Comparative metabolic state of microflora on the surface of the anode electrode in a microbial fuel cell operated at different pH conditions (original) (raw)
Related papers
2013
The number of investigation of alternative energy sources to fossil fuel is a testimony of the global awareness of the risk of air pollution. The microbial fuel cells (MFC) system contributes to the approach of green and cheap energy. The system operates with microorganisms responsible of the degradation of organic matters for production of electron and protons require in the generation of electricity. The performance of the MFC is mainly dependent on the nature of the microorganisms present and their ability to actively use the nutrients. In this study the determination of the strain composition of the microbial community in the MFC was mainly done using gene sequencing and the level of intermediate metabolites was simultaneously assessed to both monitor microbial activities and the effect of these metabolites on their growth. Several strains of microorganisms (46 in total) were identified in the anode compartment with potential of carbohydrate oxidation and electron transfer. The ...
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).
Chemosphere, 2018
The performance of miniaturized microbial fuel cells operating with five different substrates (acetate, lactate, glucose and octanoate) were studied with the aim to identify the reason for its different performance. In all cases, the COD removal rate was about 650 mg COD L d. However, the bio-electrochemical performance of the MFC was very different, showing the MFC fed with acetate the best performance: 20 A m as maximum current density, 2 W m of maximum power density, 0.376 V of OCV and 12.6% of CE. In addition, the acetate showed the best bio-electrochemical performance in the polarization curves and cyclic voltammetries. These polarization curves were modelled and the key to explain the better electrical performance of acetate was its lower ohmic losses. When working with acetate, its ohmic losses were one log-unit below those attained by the other substrates. These lower ohmic losses were not associated to the electrolyte conductivity of the fuel but to the lower ohmic loses of...
Multifactorial evaluation of the electrochemical response of a microbial fuel cell
RSC Advances, 2014
A lab-scale microbial fuel cell (MFC) with a reticulated vitreous carbon (RVC) anode and a non-catalyzed multi-layered carbon air-cathode was electrochemically characterized under various physicochemical factors: temperature (15-25 C), phosphate buffer concentration (4-8 mM), acetate concentration 7.1-14.3 mM), and equivalent solution conductivity (2.5-5 mS cm À1 ). A fundamental step was undertaken to identify and characterize the electrochemical mechanisms through multifactorial evaluation of the simultaneous effect of such factors on the functioning of the MFC. This type of analysis of cyclic voltammetry and impedance spectroscopy parameters revealed complementary features to model the electrochemical response. This multifactorial approach finds broad application in a wide variety of MFC and environmental technology studies.
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.
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
Applied Microbiology and Biotechnology, 2011
We report the electrochemical characterization and microbial community analysis of closed circuit microbial fuel cells (CC-MFCs) and open circuit (OC) cells continuously fed with propionate as substrate. Differences in power output between MFCs correlated with their polarization behavior, which is related to the maturation of the anodophilic communities. The microbial communities residing in the biofilm growing on the electrode, biofouled cation-exchange membrane and anodic chamber liquor of OC-and CC-MFCs were characterized by restriction fragment length polymorphism screening of 16S rRNA gene clone libraries. The results show that the CC-MFC anode was enriched in several microorganisms related to known electrochemically active and dissimilatory Fe(III) reducing bacteria, mostly from the Geobacter spp., to the detriment of Bacteroidetes abundant in the OC-MFC anode. The results also evidenced the lack of a specific pelagic community in the liquor sample. The biofilm growing on the cation-exchange membrane of the CC-MFC was found to be composed of a low-diversity community dominated by two microaerophilic species of the Achromobacter and Azovibrio genus.
Bioresource Technology, 2009
Four microbial fuel cells (MFCs) were inoculated with anaerobic sludge and fed four different substrates for over one year. The Coulombic efficiency (CE) and power output varied with different substrates, while the bacterial viability was similar. Acetate-fed-MFC showed the highest CE (72.3%), followed by butyrate (43.0%), propionate (36.0%) and glucose (15.0%). Glucose resulted in the lowest CE because of its fermentable nature implying its consumption by diverse non-electricity-generating bacteria. 16S rDNA sequencing results indicated phylogenetic diversity in the communities of all anode biofilms, and there was no single dominant bacterial species. A relative abundance of b-Proteobacteria but an absence of c-Proteobacteria was observed in all MFCs except for propionate-fed system in which Firmicutes dominating. The glucose-fed-MFC showed the widest community diversity, resulting in the rapid generation of current without lag time when different substrates were suddenly fed. Geobacter-like species with the most representative Geobacter sulfurreducens PCA T were integral members of the bacterial community in all MFCs except for the propionate-fed system.