微生物燃料电池中多孔电极内电解液的复杂流动机理研究

微生物燃料电池（简称MFC）是一种能够把微生物作为催化剂分解有机物质从而产生电能的新型环境友好型能源装置.到目前为止,对于微生物燃料电池内在连续流的条件下流体穿过多孔阳极的对流现象,人们已经做了大量研究.然而,流体穿过多孔阳极的力学机理和多孔介质与MFC的定量关系还不是很清晰.实验发现当MFC装置的距离在某个特定范围时输出功率明显增大.基于这些实验得到的数据,我们利用格子Boltzmann方法研究了阳极与阴极之间的距离和多孔阳极达西数对MFC输出功率的影响.结果表明阳极与阴极之间的距离影响MFC中流体的速度和流体在多孔阳极中的滞留时间.此外,还发现多孔阳极的达西数能够影响MFC的输出功率.     

微生物燃料电池阳极材料研究进展

微生物燃料电池（microbial fuel cell,MFC）是一种新型的生物电化学装置,能将可生物降解有机物中的化学能直接转化成电能,而阳极材料性能是影响MFC性能的重要因素之一。通过对阳极材料进行改性和修饰可以有效地增大其比表面积、生物相容性等,以提高其微生物负载率和电子传递速率,进而提高MFC的产电性能。本文全面介绍和总结了近年来国内外关于微生物燃料电池阳极材料的研究进展,分析微生物燃料电池阳极材料在规模放大应用中存在的问题,并对微生物燃料电池阳极材料今后的发展方向进行了展望。     

基于广州市政垃圾渗滤液的MFC性能及阳极微生物分析

为了分离纯化可适应渗滤液极端环境的产电菌,以广州市白云区李坑和兴丰两处垃圾填埋场获取的渗滤液为底物运行微生物燃料电池（microbial fuel cell, MFC）,待稳定输出多个周期后剪取阳极碳布进行单菌落培养和电镜扫描。结果显示,各组渗滤液底物MFC均能成功启动。李坑四季样的MFC峰值电压分别为0.334、0.331、0.321、0.328 V;兴丰四季样的MFC峰值电压分别为0.512、0.54、0.523、0.536 V。对各组渗滤液底物微生物燃料电池的阳极进行菌株分离纯化并单菌落培养构建阳极微生物系统发育树,发现经过MFC驯化后的阳极菌株具有较高丰度和差异性;SEM扫描发现各组实验中菌株均吸附在阳极碳布上形成稳定的膜结构,根据产电呼吸的基本电子传递机制推测渗滤液底物MFC中的微生物通过与阳极直接接触来传递电子。     

微生物燃料电池电能产生及污废水处理的研究进展

微生物燃料电池（microbial fuel cell, MFC）是采用微生物催化的电化学系统,可用于污废水处理领域。目前关于MFC的研究多集中在提高产电能力和去污效能方面。通过综述近期MFC的研究进展,建议该技术在污废水处理领域的研究重点放在产电微生物筛选培养、低成本电极材料修饰研发、调控MFC运行条件等方面,并应加强MFC与序批式反应器（sequencing batch reactor, SBR）、厌氧好氧（anoxic oxic, A/O）、膜生物反应器（membrane bio-reactor, MBR）等常见污废水处理工艺耦合联用的研究。     

微生物燃料电池混合菌群的产电特性与分布

将不同来源的污泥进行组合构建混合接种物的微生物燃料电池(MFC),通过比较微生物燃料电池的产电性能寻求更为优良的微生物群落,结果表明:将华南农业大学资源环境学院新肥室沼气池污泥、湖南省祁东县淹水稻田土和燕京啤酒厂废水处理二沉池污泥混合作为组合接种物的MFC性能较优,其最大输出电压0.59 V,最大功率密度10.81 W/m3。利用PCR-DGGE技术解析该电池阳极表面优势微生物的群落,分析发现阳极生物膜中占优势的菌种为Gammaproteobacteria菌纲中的Shewanella,其次为Pseudomonas aeruginosa,还存在Verrucomicrobiae和Flavobacteria菌纲的微生物。     

单室微生物燃料电池产电特性研究

采用石墨板为阴极构建了单室空气阴极微生物燃料电池(MFC),以混合菌种接种,并以乙酸钠和碳酸氢钠为碳源,研究了该MFC在间歇运行条件下的产电性能、电池内阻情况和COD去除率。结果表明,最高输出电压随着周期数增加而增加,由0.075 9 V上升到0.200 6 V,最大输出功率密度为34.80 mW/m2;在一个运行周期内,电池内阻随着时间的延长而逐渐增大,由376.6Ω上升到682.0Ω,电池内阻的增大将导致输出电压降低。COD去除率由起始的49.23%达到最大值86.99%,说明此单室空气阴极微生物燃料电池在产电的同时处理污水的效果也较好。     

不同接种物对微生物燃料电池利用氨氮产电的影响

文章以厌氧污泥和河底沉积物分别启动单室微生物燃料电池MFC,并通过改变氨氮浓度以及外电阻大小考察其对于MFC产电和氨氮去除的影响。结果表明,不同接种物启动的MFC对氨氮浓度的耐受性不同,厌氧污泥MFC在氨氮浓度为488.2 mg/L时最大输出功率Pmax为454.6 mW/m2,而沉积物MFC的Pmax为309.6mW/m2,出现在氨氮浓度为127.5 mg/L时;小电阻有利于氨氮的去除,但会限制MFC的产电,当外电阻从1 000Ω降低到10Ω时,厌氧污泥MFC氨氮去除率从46.1%提高到71.9%,沉积物MFC则从41.0%提高到了69.3%,并且厌氧污泥接种的MFC氨氮去除率与电阻的线性关系要优于沉积物MFC。     

MnO2为阴极催化剂的微生物燃料电池处理城市垃圾渗滤液研究

主要针对城市垃圾热解预处理过程所产生的渗滤液进行研究。首先改变城市垃圾堆放温度和堆放时间,发现城市垃圾于40℃堆放6 d后所得的渗滤液中生物需氧量(Biological Oxygen Demand,BOD)、氨氮浓度约为20800、1410 mg/L,B/C比、B/N比分别为0.32和14.8,营养物质较均衡,易于生化处理,且将其进行微生物燃料电池(Microbial Fuel Cell,MFC)处理时,电池可获得0.29 V的稳定输出电压。随后,以上述渗滤液为MFC阳极基质,考察廉价易得的Mn O2作为阴极催化剂对空气阴极单室MFC电池性能以及渗滤液中有机污染物去除率的影响。结果发现,由于Mn O2催化氧还原,加速了MFC阴极接受电子的速度,使得MFC电池性能有较大提高。其中,MFC的最大功率密度由0.16 W/m3提高到0.88 W/m3,而电池稳定输出电压明显升高至0.43 V,且阳极渗滤液中BOD和NH4+-N去除率也分别达72.9%和91.6%,比对照MFC分别提高8.1%和5.0%。     

电极间距对单室微生物燃料电池处理老龄垃圾渗滤液性能的影响

以体积分数为60%的老龄垃圾渗滤液为单室无膜空气阴极微生物燃料电池底物,考察电极间距分别为1、2、3、4、5 cm时电池产电性能及底物中物污染物的去除效果。结果表明,间距为2 cm时输出电压和最大功率密度最大,间距为4 cm时输出电压和最大功率密度最小;电极间距为1～3 cm时电池内阻随电极间距的增大而增大,而电极间距大于3 cm时电池内阻随电极间距的增大而减小。电极间距为2 cm时,微生物燃料电池(MFC)对老龄垃圾渗滤液中化学需氧量(COD)和氨氮去除率最高;5个电池的库伦效率分别为35.6%、27.6%、35.4%、14.9%和14.9%,单室无膜空气阴极MFC可在一定程度上提高老龄垃圾渗滤液的可生化性。     

泡沫镍空气阴极微生物燃料电池的产电特性

研究了泡沫镍阴极的制备和对单室微生物燃料电池产电性能的影响。研究发现,当阴极PTFE扩散层超过4+1层时,MFC的功率密度随扩散层数增加而逐渐下降;当阴极扩散层为五层(4+1层)时,微生物燃料电池最大功率密度最大,达到31.3 W/m3,电池的库仑效率为25%;当使用7+1层PTFE扩散层时,电池功率下降到25.6 W/m3;泡沫镍阴极厚度对阴极性能影响不大;研究发现,滚压后再涂一层扩散层能够抑制泡沫镍阴极的长期运行的析盐。     

Evaluating the performance of microbial fuel cells powering electronic devices

A microbial fuel cell (MFC) is capable of powering an electronic device if we store the energy in an external storage device, such as a capacitor, and dispense that energy intermittently in bursts of high-power when needed. Therefore its performance needs to be evaluated using an energy-storing device such as a capacitor which can be charged and discharged rather than other evaluation techniques, such as continuous energy dissipation through a resistor. In this study, we develop a method of testing microbial fuel cell performance based on storing energy in a capacitor. When a capacitor is connected to a MFC it acts like a variable resistor and stores energy from the MFC at a variable rate. In practice the application of this method to testing microbial fuel cells is very challenging and time consuming; therefore we have custom-designed a microbial fuel cell tester (MFCT). The MFCT evaluates the performance of a MFC as a power source. It uses a capacitor as an energy storing device and waits until a desired amount of energy is stored then discharges the capacitor. The entire process is controlled using an analog-to-digital converter (ADC) board controlled by a custom-written computer program. The utility of our method and the MFCT is demonstrated using a laboratory microbial fuel cell (LMFC) and a sediment microbial fuel cell (SMFC). We determine (1) how frequently a MFC can charge a capacitor, (2) which electrode is current-limiting, (3) what capacitor value will allow the maximum harvested energy from a MFC, which is called the “optimum charging capacitor value,” and (4) what capacitor charging potential will harvest the maximum energy from a MFC, which is called the “optimum charging potential.” Using a LMFC we find that (1) the time needed to charge a 3-F capacitor from 0 to 500 mV is 108 min, (2) the optimum charging capacitor value is 3 F, and (3) the optimum charging potential is 300 mV. Using a SMFC we find that (1) the time needed to charge a 3-F capacitor from 0 to 500 mV is 5 min, (2) the optimum charging capacitor value is 3 F, and (3) the optimum charging potential is 500 mV. Our results demonstrate that the developed method and the MFCT can be used to evaluate and optimize energy harvesting when a MFC is used with a capacitor to power wireless sensors monitoring the environment.     

Mediator-less microbial fuel cell employing Shewanella Oneidensis

This study investigated efficient energy harvesting of a mediator-less microbial fuel cell (MFC) using Shewanella Oneidensis bacteria. Synthetic wastewater made from M9 minimal growth medium and carbon source was used to generate electricity. This experiment exhibits how concentration of bacteria in the anodic chamber, different types of carbon sources, and the substance concentration affect electricity generation. The results showed that the mediator-less MFC using Shewanella Oneidensis can produce voltage close to the maximum attainable MFC voltage. The efficient MFC can be used to treat wastewater while reducing energy needs and producing an alternative form of energy.     

微生物燃料电池阴极电子受体与结构的研究进展

从工程应用的角度分析了微生物燃料电池的结构变化趋势;从电化学角度介绍了几种两室微生物燃料电池中阴极室采用不同电子受体对提高电池输出功率的影响和单室空气阴极微生物燃料电池的研究现状及应用前景;分析了电池组在电池放大过程中可能存在的串挠和电压反转等问题,为微生物燃料电池的工程应用提供了理论参考。     

Recent advances in constructed wetland‐microbial fuel cells for simultaneous bioelectricity production and wastewater treatment: A review

The coupling of constructed wetlands (CWs) to microbial fuel cells (MFCs) has turned out to be a source of renewable energy for the production of bioelectricity and for the simultaneous wastewater treatment. Both technologies have an aerobic zone in the air‐water interface and an anaerobic zone in the lower part, where the anode and the cathode are strategically placed. This hybridization is a promising bioelectrochemical technology that exerts a symbiosis between plant‐bacteria in the rhizosphere of an aquatic plant, converting solar energy into bioelectricity through the formation of root exudates as an endogenous substrate and a microbial activity. The difference between CW‐MFC and MFC conventional lies in the bioelectricity and substrate production in situ, where exogenous substrates are not required for example wastewater. However, CW‐MFC can take organic content present in wastewater, promoting the removal of some pollutants. Different areas that comprise the study of a CW‐MFC have been explored, including the structures and their operation. This review aims to provide concise information on the state of the art of CW‐MFC systems, where a summary on important aspects of the development of this technology, such as bioelectricity production, configurations, plant species, rhizodeposits, electrode materials, wastewater treatment, and future perspectives, is presented. This system is a promising technology, not only for the production of bioenergy but also to maintain a clean environment, since during its operation, no toxic byproducts were formed.     

Efficient biohydrogen and bioelectricity production from xylose by microbial fuel cell with newly isolated yeast of Cystobasidium slooffiae

Although xylose is the secondary dominant sugar derived from biomass, the conversion of xylose to energy products is quite challenging. In this work, a new exoelectrogenic yeast strain (Cystobasidium slooffiae strain JSUX1) that can generate electricity in microbial fuel cell (MFC) by using xylose as the substrate was isolated and identified. After adaptation, it produced significant current output with rapid xylose metabolism. More surprisingly, this strain produced hydrogen gas either in anerobic flask incubation or in MFC, which delivered a 67 mW/m² power output and 23 L/m³ hydrogen gas in MFC with xylose as fuel. Further electrochemical analysis indicated that riboflavin was secreted by this strain as the electron mediator for efficient electron transfer between cells and electrode in MFC. This is the first microorganism identified that can simultaneously produce bio-hydrogen and bio-electricity from xylose, which would diversify the toolbox of biomass energy.     

Dynamic modeling of a continuous two-chamber microbial fuel cell with pure culture of Shewanella

Microbial fuel cell is a bioreactor which converts the chemical energy stored in chemical bonds of the organic compounds to electrical energy through the catalytic reactions. In this work, the previous model which was proposed by our group [M. Esfandyari, M.A. Fanaei, R. Gheshlaghi, M.A. Mahdavi, Chemical Engineering Research and Design, 117 (2017) 34–42] for a batch two-chamber microbial fuel cell (MFC) is extended to the continuous operation. In the selected continuous MFC, lactate is used as the substrate, Shewanella as the microbial agent, and oxygen of air as the final electron acceptor in the cathode chamber. An experimental setup is applied for the collection of data needed for the verification of the proposed model. A Good agreement was observed between the predicted and the experimental data of the current and voltage produced by MFC as well as the substrate and carbon dioxide concentration in the liquid bulk of anode chamber of MFC. The proposed model has simple structure and can be used for the optimization, and design of control system of microbial fuel cell.     

Energy recovery from cassava peels in a single-chamber microbial fuel cell

In a number of energy-poor nations, cassava peels represent one of the most abundant forms of lignocellulosic biomass available, and thus present an opportunity for use in microbial fuel cells (MFCs). In an MFC with optimized electrode spacing, biomass produced a power density of 29 mW?m^–3 in a single-chamber air cathode MFC. This work which examines a way to reduce environmental degradation caused by indiscriminate disposal of organic waste also confirmed the presence of naturally occurring electrogenic organism which can be exploited to recover energy as well as supplement energy production in the growing regions.     

Microalgae-microbial fuel cell (mMFC): an integrated process for electricity generation,wastewater treatment,CO2 sequestration and biomass production

The world today is facing a crisis of energy and environmental pollution. Conventional or photosynthetic microbial fuel cell (MFC) is an advanced “green” energy technology that utilizes living microorganisms to convert biochemical or light energy into electricity through metabolic reaction and photosynthesis, offering a potential solution for the above-mentioned crisis. Further incorporating microalgae into MFC, microalgae-microbial fuel cell (mMFC) integrates electricity generation, wastewater treatment, CO₂ sequestration and biomass production in a single, self-sustainable technology. This review first describes the fundamentals of MFC as well as its applications in treating domestic, municipal, agricultural and industrial wastewaters. Then, mMFC-based configurations and applications with its advantages compared with MFC are explained in particular, together with the parameters governing its performance. Lastly, the opportunities and challenges involved in the development of mMFCs are also explored.     

Modeling and simulation of net energy gain by dark fermentation

For dark fermentation (DF) to be accepted as a sustainable process for biohydrogen production, the net energy gain should be positive and as high as possible. A theoretical approach is proposed in this study to evaluate the net energy gain possible from hydrogen generated by the DF process as well as from the end products of DF via anaerobic digestion (AD) and microbial fuel cells (MFC). Experimental data on hydrogen evolution and aqueous end products formation from sucrose and from sucrose/dairy manure blends were used to validate the proposed approach for estimating net energy gain via DF, DF + AD, DF + MFC. Good agreement was found between the experimental and predicted net energy gain values, with overall correlation coefficient of 0.998. Based on the results of this study, DF + MFC is recommended as the best combination to maximize net energy gain.     

Modelling and simulation of two-chamber microbial fuel cell

Microbial fuel cells (MFCs) offer great promise for simultaneous treatment of wastewater and energy recovery. While past research has been based extensively on experimental studies, modelling and simulation remains scarce. A typical MFC shares many similarities with chemical fuel cells such as direct ascorbic acid fuel cells and direct methanol fuel cells. Therefore, an attempt is made to develop a MFC model similar to that for chemical fuel cells. By integrating biochemical reactions, Butler–Volmer expressions and mass/charge balances, a MFC model based on a two-chamber configuration is developed that simulates both steady and dynamic behaviour of a MFC, including voltage, power density, fuel concentration, and the influence of various parameters on power generation. Results show that the cathodic reaction is the most significant limiting factor of MFC performance. Periodic changes in the flow rate of fuel result in a boost of power output; this offers further insight into MFC behaviour. In addition to a MFC fuelled by acetate, the present method is also successfully extended to using artificial wastewater (solution of glucose and glutamic acid) as fuel. Since the proposed modelling method is easy to implement, it can serve as a framework for modelling other types of MFC and thereby will facilitate the development and scale-up of more efficient MFCs.