor structure, has low costs, and is suitable for large-scale applications. The anodic synthetic biofilm can also construct an artificial bacterial community biofilm by screening iron-reducing bacteria, sulfur-reducing bacteria, and intermediate-degrading bacteria, further enhancing the stability and controllability of the system. Nano-FeS can be synthesized from iron- and sulfur-containing wastewater, is harmless to the environment, and conforms to the concept of resource recycling and utilization. Description of the Drawings

[0028] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the present invention provides the following drawings for description: Figure 1 It is the working principle diagram of the dual-anode single-chamber BEF system of the present invention.

[0029] Figure 2 It is the polarization curve diagram of the dual-chamber BEF group, single-chamber MFC group, single-chamber BEF group, and dual-anode single-chamber BEF group.

[0030] Figure 3 It is the degradation situation diagram of chloramphenicol for the dual-chamber BEF group, single-chamber MFC group, single-chamber BEF group, and dual-anode single-chamber BEF group.

[0031] Figure 4 It is the chloramphenicol mineralization and effluent toxicity situation diagram of the dual-chamber BEF group, single-chamber MFC group, single-chamber BEF group, and dual-anode single-chamber BEF group.

[0032] Figure 5 It is the chloramphenicol degradation rate and mineralization rate diagram of different dual-anode single-chamber BEFs (whether the air cathode contains an iron catalyst). Detailed Embodiments

[0033] The present invention will be further described in detail below with specific examples. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0034] Example 1 (1) In a dual-chamber microbial fuel cell (MFC), a carbon felt is used as the anode, anaerobic activated sludge is used as the inoculation source, and the carbon source in the anolyte is glucose. The composition is 0.31 g / L NH4Cl, 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, 1 g / L C6H 12O6·H2O, with a pH of 7. The catholyte is a phosphate buffer solution containing 50 mM potassium ferricyanide, with a specific composition of 16.472 g / L K3[Fe(CN)6], 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, and a pH of 7.

[0035] Place the MFC in an incubator at 30 °C, and replace the catholyte and anolyte every 3 days. When the power generation of the battery is stable for 2 consecutive cycles, the electricity-generating biofilm is successfully domesticated and enriched.

[0036] After that, on this basis, add 5 mM ferric chloride and 5 mM sodium thiosulfate to the anolyte, and keep the catholyte the same as above. Run the MFC under dark conditions at 39 °C, and replace the catholyte and anolyte every 3 days. In-situ synthesis is carried out for 4 cycles to obtain the first anode.

[0037] (2) In a dual-chamber microbial fuel cell (MFC), use carbon felt as the anode and anaerobic activated sludge as the inoculation source for biofilm domestication. The other components in the anolyte are 0.31 g / L NH4Cl, 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, with a pH of 7. Benzoic acid and glucose, typical chloramphenicol degradation intermediates, are also added to the anolyte. Replace the catholyte and anolyte every 3 days. In the anolyte after each replacement, the concentration of benzoic acid is higher than the previous one, while the concentration of glucose is lower than the previous one until the glucose concentration drops to 0 and the benzoic acid concentration reaches 50 mg / L. Domestication is carried out until the stable mineralization rate of the typical antibiotic degradation intermediate reaches 100% to obtain the second anode.

[0038] (3) Put the obtained first anode and second anode into the same single chamber, use carbon felt as the air cathode, and the surface of the carbon felt is coated with carbon black. Place the first anode between the second anode and the air cathode, and use chloramphenicol wastewater (chloramphenicol 50 mg / L, 0.31 g / L NH4Cl, 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, 1 g / L C6H 12 O6·H2O; pH = 7) as the electrolyte to obtain a dual-anode single-chamber BEF.

[0039] For comparison, simultaneously set: (3-1) Dual-chamber BEF: The reactor separates the anode and cathode chambers by a proton exchange membrane. The anode is carbon felt, and the cathode is a carbon felt air cathode (oxygen reduction catalyst: carbon black, Fenton catalyst: γ-FeOOH). The chloramphenicol wastewater is in the cathode chamber.

[0040] (3-2) Single-chamber MFC: The proton exchange membrane in the reactor was removed. The anode was a carbon felt, and the cathode was a carbon felt air cathode (oxygen reduction catalyst: carbon black).

[0041] (3-3) Single-chamber BEF: The proton exchange membrane in the reactor was removed. The anode was a carbon felt, and the cathode was a carbon felt air cathode (oxygen reduction catalyst: carbon black, Fenton catalyst: γ-FeOOH).

[0042] (4) The bacterial source of the bioanodes in the dual-chamber BEF group, single-chamber MFC group, and single-chamber BEF group was anaerobic activated sludge. The ratio of sludge to anolyte was 1:13, and 10 mg / L CAP was added for acclimation. After each cycle of operation for 3 days, the anolyte and catholyte were replaced. When the power generation of the system was stable for 2 consecutive cycles, it was considered that the anode biofilm was maturely acclimated. All anode biofilms were first maturely acclimated on the anode of the dual-chamber MFC and then entered the experimental operation stage by replacing the corresponding air cathode according to the experimental group settings. The reactors were placed in an incubator at 30 °C.

[0043] The anolyte of the dual-chamber BEF group was (0.31 g / L NH4Cl, 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, 1 g / L C6H 12 O6·H2O; pH = 7), and the catholyte was a phosphate buffer solution containing 50 mg / L chloramphenicol (2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl; pH = 7).

[0044] The anolyte of the single-chamber MFC group, single-chamber BEF group, and dual-anode single-chamber BEF group was the above-mentioned chloramphenicol wastewater.

[0045] The polarization curves of different experimental groups are as Figure 2 shown. The results show that the dual-anode single-chamber BEF group exhibited the optimal power density, and its maximum power density was 104.38 mW / m 2 , which was 32.63% higher than that of the single-chamber MFC group. The chloramphenicol degradation performance of different experimental groups is as Figure 3 shown. The results show that the dual-anode single-chamber BEF group exhibited the optimal chloramphenicol degradation performance. The chloramphenicol degradation rate reached 94.23% after 72 h, which was 149.81% higher than that of the single-chamber MFC group. The chloramphenicol mineralization rate and effluent toxicity of different experimental groups are as Figure 4As shown. The results showed that the dual-anode single-chamber BEF group exhibited the best chloramphenicol mineralization performance and the lowest effluent toxicity. The chloramphenicol mineralization rate (76.10%) was increased by 44.40% compared with the single-chamber MFC group, and the effluent toxicity was reduced by 70.05% compared with the single-chamber MFC group. The above experimental results demonstrated the high efficiency of the synergistic degradation of chloramphenicol by the biological anode and chemical cathode in the single-chamber BEF, and confirmed the effectiveness of the "dual-anode functional division of labor" strategy of "nano-FeS hybrid biological anode driving Fe(III) / Fe(II) cycle + intermediate degradation and biological anode-directed mineralization of accumulated intermediates".

[0046] Example 2 Based on Example 1, this example further compared the effects of the air cathode with and without Fenton catalyst on the treatment of chloramphenicol wastewater (50 mg / L) in the dual-anode single-chamber BEF system. The specific experimental group settings were as follows: (1) Dual-anode single-chamber BEF-1: The conditions were the same as those of the dual-anode single-chamber BEF in Example 1; (2) Dual-anode single-chamber BEF-2: The cathode was a carbon felt air cathode (oxygen reduction catalyst: carbon black, Fenton catalyst: γ-FeOOH), and other conditions were the same as those of dual-anode single-chamber BEF-1.

[0047] The domestication of the anode biofilm and the construction and operation of the device were the same as those in Example 1. The chloramphenicol treatment performances of the two experimental groups were as Figure 5 shown. The results showed that the dual-anode single-chamber BEF-2 group had higher chloramphenicol degradation and mineralization rates than the dual-anode single-chamber BEF-1 group, both reaching 100% after 72 h of treatment, indicating that the presence of Fenton catalyst in the air cathode could improve the treatment efficiency of the system.

[0048] Example 3 This example further verified the performance of using the dual-anode single-chamber BEF-2 in Example 2 to treat different antibiotic wastewaters: The treatment steps were the same as those in Example 1, and the antibiotics selected were typical representatives of 6 types of antibiotics, namely chloramphenicol, tetracycline, sulfamethoxazole, penicillin, metronidazole, and nitrofurazone. As shown in Table 1, the adaptation concentrations of the target antibiotics with 100% degradation and mineralization rates after 72 h of treatment by the dual-anode single-chamber BEF-2 were as follows. The adaptation concentrations of chloramphenicol and penicillin could reach 50 mg / L, that of sulfamethoxazole could reach 20 mg / L, that of tetracycline could reach 10 mg / L, and those of metronidazole and nitrofurazone could reach 5 mg / L. The experimental results showed that the device and method provided by the present invention had excellent treatment performances for typical antibiotics in the environment and had universality.

[0049] Antibiotic <![CDATA[Concentration / mg·L -1 > Degradation rate / % Mineralization rate / % Chloramphenicol 50 100 100 Tetracycline 10 100 100 Sulfamethoxazole 20 100 100 Penicillin 50 100 100 Metronidazole 5 100 100 Nitrofurazone 5 100 100

Claims

1. A device for mineralizing antibiotics based on a dual-anode single-chamber electro-Fenton, characterized in that, It includes a first anode, a second anode, an air cathode and an electrolyte disposed in the same single chamber. The first anode is arranged between the air cathode and the second anode, and an oxygen reduction catalyst is coated on the surface of the air cathode. The electrolyte contains the antibiotic. The first anode includes a first conductive matrix, and an electricity-producing biofilm and in-situ synthesized nano-FeS are provided on the surface of the first conductive matrix. The second anode includes a second conductive matrix, and a degradation biofilm of typical antibiotic degradation intermediates is provided on the surface of the second conductive matrix.

2. The device according to claim 1, wherein The electricity-producing biofilm or the degradation biofilm of the typical antibiotic degradation intermediates is obtained by domestication or artificial screening.

3. The device according to claim 1, characterized in that A Fenton catalyst is also coated on the surface of the air cathode.

4. The device according to claim 1, wherein The first anode is obtained by the following steps: (1-1) In a dual-chamber microbial fuel cell, using the first conductive matrix as the anode and activated sludge as the inoculation source, domesticate and enrich the electricity-producing biofilm to obtain a first conductive matrix with an electricity-producing biofilm on its surface; preferably, the anolyte is wastewater or simulated wastewater. (1-2) In a dual-chamber microbial fuel cell, using the first conductive matrix with an electricity-producing biofilm on its surface obtained in step (1-1) as the anode and a solution containing an iron source and a sulfur source as the anolyte, perform in-situ synthesis under dim light conditions to obtain the first anode; preferably, the iron source is one or more of ferric chloride, ferric citrate or ferric sulfate; preferably, the sulfur source is one or two of sodium thiosulfate or sodium sulfate.

5. The device according to claim 3, characterized in that, The COD of the anolyte in step (1-1) is 1000 mg / L; more preferably, the composition of the anolyte in step (1-1) is: 0.31 g / L NH4Cl, 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, 1 g / L C6H 12 O6·H2O, and the pH is 7.

6. The device according to claim 3, characterized in that, The COD of the anolyte in step (1-2) is 1000 mg / L; more preferably, the composition of the anolyte in step (1-2) is: 5 mM iron source, 5 mM sulfur source, 0.31 g / L NH4Cl, 2.452 g / L NaH2PO4·H2O, 4.576 g / L Na2HPO4, 0.13 g / L KCl, 1 g / L C6H 12 O6·H2O, and the pH is 7.

7. The device according to claim 3, characterized in that, The method of the in-situ synthesis in step (1-2) is: in an environment of 30 °C, replace the catholyte and anolyte every 3 days, and perform in-situ synthesis for 4 cycles to obtain it.

8. The device according to claim 1, characterized in that, The second anode is obtained by the following steps: (2) In a dual-chamber microbial fuel cell, using the second conductive matrix as the anode and activated sludge as the inoculation source, domesticate with wastewater or simulated wastewater containing typical antibiotic degradation intermediates and glucose as the anolyte. During the domestication process, replace the catholyte and anolyte every 3 days. Each time the anolyte is replaced, the concentration of the typical antibiotic degradation intermediate is higher than the corresponding concentration in the anolyte replaced last time, and the concentration of the glucose is lower than the corresponding concentration in the anolyte replaced last time until the mineralization rate of the typical antibiotic degradation intermediate reaches 100%.

9. The device according to claim 8, wherein The typical antibiotic degradation intermediates are selected from the degradation intermediates of chloramphenicol, tetracycline, sulfamethoxazole, penicillin, metronidazole or nitrofurazone.

10. A method for mineralizing antibiotics based on a dual-anode single-chamber electro-Fenton, characterized in that, It includes: Using the liquid to be treated containing the antibiotic as the electrolyte, operate the device for electro-Fenton mineralization of antibiotics based on a dual anode according to any one of claims 1-9.

Images