Electricity generation by an enriched phototrophic consortium in a microbial fuel cell

Microbial fuel cell (MFC) technology is a novel electricity generation process catalyzed by microorganisms. Much progress is made in the design and construction of MFCs, however the diversity of the electrochemically active microorganisms and the electricity generation mechanisms remain a black box. As sun is a predominantly unused energy resource, here we present a highly enriched phototrophic consortium that can produce electricity in an “H” typed MFC at a high power density (2650 mW m⁻², normalized to membrane area) in light, which was eightfold of that produced by non-enriched consortium in the same reactor. Light–dark shift experiments showed that light contributed to the electricity generation. A microbial excreted mediator assisted the electron transfer to the electrode. During the experiment, the accumulation of the mediator over time enhanced the electron transfer rate. The excitation–emission matrix fluorescence spectroscopy results indicated indole group containing compound representing the dominant mediator component.     

Bioenergetics and extracellular electron transfer in microbial fuel cells and microbial corrosion

Bioenergetics can be used to analyze the theoretical voltage output of a microbial fuel cell (MFC) and the thermodynamic driving force in microbiologically influenced corrosion (MIC). MFCs involve both inward and outward extracellular electron transfer (EET), whereas only inward EET is behind EET–MIC caused by an electroactive biofilm's harvest of energy from a metal. EET is often rate-limiting, and it is an important process in microbial energy metabolism. EET is critical to the understanding of MFCs and EET–MIC bioelectrochemical processes. Many advances have been made in the past decade on EET by MFC and MIC researchers. Gene manipulations have been used to improve EET in MFCs, leading to enhanced energy output. They have also been used to elucidate the EET processes for better understanding of EET–MIC, which aids in MIC analysis and decision-making of biocide treatment and its efficacy assessment. Researchers are starting to integrate EET knowledge from both fields.     

Optimization of double chamber microbial fuel cell for domestic wastewater treatment and electricity production

Microbial fuel cells (MFCs) represent a new approach for treating waste water along with electricity production. The present study addressed electricity production from domestic wastewater using a mediator-less double chamber MFC. The electricity production was monitored under different operational conditions for both summer and winter samples. Optimization of the anodic and cathodic chambers resulted in a maximal current of 0.784 and 0.645 mA with the maximal power intensity of 209 and 117 mW/m² in power duration of 24 h for the summer and winter samples, respectively. Scanning electron microscopy showed that the bacterial biofilm formation on the anode was denser for the summer sample than that when the winter sample was used, so was the total bacterial count. Therefore, samples taken during summer were considered better in electricity production and waste water treatment than those taken during winter basically because of the high microbial load during the hot season. In parallel, there was a decrease in both biological oxygen demand (BOD₅) and chemical oxygen demand (COD) values which reached 71.8% and 72.85%, respectively at the end of the operation process for the summer sample, while there was no evident decrease for the winter sample. Optimizing the operating conditions not only increased the potential of using domestic waste water in microbial fuel cells to produce electricity, but also improved the quality of the domestic waste water.     

微生物燃料电池处理餐饮废水及同步发电性能研究

针对食堂餐饮废水,建立微生物燃料电池实验系统,研究微生物燃料电池废水处理与同步发电性能。首先使用Fe(NO3)3溶液作为阴极电解液进行实验,证明餐饮废水生物降解及产电的可行性;分别采用NaCl溶液和K3[Fe(CN)6]溶液作为阴极电解液进行对比实验,研究不同运行环境下微生物燃料电池的发电性能和污水净化效果。结果表明,采用NaCl溶液和K3[Fe(CN)6]溶液作为阴极电解液时的COD去除率分别是30%和22%左右,平均电流密度分别为5.6和5.2mA/m2。在污水稀释比为2∶1、NaCl电解液浓度为0.4mol/L的情况下,微生物燃料电池系统的发电性能和净水效果达到最佳状态,稳态电流密度为8.8mA/m2,COD去除率为33.3%。     

微生物燃料电池电能原位利用及其衍生形式的研究进展

作为一种生物催化的电化学系统,微生物燃料电池(MFC)目前研究多集中于提高产电能力和污水处理能力。将MFC产生的电能进行原位利用,可以有效对废水进行处理和修复。为了更有效地原位利用MFC产生的电能并修复污染水体,本文介绍了一种电能原位利用的新形式—微生物电化学呼吸器(MES)并综述了其的研究进展。MES作为一种短路的新型MFC,将产生的电能进行原位利用,可以提高废水的优化处理效率。作为一种新型污水处理装置,MES在环保领域将会拥有广阔的应用前景。     

Stainless steel cloth modified by carbon nanoparticles of Chinese ink as scalable and high-performance anode in microbial fuel cell

Microbial fuel cells(MFCs) have various potential applications.However,anode is a main bottleneck that limits electricity production performance of MFCs.Herein,we developed a novel anode based on a stainless steel cloth(SC) modified with carbon nanoparticles of Chinese ink(Cl) using polypyrrole(PPy)as a building block(PPy/Cl/SC).After modification,PPy/Cl/SC showed a 30% shorten in start-up time(36.4 ± 3.3 h vs.52.3± 1.8 h),33% increase in the maximum current(12.4 ± 1.4 mA vs.9.3± 0.95 mA),and2.3 times higher in the maximum power density of MFC(61.9 mW/m~2 vs.27.3 mW/m~2),compared to Ppy/SC.Experimental results revealed that carbon nanoparticles were able to cover SC uniformly,owing to excellent dispersibility of carbon nanoparticles in Cl.The attachment of carbon nanoparticles formed a fluffy layer on SC increased the electrochemically-active surface area by 1.9 times to 44.5 cm2.This enhanced electron transfer between the electrode and bacteria.Further,embedding carbon nanoparticles into the PPy layer significantly improved biocompatibility as well as changed functional group contents,which were bene ficial to bacteria adhesion on electrodes.Taking adva ntage of high mechanical strength and good conductivity,a large-size PPy/Cl/SC was successfully prepared(50×60 cm~2)demonstrating a promising potential in practical applications.This simple fabrication strategy offers a new idea of developing low cost and scalable electrode materials for high-performance energy harvesting in MFCs.     

Investigation of the electrocatalytic oxidation of formate and ethanol at platinum black under microbial fuel cell conditions

In this communication, we discuss the electro-oxidation of the fermentation products formate and ethanol at platinum black modified electrodes under microbial fuel cell conditions, i.e., at neutral pH, room temperature, and in microbial culture solutions. The electrocatalytic oxidation was studied using cyclic voltammetry, chronoamperometry, and potentiostatic coulometry. Current densities up to 6 mA cm⁻² at 0.2 V oxidation potential and 97% coulombic efficiency were observed for the electro-oxidation of 100 mM solutions of formate in pH 7 buffer solution. Electrode deactivation could be successfully prevented using an oxidative potential reactivation procedure. Polymer coating, however, fully stopped the formate oxidation. As expected, the electro-oxidation of ethanol was less efficient—with a limiting current density being 600 μA cm⁻².Dedicated to Professor Dr. Alan M. Bond on the occasion of this 60th birthday.     

化学修饰炭黑在微生物燃料电池中的生物产电行为

研究发现微生物燃料电池从启动到稳定运行的过程中往往存在一种现象,就是在高电流密度下,微生物燃料电池的输出电压会出现逆转,从而限制了微生物燃料电池的规模化应用,以及它在污废水处理、脱盐等方面的功能.
　　前期研究发现,微生物燃料电池的性能逆转现象与阳极材料的电容性能有关.电极材料的电容越大,越有利于微生物燃料电池的产电性能稳定,换言之,阳极材料电容不足导致产电性能逆转.但是超级电容活性炭的制作工艺繁琐,成本高,且导电性弱,不能满足微生物燃料电池的应用需求.炭黑的导电能力强、化学稳定性高、成本低,但作为微生物燃料电池的阳极则产生产电性能逆转现象.
　　化学修饰(如酸、碱活化或者添加具有赝电容性质的金属氧化物等)可以提高材料的电容性能.低温条件(80 oC)下,对低电容材料—炭黑进行HNO3和KOH的化学活化处理,并在此基础上,进一步用5%Fe3O4修饰,采用辊压工艺,以质量分数为60%的聚四氟乙烯乳液为粘结剂,制作微生物燃料电池的阳极,与空气阴极构建单室微生物燃料电池系统.采用傅里叶变换红外光谱(FTIR)、比表面积测试、材料表面pH和X射线能量分析光谱(EDX)等手段表征炭黑活化前后的物理、化学性质;接触角润湿性测试表征活化前后电极表面的亲疏水性.电化学循环伏安法测试活化前后,电极的电子存储能力.
　　与蒸馏水的pH相比较,材料表面pH分析表明炭黑材料经化学活化处理后,其表面pH无明显变化; FTIR和EDX测试表明化学活化处理使得炭黑表面引入含O(N)官能团;吸附-脱附曲线分析表明化学活化后,炭黑的比表面积减小,微孔与介孔的体积比增加;接触角测试表明炭黑阳极活化处理后,电极表面亲水性增加;循环伏安测试证实,化学活化后的炭黑阳极电容得到0.1–0.8 F/cm2的增长.结合燃料电池的产电性能测试,发现只有当炭黑阳极电容不小于1.1 F/cm2时,微生物燃料电池的产电逆转现象才会消失.炭黑阳极的化学活化方法为微生物燃料电池的性能稳定提供了一种简便、低成本的方法.     

生物燃料电池处理生活污水同步产电特性研究

以某生活污水处理厂缺氧池活性污泥为接种体,以葡萄糖为模拟生活废水,构建双室型微生物燃料电池。利用微生物燃料电池(MFC,Microbial fuel cell)实现生活废水降解与同步产电。研究基质降解动力学及温度对MFC电极过程动力学的影响,明确微生物电化学活性、阳极传荷阻抗、阳极电势、电池产能之间的关系,考察库伦效率及COD去除率。研究结果表明,电池功率输出与基质浓度关系遵循莫顿动力学方程:P=Pmaxc/(ks+c),其中,半饱和常数ks为138.5 mg/L,最大功率密度Pmax为320.2 mW/m2。葡萄糖浓度较小时,反应遵循一级动力学规律:-dcA/dt=kcA,k=0.262 h-1。操作温度从20℃提高到35℃,生物膜电化学活性不断提高,传荷阻抗从361.2Ω减小到36.2Ω,阳极电极电势不断降低,同时,峰值功率密度从80.6 mW/m2提高到183.3 mW/m2。45℃时,产电菌活性降低,峰值功率密度减小到36.8 mW/m2。葡萄糖浓度为1 500 mg/L,温度为35℃时,MFC电化学性能最佳,稳定运行6 h后库伦效率为44.6%,COD去除率为49.2%。     

Recent advance in microbial fuel cell reactor configuration and coupling technologies for removal of antibiotic pollutants

Microbial fuel cell (MFC) technology, as a biological treatment model that can convert antibiotic pollutants into electrical energy, has attracted extensive attention in recent years. Reactor configuration and coupling process play an important role in the treatment of antibiotic wastewater by the MFC, which will affect microbial activity, pollutant removal, and electricity generation. In this review, recent advances of reactor configuration (single chamber, double chamber, and cylinder) and coupling technology (wetland-MFC, sediment-MFC and membrane-MFC, and so on) of the MFC on treating of antibiotics are summarized, and their characteristics in the aspects of pollutant removal and power output are analyzed. Finally, through comparing removal quantity (mg antibiotics per day), the double chamber MFC as the individual treatment unit and the membrane-MFC exhibit better removal quantity.     

Optimization for the improvement of power in equal volume of single chamber microbial fuel cell using dairy wastewater

Microbial fuel cells (MFCs) are a type of sustainable technology that may treat wastewater and generate power at the same time. Therefore, researchers are being challenged to design a technically feasible bio electrochemical system that generates environmentally friendly and renewable electricity from waste water. The current research examined at how MFC may be used to generate electricity while treating real dairy wastewater (RDW) with Pseudomonas aeruginosa-MTCC-7814. The experiments were carried out in fed-batch mode for 15 days in two 300 ml single chamber microbial fuel cells (SCMFCs) that were connected in series. During a fed batch investigation, three process parameters such as inoculum percentage, temperature, and pH were optimized. Inoculum percentage, temperature, and pH were found to be optimal at 5%, 37 °C, and 7.4, respectively and the highest open-circuit voltage was found to be 1025 mV. The COD removal efficiency and columbic efficiency (CE) were found to be 95.84% and 37.13% respectively. The optimized fed batch process yielded the maximum current density and power density of 313 mA/m² and 105 mW/m², respectively. Thus, this work successfully demonstrates that connecting single chamber microbial fuel cells (SCMFCs) in series is a viable technique for generating sustainable power utilizing Pseudomonas aeruginosa-MTCC-7814 from dairy wastewater.     

Analysis of pharmaceuticals in wastewater and removal using a membrane bioreactor

Much attention has recently been devoted to the life and behaviour of pharmaceuticals in the water cycle. In this study the behaviour of several pharmaceutical products in different therapeutic categories (analgesics and anti-inflammatory drugs, lipid regulators, antibiotics, etc.) was monitored during treatment of wastewater in a laboratory-scale membrane bioreactor (MBR). The results were compared with removal in a conventional activated-sludge (CAS) process in a wastewater-treatment facility. The performance of an MBR was monitored for approximately two months to investigate the long-term operational stability of the system and possible effects of solids retention time on the efficiency of removal of target compounds. Pharmaceuticals were, in general, removed to a greater extent by the MBR integrated system than during the CAS process. For most of the compounds investigated the performance of MBR treatment was better (removal rates >80%) and effluent concentrations of, e.g., diclofenac, ketoprofen, ranitidine, gemfibrozil, bezafibrate, pravastatin, and ofloxacin were steadier than for the conventional system. Occasionally removal efficiency was very similar, and high, for both treatments (e.g. for ibuprofen, naproxen, acetaminophen, paroxetine, and hydrochlorothiazide). The antiepileptic drug carbamazepine was the most persistent pharmaceutical and it passed through both the MBR and CAS systems untransformed. Because there was no washout of biomass from the reactor, high-quality effluent in terms of chemical oxygen demand (COD), ammonium content (N-NH₄), total suspended solids (TSS), and total organic carbon (TOC) was obtained.     

Enhanced response of microbial fuel cell using sulfonated poly ether ether ketone membrane as a biochemical oxygen demand sensor

The present study is focused on the development of single chamber microbial fuel cell (SCMFC) using sulfonated poly ether ether ketone (SPEEK) membrane to determine the biochemical oxygen demand (BOD) matter present in artificial wastewater (AW). The biosensor produces a good linear relationship with the BOD concentration up to 650 ppm when using artificial wastewater. This sensing range was 62.5% higher than that of Nafion^®. The most serious problem in using MFC as a BOD sensor is the oxygen diffusion into the anode compartment, which consumes electrons in the anode compartment, thereby reducing the coulomb yield and reducing the electrical signal from the MFC. SPEEK exhibited one order lesser oxygen permeability than Nafion^®, resulting in low internal resistance and substrate loss, thus improving the sensing range of BOD. The system was further improved by making a double membrane electrode assembly (MEA) with an increased electrode surface area which provide high surface area for electrically active bacteria.     

Recent advances in osmotic microbial fuel cell technology: A review

Integration of Forward Osmosis (FO) and Microbial Fuel Cell (MFC) technology is called Osmotic Microbial Fuel Cell (OMFC). It has several advantages, including improved performance in electricity generation and drinking water recovery compared to MFC. Making OMFC efficient for treatment and resource recovery, basic concepts of MFC and FO must be properly understood and implemented. Various researchers have focused on its components, degradation of wastewater, electron and proton transport mechanism, designs, the role of draw solution, etc. Recent publications have also shown growth in FO membrane composition and OMFC design. Utilizations of an efficient draw solution for better compatibility of anodic bacteria along with its recovery are also a big challenge. The aim of this review paper is to compile all the scattered information on the above aspects and present it in a more logical way in one place for the easy understanding of researchers. The paper also focuses on encouraging OMFC technology for commercial use by developing cost-effective FO membranes and electrodes, improving bacterial metabolic activity for energy production, and enhancing draw solution and cost-effective draw solution recovery methods. Therefore, OMFC technology seems the ultimate solution for wastewater treatment, electricity generation, and freshwater recovery in the coming future.     

周期性负载变化提高乙醇燃料电池效率(英文)

We present a simple method to increase the efficiency of a direct ethanol fuel cell by a periodic modulation of the load(pulsed mode). The fuel cell was periodically short circuited with a resistor(1 Ω) for a few seconds(high load period) followed by a low load period of up to 100 s when the resistor was disconnected. The open circuit voltage(OCV) values before and after the short circuit of the cell showed an increase of up to 70 mV. The higher OCV was due to the oxidation and removal of strongly adsorbed CO during the electric short circuit when the electric potential of the anode was increased to be close to the cathode potential. The depoisoned anode surface was much more active directly after the short circuit. The slow decrease of the OCV observed after the short circuit was caused by the subsequent poisoning of the anode surface, which can be neutralized by another short circuit. In general, a stable increase in cell performance was obtained by repetition of the electric short circuit. The data showed that the pulse mode gave an increase in the power generated by the direct ethanol fuel cell by up to 51% and was 6% on average. It is anticipated that this mode of operation can be used also in different types of polymer electrolyte membrane fuel cells where CO poisoning is a problem, and after optimization of the parameters, a much higher gain in efficien-cy can be obtained.     

Improving the efficiency of a direct ethanol fuel cell by a periodic load change

We present a simple method to increase the efficiency of a direct ethanol fuel cell by a periodic modulation of the load (pulsed mode). The fuel cell was periodically short circuited with a resistor (1...     

电沉积制备MnO2催化剂及其在微生物燃料电池中的应用

通过电沉积的方法获得了一种具有均匀孔隙结构的海绵状二氧化锰催化剂,结合扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)等手段表征了所制备材料的表面形貌、结构及元素构成和赋存价态,采用线性伏安扫描(LSV)法对电沉积材料的电化学性能进行分析,考察其催化氧还原反应的活性,最后以合成的材料为阴极催化剂,构建微生物燃料电池系统,考察其在微生物燃料电池中的应用效果。结果表明,以电沉积二氧化锰为阴极催化剂的微生物燃料电池最大功率密度为975.6 mW/m~2,是以商业二氧化锰为阴极催化剂的电池的1.7倍;这表明作为一种经济、高效、环境友好的阴极氧还原催化剂,电沉积法制备的二氧化锰为实现阴极催化剂的低成本制备以及微生物燃料电池放大化推进提供了新的研究途径。     

A review on key factors influencing the electrical conductivity of proton exchange membrane fuel cell composite bipolar plates

Fuel cells are gaining increasing importance as a promising alternative to traditional energy sources, primarily due to their exceptional efficiency and environmental advantages. The electrical performance of proton exchange membrane fuel cells (PEMFCs) largely depends on the effectiveness of proton and electron transport within the cell components. A critical factor impacting this efficiency is the electrical conductivity of polymer-based bipolar plates (BPPs), which play a fundamental role as current collectors. BPPs in PEMFCs can be made from various materials including coated metallic materials, graphitic materials, and polymer composites. This review exclusively concentrates on polymer composite BPPs. Enhancing the overall cell performance is achievable through the integration of electrically conductive additives into the polymer matrix of these plates. Graphite (GR), carbon black (CB), carbon fibers (CF), carbon nanotubes (CNT), and graphene (Gr) all emerge as highly promising functional materials capable of substantially elevating BPPs performance. This study, among its various objectives, delves into the synergistic effects of these electrically conductive additives and their capacity to enhance the electrical conductivity within polymeric matrices. Furthermore, this review article thoroughly explores the influence of the polymeric matrix, encompassing co-continuous morphology and processing conditions. In essence, it focuses on the improvement of BPPs electrical conductivity through innovative designs of their polymer-based composites and nanocomposites and the particular selection of the electrically conductive fillers. The insights derived from this study significantly contribute to a more profound understanding of how to effectively harness the potential of this vital PEMFC component.     

Enhanced power production of microbial fuel cells by reducing the oxygen and nitrogen functional groups of carbon cloth anode

The physicochemical properties of anode material are important for the electron transfer of anode bacteria and electricity generation of microbial fuel cells (MFCs). In this work, carbon cloth anode was pretreated with isopropanol, hydrogen peroxide (H₂O₂) and sodium hypochlorite (NaOCl) in order to reduce the anode functional groups. The influence of functional groups on the electrochemical properties of carbon cloth anode and power generation of MFCs was investigated. The anode pretreatments removed the surface sizing layer of carbon cloth and substantially reduced the contents of C‐O and pyridinic/pyrrolic N groups on the anode. Electrochemical impedance spectroscopy and cyclic voltammetry analyses of the biofilm‐matured anodes revealed an enhanced electrochemical electron transfer property because of the anode pretreatments. As compared with the untreated control (612 ± 6 mW m^?2), the maximum power density of an acetate‐fed single‐chamber MFC was increased by 26% (773 ± 5 mW m^?2) with the isopropanol treated anode. Additional treatment with H₂O₂ and NaOCl further increased the maximum power output to 844 ± 5 mW m^?2 and 831 ± 4 mWm^?2. A nearly inverse liner relationship was observed between the contents of C‐O and pyridinic/pyrrolic N groups on anodes and the anodic exchange current density and the power output of MFCs, indicating an adverse effect of these functional groups on the electricity production of anodes. Results from this study will further our understanding on the microbial interaction with carbon‐based electrodes and provide an important guidance for the modification of anode materials for MFCs in future studies. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of sludge retention time on membrane fouling and microbial community structure in a membrane bioreactor

In this study, the effect of sludge retention time (SRT) on membrane bio-fouling was investigated in a membrane bioreactor (MBR) equipped with a sequential anoxic/anaerobic reactor. Specific cake resistance (α), trans-membrane pressure (TMP), mixed liquor suspended solids (MLSS), particle sizes, extracellular polymer substances bound in sludge (bound-EPS) and their correlations with membrane bio-fouling were studied at different SRTs. As SRT decreased to 20 days, the bound-EPS per unit of biomass increased, and consequently, the value of α increased, which resulted in the rise of TMP. However, the reduction of the bound-EPS content was relatively small as compared to a significant decrease in the value of α at longer SRTs (above 60 days). These observations suggest that colloidal particles significantly contribute to membrane bio-fouling. In addition, the diversity of the microbial community structure of activated sludge in the MBRs was observed using the respiratory quinone profile. The ubiquinone species containing UQ-8, belonging to the class β-Proteobacteria type were the major constituents of the microbial community structure. The mole fraction of menaquinone MK-6, -7 and -8(H2) increased as SRT increased. Thus, the results of this study indicate that growth of microorganisms belonging to the δ- and ?-subclass of Proteobacteria as well as the members of the Cytophaga–Flavobacterium cluster increased at longer SRTs.