Marta A. Silva, Pilar C. Portela, Carlos A. Salgueiro

Biochemical Journal • 2021

The redox potential values of cytochromes can be modulated by the protonation/deprotonation of neighbor groups (redox-Bohr effect), a mechanism that permits the proteins to couple electron/proton transfer. In the respiratory chains, this effect is particularly relevant if observed in the physiological pH range, as it may contribute to the electrochemical gradient for ATP synthesis. A constitutively produced family of five triheme cytochromes (PpcA−E) from the bacterium Geobacter sulfurreducens plays a crucial role in extracellular electron transfer, a hallmark that permits this bacterium to be explored for several biotechnological applications. Two members of this family (PpcA and PpcD) couple electron/proton transfer in the physiological pH range, a feature not shared with PpcB and PpcE. That ability is crucial for G. sulfurreducens’ growth in Fe(III)-reducing habitats since extra contributors to the electrochemical gradient are needed. It was postulated that the redox-Bohr effect is determined by the nature of residue 6, a leucine in PpcA/PpcD and a phenylalanine in PpcB/PpcE. To confirm this hypothesis, Phe6 was replaced by leucine in PpcB and PpcE. The functional properties of these mutants were investigated by NMR and UV–visible spectroscopy to assess their capability to couple electron/proton transfer in the physiological pH range. The results obtained showed that the mutants have an increased redox-Bohr effect and are now capable of coupling electron/proton transfer. This confirms the determinant role of the nature of residue 6 in the modulation of the redox-Bohr effect in this family of cytochromes, opening routes to engineer Geobacter cells with improved biomass production.

Yue Zhu

Highlights in Science, Engineering and Technology • 2022

The use of bacteria to degrade heavy soil metal concentrations and boost plant tolerance to elevated metal levels has significant ecological and financial benefits. Soil contaminated with heavy metals may cause a variety of problems. First, the soil respiration is affected by the heavy metal content because of the way it affects the respiration, metabolism (the metabolic entropy response), and activity of soil microbes. There is less organic carbon converted to bio-carbon and higher microbial metabolic entropy in metal-contaminated soil. Last but not least, heavy metals may be absorbed by seeds, leading to physiological dysfunction and malnutrition in the developing plant. Having an excess of metals in the body might be dangerous. Therefore, the use of bacterial which use various mechanism to degrade heavy metals is the best approach of this paper in getting reed of the heavy metals in soil.

Makwin Danladi Makut, Toyosi Michelle Adebayo, Jibril Egwu Owuna

BIOMED Natural and Applied Science • 2022

Background: The presence of spent hydrocarbon in soil is a serious problem to the environment hence study on bioremediation of soil polluted with auto-mechanic oil in Abuja Metropolis was carried out. Methods: A total of twenty (20) soil samples were collected, bacteria were isolated from the contaminated soil and identified using standard microbiological methods. The spent hydrocarbon utilization was determined using Atomic Adsorption UV Spectrometer. Results: The total viable count of the bacteria was 1.07 x 106 from Apo Mechanic village, 1.10 x 106 from Utako Mechanic workshops, 0.40 x 106 from Gwarinpa Mechanic workshops and 2.04 x 106 from Area one Mechanic workshops. The percentage occurrence of bacteria from Apo Mechanic village was Enterobacter species 40.0%, Pseudomonas synxantha 60.0%, Bacillus zanthoxyli 40.0% and Proteus vulgaris 20.0%. Utako Mechanic workshops were Enterobacter kobei 20.0%, Pseudomonas synxantha 40.0%, Bacillus zanthoxyli 20.0% and Proteus vulgaris 40.0%. Gwarinpa Mechanic workshops were Pseudomonas synxantha 20.0% and Bacillus zanthoxyli 20.0%. Area one Mechanic workshops were Enterobacter kobei 40.0% and Pseudomonas synxantha 40.0%. The effect of days on utilization of spent hydrocarbon showed that Pseudomonas synxantha had highest utilized of spent hydrocarbon 19.55mg/ml after 21 days. The effect of pH on utilization of spent hydrocarbon show that at pH 7.5, Enterobacter kobei, Bacillus zanthoxyli and Proteus vulgaris species had the highest utilization of spent hydrocarbon ranging from 5 9.33mg/ml-12.70mg/ml. Effect of temperature on utilization of spent hydrocarbon showed that at 28OC Enterobacter kobei, Pseudomonas synxantha, Bacillus zanthxyli and Proteus vulgaris had the highest utilization of spent hydrocarbon ranging from 5.51mg/ml- 11.11mg/ml. the bacteria isolated from the contaminated soil have the ability to utilized the hydrocarbon if the soil is amended with some mineral element as shown in this study. Conclusion: In conclusion bacteria isolates effectively bioremediated the automechanic oil polluted soil with a reduction of hydrocarbon pollutants.

Gian Luigi Garbini, Anna Barra Caracciolo, Paola Grenni

Microorganisms • 2023

Electroactive bacteria (EAB) are natural microorganisms (mainly Bacteria and Archaea) living in various habitats (e.g., water, soil, sediment), including extreme ones, which can interact electrically each other and/or with their extracellular environments. There has been an increased interest in recent years in EAB because they can generate an electrical current in microbial fuel cells (MFCs). MFCs rely on microorganisms able to oxidize organic matter and transfer electrons to an anode. The latter electrons flow, through an external circuit, to a cathode where they react with protons and oxygen. Any source of biodegradable organic matter can be used by EAB for power generation. The plasticity of electroactive bacteria in exploiting different carbon sources makes MFCs a green technology for renewable bioelectricity generation from wastewater rich in organic carbon. This paper reports the most recent applications of this promising technology for water, wastewater, soil, and sediment recovery. The performance of MFCs in terms of electrical measurements (e.g., electric power), the extracellular electron transfer mechanisms by EAB, and MFC studies aimed at heavy metal and organic contaminant bioremediationF are all described and discussed.

Dewu Ding, Xiao Sun

Genes • 2018

Shewanella oneidensis MR-1 can transfer electrons from the intracellular environment to the extracellular space of the cells to reduce the extracellular insoluble electron acceptors (Extracellular Electron Transfer, EET). Benefiting from this EET capability, Shewanella has been widely used in different areas, such as energy production, wastewater treatment, and bioremediation. Genome-wide proteomics data was used to determine the active proteins involved in activating the EET process. We identified 1012 proteins with decreased expression and 811 proteins with increased expression when the EET process changed from inactivation to activation. We then networked these proteins to construct the active protein networks, and identified the top 20 key active proteins by network centralization analysis, including metabolism- and energy-related proteins, signal and transcriptional regulatory proteins, translation-related proteins, and the EET-related proteins. We also constructed the integrated protein interaction and transcriptional regulatory networks for the active proteins, then found three exclusive active network motifs involved in activating the EET process—Bi-feedforward Loop, Regulatory Cascade with a Feedback, and Feedback with a Protein–Protein Interaction (PPI)—and identified the active proteins involved in these motifs. Both enrichment analysis and comparative analysis to the whole-genome data implicated the multiheme c-type cytochromes and multiple signal processing proteins involved in the process. Furthermore, the interactions of these motif-guided active proteins and the involved functional modules were discussed. Collectively, by using network-based methods, this work reported a proteome-wide search for the key active proteins that potentially activate the EET process.

Peilu Xie, Yuanyou Xu, Jiaxin Tang et al.

Communications Biology • 2024

AbstractSiderophore-dependent iron uptake is a mechanism by which microorganisms scavenge and utilize iron for their survival, growth, and many specialized activities, such as pathogenicity. The siderophore biosynthetic system PubABC in Shewanella can synthesize a series of distinct siderophores, yet how it is regulated in response to iron availability remains largely unexplored. Here, by whole genome screening we identify TCS components histidine kinase (HK) BarA and response regulator (RR) SsoR as positive regulators of siderophore biosynthesis. While BarA partners with UvrY to mediate expression of pubABC post-transcriptionally via the Csr regulatory cascade, SsoR is an atypical orphan RR of the OmpR/PhoB subfamily that activates transcription in a phosphorylation-independent manner. By combining structural analysis and molecular dynamics simulations, we observe conformational changes in OmpR/PhoB-like RRs that illustrate the impact of phosphorylation on dynamic properties, and that SsoR is locked in the ‘phosphorylated’ state found in phosphorylation-dependent counterparts of the same subfamily. Furthermore, we show that iron homeostasis global regulator Fur, in addition to mediating transcription of its own regulon, acts as the sensor of iron starvation to increase SsoR production when needed. Overall, this study delineates an intricate, multi-tiered transcriptional and post-transcriptional regulatory network that governs siderophore biosynthesis.

Aisha Awad Alshahrani

ECS Meeting Abstracts • 2018

The goal of this study is understanding phenomena which may help design electrode modifications enhancing efficiency of microbial fuel cells. Our hypothesis is that the rate of deposition is proportional to both composition of the outer cell membrane and the bulk concentration. We also suggest that ionic strength and ion identity can affect the efficiency of sticking after initial encounter. Shown here are electrochemical studies on effect of salt concentration on S. oneidensis MR-1 attachment and growth at ITO electrodes. Initial surface coverage of bacteria can be measured with respect to four metric. One metric is the observed lag time before currents increase during bacterial loading at the ITO surface. A second one is the current associated with that lag time. The third is the maximum anodic current that occurs after the lag period. Finally a cyclic voltammetric experiment following loading has a metric associated with the cathodic peak current. The peak current is very large for NaCl compare to CsCl. The final coverage (as measured by cathodic peak current in cyclic voltammetry, ipc) increases with increasing ionic strength (IS). We suggest that the behavior of cathodic peak current is very sensitive to the salt concentrations and bacteria harvest time. Our results clearly show a major difference in attachment and behavior of S. oneidensis MR-1 for NaCl compared to CsCl. CsCl inhibits all four metrics associated with loading at +0.2 vs Ag/AgCl (lag time, lag current, maximum loading current and cyclic voltammetric peak current).

Kenneth L. Brockman, Sheetal Shirodkar, Trevor J. Croft et al.

Scientific Reports • 2020

AbstractShewanella oneidensis, a metal reducer and facultative anaerobe, expresses a large number of c-type cytochromes, many of which function as anaerobic reductases. All of these proteins contain the typical heme-binding motif CXXCH and require the Ccm proteins for maturation. Two c-type cytochrome reductases also possess atypical heme-binding sites, the NrfA nitrite reductase (CXXCK) and the SirA sulfite reductase (CX12NKGCH). S. oneidensis MR-1 encodes two cytochrome c synthetases (CcmF and SirE) and two apocytochrome c chaperones (CcmI and SirG). SirE located in the sir gene cluster is required for the maturation of SirA, but not NrfA. Here we show that maturation of SirA requires the combined function of the two apocytochrome c chaperones CcmI and SirG. Loss of either protein resulted in decreased sulfite reductase. Furthermore, SirA was not detected in a mutant that lacked both chaperones, perhaps due to misfolding or instability. These results suggest that CcmI interacts with SirEFG during SirA maturation, and with CcmF during maturation of NrfA. Additionally, we show that CRP regulates expression of sirA via the newly identified transcriptional regulatory protein, SirR.

A. A. Samkov, Yu. A. Chugunova, M. N. Kruglova et al.

Прикладная биохимия и микробиология • 2023

The effect of the polarity of the electrical stimulation of the external circuit of the bioelectrochemical systems, as well as the immobilization of Shewanella oneidensis MR-1 cells containing the DyP peroxidase gene on the rate of discoloration of dyes of different types was found. For the crystal violet triphenylmethane dye, the maximum decolorization rate by suspended S. oneidensis MR-1 cells 2.05 ± 0.07 μM/h was noted in the case of connecting a 1.2 V direct polarity DC voltage source. One of the minimum rates was observed in the case of reverse polarity of the connection. In the case of cells immobilized on the anode, the rate was higher, reaching 2.91 ± 0.09 μM/h and did not decrease with increasing substrate concentration. The lowest values were also noted for the reverse connection of the voltage source. In case of the azo dye congo red, the maximum rate was found for a source with direct connection and an open circuit (0.26 ± 0.01 and 0.29 ± ± 0.02 μM/h, respectively), the minimum value is 0.11 ± 0.02 μM/h for reverse connection. For the crystal violet decolorization products, a significant decrease in the intensity of the main absorption peak at 590 nm band was found, with no notable hypsochromic shift. The qualitative changes in the decolorization products composition are indicated by the appearance, in case of a direct polarity of the ionistor connection, of a new absorption maximum in the region of 360 nm. The results may be of interest for the development of new methods of bioelectrochemical cleaning.

Reem Alshehri, Alanah Fitch

ECS Meeting Abstracts • 2020

The role of structural iron in clays to enhance the electron transfer of Shewanella Oneidensis MR-1 was investigated. Three types of clays containing different amounts of iron situated in the octahedral sites have been used to modify the ITO electrodes: nontronite NAu-1, montmorillonite (Wyoming) SWy-1, and synthetic montmorillonite SYn-1. The interaction between bacterial cells and the clay, which modified the ITO electrodes were studied by potential step, cyclic voltammetry, confocal microscope, and scanning electron microscope SEM. Experimental results showed that the current density generated using iron containing clays NAu-1 and SWy-1 to modify the ITO electrode was 19 and 3 times higher than that produced using the bare ITO electrode. Mechanism of electrochemical production deviated for the iron containing clay NAu-1 Keywords Shewanella Oneidensis MR-1, Clay, Modified ITO electrode, MFC

Shuai Xu, Mohamed El-Naggar

ECS Meeting Abstracts • 2018

Shewanella oneidensis MR-1 can gain energy by performing extracellular electron transport (EET) to external insoluble electron acceptors ranging from natural minerals to synthetic electrode surfaces when poised at proper potentials. Outer membrane c-type multi-heme cytochromes play a critical role in mediating this electron transport. The abundance of these cytochromes on the cell surface has also been hypothesized to facilitate long-distance electron transport along multicellular biofilms, in a manner similar to redox active polymers containing discrete redox moieties. Here we report measurements of electron transport in living S. oneidensis biofilms that bridged interdigitated array (IDA) microelectrodes. Electrochemical gating reveals a peak in the conduction current at the expected formal potential of the cytochrome conduits, consistent with redox conductivity where transport is driven by a multistep electron hopping mechanism through the heme network. The temperature dependency of the biofilm conduction is also consistent with such a thermally activated process, where conductivity increases with increasing temperature. In addition, the measured activation energy (0.315 eV) is consistent with the computationally-determined activation energy of the S. oneidensis Mtr decaheme cytochromes.

O. Gasyuk, N. Volchenko, A. Lazukin et al.

Russian Journal of Biological Physics and Chemisrty • 2022

The high anthropogenic load on the environment makes it necessary to develop new ways of cleaning the environment. One of the promising methods in remediation processes is the use of living organisms. So, for almost every pollutant, it is possible to select the appropriate strain of microorganisms capable of decomposing certain pollutants. The study used benthic-type microbial fuel cells as promising bioengineering systems that can be applied in various areas of human life - medicine, cleaning and environmental monitoring, in the Internet of Things, etc. In addition, the electrogenic potential created by MFC will facilitate the migration of heavy metals towards the anode, which will simplify the process of their removal from the environment or inclusion in the food chains of anodophilic microbiota. As a result of the study, it was found that the most effective in the design of the MFC are horizontal electrodes. Also, pollutants eventually begin to have a negative impact on the bioelectrogenesis of microbial fuel cells and, accordingly, on the local microbiota.

Sheldon Cotts, Bijentimala Keisham, Vikas Berry

ECS Meeting Abstracts • 2019

With the increased interest in developing cost-effective and readily available energy sources, the research in the microbial fuel cell (MFC) field has gained increased attention. Here, we report the use of graphene’s high electron mobility coupled with Geobacter sulfurreducens’ biocatalyst nature to increase the current response of a MFC. It is well-accepted that one of the limiting factors of current generation of a Geobacter based MFC is the electron transport process in the anodic chamber. We attempt to address this limitation by utilizing the enhanced electrical conductivity of graphene. To study the interface of graphene- Geobacter, Raman spectroscopy and scanning electron microscopy (SEM) were employed. The Raman characterization studies of the interface revealed an n-doping effect on graphene, with an approximate shift of 5 cm-1. These results demonstrate that the graphene- Geobacter interface provides an approach to overcoming the challenges of conventional MFCs.

Mir Pouyan Zarabadi, Manon Couture, Steve J. Charette et al.

ChemElectroChem • 2019

AbstractA common kinetic framework for studies of whole‐cell catalysis is vital for understanding and optimizing bioflow reactors. In this work, we demonstrate the applicability of a flow‐adapted version of Michaelis‐Menten kinetics to an electrocatalytic bacterial biofilm. A three‐electrode microfluidic biofilm flow reactor measured increased turnover rates by as much as 50 % from a Geobacter sulfurreducens biofilm as flow rate was varied. Based on parameters from the applied kinetic framework, flow‐induced increases to turnover rate, catalytic efficiency and device reaction capacity could be linked to an increase in catalytic biomass. This study demonstrates that a standardized kinetic framework is critical for quantitative measurements of new living catalytic systems in flow reactors and for benchmarking against well‐studied catalytic systems such as enzymes.

Madeline Ammend, Chi Chan, Daniel Bond

ARPHA Conference Abstracts • 2023

Geobacter sulfurreducens is a dissimilatory metal-reducing microorganism capable of utilizing insoluble acceptors via extracellular electron transfer. While a large number of multiheme c-type cytochromes expressed by G. sulfurreducens are implicated in linking its cytoplasmic respiratory chain to materials beyond its outer membrane, whether these proteins have specific roles in reduction or recognition of particular metals is unknown. Recently, structures of three extracellular conductive c-type cytochrome filaments, often referred to as nanowires, were reported. Comprised of either OmcS, OmcE, or OmcZ, these nanowires are long polymers of protein subunits with a core of closely spaced hemes, with no similarity in sequence, fold, glycosylation, subunit size, or diameter. We utilized a markerless deletion approach to construct single, double, and triple-deletion strains in an isogenic background to investigate possible roles of OmcS, OmcE, and OmcZ. When soluble Fe(III) or the organic acceptor fumarate were electron acceptors, no defects were observed in any mutant. When freshly precipitated Fe(III) oxide was tested as an electron acceptor, mutants lacking omcE were strongly affected, reducing Fe(III) approximately half as fast. No other single mutant (∆omcS or ∆omcZ) showed a defect. Double mutants containing only omcE (∆omcSZ) also showed a defect, suggesting other proteins could be required in addition to OmcE. The double mutant containing only omcZ (∆omcSE) also showed a partial defect, while double mutants containing only omcS (∆omcEZ) were completely unable to reduce Fe(III) oxide. The triple (∆omcESZ) mutant was also unable to reduce Fe(III) oxides. Taken together, this indicates that genes for two separate nanowires are necessary to completely reduce this form of Fe(III) oxide. This is the first evidence that omcZ, which has only been implicated in electron transfer to electrodes, could also be needed for metal reduction. With the recent discovery of two completely unrelated mutltiheme cytochrome nanowires in thermophilic Archaea, different conductive filaments with different substrate specificities may have repeatedly evolved to facilitate extracellular respiration.

Mathias Fessler, Jonas Stenløkke Madsen, Yifeng Zhang

Frontiers in Microbiology • 2023

Geobacter sulfurreducens is part of a specialized group of microbes with the unique ability to exchange electrons with insoluble materials, such as iron oxides and electrodes. Therefore, G. sulfurreducens plays an essential role in the biogeochemical iron cycle and microbial electrochemical systems. In G. sulfurreducens this ability is primarily dependent on electrically conductive nanowires that link internal electron flow from metabolism to solid electron acceptors in the extracellular environment. Here we show that when carrying conjugative plasmids, which are self-transmissible plasmids that are ubiquitous in environmental bacteria, G. sulfurreducens reduces insoluble iron oxides at much slower rates. This was the case for all three conjugative plasmids tested (pKJK5, RP4 and pB10). Growth with electron acceptors that do not require expression of nanowires was, on the other hand, unaffected. Furthermore, iron oxide reduction was also inhibited in Geobacter chapellei, but not in Shewanella oneidensis where electron export is nanowire-independent. As determined by transcriptomics, presence of pKJK5 reduces transcription of several genes that have been shown to be implicated in extracellular electron transfer in G. sulfurreducens, including pilA and omcE. These results suggest that conjugative plasmids can in fact be very disadvantageous for the bacterial host by imposing specific phenotypic changes, and that these plasmids may contribute to shaping the microbial composition in electrode-respiring biofilms in microbial electrochemical reactors.

Elena Yunda, Mareike Gutensohn, Madeleine Ramstedt et al.

Frontiers in Microbiology • 2023

IntroductionMercury (Hg) is a major environmental pollutant that accumulates in biota predominantly in the form of methylmercury (MeHg). Surface-associated microbial communities (biofilms) represent an important source of MeHg in natural aquatic systems. In this work, we report MeHg formation in biofilms of the iron-reducing bacterium Geobacter sulfurreducens.MethodsBiofilms were prepared in media with varied nutrient load for 3, 5, or 7 days, and their structural properties were characterized using confocal laser scanning microscopy, cryo-scanning electron microscopy and Fourier-transform infrared spectroscopy.ResultsBiofilms cultivated for 3 days with vitamins in the medium had the highest surface coverage, and they also contained abundant extracellular matrix. Using 3 and 7-days-old biofilms, we demonstrate that G. sulfurreducens biofilms prepared in media with various nutrient load produce MeHg, of which a significant portion is released to the surrounding medium. The Hg methylation rate constant determined in 6-h assays in a low-nutrient assay medium with 3-days-old biofilms was 3.9 ± 2.0 ∙ 10−14 L ∙ cell−1 ∙ h−1, which is three to five times lower than the rates found in assays with planktonic cultures of G. sulfurreducens in this and previous studies. The fraction of MeHg of total Hg within the biofilms was, however, remarkably high (close to 50%), and medium/biofilm partitioning of inorganic Hg (Hg(II)) indicated low accumulation of Hg(II) in biofilms.DiscussionThese findings suggest a high Hg(II) methylation capacity of G. sulfurreducens biofilms and that Hg(II) transfer to the biofilm is the rate-limiting step for MeHg formation in this systems.

Khuthadzo Mudzanani, Sunny Iyuke, Michael O. Daramola

Fermentation • 2023

This study evaluates the potential to synthesize an adsorbent for wastewater remediation applications from an anaerobic digestion by-product synthesized using biomaterials and a less energy-intensive process. The synthesized sludge-based granular activated carbon (GAC) was used to adsorb Cr(VI) and Cd(II) in a batch reactor stirred for 24 h at 25 °C. The surface chemistry of the material was assessed porosity with BET, SEM for morphology, EDS-XRF for elemental analysis, and functional groups on these materials using FTIR and TGA for thermal profile. SBET of the SAC was discovered to be 481.370 m2/g with a VT of 0.337 cm3/g, respectively 9.02 and 2.23 times greater than raw sludge. The modification to SAC shows a dramatic increase in performance from 40% to 98.9% equilibrium adsorption rate. The maximum or equilibrium removal (99.99%) of Cr(VI) and Cd(II) was achieved by 0.8 and 1.4 g SAC dosage, respectively. Thus, it can be concluded that activation of sewage sludge was effective in enhancing the surface area and pore volume which made it suitable for AMD remediation application.

Sanette Marx, Karina van der Merwe

Water Practice and Technology • 2021

Abstract Hydrothermal liquefaction derived hydrochar produced from industrial paper sludge was used as an adsorbent to remove phenol derivatives from an industrial wastewater stream. Removal efficiency for phenol was determined using synthetic solutions (10–150 ppm) using batch adsorption experiments at a constant solution pH (8), temperature (25 ± 2 °C) and rotary speed (150 rpm). The adsorption of phenol onto hydrochar followed a Freundlich isotherm and could be described with pseudo-second-order kinetic models. Analysis of the adsorption mechanisms showed that particle film mass transport was the rate-determining step in the adsorption process. A COD removal efficiency of 31 ± 1% was achieved for the industrial wastewater stream. All phenol components in the wastewater stream could be removed, but not all organic acids and cyclic ketones. The performance of the paper sludge-based hydrochar compared well with that of activated carbon (44% COD removal). The final phenol concentration in the wastewater stream was below the acceptable phenol concentration for industrial effluents (1 mg/L). The results show that paper sludge can be converted to a valuable marketable commodity that could reduce waste management costs for a paper mill, while also reducing the cost of expensive adsorbents.

Norsafiah Fazli, Noor Sabrina Ahmad Mutamim, Mohd Faizal Ali

Journal of Chemical Engineering and Industrial Biotechnology • 2018

Some of the major problems encountered by the world are water pollution and natural resources depletion. One of the major factors which contribute to water pollution is insufficiently treated wastewater whereas the depletion of natural resources is due to the dependability of the fossil fuel as the main energy source. Both of these issues show the world urgently required an effective technology of wastewater treatment and energyrecovery. Microbial Fuel Cell (MFC) is a treatment method that can achieve the needs of effective treatment of wastewater and energy recovery simultaneously. As mentioned, insufficiently treated wastewater is one of the main causes which contributes to water pollution. Spent caustic wastewater is one of the industrial wastewater that is difficult to be treated, handled and disposed due to its noxious properties. Existing treatment method of treating spent caustic wastewater are limited by low efficiency. However, by applying MFCs, organic and inorganic contaminants are oxidized by biomass and produce electron that is transferred to electrode. The movement of the electron from anode to cathode generate electricity and turns MFC into a treatment method that able to provide both wastewater treatment and energy production. This article presents a review of spent caustic wastewater and its existing treatment method as well as the MFC researches in terms of its configuration and factors affecting its performance

Serkan EKER

Deu Muhendislik Fakultesi Fen ve Muhendislik • 2023

A microbial fuel cell (MFC) with cathode and anode chambers was utilized to generate power while simultaneously removing COD from wastewater. By utilizing various oxidant solutions, it is possible to increase the generated voltage. The anode chamber was used for anaerobic treatment of synthetic wastewater (approximately 1000 mg/L), whereas the cathode chamber contained various oxidant solutions such as dilute hydrogen peroxide (300 mg/L), KMnO4 (300 mg/L), K2Cr2O7 (300 mg/L) and Fenton reagent (H2O2/Fe(II), 300/20 mg/L). Aerobic wastewater treatment and intermittent ozonation were also tested in the cathode chamber. With intermittent ozonation of the cathode chamber, the highest power output (382 mW/m2) was obtained. At the conclusion of the operation period, the COD concentration in the anode chamber decreased from 1170 mg/L to 650 mg/L, resulting in nearly 45% COD removal. In the cathode chamber, the use of diluted KMnO4 and H2O2 solutions produced high power densities of 35 and 23 W/m2, respectively, while the other oxidants produced low power densities. At the end of 72 hours, the COD content of the anaerobic chamber decreased from 800 mg/L to nearly 333 mg/L, resulting in nearly 59% COD removal for the KMnO4 solution. Considering the high cost of ozonation, it is recommended that either aerobic wastewater treatment or dilute KMnO4/H2O2 solutions should be used in the cathode chamber for high power generation.

Aris Mukimin

E3S Web of Conferences • 2020

Microbial fuel cell (MFC) is a technology that is not only able to produce energy but also treats wastewater. The membraneless microbial fuel cell (ML-MFC) system was developed to avoid the use of membranes that are prone to clogging and are less applicable. The reactor was made and arranged in two chambers connected by pipes and the fluid flow rate is set using a peristaltic pump. Three anodes (carbon cloth) were paired with a carbon-Pt cathode GDL (Gas Diffusion Layer) type. The reactor was applied to wastewater taken from the industrial WWTP unit at the point before and after UASB. ML-MFC reactors can produce currents of 0.2 mA (before UASB) and 0.25 mA (after UASB). Current production is strongly influenced by the flow rate and characteristics of wastewater. Increased flow rates and complex character of wastewater will reduce current production. The electric power produced is 0.035 mwatt for wastewater before UASB and 0.086 mwatt after UASB with a COD removal is close to the same, which is 21% at a flow rate of 11 L / min1

Nikita Kundu, Smriti Yadav, Ananya Bhattacharya et al.

Letters in Applied Microbiology • 2025

Abstract Azo dyes constitute 60%–70% of commercially used dyes and are complex, carcinogenic, and mutagenic pollutants that negatively impact soil composition, water bodies, flora, and fauna. Conventional azo dye degradation techniques have drawbacks such as high production and maintenance costs, use of hazardous chemicals, membrane clogging, and sludge generation. Constructed wetland–microbial fuel cells (CW–MFCs) offer a promising sustainable approach for the bio-electrodegradation of azo dyes from textile wastewater. CW–MFCs harness the phytodegradation capabilities of wetland plants like Azolla, water hyacinth, and Ipomoea, along with microalgae such as Nostoc, Oscillatoria, Chlorella, and Anabaena, to break down azo dyes into aromatic amines. These intermediates are then reduced to CO2 and H2O by microalgae in the fuel cells while simultaneously generating electricity. CW–MFCs offer advantages including low cost, sustainability, and use of renewable energy. The valorization of the resulting algal and plant biomass further enhances the sustainability of this approach, as it can be used for biofuel production, nutraceuticals, pharmaceuticals, and bio-composting. Implementing CW–MFCs as a tertiary treatment step in textile industries aligns with the circular economy concept and contributes to achieving several sustainable development goals.

Hussain & Ismail

IRAQI JOURNAL OF AGRICULTURAL SCIENCES • 2020

Three identically designed systems named designate as MFC-CW, CW1,and CW2 were constructed and setup in this study for simultaneous biotreatment of real petroleum refinery wastewater (PRW) and bioelectricity generation. The three systems were planted with emergent wetland plant of Canna indica. These systems were operated simultaneously in a single batch mode to identify the dominant mechanism for organics removal from PRW. The operation period for each cycle was 8 days. Results demonstrated that maximum removal efficiency of the organic content represented as chemical oxygen demand (COD) were 96.5%, 89.3%, and 91% observed in MFC-CW, CW1, and CW2, respectively, whereby, the highest power generated in MFC-CW only was 12.36 mW/m2. The potential convergence of the results in the three systems indicated that the dominant mechanism of organic content removal from PRW was via bioelectrochemical reactions by the anodic biofilm in the MFC.

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International Journal of Recent Technology and Engineering • 2019

Recent research have found out that Bio Electrochemical Systems (BES) are proving to be efficient in both power generation and in waste disposal. The best example for a BES is a microbial fuel cell. The microbial fuel cell (MFC) uses the organic and the inorganic materials in the wastewater to produce electricity by the action of the microbes on them. Thus the MFC’s can be used for both bio-electricity generation and wastewater treatment. The power generation and the efficiency of the MFC depends on various factors like the type of bacteria, type of electrode used and organic content in the effluent. Experiments were carried out to treat textile industry wastewater using Microbial Fuel Cell. Graphite was used as anode, stainless steel and aluminium mesh were used as cathode. Influence of cathodes on power production and COD reduction on process has been critically examined. The maximum power density and COD reduction were observed in graphite and stainless steel electrode system

Paweł P. Włodarczyk, Barbara Włodarczyk

Energies • 2018

Wastewater originating from the yeast industry is characterized by high concentration of pollutants that need to be reduced before the sludge can be applied, for instance, for fertilization of croplands. As a result of the special requirements associated with the characteristics of this production, huge amounts of wastewater are generated. A microbial fuel cell (MFC) forms a device that can apply wastewater as a fuel. MFC is capable of performing two functions at the same time: wastewater treatment and electricity production. The function of MFC is the production of electricity during bacterial digestion (wastewater treatment). This paper analyzes the possibility of applying yeast wastewater to play the function of a MFC (with Ni–Co cathode). The study was conducted on industrial wastewater from a sewage treatment plant in a factory that processes yeast sewage. The Ni–Co alloy was prepared by application of electrochemical method on a mesh electrode. The results demonstrated that the use of MFC coupled with a Ni–Co cathode led to a reduction in chemical oxygen demand (COD) by 90% during a period that was similar to the time taken for reduction in COD in a reactor with aeration. The power obtained in the MFC was 6.1 mW, whereas the volume of energy obtained during the operation of the cell (20 days) was 1.27 Wh. Although these values are small, the study found that this process can offer an additional level of wastewater treatment as a huge amount of sewage is generated in the process. This would provide an initial reduction in COD (and save the energy needed to aerate wastewater) as well as offer the means to generate electricity.

Hagos Mebrahtu Gebrehiwot, Shimelis Kebede Kassahun

Chemical Engineering & Technology • 2024

AbstractThis study investigates the potential of a salt bridge‐mediated microbial fuel cell (MFC) for power generation and wastewater sludge treatment in breweries. Unlike traditional “one‐parameter‐at‐a‐time” methodologies, this study uses a three‐variable Box–Behnken design response surface methodology to optimize critical MFC operational parameters. The effects of parameters such as solution pH, salt bridge molarity, and temperature were studied in the range of 4 to 10, 1 to 5 M, and 20 to 45 g L−1. The optimum operating parameters were found to be solution pH of 5.853, salt bridge molarity of 3.343 M, and temperature of 32.5 °C for chemical oxygen demand and biological oxygen demand removal efficiencies of 92.485 % and 88.51 %, respectively. Temperature was found to be the most significant factor affecting the reactor's performance.

Olivia Zapata-Martínez, Denys Villa-Gomez, Raul Tapia-Tussell et al.

Beverages • 2024

Craft breweries release wastewater into the environment, posing serious environmental concerns. Microbial fuel cells (MFCs) are an attractive technology that has been used in industrial wastewater treatment. This study used a scalable system of nine MFCs (stacked) to treat 150 L of craft brewery wastewater (CBW). The CBW had 1831 ± 85 mg COD (chemical oxygen demand) L−1. The hydraulic retention time was 5 days, with a COD removal percentage of 93 ± 1.8%. The total internal resistance of the stack was 204.8 ± 5.2 Ω at 26 ± 2 °C without the use of a metal catalyst; the reduction of oxygen was the limiting process. Finally, the sequence of treatments applied with this proposed system demonstrated its self-sustainability, which could be a viable option for the real-life conditions of this kind of wastewater. Further research is needed.

Minjeong Park, Joohee Kim, Hanjung Song et al.

Sensors • 2018

Ionic electroactive polymer (IEAP) actuators that are driven by electrical stimuli have been widely investigated for use in practical applications. However, conventional electrodes in IEAP actuators have a serious drawback of poor durability under long-term actuation in open air, mainly because of leakage of the inner electrolyte and hydrated cations through surface cracks on the metallic electrodes. To overcome this problem, a top priority is developing new high-performance ionic polymer actuators with graphene electrodes that have superior mechanical, electrical conductivity, and electromechanical properties. However, the task is made difficultby issues such as the low electrical conductivity of graphene (G). The percolation network of silver nanowires (Ag-NWs) is believed to enhance the conductivity of graphene, while poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), which exhibits excellent stability under ambient conditions, is expected to improve the actuation performance of IEAP actuators. In this study, we developed a very fast, stable, and durable IEAP actuator by employing electrodes made of a nanocomposite comprising PEDOT:PSS and graphene–Ag-NWs (P/(G–Ag)). The cost-effective P/(G–Ag) electrodes with high electrical conductivity displayed a smooth surface resulting from the PEDOT:PSS coating, which prevented oxidation of the surface upon exposure to air, and showedstrong bonding between the ionic polymer and the electrode surface. More interestingly, the proposed IEAP actuator based on the P/G–Ag electrode can be used in active biomedical devices, biomimetic robots, wearable electronics, and flexible soft electronics.

Qianyong Zhang, Zhirao Yin, Rui Sun et al.

Academic Journal of Science and Technology • 2024

Microbial fuel cells (MFCs) have emerged as a promising technology for sustainable energy production and environmental remediation, particularly in treating oily wastewater in the maritime industry. However, their practical application has been limited by low power output and energy conversion efficiency. Research has explored enhancing MFC power output through anode modification and electrode material optimization, with biochar showing potential as an alternative anode material. Our study developed pine cone biochar as an anode for MFCs, demonstrating excellent biocompatibility and significantly improved power generation and degradation performance. FT-IR, contact angle measurements, and electrochemical techniques characterized the MFC performance, with biochar-based MFCs achieving higher voltage, power output, and current density compared to carbon felt. Additionally, biochar MFCs exhibited a higher oil wastewater degradation rate and COD removal efficiency. These findings suggest that biochar is a promising anode material for MFCs, warranting further research to optimize MFC design and operational conditions for effective wastewater treatment and energy recovery.

Tesfalem Atnafu, Seyoum Leta

Bioresources and Bioprocessing • 2021

Abstract Background The critical MFC design challenge is to increase anode surface area. A novel FAB–MFC integrated system was developed and evaluated for domestic wastewater treatment. It was operated in fed-batch flow mode at 1–3 days of HRT with 755 mg/L CODIN and 0.76 kg-COD/m3/day. The study includes anaerobic-MFC and aerobic-MFC integrated systems. Microbial electrode jacket dish (MEJ-dish) with hybrid dimension (HD) was invented, first time to authors’ knowledge, to boost anode biofilm growth. The treatment system with MEJ+ (FAB) and MEJ− (MFC) anode are called FAB–MFC and MFC, respectively. Results Fragmented variable anode biofilm thickness was observed in FAB than MFC. The FAB–MFC (FAB+) simple technique increases the anode biofilm thickness by ~ 5 times MFC. Due to HD the anode biofilm was fragmented in FAB+ system than MFC. At the end of each treatment cycle, voltage drops. All FAB+ integrated systems reduced voltage drop relative to MFC. FAB reduces voltage drops better than MFC in anaerobic-MFC from 6 to 20 mV and aerobic-MFC from 35–47 mV at 1 kΩ external load. The highest power density was achieved by FAB in anaerobic-MFC (FAB = 104 mW/m2, MFC = 98 mW/m2) and aerobic-MFC integrated system (FAB = 59 mW/m2, MFC = 42 mW/m2). Conclusions The ∆COD and CE between FAB and MFC could not be concluded because both setups were inserted in the same reactor. The integrated system COD removal (78–97%) was higher than the solitary MFC treatment (68–78%). This study findings support the FAB+ integrated system could be applied for real applications and improve performance. However, it might depend on influent COD, the microbial nature, and ∆COD in FAB+ and MFC, which requires further study. Graphic abstract

Megan Carey Freyman, Tianyi Kou, Shanwen Wang et al.

ECS Meeting Abstracts • 2020

3D printing helps to provide further control on electrode design. By using 3D printing to tune the geometry, porosity and dimensions of the structure, mass transport to functional microbes or sites in the structure can be improved. By embedding living microbes directly into the ink we can create 3D printed structures to help harness the activity of microbes and use them in functional devices. Here we demonstrate the incorporation of the living bacteria Shewanella Oneidensis MR-1 (S. Oneidensis MR-1) directly into an ink used for creating 3D printed structures. By incorporating S. Oneidensis MR-1 into a sodium alginate-cellulose ink we showed that S. Oneidensis MR-1 survives the 3D printing process through the prominent degradation of methyl orange azo dye from the surrounding solution in the presence of the living 3D printed structure. The viability was further confirmed using confocal microscopy. By incorporating carbon black into this ink we further demonstrate the direct printing of a living microbial fuel cell (MFC) anode. Electrochemical measurements showed there was good charge transfer between the S. Oneidensis MR-1 and the electrode surface. To our knowledge, this is the first report on implementing 3D printed bacteria structure as a living electrode for an MFC system. The capability of printing living and functional 3D bacterial structure could open up new possibilities in design and fabrication of microbial devices as well as fundamental research on the interaction between different bacterial strains, electrode materials, and surrounding environments.

Aparna Paul, Shraban Dey, Gopal Sebak Goswami et al.

Advanced Sustainable Systems • 2025

AbstractRecent advancements in negative electrode materials for supercapacitors have garnered significant attention due to their potential to enhance energy density. These materials are crucial in improving the performance of supercapacitors, particularly in terms of specific capacitance. Fe oxide‐based composites are attractive negative electrode materials for cutting‐edge supercapacitor technologies because of their high specific capacitance, broad potential window, outstanding cycle stability and adaptability in asymmetric design. The synthesized Fe─Ni oxide/reduced graphene oxide (FNG) composite delivered ≈500 F g−1 specific capacitance at ≈2 A g−1 current density. The work also describes the hydrothermal synthesis of a bimetallic oxide like zinc oxide‐manganese oxide (ZMO) as a positive material to fabricate asymmetric supercapacitor (ASC). The electrochemical results achieved from the three‐electrode configuration of ZMO indicate true pseudocapacitive behavior with the triangular charge–discharge curve. The fabricated ASC with ZMO as cathode and FNG as anode delivered energy, and power densities are ≈32 W h kg−1 and ≈2.3 kW kg−1, respectively.

Yilkal Dessie, Sisay Tadesse

Frontiers in Nanotechnology • 2022

The use of nanotechnology in bioelectrochemical systems to recover bioelectricity and metals from waste appears to be a potentially appealing alternative to existing established procedures. This trend exactly characterizes the current renewable energy production technology. Hence, this review focuses on the improvement of the anode electrode by using different functional metal oxide-conducting polymer nanocomposites to enhance microbial fuel cell (MFC) performance. Enhancement of interfacial bioelectrocatalysis between electroactive microorganisms and hierarchical porous nanocomposite materials could enhance cost-effective bioanode materials with superior bioelectrocatalytic activity for MFCs. In this review, improvement in efficiency of MFCs by using iron oxide- and manganese oxide-based polypyrrole hybrid composites as model anode modifiers was discussed. The review also extended to discussing and covering the principles, components, power density, current density, and removal efficiencies of biofuel cell systems. In addition, this research review demonstrates the application of MFCs for renewable energy generation, wastewater treatment, and metal recovery. This is due to having their own unique working principle under mild conditions and using renewable biodegradable organic matter as a direct fuel source.

Gean Arteaga-Arroyo, Andrea Ramos-Hernández, Aldeir De Los Reyes-Rios et al.

Polymers • 2024

A comprehensive investigation into the design and electrochemical optimization of composite electrodes consisting of poly(3,4-ethylenedioxythiophene) (PEDOT)/graphene oxide (GO)/Methanococcus deltae and reduced graphene oxide (rGO)/Methanococcus deltae hybrids, anchored onto stainless-steel (SS) substrates, has been conducted. The GO and rGO materials were synthesized using a modified Hummer method. The resulting SS/PEDOT/GO and SS/PEDOT/rGO composite electrodes were subjected to systematic electrochemical characterization, focusing on the PEDOT p-type and n-type doping/undoping processes within diverse solvent environments (CH3CN and H2O) and electrolyte compositions (LiClO4 and KCl). Raman spectroscopy analysis confirmed the successful integration of graphene derivatives into the electrode structures, while field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) revealed increased surface roughness upon GO and rGO incorporation. This increase in surface roughness is believed to enhance the adhesion of Methanococcus deltae microorganisms and facilitate efficient electron transport. Electrochemical measurements showed that the resulting SS/PEDOT/GO and SS/PEDOT/rGO anodes exhibit remarkable electrocatalytic activity. The SS/PEDOT/GO electrode achieved a maximum power density of 1014.420 mW/cm2, while the SS/PEDOT/rGO electrode reached 632.019 mW/cm2.

Yuvraj Maphrio Mao, Khairunnisa Amreen, Rajnish Kaur Calay et al.

Scientific Reports • 2024

AbstractThis paper demonstrates screen-printing technique, Glass Screen printed (GSP) on glass layer with Graphene Quantum Dots (GQDs) via drop casting approach to manufacture electrodes for Miniaturized Microbial Fuel Cells (MMFCs). MMFCs are viable options to sustainably operate low-power devices such as sensors, implantable medical devices, etc. However, the technology is still not fully mature for practical applications due to limitations of output power. Materials and design improvements are required for decreasing internal resistance for better electron transfer and improving overall performance. In this work the electrodes manufactured by GSP technique, and anode modified by GQD was tested in MMFC using RO wastewater. It was found that the GQDs increased the surface area to improve electron transfer kinetics at the anode. As a result, GQDs-based GSPEs showed 7.4 times higher power output 332 nW/cm2 compared to its unaltered electrode which displayed a power output of 44.8 nW/cm2. Electrodes made by GSP technique are more durable and less susceptible to biofouling and corrosion compared to conventional methods. The modified anodes further showed sustained output for long term operation.

Bishir Musa, Pablo José Arauzo, Maciej Pawel Olszewski et al.

Fuel Cells • 2021

AbstractCorncob pyrochar activated with steam (CCA) and nonactivated corncob pyrochar (NCC) were produced and characterized. The performance of the best material was tested in a dual‐chambered microbial fuel cell (MFC) as an electrode for bioelectricity generation using wet torrefaction wastewater as substrate. Pyrolysis of 80.3 g of dried corncobs was carried out at 600°C under a constant N2 flow of 3 L min−1 for 30 min and the resulting pyrochar was activated using steam also at 600°C. Voltage and current outputs from the MFC were recorded daily for 18 days. The proximate and Brunauer–Emmett–Teller (BET) surface area analyses revealed that CCA had the highest fixed carbon content of 71.9 % and higher surface area of 104.0 m2 g−1 respectively. A larger pore diameter of 1.9 × 10−3 µm was also recorded with the CCA than 1.2 × 10−3 µm for NCC. The MFC produced a maximum power output of 21.5 mW. The physicochemical analyses of the wastewater effluent revealed an increased electrical conductivity from 1724 to 3460 µS cm−1 with a significant decrease by 91.9% in the total organic carbon (TOC) from 3700 to 298 mg L−1. Steam activation increases the surface area, porosity, stability and redox reversibility of the corncob pyrochar. Therefore, steam‐activated corncob pyrochar performed well in MFCs due to the high power output observed.

Vladyslav Mishyn, David Hickey, Sofiene Abdellaoui

ECS Meeting Abstracts • 2023

Non-renewable and limited fossil resources (i.e. petroleum, coal, and natural gas) have been used over the last years for the production of energy, commodity chemicals, and polymer materials. Nonetheless, the extraction and consumption of these resources leads to deleterious and irreversible environmental impacts. As a sustainable alternative, lignin, one of the major components of lignocellulosic biomass, represents the most promising renewable raw material to produce aromatic-based chemicals and high value-added products. However, the use of lignin as a source of valuable molecules similar to the petroleum-derived chemicals is hindered due to its recalcitrance and structural heterogeneity. Biological approaches have been studied to develop selective and ecofriendly pathways for lignin valorization. It has been reported that some microorganisms can cleave selectively β-ether bonds representing more than a half of lignin bonding pattern.[1] The etherolytic pathway of the soil probacterium Sphingobium paucimobilis, which involves NAD-dependent dehydrogenases and β-etherases, has been well characterized for this purpose.[2] Here we focus on the design of a bioanode combining NAD-regenerating properties and the immobilization of lignin degrading enzymatic cascade to cleave such bonds. We explored the possibility of combing in situ electrochemical regeneration of NAD+ cofactor with a surface immobilized biocatalysts on a single interface. First, we have demonstrated that the electrodes based on multiwalled carbon nanotubes modified with toluidine blue are capable to regenerate NAD+ cofactor at low potential from its reduced form. This process is essential for dehydrogenases activities. Secondly, we used cross-linked hydrogel of pyrene-modified linear poly(ethyleneimine) to entrap the enzymes on the electrode surface.[3] The obtained bioanode modified with NAD-regenerating catalyst and the multi-enzymatic cascade of Lig enzymes was tested in the presence of guaiacylglycerol-β-guaiacylether (GGE), a lignin dimer substrate with β-ether bond, to produce γ-hydroxypropiovanillone (HPV). We believe that such electrochemical systems employing the enzymatic cascade acting like a metabolic funnel with the simultaneous regeneration of the cofactor would permit to refine the heterogeneous mixture of aromatics from lignin depolymerization products into a uniform distribution of value-added compounds. [1] Renewable Sustainable Energy Rev., 2022, 157, 112025. [2] Catal. Sci. Technol., 2016,6, 2195-2205. [3] Chem. Sci., 2018,9, 5172-5177. Figure 1

Jiayin Ling, Yanbin Xu, Chuansheng Lu et al.

Energies • 2019

The electricity output from microbial fuel cell (MFC) with a microalgae assisted cathode is usually higher than that with an air cathode. The output of electricity from a photosynthetic microalgae MFC was positively correlated with the dissolved oxygen (DO) level in the microalgae assisted biocathode. However, DO is highly affected by the photosynthesis of microalgae, leading to the low stability in the electricity output that easily varies with the change in microalgae growth. In this study, to improve the electricity output stability of the MFC, a partially submerged carbon cloth cathode electrode was first investigated to use oxygen from both microalgae and air, with synthetic piggery wastewater used as the anolyte and anaerobically digested swine wastewater as the catholyte. When the DO levels dropped from 13.6–14.8 to 1.0–1.6 mg/L, the working voltages in the MFCs with partially submerged electrodes remained high (256–239 mV), whereas that for the conventional completely submerged electrodes dropped from 259 to 102 mV. The working voltages (average, 297 ± 26 mV) of the MFCs with the 50% submerged electrodes were significantly (p < 0.05) higher than with other partially or completely submerged electrodes. The associated maximum lipid production from wastewater was 250 ± 42 mg/L with lipid content of 41 ± 6% dry biomass. Although the partially submerged electrode had no significant effects on lipid production or nitrogen removal in wastewater, there was significant improvement in the stability of the electricity generated under variable conditions.

Wenying Li, Yuxiang Liu, Lijie Wu et al.

Journal of Chemical Technology &amp; Biotechnology • 2020

AbstractBACKGROUNDAn innovative microbial fuel cell (MFC) using Cupriavidus sp. S1 as the biocathode catalyst was developed to improve nitrogen removal from low carbon/nitrogen (C/N) wastewater.RESULTSThe desirable external resistance was 100 Ω in this study, with an optimal total nitrogen (TN) removal efficiency of 95.71%, and a maximum current density and power density of 7583.89 ± 318.11 mA m−3 and 932 mW m−3 at C/N = 2, respectively, which initially confirmed the ability of Cupriavidus sp. S1 to obtain electrons from the electrode. The maximum tolerance of the system at Rext of 100 Ω was C/N = 1, with a TN removal efficiency of 90.87%. Compared with the open circuit, the TN removal increased by approximately 21.60% and 52.02% at C/N = 2 and 1, respectively, which expanded the application area for the dominant denitrifying bacteria S1. Additionally, the system exhibits the obvious merits of less sludge production, low energy consumption and the recovery of some energy.CONCLUSIONBased on these results, domesticated Cupriavidus sp. S1 possesses electrochemical activity. Thus, the system has great potential for efficient and cost‐effective nitrogen removal from nitrate‐containing low C/N wastewater and energy recovery. © 2019 Society of Chemical Industry