1
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Klein E, Wurst R, Rehnlund D, Gescher J. Elucidating the development of cooperative anode-biofilm-structures. Biofilm 2024; 7:100193. [PMID: 38601817 PMCID: PMC11004076 DOI: 10.1016/j.bioflm.2024.100193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 03/13/2024] [Accepted: 03/21/2024] [Indexed: 04/12/2024] Open
Abstract
Microbial electrochemical systems are a highly versatile platform technology with a particular focus on the interplay of chemical and electrical energy conversion and offer immense potential for a sustainable bioeconomy. The industrial realization of this potential requires a critical focus on biofilm optimization if performance is to be controlled over a long period of time. Moreover, the aspect and influence of cooperativity has to be addressed as many applied anodic bioelectrochemical systems will most likely be operated with a diversity of interacting microbial species. Hence, the aim of this study was to analyze how interspecies dependence and cooperativity of a model community influence the development of anodic biofilms. To investigate biofilm activity in a spatially resolved manner, a microfluidic bioelectrochemical flow cell was developed that can be equipped with user-defined electrode materials and operates under laminar flow conditions. With this infrastructure, the development of single and co-culture biofilms of the two model organisms Shewanella oneidensis and Geobacter sulfurreducens on graphite electrodes was monitored by optical coherence tomography analysis. The interdependence in the co-culture biofilm was achieved by feeding the community with lactate, which is converted by S. oneidensis into acetate, which in turn serves as substrate for G. sulfurreducens. The results show that co-cultivation resulted in the formation of denser biofilms than in single culture. Moreover, we hypothesize that S. oneidensis in return utilizes the conductive biofilm matrix build by G. sulfurreducens for direct interspecies electron transfer (DIET) to the anode. FISH analysis revealed that the biofilms consisted of approximately two-thirds G. sulfurreducens cells, which most likely formed a conductive 3D network throughout the biofilm matrix, in which evenly distributed tubular S. oneidensis colonies were embedded without direct contact to the anode surface. Live/dead staining shows that the outermost biofilm contained almost exclusively dead cells (98 %), layers near the anode contained 45-56 % and the entire biofilm contained 82 % live cells. Our results exemplify how the architecture of the exoelectrogenic biofilm dynamically adapts to the respective process conditions.
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Affiliation(s)
- Edina Klein
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
| | - René Wurst
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
| | - David Rehnlund
- Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, SE-751 21, Uppsala, Sweden
| | - Johannes Gescher
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
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2
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Häuser L, Erben J, Pillot G, Kerzenmacher S, Dreher W, Küstermann E. In vivo characterization of electroactive biofilms inside porous electrodes with MR Imaging. RSC Adv 2022; 12:17784-17793. [PMID: 35765339 PMCID: PMC9199086 DOI: 10.1039/d2ra01162j] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/30/2022] [Indexed: 12/03/2022] Open
Abstract
Identifying the limiting processes of electroactive biofilms is key to improve the performance of bioelectrochemical systems (BES). For modelling and developing BES, spatial information of transport phenomena and biofilm distribution are required and can be determined by Magnetic Resonance Imaging (MRI) in vivo, in situ and in operando even inside opaque porous electrodes. A custom bioelectrochemical cell was designed that allows MRI measurements with a spatial resolution of 50 μm inside a 500 μm thick porous carbon electrode. The MRI data showed that only a fraction of the electrode pore space is colonized by the Shewanella oneidensis MR-1 biofilm. The maximum biofilm density was observed inside the porous electrode close to the electrode-medium interface. Inside the biofilm, mass transport by diffusion is lowered down to 45% compared to the bulk growth medium. The presented data and the methods can be used for detailed models of bioelectrochemical systems and for the design of improved electrode structures. The use of magnetic resonance imaging can contribute to a better understanding of limiting processes occurring in electroactive biofilms especially inside opaque porous electrodes.![]()
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Affiliation(s)
- Luca Häuser
- Center for Environmental Research and Sustainable Technology (UFT), University of Bremen 28359 Bremen Germany
| | | | - Guillaume Pillot
- Center for Environmental Research and Sustainable Technology (UFT), University of Bremen 28359 Bremen Germany
| | - Sven Kerzenmacher
- Center for Environmental Research and Sustainable Technology (UFT), University of Bremen 28359 Bremen Germany
| | - Wolfgang Dreher
- In-vivo-MR Group, Faculty 02 (Biology/Chemistry), University of Bremen 28359 Bremen Germany
| | - Ekkehard Küstermann
- In-vivo-MR Group, Faculty 02 (Biology/Chemistry), University of Bremen 28359 Bremen Germany
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3
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Yin F, Yang X, Zheng L, Fang L, Wang S, Liu H. Acid‐base transport model depicting the dynamic
pH
response of interfacial reactions. AIChE J 2022. [DOI: 10.1002/aic.17669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Fengjun Yin
- Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing China
- Key Laboratory of Reservoir Aquatic Environment Chinese Academy of Sciences Chongqing China
- University of Chinese Academy of Sciences Beijing China
| | - Xiaohui Yang
- Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing China
- Key Laboratory of Reservoir Aquatic Environment Chinese Academy of Sciences Chongqing China
| | - Lei Zheng
- Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing China
- Key Laboratory of Reservoir Aquatic Environment Chinese Academy of Sciences Chongqing China
| | - Ling Fang
- Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing China
- Key Laboratory of Reservoir Aquatic Environment Chinese Academy of Sciences Chongqing China
| | - Sha Wang
- Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing China
- Key Laboratory of Reservoir Aquatic Environment Chinese Academy of Sciences Chongqing China
| | - Hong Liu
- Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing China
- Key Laboratory of Reservoir Aquatic Environment Chinese Academy of Sciences Chongqing China
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4
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Li X, Lu Y, Luo H, Liu G, Torres CI, Zhang R. Effect of pH on bacterial distributions within cathodic biofilm of the microbial fuel cell with maltodextrin as the substrate. CHEMOSPHERE 2021; 265:129088. [PMID: 33280848 DOI: 10.1016/j.chemosphere.2020.129088] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 11/09/2020] [Accepted: 11/20/2020] [Indexed: 06/12/2023]
Abstract
The aim of this study was to investigate pH effect on stratification of bacterial community in cathodic biofilm of the microbial fuel cell (MFC) under alkaline conditions. A single-chamber MFC with air-cathode was operated with 0.8 g/L maltodextrin and bicarbonate buffer solutions under pH values of 8.5, 9.5, and 10.5, respectively. The cathodic biofilms were characterized by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), confocal laser scanning microscopy (CLSM), freezing microtome and high-throughput sequencing analysis on bacterial communities, respectively. Results showed that the maximum power densities in the MFC increased with the pH values and reached 1221 ± 96 mW/m2 at pH = 10.5 during ∼30 d of operation. With different pH values, the composition and relative abundance of bacterial community significantly changed in the bottom (0-50 μm), middle (50-100 μm), and top (100-150 μm) layers of the cathodic biofilm. With pH = 10.5, aerobic bacteria accounted for 12%, 13%, and 34% of the bacterial community in the top, middle, and bottom layers, respectively. The amount of anaerobic bacteria in the top and middle layers (i.e., 52%, and 50% of the bacterial community, respectively) was higher than that in the bottom layer (22%). The distribution of aerobic and anaerobic bacteria showed a "valley-peak" structure within the layers. The high CO32- concentration facilitates the hydroxyl transfer and the neutralization in the anode of the MFC under high alkali conditions. The results from this study should be useful to develop new catalyst and cathode in the MFC.
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Affiliation(s)
- Xiao Li
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China
| | - Yaobin Lu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China
| | - Haiping Luo
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China
| | - Guangli Liu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China.
| | - César I Torres
- School for Engineering of Matter, Transport and Energy, Chemical Engineering Program, Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, 85287-5701, USA
| | - Renduo Zhang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China
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5
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Cario BP, Rossi R, Kim KY, Logan BE. Applying the electrode potential slope method as a tool to quantitatively evaluate the performance of individual microbial electrolysis cell components. BIORESOURCE TECHNOLOGY 2019; 287:121418. [PMID: 31078815 DOI: 10.1016/j.biortech.2019.121418] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/01/2019] [Accepted: 05/02/2019] [Indexed: 06/09/2023]
Abstract
Improving the design of microbial electrolysis cells (MECs) requires better identification of the specific factors that limit performance. The contributions of the electrodes, solution, and membrane to internal resistance were quantified here using the newly-developed electrode potential slope (EPS) method. The largest portion of total internal resistance (120 ± 0 mΩ m2) was associated with the carbon felt anode (71 ± 5 mΩ m2, 59% of total), likely due to substrate and ion mass transfer limitations arising from stagnant fluid conditions and placement of the electrode against the anion exchange membrane. The anode resistance was followed by the solution (25 mΩ m2) and cathode (18 ± 2 mΩ m2) resistances, and a negligible membrane resistance. Wide adoption and application of the EPS method will enable direct comparison between the performance of the components of MECs with different solution characteristics, electrode size and spacing, reactor architecture, and operating conditions.
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Affiliation(s)
- Benjamin P Cario
- Department of Civil and Environmental Engineering, The Pennsylvania State University, 231Q Sackett Building, University Park, PA 16802, USA
| | - Ruggero Rossi
- Department of Civil and Environmental Engineering, The Pennsylvania State University, 231Q Sackett Building, University Park, PA 16802, USA
| | - Kyoung-Yeol Kim
- Department of Environmental and Sustainable Engineering, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Bruce E Logan
- Department of Civil and Environmental Engineering, The Pennsylvania State University, 231Q Sackett Building, University Park, PA 16802, USA.
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6
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Rittmann BE. Biofilms, active substrata, and me. WATER RESEARCH 2018; 132:135-145. [PMID: 29324293 DOI: 10.1016/j.watres.2017.12.043] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/18/2017] [Accepted: 12/19/2017] [Indexed: 06/07/2023]
Abstract
Having worked with biofilms since the 1970s, I know that they are ubiquitous in nature, of great value in water technology, and scientifically fascinating. Biofilms are naturally able to remove BOD, transform N, generate methane, and biodegrade micropollutants. What I also discovered is that biofilms can do a lot more for us in terms of providing environmental services if we give them a bit of help. Here, I explore how we can use active substrata to enable our biofilm partners to provide particularly challenging environmental services. In particular, I delve into three examples in which an active substratum makes it possible for a biofilm to accomplish a task that otherwise seems impossible. The first example is the delivery of hydrogen gas (H2) as an electron donor to drive the reduction and detoxification of the rising number of oxidized contaminant: e.g., perchlorate, selenate, chromate, chlorinated solvents, and more. The active substratum is a gas-transfer membrane that delivers H2 directly to the biofilm in a membrane biofilm reactor (MBfR), which makes it possible to deliver a low-solubility gaseous substrate with 100% efficiency. The second example is the biofilm anode of a microbial electrochemical cell (MxC). Here, the anode is the electron acceptor for anode-respiring bacteria, which "liberate" electrons from organic compounds and send them ultimately to a cathode, where we can harvest valuable products or services. The anode's potential is a sensitive tool for managing the microbial ecology and reaction kinetics of the biofilm anode. The third example is intimately coupled photobiocatalysis (ICPB), in which we use photocatalysis to enable the biodegradation of intrinsically recalcitrant organic pollutants. Photocatalysis transforms the recalcitrant organics just enough so that the products are rapidly biodegradable substrates for bacteria in a nearby biofilm. The macroporous substratum, which houses the photocatalyst on its exterior, actively provides donor substrate and protects the biofilm from UV light and free radicals in its interior. These three well-developed topics illustrate how and why an active substratum expands the scope of what biofilms can do to enhance water sustainability.
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Affiliation(s)
- Bruce E Rittmann
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ 85287-5701, USA.
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7
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Dhar BR, Sim J, Ryu H, Ren H, Santo Domingo JW, Chae J, Lee HS. Microbial activity influences electrical conductivity of biofilm anode. WATER RESEARCH 2017; 127:230-238. [PMID: 29055828 PMCID: PMC7321815 DOI: 10.1016/j.watres.2017.10.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 10/11/2017] [Accepted: 10/12/2017] [Indexed: 05/14/2023]
Abstract
This study assessed the conductivity of a Geobacter-enriched biofilm anode in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH gradient across the biofilm anode at 100 mM phosphate buffer (current density 2.38 A/m2) and biofilm conductivity (Kbio) was as high as 0.87 mS/cm. In comparison, an inner biofilm became acidic at 2.5 mM phosphate buffer in which dead cells were accumulated at ∼80 μm of the inner biofilm anode. At this low phosphate buffer, Kbio significantly decreased by 0.27 mS/cm, together with declined current density of 0.64 A/m2. This work demonstrates that biofilm conductivity depends on the composition of live and dead cells in the conductive biofilm anode.
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Affiliation(s)
- Bipro Ranjan Dhar
- Civil and Environmental Engineering, University of Alberta, 9211-116 Street NW, Edmonton, Alberta, T6G 1H9, Canada; Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
| | - Junyoung Sim
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
| | - Hodon Ryu
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Hao Ren
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA.
| | - Jorge W Santo Domingo
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Junseok Chae
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA.
| | - Hyung-Sool Lee
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
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8
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Hou J, Liu Z, Zhou Y, Chen W, Li Y, Sang L. An experimental study of pH distributions within an electricity-producing biofilm by using pH microelectrode. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.08.101] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Engineering of Microbial Electrodes. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2017; 167:135-180. [PMID: 28864879 DOI: 10.1007/10_2017_16] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This chapter provides an overview of the current state-of-the-art in the engineering of microbial electrodes for application in microbial electrosynthesis. First, important functional aspects and requirements of basic materials for microbial electrodes are introduced, including the meaningful benchmarking of electrode performance, a comparison of electrode materials, and methods to improve microbe-electrode interaction. Suitable current collectors and composite materials that combine different functionalities are also discussed. Subsequently, the chapter focuses on the design of macroscopic electrode structures. Aspects such as mass transfer and electrode topology are touched upon, and a comparison of the performance of microbial electrodes relevant for practical application is provided. The chapter closes with an overall conclusion and outlook, highlighting the future prospects and challenges for the engineering of microbial electrodes toward practical application in the field of microbial electrosynthesis. Graphical Abstract.
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10
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Popat SC, Torres CI. Critical transport rates that limit the performance of microbial electrochemistry technologies. BIORESOURCE TECHNOLOGY 2016; 215:265-273. [PMID: 27211921 DOI: 10.1016/j.biortech.2016.04.136] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 04/26/2016] [Accepted: 04/29/2016] [Indexed: 05/21/2023]
Abstract
Microbial electrochemistry technologies (METs) take advantage of the connection of microorganisms with electrodes. In the classic case of a microbial anode, the maximization of current density produced is often the goal. But, current production is dependent on many transport processes occurring, which can be rate-limiting. These include the fluxes of electron donor and acceptor, the ionic flux, the acidity and alkalinity fluxes at anode and cathode respectively, the electron transport flux at the biofilm, and the reactant/product crossover flux. Associated with these fluxes are inherent concentration gradients that can affect performance. This critical review provides an analysis on how these transport processes have hindered the development of METs, and how MET designs have evolved as more knowledge of these transport limitations is gained. Finally, suggestions are provided on how to design MET systems taking into consideration critical transport processes that are intimately linked to the current produced.
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Affiliation(s)
- Sudeep C Popat
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - César I Torres
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA.
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11
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Ye Y, Zhu X, Logan BE. Effect of buffer charge on performance of air-cathodes used in microbial fuel cells. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.02.095] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Kretzschmar J, Rosa LFM, Zosel J, Mertig M, Liebetrau J, Harnisch F. A Microbial Biosensor Platform for Inline Quantification of Acetate in Anaerobic Digestion: Potential and Challenges. Chem Eng Technol 2016. [DOI: 10.1002/ceat.201500406] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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13
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Watson VJ, Hatzell M, Logan BE. Hydrogen production from continuous flow, microbial reverse-electrodialysis electrolysis cells treating fermentation wastewater. BIORESOURCE TECHNOLOGY 2015; 195:51-56. [PMID: 26051523 DOI: 10.1016/j.biortech.2015.05.088] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 05/23/2015] [Accepted: 05/25/2015] [Indexed: 06/04/2023]
Abstract
A microbial reverse-electrodialysis electrolysis cell (MREC) was used to produce hydrogen gas from fermentation wastewater without the need for additional electrical energy. Increasing the number of cell pairs in the reverse electrodialysis stack from 5 to 10 doubled the maximum current produced from 60 A/m(3) to 120 A/m(3) using acetate. However, more rapid COD removal required a decrease in the anolyte hydraulic retention time (HRT) from 24 to 12 h to stabilize anode potentials. Hydrogen production using a fermentation wastewater (10 cell pairs, HRT=8 h) reached 0.9±0.1 L H2/Lreactor/d (1.1±0.1 L H2/g-COD), with 58±5% COD removal and a coulombic efficiency of 74±5%. These results demonstrated that consistent rates of hydrogen gas production could be achieved using an MREC if effluent anolyte COD concentrations are sufficient to produce stable anode potentials.
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Affiliation(s)
- Valerie J Watson
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Marta Hatzell
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA; George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Bruce E Logan
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA.
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14
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Ping Q, Zhang C, Chen X, Zhang B, Huang Z, He Z. Mathematical model of dynamic behavior of microbial desalination cells for simultaneous wastewater treatment and water desalination. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:13010-9. [PMID: 25316438 DOI: 10.1021/es504089x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Microbial desalination cells (MDCs) are an emerging concept for simultaneous wastewater treatment and water desalination. This work presents a mathematical model to simulate dynamic behavior of MDCs for the first time through evaluating multiple factors such as organic supply, salt loading, and current generation. Ordinary differential equations were applied to describe the substrate as well as bacterial concentrations in the anode compartment. Local sensitivity analysis was employed to select model parameters that needed to be re-estimated from the previous studies. This model was validated by experimental data from both a bench- and a large-scale MDC system. It could fit current generation fairly well and simulate the change of salt concentration. It was able to predict the response of the MDC with time under various conditions, and also provide information for analyzing the effects of different operating conditions. Furthermore, optimal operating conditions for the MDC used in this study were estimated to have an acetate flow rate of 0.8 mL·min(-1), influent salt concentration of 15 g·L(-1) and salt solution flow rate of 0.04 mL·min(-1), and to be operated with an external resistor less than 30 Ω. The MDC model will be helpful with determining operational parameters to achieve optimal desalination in MDCs.
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Affiliation(s)
- Qingyun Ping
- Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University , Blacksburg, Virginia 24061, United States
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15
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Strycharz-Glaven SM, Roy J, Boyd D, Snider R, Erickson JS, Tender LM. Electron Transport through Early Exponential-Phase Anode-GrownGeobacter sulfurreducensBiofilms. ChemElectroChem 2014. [DOI: 10.1002/celc.201402168] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Popat SC, Ki D, Young MN, Rittmann BE, Torres CI. Buffer pKaand Transport Govern the Concentration Overpotential in Electrochemical Oxygen Reduction at Neutral pH. ChemElectroChem 2014. [DOI: 10.1002/celc.201402058] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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17
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Merkey BV, Chopp DL. Modeling the Impact of Interspecies Competition on Performance of a Microbial Fuel Cell. Bull Math Biol 2014; 76:1429-53. [DOI: 10.1007/s11538-014-9968-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 04/16/2014] [Indexed: 10/25/2022]
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18
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Torres CI. On the importance of identifying, characterizing, and predicting fundamental phenomena towards microbial electrochemistry applications. Curr Opin Biotechnol 2014; 27:107-14. [PMID: 24441074 DOI: 10.1016/j.copbio.2013.12.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/04/2013] [Accepted: 12/16/2013] [Indexed: 11/18/2022]
Abstract
The development of microbial electrochemistry research toward technological applications has increased significantly in the past years, leading to many process configurations. This short review focuses on the need to identify and characterize the fundamental phenomena that control the performance of microbial electrochemical cells (MXCs). Specifically, it discusses the importance of recent efforts to discover and characterize novel microorganisms for MXC applications, as well as recent developments to understand transport limitations in MXCs. As we increase our understanding of how MXCs operate, it is imperative to continue modeling efforts in order to effectively predict their performance, design efficient MXC technologies, and implement them commercially. Thus, the success of MXC technologies largely depends on the path of identifying, understanding, and predicting fundamental phenomena that determine MXC performance.
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Affiliation(s)
- César Iván Torres
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, 1001 S McAllister Avenue, Tempe, AZ 85287-5701, USA; School for Engineering of Matter Transport and Energy, Arizona State University, 501 E. Tyler Mall ECG 301, Tempe, AZ 85287, USA.
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19
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Renslow R, Babauta J, Kuprat A, Schenk J, Ivory C, Fredrickson J, Beyenal H. Modeling biofilms with dual extracellular electron transfer mechanisms. Phys Chem Chem Phys 2013; 15:19262-83. [PMID: 24113651 PMCID: PMC3868370 DOI: 10.1039/c3cp53759e] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electrochemically active biofilms have a unique form of respiration in which they utilize solid external materials as terminal electron acceptors for their metabolism. Currently, two primary mechanisms have been identified for long-range extracellular electron transfer (EET): a diffusion- and a conduction-based mechanism. Evidence in the literature suggests that some biofilms, particularly Shewanella oneidensis, produce the requisite components for both mechanisms. In this study, a generic model is presented that incorporates the diffusion- and the conduction-based mechanisms and allows electrochemically active biofilms to utilize both simultaneously. The model was applied to S. oneidensis and Geobacter sulfurreducens biofilms using experimentally generated data found in the literature. Our simulation results show that (1) biofilms having both mechanisms available, especially if they can interact, may have a metabolic advantage over biofilms that can use only a single mechanism; (2) the thickness of G. sulfurreducens biofilms is likely not limited by conductivity; (3) accurate intrabiofilm diffusion coefficient values are critical for current generation predictions; and (4) the local biofilm potential and redox potential are two distinct parameters and cannot be assumed to have identical values. Finally, we determined that simulated cyclic and squarewave voltammetry based on our model are currently not capable of determining the specific percentages of extracellular electron transfer mechanisms in a biofilm. The developed model will be a critical tool for designing experiments to explain EET mechanisms.
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Affiliation(s)
- Ryan Renslow
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, 118 Dana Hall Spokane St., P.O. Box 642710, Pullman, WA 99164-2710, USA.
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Parameswaran P, Bry T, Popat SC, Lusk BG, Rittmann BE, Torres CI. Kinetic, electrochemical, and microscopic characterization of the thermophilic, anode-respiring bacterium Thermincola ferriacetica. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:4934-4940. [PMID: 23544360 DOI: 10.1021/es400321c] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Thermincola ferriacetica is a recently isolated thermophilic, dissimilatory Fe(III)-reducing, Gram-positive bacterium with capability to generate electrical current via anode respiration. Our goals were to determine the maximum rates of anode respiration by T. ferriacetica and to perform a detailed microscopic and electrochemical characterization of the biofilm anode. T. ferriacetica DSM 14005 was grown at 60 °C on graphite-rod anodes poised at -0.06 V (vs) SHE in duplicate microbial electrolysis cells (MECs). The cultures grew rapidly until they achieved a sustained current density of 7-8 A m(-2) with only 10 mM bicarbonate buffer and an average Coulombic Efficiency (CE) of 93%. Cyclic voltammetry performed at maximum current density revealed a Nernst-Monod response with a half saturation potential (EKA) of -0.127 V (vs) SHE. Confocal microscopy images revealed a thick layer of actively respiring cells of T. ferriacetica (~38 μm), which is the first documentation for a gram positive anode respiring bacterium (ARB). Scanning electron microscopy showed a well-developed biofilm with a very dense network of extracellular appendages similar to Geobacter biofilms. The high current densities, a thick biofilm (~38 μm) with multiple layers of active cells, and Nernst-Monod behavior support extracellular electron transfer (EET) through a solid conductive matrix - the first such observation for Gram-positive bacteria. Operating with a controlled anode potential enabled us to grow T. ferriacetica that can use a solid conductive matrix resulting in high current densities that are promising for MXC applications.
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Affiliation(s)
- Prathap Parameswaran
- Swette Center for Environmental Biotechnology, The Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, Arizona 85287, USA.
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Renslow R, Babauta J, Majors P, Beyenal H. DIFFUSION IN BIOFILMS RESPIRING ON ELECTRODES. ENERGY & ENVIRONMENTAL SCIENCE 2013; 6:595-607. [PMID: 23420623 PMCID: PMC3571104 DOI: 10.1039/c2ee23394k] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (D(e)) in biofilms respiring on electrodes. Two model electrochemically active biofilms, Geobacter sulfurreducens PCA and Shewanella oneidensis MR-1, were investigated. A novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) techniques was used. PFG-NMR allowed noninvasive, nondestructive, high spatial resolution in situ D(e) measurements in living biofilms respiring on electrodes. The electrodes were polarized so that they would act as the sole terminal electron acceptor for microbial metabolism. We present our results as both two-dimensional D(e) heat maps and surface-averaged relative effective diffusion coefficient (D(rs)) depth profiles. We found that 1) D(rs) decreases with depth in G. sulfurreducens biofilms, following a sigmoid shape; 2) D(rs) at a given location decreases with G. sulfurreducens biofilm age; 3) average D(e) and D(rs) profiles in G. sulfurreducens biofilms are lower than those in S. oneidensis biofilms-the G. sulfurreducens biofilms studied here were on average 10 times denser than the S. oneidensis biofilms; and 4) halting the respiration of a G. sulfurreducens biofilm decreases the D(e) values. Density, reflected by D(e), plays a major role in the extracellular electron transfer strategies of electrochemically active biofilms.
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Affiliation(s)
- Rs Renslow
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
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Bond DR, Strycharz-Glaven SM, Tender LM, Torres CI. On electron transport through Geobacter biofilms. CHEMSUSCHEM 2012; 5:1099-1105. [PMID: 22615023 DOI: 10.1002/cssc.201100748] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 12/14/2011] [Indexed: 06/01/2023]
Abstract
Geobacter spp. can form a biofilm that is more than 20 μm thick on an anode surface by utilizing the anode as a terminal respiratory electron acceptor. Just how microbes transport electrons through a thick biofilm and across the biofilm/anode interface, and what determines the upper limit to biofilm thickness and catalytic activity (i.e., current, the rate at which electrons are transferred to the anode), are fundamental questions attracting substantial attention. A significant body of experimental evidence suggests that electrons are transferred from individual cells through a network of cytochromes associated with cell outer membranes, within extracellular polymeric substances, and along pili. Here, we describe what is known about this extracellular electron transfer process, referred to as electron superexchange, and its proposed role in biofilm anode respiration. Superexchange is able to account for many different types of experimental results, as well as for the upper limit to biofilm thickness and catalytic activity that Geobacter biofilm anodes can achieve.
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Affiliation(s)
- Daniel R Bond
- BioTechnology Institute and Department of Microbiology, University of Minnesota, St. Paul, MN 55108, USA
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Deo RP, Rittmann BE. A biogeochemical framework for bioremediation of plutonium(V) in the subsurface environment. Biodegradation 2012; 23:525-34. [DOI: 10.1007/s10532-011-9530-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 12/17/2011] [Indexed: 11/24/2022]
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The Performance of a Microbial Fuel Cell Depends Strongly on Anode Geometry: A Multidimensional Modeling Study. Bull Math Biol 2011; 74:834-57. [DOI: 10.1007/s11538-011-9690-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 08/05/2011] [Indexed: 10/16/2022]
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Babauta JT, Nguyen HD, Beyenal H. Redox and pH microenvironments within Shewanella oneidensis MR-1 biofilms reveal an electron transfer mechanism. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:6654-60. [PMID: 21648431 PMCID: PMC3238545 DOI: 10.1021/es200865u] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The goal of this research was to quantify the variations in redox potential and pH in Shewanella oneidensis MR-1 biofilms respiring on electrodes. We grew S. oneidensis MR-1 on a graphite electrode, which was used to accept electrons for microbial respiration. We modified well-known redox and pH microelectrodes with a built-in reference electrode so that they could operate near polarized surfaces and quantified the redox potential and pH profiles in these biofilms. In addition, we used a ferri-/ferrocyanide redox system in which electrons were only transferred by mediated electron transfer to explain the observed redox potential profiles in biofilms. We found that regardless of the polarization potential of the biofilm electrode, the redox potential decreased toward the bottom of the biofilm. In a fully redox-mediated control system (ferri-/ferrocyanide redox system), the redox potential increased toward the bottom when the electrode was the electron acceptor. The opposite behavior of redox profiles in biofilms and the redox-controlled system is explained by S. oneidensis MR-1 biofilms not being redox-controlled when they respire on electrodes. The lack of a significant variation in pH implies that there is no proton transfer limitation in S. oneidensis MR-1 biofilms and that redox potential profiles are not caused by pH.
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