Front Cover: How Comparable are Microbial Electrochemical Systems around the Globe? An Electrochemical and Microbiological Cross‐Laboratory Study (ChemSusChem 11/2021) (original) (raw)
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Applied Biochemistry and Biotechnology, 2010
This objective of this study is to conduct a systematic investigation of the effects of configurations, electrolyte solutions, and electrode materials on the performance of microbial fuel cells (MFC). A comparison of voltage generation, power density, and acclimation period of electrogenic bacteria was performed for a variety of MFCs. In terms of MFC configuration, membrane-less two-chamber MFCs (ML-2CMFC) had lower internal resistance, shorter acclimation period, and higher voltage generation than the conventional two-chamber MFCs (2CMFC). In terms of anode solutions (as electron donors), the two-chamber MFCs fed with anaerobic treated wastewater (AF-2CMFCs) had the power density 19 times as the two-chamber MFCs fed with acetate (NO3−2CMFCs). In terms of cathode solutions (as electron acceptors), AF-2CMFCs with ferricyanide had higher voltage generation than that of ML-2CMFCs with nitrate (NO3−ML-2CMFCs). In terms of electrode materials, ML-2CMFCs with granular-activated carbon as the electrode (GAC-ML-2CMFCs) had a power density 2.5 times as ML-2CMFCs with carbon cloth as the electrode. GAC-ML-2CMFCs had the highest columbic efficiency and power output among all the MFCs tested, indicating that the high surface area of GAC facilitate the biofilm formation, accelerate the degradation of organic substrates, and improve power generation.
Characterization of Microbial Fuel Cells at Microbially and Electrochemically Meaningful Time scales
2011
The variable biocatalyst density in a microbial fuel cell (MFC) anode biofilm is a unique feature of MFCs relative to other electrochemical systems, yet performance characterizations of MFCs typically involve analyses at electrochemically relevant time scales that are insufficient to account for these variable biocatalyst effects. This study investigated the electrochemical performance and the development of anode biofilm architecture under different external loadings, with duplicate acetate-fed singlechamber MFCs stabilized at each resistance for microbially relevant time scales. Power density curves from these steady-state reactors generally showed comparable profiles despite the fact that anode biofilm architectures and communities varied considerably, showing that steady-state biofilm differences had little influence on electrochemical performance until the steady-state external loading was much larger than the reactor internal resistance. Filamentous bacteria were dominant on the anodes under high external resistances (1000 and 5000 Ω), while more diverse rod-shaped cells formed dense biofilms under lower resistances (10, 50, and 265 Ω). Anode charge transfer resistance decreased with decreasing fixed external resistances, but was consistently 2 orders of magnitude higher than the resistance at the cathode. Cell counting showed an inverse exponential correlation between cell numbers and external resistances. This direct link of MFC anode biofilm evolution with external resistance and electricity production offers several operational strategies for system optimization.
Revista de Ciencias, 2019
A dual-chambered microbial fuel cell with aqueous cathode was operated with domestic wastewater to investigate the electrogenic ability of anaerobic bacteria from a municipal wastewater treatment plant. Curves of cell potential vs. current density, power density vs. current density and current at a fixed load of 100 Ω, were obtained daily to monitor the electrochemical evolution of the system as a function of substrate use in several batch cycles. A maximum power density of 1.11 µWcm-2 was obtained after 65 days of continuous operation and a coulombic efficiency of 7% and a chemical oxygen demand removal of 76% were found in the last batch cycle. Anaerobic culture of the bacteria from the anode biofilm resulted in the isolation of two Gram-positive and two Gram-negative bacteria with divergent sugar fermentation capabilities, while analysis of 16S rRNA gene fragments showed three clones from the phyla Firmicutes, δ-Proteobacteria and α-Proteobacteria. Scanning electron imaging analy...
Journal of Water Process Engineering, 2020
This study investigated the microbial community structure on the anode surface of four dual chamber bioelectrochemical systems. These systems were Microbial Fuel Cell (MFC) and Microbial Electrolysis Cell (MEC). The systems were inoculated with activated sludge and operated for electricity generation/hydrogen (H 2) production, and phosphorus (P) recovery. The MFC achieved a maximum power output of 185 mW/m 2 (1.62 kW h/m 2), whilst the MEC achieved a maximum H 2 production rate of 0.28 m 3-H 2 /m 3-d. Results from Illumina highthroughput sequencing of 16S rRNA genes showed that the microbial community structure of the MFCs was more diverse than that of the MECs, and this variation may be attributed to the differences in the operational conditions of the MFC and the MEC. MFC and MEC shared the same dominant bacterial phyla; Bacteroidetes, Proteobacteria and Firmicutes, with the most abundant bacterial genus in both systems belonging to Desulfovibrio. However, the abundance of Desulfovibrio in the MECs (13.2 ± 0.7 %) was greater than that in the MFCs (4.25 ± 0.2 %).
In-Situ Electrochemical Behaviour of Biocathode Microbial Fuel Cell (MFC)
2020
In the present work the electrochemical behaviour of microbial cells from a biocathode microbial fuel cell (MFC) functioning with wastewater was evaluated by cyclic voltammetry. In-situ electrochemical assays were performed and, under the tested experimental conditions, the biocathode medium was found to be the most e cient for the cathodic catalysed electrochemical reduction of oxygen. Different controls using sterile media and membranes covering the electrodes were performed and compared with the regular biocathode results. In the biocathode chamber, the presence of bacteria was associated with the enhanced active redox processes and with the higher electrochemical reduction of oxygen activity. The present study is a contribution to the understanding of the viability and advantages of the biocathodes use in MFC.
Nigerian Journal of Engineering Science and Technology Research, 2024
Microbial Fuel Cells (MFCs) offer a sustainable method for generating electricity from waste materials while treating wastewater. However, their efficiency is influenced by various operational parameters. This study addresses the problem of optimizing MFC performance by investigating the effects of external resistance and substrate pH on voltage, current, power, power density, and current density in dual-chamber MFCs using abattoir wastewater. The aim is to identify optimal conditions for maximizing power output and stabilizing microbial growth. The methodology involves operating MFCs under batch anaerobic conditions for 15 days, with experiments conducted at varying external resistances (10Ω, 100Ω, 200Ω,470Ω, 1000Ω) and initial pH values (6, 7, 8, and 9). Results demonstrate that a high-power output of 21.1mW·m^-2 was achieved at pH 9 with the highest bacterial count of 7.9×10^7 CFU/ml, indicating significant microbial activity and a voltage of 350 mV over a 1000 Ω resistor. The study recommends adjusting initial substrate pH to stabilize MFC performance by controlling microbial activity and reducing methanogenesis. These findings highlight the importance of optimizing external resistance and pH to enhance the efficiency of MFCs for practical applications in renewable energy generation and environmental remediation.
Evaluation of hydrolysis and fermentation rates in microbial fuel cells
Applied Microbiology and Biotechnology, 2011
This study determined the influence of substrate degradation on power generation in microbial fuel cells (MFCs) and microbial community selection on the anode. Air cathode MFCs were fed synthetic medium containing different substrates (acetate, glucose and starch) using primary clarifier sewage as source of electroactive bacteria. The complexity of the substrate affected the MFC performance both for power generation and COD removal. Power output decreased with an increase in substrate complexity from 99±2 mW m −2 for acetate to 4±2 mW m −2 for starch. The organic matter removal and coulombic efficiency (CE) of MFCs with acetate and glucose (82% of COD removal and 26% CE) were greater than MFCs using starch (60% of COD removal and 19% of CE). The combined hydrolysisfermentation rate obtained (0.0024 h −1 ) was considerably lower than the fermentation rate (0.018 h −1 ), indicating that hydrolysis of complex compounds limits current output over fermentation. Statistical analysis of microbial community fingerprints, developed on the anode, showed that microbial communities were enriched according to the type of substrate used. Microbial communities producing high power outputs (fed acetate) clustered separately from bacterial communities producing low power outputs (fed complex compounds).
Factors affecting current production in microbial fuel cells using different industrial wastewaters
Bioresource Technology, 2011
This study evaluated how different types of industrial wastewaters (bakery, brewery, paper and dairy) affect the performance of identical microbial fuel cells (MFCs); and the microbial composition and electrochemistry of MFC anodes. MFCs fed with paper wastewater produced the highest current density (125 ± 2 mA/m 2 ) at least five times higher than dairy (25 ± 1 mA/m 2 ), brewery and bakery wastewaters (10 ± 1 mA/m 2 ). Such high current production was independent of substrate degradability. A comprehensive study was conducted to determine the factor driving current production when using the paper effluent. The microbial composition of anodic biofilms differed according to the type of wastewater used, and only MFC anodes fed with paper wastewater showed redox activity at À134 ± 5 mV vs NHE. Electrochemical analysis of this redox activity indicated that anodic bacteria produced a putative electron shuttling compound that increased the electron transfer rate through diffusion, and as a result the overall MFC performance.
Editorial In Focus: Microbial Fuel Cells, some considerations
Journal of Chemical Technology and Biotechnology, 2019
The discovery by M.C. Potter in 1911 that some bacteria can generate electricity in devices called microbial fuel cells (MFCs) opened up a new opportunity in exploitation of microbes' potential; but limited interest was shown for some time. However, since 1980's research in this area has intensified. MFCs work on the principle that electricigens can oxidise substrates in an anode chamber releasing electrons and protons. The electrons go through an external circuit to a cathode chamber, while protons travel from the anode to the cathode through a membrane that separates the two chambers. Recombination of electrons and protons in the cathodic chamber completes the circuit in presence of an oxidant, typically oxygen. MFCs have promise in a number of areas including bioremediation, electricity production, biosensing and water desalination. To enhance feasibility of MFC technology in biotechnology sectors, a number of challenges need to be overcome. These include selection/design of efficient microbes, electrodes, membranes and chambers; better understanding of the mechanism and improving the process of electron transfer from the microorganisms to the electrodes; integration of MFCs in the wastewater treatment train; extending potential of MFCs from applications in bioremediation to bioproduction; and cost-effective scale-up of the reactors. This 'In-focus' section of the Journal of Chemical Technology and Biotechnology (JCTB) covers a total of six manuscripts (two review papers 1,6 and four original research articles 2-4) in microbial fuel cells reporting recent developments in MFC technology. Alleviating the accumulation of xenobiotics in the environment, has been subject to extensive research. However, the use of bioelectrochemical systems (BES) in remediation is a relatively new endeavour. Fernando et al. 1 report in a comprehensive review, the history of electromicrobiology, contaminants treated by MFC, and types of BES used, addressing BES advantages. The review concludes that BES is promising for both in situ and ex situ environmental remediation applications in a sustainable manner. Gomaa et al. 2 address the mechanism of concomitant degradation of the dye Congo red and bioelectricity generation using a recombinant strain of E. coli. Their work shows that although there seems to exist a link between dye decolourisation and COD values in their reactor, the efficiency of the system for generation of electricity is low. This highlights the importance of appropriately engineered efficient strains for multiple desired outputs. In another study investigating multifunctional