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微生物燃料电池(microbial fuel cells,MFC)是一种通过可产电菌种的代谢作用来降解有机物,并将代谢过程中产生的电子通过外电路传输进而产生电能[1-2]的装置。双阴极MFC可在去除COD的同时、进行硝化和反硝化过程,从而提高了传统MFC的脱氮能力。ZHANG等[3]在传统MFC阳极的两侧添加了好氧和厌氧阴极室,这种复合多室的MFC系统可去除污水中76%的氮。LEE等[4]构建了双阴极MFC,好氧阴极对氨氮的去除率可达97.9%,在缺氧阴极处理硝态氮,其去除率为89.9%。外电阻被认为是影响MFC性能的一项重要因素,增大外阻不但会影响电池产电性能,对电池内有机物的去除也有较大的影响。JANG等[5]的研究表明,在双室MFC中,随外阻的增加,电流和COD去除率均会降低。荣宏伟等[6]构建了阴极硝化和阳极反硝化的双室MFC发现,外阻越小,有机物降解速率越快,TN去除率越高,阳极表面生物膜产电菌的氧化能力越强。这些报道均集中在研究外电阻对双室MFC的影响,但在3室MFC中,外电阻变化是否会有相同的结论尚需进一步的研究。本研究构建了3室MFC,目的在于寻求优化3室MFC脱氮产电性能的组合。该系统的运行方式与传统A2O工艺相似,能同时去除有机物和氮,便于驯化适用于不同阴极的微生物,易与传统污水处理工艺相结合,且较双室MFC产电多。本研究通过变换不同的电阻组合以探明外阻变化对双阴极MFC产电脱氮性能的影响,为进一步提高MFC的脱氮产电性能提供参考。
外电阻对双阴极微生物燃料电池脱氮产电性能的影响
Effect of external resistance on denitrification and electricity generation performance of double-cathode microbial fuel cell
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摘要: 为提高双阴极MFC的脱氮产电性能,构建了双阴极微生物燃料电池系统,考察了连续进水状态下阳极与缺氧阴极间外阻(RA-A)以及阳极与好氧阴极间外阻(RA-O)的变化对系统脱氮产电性能的影响。结果表明:只增大一侧电阻会降低厌氧阳极的库仑效率和功率密度,但能提高系统的脱氮效果;当RA-O由200 Ω增大到1 000 Ω时,TN去除率由43.81%提高到60.71%,当RA-A由200 Ω增大到1 000 Ω时,TN去除率由38.88%提高到61.52%;当总外阻固定在1 000 Ω时,两侧电阻变化不影响阳极的功率密度和库仑效率,其分别保持在305.53 mW·m−3和0.35%左右;电阻组合(RA-A /RA-O)由500 Ω/500 Ω变化为100 Ω/900 Ω,TN去除率由62.32%提高到64.41%;系统的硝化效果随RA-O的增大而增强,反硝化效果随RA-A的减小而增强,总氮去除效果随总外阻的增大而提升。低RA-A与高RA-O的外阻组合能有效提高双阴极三室MFC的脱氮能力。增大总外阻,系统产电性能降低,阳极表面微生物膜氧化性不断减弱,总外阻不变,阳极表面氧化性变化不大。研究探明了外电阻变化对三室双阴极MFC脱氮产电性能的影响,为进一步提高MFC脱氮产电性能提供参考。Abstract: In order to improve the nitrogen removal and electricity generation performance of dual cathode MFC, a dual cathode microbial fuel cell system was built. Under continuous water inflow, the effects of change in the external resistance between the anode and the anoxic cathode (RA-A) and the external resistance between the anode and the aerobic cathode (RA-O) on the nitrogen removal and electricity generation performance of the system were examined. The results showed that when the resistance on one side increased, the coulomb efficiency and power density of the anaerobic anode decreased, but the nitrogen removal effect of the system increased. When RA-O increased from 200 Ω to 1 000 Ω, TN removal rate increased from 43.81% to 60.71%. When RA-A increased from 200 Ω to 1 000 Ω, TN removal rate increased from 38.88% to 61.52%. When the total external resistance was fixed at 1 000 Ω, the changes in the resistance on both sides did not affect the power density and Coulomb efficiency of the anode, which could maintain at about 305.53 mW·m−3 and 0.35%, respectively. The combination of small RA-A and large RA-O could improve the nitrogen removal effect of dual cathode MFC, when the resistance combination (RA-A/RA-O) changed from 500 Ω/500 Ω to 100 Ω/900 Ω, TN removal rate increased from 62.32% to 64.41%. The nitrification effect of the system increased with the increase of RA-O, the denitrification effect increased with the decrease of RA-A, and the total nitrogen removal effect increased with the increase of total external resistance. The external resistance combination of low RA-A and high RA-O could effectively improve the nitrogen removal capacity of the dual cathode three-chamber MFC. Increasing the total external resistance reduced the power generation performance of the system, and weakened the oxidizing ability of the microbial membrane on the anode surface. The total external resistance did not change, then little change in surface oxidation of the anode occurred. This study clarified the effects of change in the external resistance on the nitrogen removal and electricity generation performance of the dual cathode three-chamber MFC, and provided the reference for the further improvement of the nitrogen removal and electricity generation performance of MFC.
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Key words:
- dual-cathode /
- microbial fuel cells /
- resistance /
- nitrogen removal /
- cyclic voltammetric scanning
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表 1 RA-O增大对产电性能的影响
Table 1. Effect of increasing RA-O on electrical performance
RA-A/Ω 功率密度/(mW·m−3) 库仑效率/% 厌氧阳极 缺氧阴极 好氧阴极 厌氧阳极 缺氧阴极 200 411.68 74.91 90.25 0.49 1.63 400 345.16 64.03 70.81 0.40 1.51 600 303.71 46.48 66.97 0.35 1.36 800 300.80 41.61 65.28 0.32 1.29 1 000 288.13 34.57 64.68 0.30 1.28 表 2 RA-A增大对产电性能的影响
Table 2. Effect of increasing RA-A on electrical performance
RA-A/Ω 功率密度/(mW·m−3) 库仑效率/% 厌氧阳极 缺氧阴极 好氧阴极 厌氧阳极 缺氧阴极 200 419.97 73.85 91.51 0.48 1.95 400 341.47 58.96 73.96 0.40 1.19 600 327.21 56.53 65.61 0.37 0.86 800 320.38 59.51 59.29 0.35 0.72 1 000 316.39 55.76 53.78 0.33 0.67 表 3 总外阻不变不同组合对双阴极MFC产电性能的影响
Table 3. Influence of the combination of total external resistance and invariable resistance onelectricity properties of the dual cathode three-chamber MFC
实验编号 电阻/Ω 功率密度/(mW·m−3) 库仑效率/% RA-A RA-O 厌氧阳极 缺氧阴极 好氧阴极 厌氧阳极 缺氧阴极 1 500 500 304.65 48.24 73.62 0.32 0.61 2 400 600 305.74 51.66 77.35 0.34 0.68 3 300 700 304.62 52.32 75.91 0.34 0.75 4 200 800 309.38 50.46 70.56 0.36 0.95 5 100 900 305.53 52.56 65.23 0.39 1.53 -
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