Marie Douma, Musong Katche, Nicole Telem et al.

American Journal of Electrical Power and Energy Systems • 2025

The increasing demand for sustainable electricity generation necessitates the exploration of innovative technologies. Biomass technology is emerging as a promising alternative to address the energy crisis for low-power devices and reduce reliance on fossil fuels. One of the methods to generate energy from this biomass is by using microbial fuel cells (MFC). However, the efforts made with this technology are still mainly limited at the laboratory scale, limiting its interest and its utilization for electrical power generation. This paper presents the real-life implementation and feasibility of a dual-chamber microbial fuel cell fabricated with concrete. 15 dual-chamber reactors were manufactured, with a volume of 0.5 liters for each chamber. Inside the anodic chamber, a carbon foam measuring 4.5 x 4.5 cm² was placed and used as the anode electrode. Two different electrode materials were used for the cathode electrodes. Six reactors used 4.5 x 4.5 cm<sup>2</sup> carbon foam while the other 9 used graphite rods of 5 mm diameter and 15 cm long. The anode chamber was inoculated with a mixture of 25% cow dung and 75% tap water and then sealed airtight. Each cathode chamber was filled with 0.5 liters of saline solution. After 7 days of manipulation, the Open Circuit Voltage (OCV) obtained from this investigation ranged from 0.415 V to 0.732 V. That reflects the successful conversion of chemical energy of this waste in the concrete-based microbial fuel cell reactor into electrical energy. The average maximum power density obtained using graphite rod cathodes was 14.15 mW/m² while an average of 20.21 mW/m² was obtained from the MFCs using carbon foam cathodes. When the MFCs were stacked together in series, a total voltage of 8.5 V was observed.

Huong V. H. Tran, Eojin Kim, Bonyoung Koo et al.

Preprints.org • 2020

To obtain an accurate and reproducible experimental results in microbial fuel cell (MFC), it is important to know ‘anode maturation biofilm’ to produce a stable and maximum performance. For this purpose, four single chamber MFCs were tested in this study. The linear sweep voltammetry (LSV) polarization tests illustrated that maximum power densities of three MFCs became stable after 9 weeks. Although there were variations afterwards, such variations were negligible. Average maximum power densities from the 9th to the 17th week were 2,990 mW/m2 (MFC-4), 2,983 mW/m2 (MFC-2), 2,368 mW/m2 (MFC-3) and 837 mW/m2 (MFC-1). Polarization resistance shows that MFC-1 had much larger anode resistance (36.6-85.4 Ω) than the other MFCs (1.7-11.6 Ω). Anodic cyclic voltammetry (CV) shows that current production increased over time and MFC-1 had much smaller current production (24.4 mA) than the other MFCs (31.0-34.9 mA) at 17th week. The increased current production indicates anode biofilm became more mature over time, but overall cell performance did not increased accordingly. Possibly due to the bad inoculation, MFC-1 showed the lowest performance. However, its performance was restored to the initial performance and anode resistance was reduced by 47% at 17th week. This study shows that the optimum anode maturation time is 9 weeks and that bioanode performance is a key factor for MFC performance. This study also shows than LSV polarization and CV tests are accurate and non-destructive measurement methods for diagnosing anode performance.

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Global NEST Journal • 2017

<p>This study investigates the feasibility of using cathode catalyst (Iron phthalocyanine (FePc) combined multi walled carbon nano tubes (MWCNT) and compares the oxygen reduction rate under different conductivity of catholite solution (50 mM, 100mM) in double chamber Microbial Fuel Cell. Microbial fuel cell (MFC) research is going on for few decades to increase the power density and improve the removal efficiency. Iron phthalocyanine (FePc) combined multi walled carbon nano tubes (MWCNT) cathode catalyst showed the highest power density (9.34 w/m2) in 100 mM PBS than 50 mM (7.58 W/m2). The electrodes are characterized by scanning electron microscopy (SEM) and the electrocatylitic activity of the catalyst coated electrodes were examined by cyclic voltammetry(CV). The high power density indicates a potential alternative to precious platinum metal catalyst in treatment as well as electricity production Microbial Fuel cell.</p>

Kumar Sonu, Monika Sogani, Zainab Syed et al.

Research Square • 2024

Abstract The increasing trend in global atmospheric temperature caused by a spike in atmospheric concentrations of carbon dioxide must be addressed as soon as feasible to avoid approaching the point of zero return. Innovative technologies based on the concepts of plant microbial fuel cell (PMFC) may help in this direction by sequestering CO 2 while creating a massive amount of biomass. In the present study, the Aloe vera plant was employed to generate Cleaner and viable bioenergy in a PMFC. The carbonized Ipomoea carnea had a synergistic effect on power production and plant Growth. The highest power output of the PMFC with a carbonized Ipomoea carnea anode was 260 mW/m 2 , which was 186.1 mW/m 2 more than the carbon rod anode. Within 35 working days, high biomass was identified in the carbonized Ipomoea carnea anode, allowing for increased generation bioelectricity.

Akiyama Shingo, Kiyoharu Nakagawa

• 2020

In this study, the effect of the mesopores of Marimo nano carbon (MNC) on power generation performance for anode material of direct glucose fuel cell was investigated. Three types of MNC with different mesopore distributions were used for the catalyst support material, Pt was used as loaded metal. In the glucose fuel cell performance test, MNC having many pores of about 35 nm showed the highest maximum output density of 0.72 mW cm-2 at 5 wt% metal loading and 0.3 M Glucose aqueous solution. The pores of about 30 nm may promote ion diffusion and rapid mass transport of reactants and products. These results indicated that MNC was an effective material as anode material for direct glucose fuel cell.

En Ren Zhang, Yong Cai Zhang

Advanced Materials Research • 2011

The electrochemical interaction between bacteria and electrode should be further strengthened at the present stage in order to develop microbial fuel cells (MFCs) to practical power sources. Developing effective anode materials is an alternative to achieving this goal. In this study, the redox activity of polyaniline (PAn) in neutral pH solution was improved by doping ionic liquid (IL) into the synthesized PAn; and the current output of MFC could be enhanced by using IL doped polyaniline (PAnIL) film as anode material. Both cyclic voltermmeter (CV) measurement and MFC operation showed that PAnIL electrochemically synthesized in solution with 30%(v/v) IL addition exhibited the best performance.

Hamed Farahani, Mostafa Ghasemi, Mehdi Sedighi et al.

Sustainability • 2024

The culture medium composition plays a critical role in optimizing the performance of microbial fuel cells (MFCs). One under-investigated aspect of the medium is the impact of the Wolf vitamin solution. This solution, known to contain essential vitamins like biotin, folic acid, vitamin B12, and thiamine, is believed to enhance bacterial growth and biofilm formation within the MFC. The influence of varying Wolf vitamin solution concentrations (2, 4, 6, 8, and 10 mL) on microbial fuel cell (MFC) performance is investigated in this study. Python 3.7.0 software is employed to enhance and anticipate the performance of MFC systems. Four distinct machine-learning algorithms, namely adaptive boosting (AdaBoost), extreme gradient boosting (XGBoost), categorical boosting algorithm (CatBoost), and support vector regression (SVR), are implemented to predict power density. In this study, a data split of 80% for training and 20% for testing was employed to optimize the artificial intelligence (AI) model. The analysis revealed that the optimal concentration of Wolf mineral solution was 5.8 mL. The corresponding error percentages between the experimental and AI-predicted values for current density, power generation, COD removal, and coulombic efficiency were found to be remarkably low at 0.79%, 0.5%, 1.89%, and 1.27%, respectively. These findings highlight the significant role of Wolf mineral solution in maximizing MFC performance and demonstrate the exceptional precision of the AI model in accurately predicting MFC behavior.

Maksudur R. Khan, M.S.A. Amin, M.T. Rahman et al.

pjct • 2013

Electricity generation from the readily biodegradable organic substrate (glucose) accompanied by decolorization of azo dye was investigated using a two-chamber microbial fuel cell (MFC). Batch experiments were conducted to study the effect of dye and substrate concentration on MFC performance. Electricity generation was not significantly affected by the azo dye at 300 mg/L, while higher concentrations inhibited electricity generation. The chemical oxygen demand (COD) removal and decolorization of dye containing wastewater used in the MFC were studied at optimum operation conditions in anode and cathode, 57% COD removal and 70% dye removal were achieved. This study also demonstrated the effect of different catholyte solutions, such as KMnO 4 and K 2 Cr 2 O 7 on electricity generation. As a result, KMnO 4 solution showed the maximum electricity generation due to its higher standard reduction potential.

Yang Song, Munir H. Nayfeh, Siu-Tung Yau

RSC Advances • 2014

The performance of a yeast MFC is improved by applying a dc voltage V appl to its anode without causing extra energy to be spent on the MFC.

Umair Fazal, AN Tabish, Samina Akbar et al.

Research Square • 2023

Abstract Discharge of wastewater containing traces of cow dung from a dairy farm poses significant threat to the environment, which necessitates the effluent treatment. Microbes present in organic rich dairy effluent containing traces of cow dung produced electricity. The performance of Microbial Fuel Cell(MFC) was analyzed by drawing I-V curves and performing electrochemical impedance spectroscopy (EIS). The MFC produced maximum power density of 203 mWm -2 at a current density of 1191 mAm -2 . The Chemical Oxygen Demand (COD) removal efficiency was found to be 81% after 10 days of MFC operation. Decrease in anode polarization resistance confirmed the formation of biofilm at anode surface.

Linlin Liu, William Varroy, Marc-Antoine Bansept et al.

ChemRxiv • 2024

In this work, we present a new “all-graphite” concept in microfluidic fuel cells, applied to microbial fuel cells (MFCs). The all-graphite microfluidic MFCs were fabricated by milling channels directly into the electrodes. Two such electrode channels were affixed face-to-face with separation by an ion exchange membrane to form a complete MFC. Three such MFCs were fabricated with simple straight channels having different channel heights and activated with pure culture anaerobic Geobacter sulfurreducens electroactive biofilm. After the proof-of-principle and correlation between the channel height and electroactive biofilm thickness, we demonstrated improvements on power and current outputs using a fourth design, which featured a high surface area provided by pillars. A high acetate conversion efficiency of more than 80% and low internal resistance of 1.2 kΩ were achieved using the pillar MFC. Additionally, a high-power density of 4.7 W m-2 was obtained with a straight channel MFC.

Charitha Basnayaka, Maheshi Somasiri, Ahmed Ahsan et al.

Research Square • 2024

Abstract Marine photosynthetic Microbial fuel cells (mpMFCs) can utilize marine photosynthetic microorganisms to drive electrical energy generating electrochemical reactions. Due to improved ionic mobility and superior electrical conductivity of sea water, it is a suitable electrolyte for operating bio-electrochemical devices at operating elevated salinities. This study examined the use of seawater as a conducting medium in two-chambered MFCs to enhance power production in conjunction with a marine photosynthetic bio-cathode as an alternative to the abiotic chemical cathode. Using a modified BG11 seawater medium as catholyte, marine cyanobacteria were grown and maintained in the MFC cathode compartment. After a significant quantity of biomass had formed, it was harvested for use as the substrate for anode microorganisms. Isolated marine cyanobacteria from photosynthetic biocathode were identified using 16s rRNA and Sanger DNA sequencing. In electrochemical characterization, mMFC, maximum power density (P max ) was 147.84 mW/m 2 and maximum current density (J max ) reached 1311.82 mA/m 2 . In mpMFC, P max was 104.48 mW/m 2 and J max was 1107.27 mA/m 2 . P max was 53.14 mW/m 2 and J max was 501.81 mA/m 2 in comparable freshwater MFC employing platinum catalyst, which proves that mMFC & mpMFC worked better. Dapis pleousa & Synechococcus moorigangaii were identified as dominant marine cyanobacteria. It was demonstrated that mpMFC, operated using seawater, employing a cyanobacteria biocathode, is suitable for circularized renewable energy production. The outcomes of this study implies that, mpMFCs are good candidates for circular renewable energy production.

Tesfalem Atnafu, Seyoum Leta

Research Square (Research Square) • 2021

Abstract BackgroundMicrobial fuel cells (MFCs) drawbacks are anode (cathode) limitation and electrochemical loss. Engineering the biofilm for enhanced attachment to the electrode is the prospect of MFC. Recent studies, recommend the formation of thick anode biofilm that could result in a synergetic effect between microbial communities. To address these issues, a microbial electrode jacket dish (MEJ-dish) was invented that supports microbial growth over the anode electrode surface. The MFC reactor with MEJ-dish was hypothesized to develop a fragment of biofilm (thick and thin) across the electrode. This reactor is called a fragmented electroactive biofilm-microbial fuel cell reactor (FAB-MFC).ResultsThe maximum voltage generated (0.87 V) was recorded in FAB-MFC. In addition, during the first 3-10 days, the FAB system enables to significantly (p<0.05) maximize the voltage generation at pH variation from 6.5 to 7.5. However, at alkaline pH 8.5, the FAB system generates a lower voltage relative to non-FAB. On the contrary, in FAB reactors the COD removal was improved regardless of pH variation (6.5-8.5). This shows, unlike voltage generation, the biofilms (either electroactive or not) formation were vital for COD removal even without voltage generation. At acidic and neutral pH (7.5), the fragmented (hybrid) biofilm formation across the bioelectrode (anode) could not only important for voltage generation but also contributes to the effective functioning of electroactive biofilm (EABs) growth and development by reducing the effect of pH variation. To address this contradictory effect of increasing COD removal associated with the lower voltage at higher pH, might be to use both FAB and non-FAB in a single MFC reactor. There might be a mutualistic effect across the bioelectrode biofilms.ConclusionsThis study showed that the voltage generated was significantly higher in FAB-MFC as compared with non-FAB-MFC setup within limited pH (6.5-7.5); relatively, COD removal was enhanced within wider pH 6.5-8.5. This supports the conclusion that biofilm formed across the FAB was vital for COD removal, even though not participated in voltage generation. However, this might be affected by the degradable organic content and the nature of the microbial community in the inoculum and domestic wastewater, which requires further studies.

Praveena Gangadharan, Indumathi M Nambi

Research Square • 2020

Abstract The study investigates the performance of Cu 2+ as dissolved cathodic electron-shuttle mediator (dcESM) for simultaneous Cr 6+ reduction and electricity generation in a microbial fuel cell (MFC) at pH 2 and 4 conditions. The dcESM behavior of Cu 2+ on carbon cloth (CC) catalyzes the reduction of Cr 6+ into Cr 3+ at pH 2 by undergoing redox reactions. However, at pH 4, a simultaneous reduction of Cu 2+ and Cr 6+ was observed. Cyclic voltammetry (CV) studies were performed at pH 2 and 4 to probe the dcESM behavior of Cu 2+ for Cr 6+ reduction on CC electrode. Also, at pH 2, increasing the concentration of Cu 2+ from 50 mg L -1 to 500 mg L -1 favors the Cr 6+ reduction by reducing the reaction time from 108 h to 48 h and improving the current production from 3.94 mA m -2 to 6.24 mA m -2 , respectively. Nevertheless, at pH 4, the efficacy of Cr 6+ reduction and electricity generation from MFC is decreased from 62.91% to 18.21% and 4.42 mA m -2 to 1.10 mA m -2 , respectively, by increasing the Cu 2+ concentration from 50 mg L -1 to 500 mg L -1 . Furthermore, the performance of dcESM behavior of Cu 2+ was explored on carbon felt (CF) and platinum (Pt) electrodes, and compare the results with CC. In MFC, at pH 2, with an initial concentration of 100 mg L -1 , the reduction of Cr 6+ in 60 h is 9.63 mg L -1 for CC, 0.17 mg L -1 for CF, and 51.32 mg L -1 for Pt cathodes. The reduction of Cr 6+ (initial concentration of 100 mg L -1 ) at pH 4 in 120 h is 44.72 mg L -1 for CC, 32.13 mg L -1 for CF, and 70.85 mg L -1 for Pt cathodes. Maximum power densities of 1659 mW m -2 , 1509 mW/m -2 , and 1284 mW/m -2 were achieved when CF, CC, and Pt, respectively were employed as cathodes in the MFC.

Xinhong Peng, Xizhang Chu, Shenghui Wang et al.

RSC Advances • 2016

Ni–ferrite-decorated anode enhanced the MPD by 26% to 806.4 mW m −2 .

Paulo Henrique da Silva, Ilka Djanira Ferreira do Nascimento, Galba Maria de Campos-Takaki

Research, Society and Development • 2022

For decades, non-renewable energy resources have been used indiscriminately, but their slow depletion and extremely harmful impacts on the environment have shifted the focus to sustainable and renewable energy sources. Among the renewable energy sources, biofuel cells are defined as devices that convert chemical energy present in chemical bonds into electrical energy. Biocells are classified into two broad categories of enzymatic fuel cells, which employ enzymes as biocatalysts, and microbial fuel cells, which use microorganisms as biocatalysts. An important requirement in the functioning of a biofuel cell is the transfer of electrons from inside an active site of an enzyme to the outside, as the electrodes being solid cannot penetrate the enzymes. A wide range of molecules can be used as electrochemical mediators, some with high toxicity and many non-toxic fungal substances having an enormous potential to be used as electrochemical mediators. In this work, the fungal pigment bikaverin was compared to the synthetic dye Congo red, in order to obtain the best energy-optimizing molecule in an enzymatic fuel cell. Congo red presented a higher current density of 273 mA.cm-2 compared to bikaverin, 230 mA.cm-2, but because it presents a more stable chronoamperometric graph and does not have high toxicity, the fungal biopigment proved to be the best option for optimization. on the potential of energy generated in an enzymatic fuel cell.

Hussein H. Abd-almohi, Ziad T. Alismaeel, Mohanad J. M-Ridha

Al-Khwarizmi Engineering Journal • 2022

Microbial Desalination Cell (MDC) is capable of desalinating seawater, producing electrical power and treating wastewater. Previously, chemical cathodes were used, which were application restrictions due to operational expenses are quite high, low levels of long-term viability and high toxicity. A pure oxygen cathode was using, external resistance 50 and 150 k Ω were studied with two concentrations of NaCl in the desalination chamber 15-25 g/L which represents the concentration of brackish water and sea water. The highest energy productivity was obtained, which amounted to 44 and 46 mW/m3, and the maximum limit for desalination of saline water was (31% and 26%) for each of 25 g / L and 15 g / L, respectively, when using an external resistance of 150 KΩ. At 50 KΩ, 13 and 12 mW/m3 were obtained, and the maximum desalination limit were 20% and 2% when using 25 g / L and 15 g / L, respectively. The concept of the mixing process was introduced in the desalination chamber to improve the performance of the system, where the highest energy productivity was obtained, which amounted 45 and 47 mW/m3, and the percentage of salt removal in the desalination chamber were 40% and 55% when using 15 g/L and 25 g/L and 150 KΩ, respectively. This study demonstrated a promising approach to using the mixing process in the desalination room in order to increase the desalination and electrical productivity.

Yucui Shi, Yongwei Li, Qing Liu et al.

Environment Protection Engineering • 2023

A new type of bioelectrochemical system features a constructed wetland (CW) coupled with a microbial fuel cell (MFC) to treat Cr(VI) wastewater while generating electricity. The optimal operating parameters for treating wastewater containing Cr(VI) are discussed. The results show that the CW-MFC system is more effective in the treatment of Cr(VI)-containing wastewater and generating electricity. A COD concentration of 300 mg/dm 3 corresponded to the greatest COD and Cr(VI) removal rates with a maximum power density of 505.62 mW/m 3 , whereas a Cr(VI) concentration of 80 mg/dm 3 yielded the greatest COD removal rate, with a maximum power density of 484.43 mW/m 3 . A hydraulic retention time (HRT) of 3 days yielded the largest pollutant removal rates with a maximum power density of 479.21 mW/m 3 . Considering that the comprehensive operating conditions of CW-MFC are based on planting plants, the COD concentration is 300 mg/dm 3 , the Cr(VI) concentration is 80 mg/dm 3 , and the HRT is 3 days. The abundance of electrogenic bacteria Geobacter and metal dissimilatory reducing bacteria Acinetobacter in CW-MFC is higher than that in the control group. The results of this study provide theoretical guidance for determining the optimal operating conditions and energy recovery of the CW-MFC system for treating chromium wastewater.

Lisa Deleebeeck, Kent Kammer Hansen

Journal of Fuel Cell Science and Technology • 2015

The influence of the current collector on the performance of a hybrid direct carbon fuel cell (HDCFC), consisting of solid oxide fuel cell (SOFC) with a molten carbonate–carbon slurry in contact with the anode, has been investigated using current–voltage curves. Four different anode current collectors were studied: Au, Ni, Ag, and Pt. It was shown that the performance of the direct carbon fuel cell (DCFC) is dependent on the current collector materials, Ni and Pt giving the best performance, due to their catalytic activity. Gold is suggested to be the best material as an inert current collector, due to its low catalytic activity.

Subhashis Das, Rajnish Kaur Calay

Energies • 2022

Microbial fuel cells (MFCs) are a kind of bioreactor for generating electricity, facilitated by exoelectrogens while treating wastewater. The present article focuses on the performance of an air cathode plexiglass MFC in terms of chemical oxygen demand (COD) removal efficiency and power output by performing two sets of experiments. The proton exchange membrane and electrode materials were Nafion 117 and carbon felts, whereas, for stable biofilm formation on the anode surface, a pure culture of Shewanella baltica 20 was used. Firstly, sterile Luria-Bertani (LB) media containing lactate, ranging from 20 to 100 mM, was continuously fed to an MFC, and a maximum power density of 55 mW/m2 was observed. Similarly, artificial wastewater with COD ranging from 3250 mg/L to 10,272 mg/L was supplied to the MFC in the second set of experiments. In this case, the maximum power density and COD removal efficiency were 12 mW/m2 and 57%, respectively. In both cases, the hydraulic retention time (HRT) was 1.5 h. It was found that electricity generation depends on the characteristics of the wastewater. These initial findings confirm that the design aspects of an MFC, i.e., surface area to volume ratio, and external resistance with respect to the quality of influent need to be optimised to improve the MFC’s performance.

D. Vidhyeswari, A. Surendhar, S. Bhuvaneshwari

Water Science and Technology • 2021

Abstract The aim of this study is to synthesise SPEEK composite proton exchange membrane with the addition of TiO2 nanofillers for microbial fuel cell application. SPEEK composite membrane with varying weight percentage of TiO2 (2.5, 5, 7.5 and 10%) was prepared to study the effect of TiO2 concentration on membrane performance. Synthesized composite membranes were subjected to various characterization studies such as FT-IR, XRD, Raman spectroscopy, TGA, UTM and SEM. Physico-chemical properties of membrane such as water uptake capacity, ion exchange capacity and thickness were also analyzed. 5% TiO2 – SPEEK composite membrane exhibited the higher water uptake capacity value and Ion exchange capacity value of 31% and 1.71 meq/g respectively. Performance of the MFC system with TiO2 – SPEEK membranes were evaluated and compared with the pristine SPEEK and Nafion membrane. 5% TiO2 – SPEEK membrane produced the higher power density (1.22 W/m2) and voltage (0.635 V) than the other membranes investigated. Efficacy of MFC in wastewater treatment was evaluated based on the chemical oxygen demand (COD), total organic carbon content and turbidity. Biofilm growth over the surface of the electrodes was also analyzed using scanning electron microscopy.

Iwona Gajda, Buddhi Arjuna Mendis, John Greenman et al.

• 2020

<p>A microbial fuel cell (MFC) is a renewable energy converter, which transforms organic biomass directly into electricity, using biofilm-electrode metabolic interaction within a bioelectrochemical cell. Efficiency of this transformation can be enhanced through miniaturisation. Miniaturisation of MFCs offers higher surface-area-to-volume ratio and improved mass transfer.</p> <p>The development of mL-scale; power dense and low cost MFCs, are of great interest in diverse areas of research, ranging from modern bio-robotics, internet-of-things devices, electrical energy generation, remote sensing to wastewater treatment and mineral recovery. The biofilms increased ability in converting organic pollutants into electric power more efficiently, makes mL-sized MFCs attractive for the development of multi-modular stacks and usable off-grid power sources with an ability of enhanced wastewater treatment. This work focuses on small scale MFCs; i) minimising the distance between feeding stream and the biofilm, ii) construction and analysis of a  millilitre scale prototype, using a low cost ceramic separator for higher energy recovery efficiency and sensitivity enhancement to substrates and pollutants. The study aims to test efficient cathode modifications, using graphene ink and magnetite (Fe<sub>3</sub>O<sub>4</sub>); in order to improve the oxygen reduction reaction (ORR). This in turn is envisioned in an increase of the output, reaching comparable power levels to the larger MFC prototypes tested so far. The additives are chosen such that,  both graphene and iron–based oxides are known from the literature to be catalysts for electrochemical processes, this work focusses on their incorporation into the open-to air cathode in novel, low cost MFC bioreactors.</p> <p>The miniaturised MFC construction constituted of an in-house fabricated small scale ceramic cylinder of internal volume of 3.88 mL. An anode, made of carbon veil fibre with a coating of activated carbon powder, was placed inside the ceramic cylinder, while the cathode was attached to the outer surface of the structure. Three types of cathodes were tested: i) activated carbon as the control (AC), ii) AC with a graphene ink coating (AC+G) and iii) AC with graphene ink and magnetite powder blend (AC+G+M). Experiments were conducted in triplicate using activated sludge and urine inoculum and thereafter continuously supplemented with 100% real human urine. The results show that the control produced up to 0.85 mW (219 W/m<sup>3</sup>), while AC+G produced 1.22 mW (312 W/m<sup>3</sup>), and AC+G+M 1.12 (288 W/m<sup>3</sup>) which is a 44 % and a 32 % increase respectively in comparison to the control. Comparison of linear sweep voltammetry (LSV) showed superior performance of both modified electrodes against the unmodified AC cathode; further resulting in an enhancement of ORR reaction rate. Power outputs from this work show over 14 times improvement in power density levels in comparison to larger reactors of 20 times the volume, as well as comparable raw (actual) power levels. This makes these novel small-scale bioreactors particularly attractive for use in numerous practical applications such as energy autonomous robots (e.g. EcoBots) and multi-modular stacks for off-grid energy sources.</p> <p> </p>

Ankisha Vijay, Prakash C. Ghosh, Suparna Mukherji

Energies • 2023

Saline wastewater pollution is a critical issue that needs to be addressed. The present study focused on the development of a dual-chambered microbial fuel cell (MFC) treating saline wastewater at the anode. Halophilic exo-electrogenic bacteria enriched from seawater (Arabian Sea, Mumbai, India) were used in the anodic chamber of the MFC. Denitrification using denitrifying bacteria was employed in the cathodic chamber. The maximum power density was significantly increased from 96.77 mW/m2 to 162.09 mW/m2 with a rise in NaCl concentration from 20 to 40 g/L. Nitrate removal in the cathode chamber increased from 80 ± 3% to 89 ± 3.2% with increase in salt concentration from 20 g/L to 40 g/L and concomitantly COD removal in the anode chamber increased from 76 ± 3.8% to 83 ± 4%. Cyclic voltammetry (CV) analysis revealed higher electrochemical activity at 40 g/L salt concentration. Electrochemical impedance spectroscopy (EIS) analysis exhibited that charge transfer and solution resistances were lower when the salinity was increased. Microbial community analysis revealed the presence of Clostridium, Shewanella, and Bacillus as the most abundant genera in the anodic chamber. This study demonstrated the dual applicability of the system targeted for removal of organics from saline wastewater and nitrate removal from contaminated wastewater accompanied by power generation from the MFC.

Shunliang Liu, Yali Feng, Haoran Li

bioRxiv (Cold Spring Harbor Laboratory) • 2021

Abstract The inhibitory effect of electron mediator 2,6-anthraquinone disulphonate (AQDS) on Geobacter metallireducens nanowire in the microbial fuel cell (MFC) was studied. In the culture process of G.metallireducens with Fe(OH) 3 as an electron acceptor, the concentration of reduction product Fe (II) in solution without AQDS was higher than that with AQDS after 10 days, due to the formation of microbial nanowires. The effects of nanowire on electron transfer efficiency and electrical current characteristic were studied using a double chamber MFC reactor. The transfer efficiency between biofilm and electrodes was increased by nanowire, which increased the maximum output voltage of MFC was 442 mV. The nanowire biofilm electrode had a bigger cyclic voltammetry curve peak, smaller activation resistance, and a stronger current response signal through electrochemical measurement, which indicates that the nanowire enhanced the electrochemical activity of the electrode.

Yan-Ming Chen, Chin-Tsan Wang, Yung-Chin Yang

Energies • 2018

Hydrodynamic boundary layer is a significant phenomenon occurring in a flow through a bluff body, and this includes the flow motion and mass transfer. Thus, it could affect the biofilm formation and the mass transfer of substrates in microbial fuel cells (MFCs). Therefore, understanding the role of hydrodynamic boundary layer thicknesses in MFCs is truly important. In this study, three hydrodynamic boundary layers of thickness 1.6, 4.1, and 5 cm were applied to the recirculation mode membrane-less MFC to investigate the electricity production performance. The results showed that the thin hydrodynamic boundary could enhance the voltage output of MFC due to the strong shear rate effect. Thus, a maximum voltage of 22 mV was obtained in the MFC with a hydrodynamic boundary layer thickness of 1.6 cm, and this voltage output obtained was 11 times higher than that of MFC with 5 cm hydrodynamic boundary layer thickness. Moreover, the charge transfer resistance of anode decreased with decreasing hydrodynamic boundary layer thickness. The charge transfer resistance of MFC with hydrodynamic boundary layer of thickness 1.6 cm was 39 Ω, which was 0.79 times lesser than that of MFC with 5 cm thickness. These observations would be useful for enhancing the performance of recirculation mode MFCs.

Linlin Liu, Haleh Baghernavehsi, Jesse Greener

Preprints.org • 2024

High-power output and high conversion efficiency are crucial in the study of microfluidic microbial fuel cells (MFCs). In our previous work, we attempted various methods to increase the power density of the MFCs, but nutrient consumption was limited to the bottom (electrode) layer of the microfluidic channel due to the diffusion limitations. In this work, long-term experiments were conducted on a new 4-electrode microfluidic MFC design, which grew Geobacter sulfurreducens biofilms on upward- and downward-facing electrodes in the microchannel. It was discovered that inoculation and growth of the electroactive biofilm did not proceed as fast as the downward facing anode, which we hypothesize is due to gravity effects that negatively impacted bacterial settling on that surface. Rotating the device during the growth phase resulted in uniform and strong outputs from both sides, yielding individual power densities of 4.03 and 4.13 W m-2, which was increased to nearly double when the top- and bottom-side electrodes were operated in parallel as a single 4-electrode MFC. Similarly, acetate consumption could be doubled with the 4-electrodes operated in parallel.

, Sarunyou Kasemanand

• 2015

In this research, a biogas sorption enhanced chemical looping reforming (SECLR) process integrated with high temperature proton exchange membrane fuel cell (HT-PEMFC)is analyzed. The thermodynamic concept and electrochemical model are used to identify the suitable operating conditions of the proposed process. Exergy and energy analyses are used to describe the effect of various parameters, such as reforming temperature, steam-to-biogas molar ratio, CaO-to-biogas molar ratio and NiO-to-biogas molar ratio, on the process performance. The exergy destruction of each unit is employed to identify the quality of energy that is used in each unit. The data obtained can be used to improve the energy and exergy efficiencies of the process. The simulation results show that the exergy efficiency of the process is improved from 16.60% to 26.72% when a process heat integration is applied.

, Juan Carlos Trujillo Caballero

• 2012

PEMFCs are the most popular type of Fuel Cells (FCs) and traditionally use hydrogen as the fuel. One FC problem is its relative slow dynamics caused by the time constant of the hydrogen and oxygen supply systems that can be in the range of several seconds. In this sense, supercapacitors (SCs) respond faster than FC to a fast increase or decrease in power demand. Thus, using SCs together with FCs improves FC life and performance by absorbing faster load changes and preventing fuel starvation of the FC. Therefore, it becomes necessary to study structures of power conditioners with their respective control systems that can mitigate the disadvantages mentioned of the FC itself. Several researches have studied the different topologies with their respective control proposals to operate FC and SC. This thesis proposes a digital control scheme to operate a PEMFC module of 1.2 kW and a SC through a DC/DC hybrid converter. A FC has been proposed as a primary source of energy and a SC has been proposed as an auxiliary source of energy. An experimental validation of the system implemented in the laboratory is provided. Several tests have been performed to verify that the system achieves an excellent output voltage (V0) regulation and SC Voltage (VSC) control, under disturbances from FC power (PFC) and output power (P0) as well as other perturbations described in analysis results.

, Ana Sotres Fernández

• 2015

A microbial fuel cell (MFC) is a bioelectrochemical system (BES) capable of converting the chemical energy contained in the chemical bonds of a substrate into electrical energy by means of electrochemical reactions catalyzed by microorganisms. The amount of energy to be gained by bacteria capable of transferring electrons to an anode is significantly higher compared to other alternative electron acceptors. Exoelectrogenic microbial populations tend to be selectively enriched on the anode electrode, being essential for the performance improvement of the MFC in terms of electricity production from organic matter oxidation. MFC technology arises as an attractive alternative for the treatment of high strength animal wastewater, such as pig slurries, to potentially improve energetic valorisation of organic wastes, concomitantly to carbon and nitrogen content reduction or recovery. The first part of the thesis (Chapters 4, 5 and 6) focuses on the study of microbial populations harboured on the anode electrode of MFCs. The effect of different ion exchange membrane materials and different inoculum sources over the microbial population was studied in discontinuously fed MFCs. A detailed study of the microbial community dynamics and composition onto the anode biofilms, under different feeding conditions (synthetic wastewater and the liquid fraction of pig slurry), was then studied in continuously fed MFC. A highly diverse microbial community is shown to be present under these different scenarios and, its final composition is being dependent on the factors studied. The second part of the thesis is focused on understanding the nitrogen dynamics in a two-chambered MFC, and the possible strategies available to remove or recover it. First of all, the diffusion/migration of ammonia nitrogen through the cation exchange membrane was studied in batch essays under different operational conditions (Chapter 7). The results obtained showed that the diffusion/migration of ammonia nitrogen is dependent on the voltage applied and, when using pig slurry, ammonia migration reaches values close to 50%. These results suggested that the use of MFC technology could be a good strategy to deal with the nitrogen excess in this kind of substrates. Two different processes for MFC nitrogen recovery and removal were developed. First, a physicochemical-based process for nitrogen recovery was developed coupling a stripping-absorption unit to the cathode chamber (Chapter 7). Results showed the stripping/absorption-BES system is a feasible technology to recover ammonia from pig slurries. Second, a nitrogen removal strategy by means of biological processes was studied using synthetic high strength wastewater as feed (Chapter 8). In this case, the ammonia nitrogen migrating from the anode to the cathode, was removed applying intermittent aeration cycles in the cathode chamber of the MFC where a concomitant nitrifying-denitrifying microbial community being established. The feasibility to recover/remove nitrogen from high strength animal wastewater, such as pig slurries, using different MFC strategies has been demonstrated at lab scale. Hence, it can be considered as a potential technology for scaling up the treatment of high strength (organic and nitrogen) wastewaters, so as to accomplish the requirements needed for agricultural uses. Likewise, the knowledge acquired about the biofilm developed on the anode reveals itself as a key point for the resilience of BES at different environmental conditions and for further developments. Una celda de combustible microbiana (MFC), es un tipo de sistema bioelectroquímico (BES) capaz de convertir la energía contenida en los compuestos químicos en energía eléctrica mediante reacciones electroquímicas catalizadas por microorganismos. Las poblaciones de microorganismos exoelectrogénicos tienden a enriquecerse selectivamente en los electrodos del compartimento ánodico, siendo esenciales para la mejora del rendimiento de las MFCs en términos de producción de electricidad a partir de la oxidación de la materia orgánica. La tecnología de las MFCs se plantea como una alternativa para el tratamiento de aguas residuales de alta carga de origen animal, como por ejemplo los purines, para mejorar potencialmente su valorización energética, vinculada a la reducción o recuperación del contenido de carbono y nitrógeno. La primera parte de esta tesis (Capítulos 4, 5 y 6) está centrada en el estudio de las poblaciones microbianas hospedadas en los electrodos de las MFCs. Se estudió el efecto de diferentes tipos de materiales de membranas de intercambio iónico, así como inóculos de diferente naturaleza, sobre las poblaciones de microorganismos en MFCs operando en discontinuo. Posteriormente, se realizó un estudio más detallado de la dinámica y la composición microbiana establecida sobre el biofilm del ánodo, bajo diferentes condiciones de alimentación (agua residual sintética y la fracción líquida de purín porcino), en MFCs operadas en modo continuo. Bajo estas condiciones de estudio, se mostró una elevada diversidad de la comunidad microbiana, siendo la composición final dependiente de los factores estudiados. La segunda parte de la tesis está centrada en el estudio de la dinámica del nitrógeno en MFCs de doble compartimento, y el desarrollo de posibles estrategias para eliminarlo o recuperarlo. Primero, se estudió la difusión/migración del amonio a través de una membrana de intercambio catiónico, en experimentos en discontinuo bajo diferentes condiciones de operación (Capítulo 7). Los resultados obtenidos mostraron que la difusión/migración del amonio es función del voltaje aplicado, y cuando se usan purines, la migración de amonio llega a valores cercanos al 50%. Estos resultados sugirieron que el uso de la tecnología de las MFCs podría ser una buena estrategia para tratar el exceso de nitrógeno de esta clase de residuos orgánicos. Se desarrollaron dos procesos diferentes de recuperación y eliminación de nitrógeno. Primero, se desarrolló un proceso fisicoquímico para la recuperación de nitrógeno acoplando una unidad de stripping/absorción al compartimento catódico (Capítulo 7). Los resultados mostraron que este sistema de BES-stripping/absorción se puede considerar como una tecnología factible para llevar a cabo la recuperación del nitrógeno de los purines. En segundo lugar, se estudió una estrategia de eliminación de nitrógeno mediante procesos biológicos, utilizado en este caso agua residual sintética de alta carga (Capítulo 8). En este caso, el amonio que migró desde el ánodo al cátodo, fue eliminado aplicando ciclos intermitentes de aireación en el compartimento catódico de la MFC, lo que provoca el establecimiento de una población nitrificante-desnitrificante. La viabilidad para recuperar/eliminar nitrógeno de aguas residuales de alta carga de origen animal, como purines, mediante MFCs ha sido demostrada a escala de laboratorio utilizando diferentes estrategias. Por lo tanto, se puede considerar, que es una tecnología potencialmente aplicable en el tratamiento de aguas residuales de alta carga (carbono y nitrógeno), así como para lograr los requerimientos necesarios para uso agrícola. Igualmente, el conocimiento adquirido sobre el desarrollo del biofilm en el ánodo, revela que es un factor clave para la adaptabilidad de BES en diferentes condiciones medioambientales y para futuros desarrollos.

, Nattakarn Prasertsung

• 2011

This study examined the effects of the organic loading rate (OLR), pH and the temperature in cassava wastewater treatment and the power generated by a single microbial fuel cell. The study was divided into two parts under temperature of 45 ℃ and 30 ℃. The first part was examined the effect of OLR of 0.56, 1.44, 2.79, 4.14 to 6.25 kg-COD/m³-d at pH 7.0 to remove COD and generate electricity. The second part was examined the effect of pH at 5.0, 5.5, 6.0, 6.5, 7.5, 8.0, 8.5 and 9.0 on OLR of 0.56 kg-COD/m³-d to remove COD and generate electricity. When controlled pH 7.0, the efficiency of COD removal was achieved at maximum from the OLR of 0.56 kg-COD/m³-d at both temperatures. The efficiency of COD removal was 91.44 ± 0.72% and 90.72± 0.87% at 30 ℃ and 45 ๐C respectively. The maximum of power density was obtained from OLR of 6.25 kg-COD/m³-d, which the value was 28.68 W/m3 at 30 ๐C and 27.85 W/m3 at 45 ℃. The maximum of coulombic efficiency was obtained from the OLR of 0.56 kg-COD/m³-d which was 30.2% at 30 ℃ and 28.5% at 45 ℃. The temperature affected on the electron transferring from anode to cathode. At the lower temperature, electron was able to transfer from anode to cathode more effectively than at higher temperature. High temperature caused high electrical resistant, so the power output decreased when temperature increased. At OLR of 0.56 kg-COD/m³-d, the maximum efficiency of COD removal was achieved at a pH of 7.5 at both temperatures. The efficiency of COD removal was as 96.77 ± 0.93% and 95.93± 1.44% at 30 ℃ and 45 ℃ respectively. The maximum of power density obtained from pH 8.5 which the values were 30.30 W/m³ at 30 ℃ and 26.06 W/m³ at 45 ℃. The maximum of coulombic efficiency was obtained from pH 8.5 which was 52.9% at 30 ℃ and 50.6% at 45 ℃. The microbial communities in the anode of a single chamber microbial fuel cell under 30 ℃ could be divided into four groups as Gammaproteobacteria, Betaprotobacteria, Bacteroidetes and Firmicutes. While under 45 ℃ operation, the microbial communities could be divided into three groups as Gammaproteobacteria, Betaprotobacteria and Firmicutes. The microbial communities included several fermentative bacteria, exocellular electron-transfer, methane oxidizers, sulfate-reducing bacteria and groups of facultative bacteria.

, Kamol Rodyou

• 2008

Bacteria enriched under various electricity currents, were selected for tested in mediator-less microbial fuel cell. Total of 72 electricity enriched bacteria were isolated from three sources including, 28 isolates from sediment of pond in front of Physic I building, Chulalongkorn University, 40 and 4 isolates from sub-sediment from Koh Larn, Chonburi and soil from Phu Rua, Loei, respectively. Ferric reduction activity of all isolates under anaerobic condition was also characterized. Preliminary experiment found that acrylic model was not suitable for operating mediator-less MFC. Glass I and Glass II models were later designed and constructed for sterile system that suitable for microbiological aseptic techniques. Pure culture of 40 isolates of electricity enriched bacteria from Koh Larn were determined the ability of their self-mediate electron transfer in Glass I model. It can be concluded that ferric reduction activity has more impact than electricity current that used for selection and enrichment on the electricity generation of isolates in mediator-less MFC. In Glass I model, 12 isolates of Gram’s negative, ferric reducing, swarming bacteria from Koh Larn gave high current density ~11-13 mA m-2. After tested in Glass II, the highest of 18.57 mA m-2 and 0.62 mW m-2 for current density and power density, respectively were generated by KL22. These indicated that the increase of current density and power density more than those of Glass I, 67 % and 179%, respectively. As the results, anaerobic condition in anodic compartment enhanced electron transfer to anode electrode led to the increasing of electricity output. KL22 was identified as Proteus vulgaris by using 16S rDNA analysis and rapid identification kit API 20E. Proteus vulgaris can biocatalyse successfully in mediator-less MFC system from this study is firstly reported. Further improvements by optimizing the physical and chemical parameters of microbial fuel cells for the sustainable alternative energy in the future are required.

, Kamol Rodyou

• 2015

This dissertation studied the effect of anode electric current stimulation on open circuit voltage (Voc), current density and power density of MFC. Parameters which were used for electric current stimulation were stimulation periods, enrichment medium, carbon source in MFC, type and magnitude of electric current, and source of sediment. In addition, effect of nutrient broth (NB) and phosphate buffer basal medium (PBBM) on biofilm formation of stimulated anode were examined. Biofilm formation on anode was investigated under field emission scanning electron microscope (FESEM). It was found that thick biofilm was observed on AC stimulated anode at 10-15 mA. In addition, the different medium used in the enrichment of biofilm during AC stimulation led to the different characteristics of biofilm. Bacterial community on stimulated anode was isolated from biofilm anode. Electrochemical active bacteria (EAB) such as Shewanella putrefaciens, which effectively transferred electron to anode was isolated. The effect of AC stimulation on pure isolate showed that S. putrefaciens viable cell count was dramatically decreased (4 logCFU) when stimulated with 15 mA AC stimulation. In this dissertation, the highest Voc of 989 mV, produced from propionate-fed MFC with 60 days unstimulated anode in PBBM medium. However, the highest current density of 72.9 mA and power density of 13.4 mW m-2, produced from acetate-fed MFC with 60 days, 5-10 mA AC stimulated anode in PBBM medium. Moreover, AC stimulation on anode can be used to stimulate different sources of sediments. Furthermore, application of stimulated anode for COD removal and electricity production was also investigated. It was found that the highest COD removal of 60% and 48 mA m-2 current density was obtained from molasses-fed MFC by using 10 mA AC stimulated anode. Thus, it could be concluded that electric current stimulation is a high potential tool for selecting effective bacterial community on electrode and using as anode for the MFC.

Manuela Rueda, Francisco Prieto, Julia Alvarez-Malmagro

ECS Meeting Abstracts • 2016

Biological relevant molecules are known to get adsorbed at the electrode/electrolyte interface and the study of their adsorption is interesting in relation to biosensors design and development of supra-molecular vectors for drugs delivery. On the other hand, the structure and electrical properties of biomembranes are frequently modeled by modifying electrode surfaces with lipidic films. The study of these lipidic film coated electrodes is also relevant in relation to drugs delivery vectors. Both cases of electrode interfaces are usually characterized by capacitance measurements as a function of potential with the implicit assumption of a serial RC model circuit for the metal/solution interface. However, the application of the electrochemical impedance spectroscopy (EIS) and the corresponding analysis of data as a function of the frequency and of the applied potential to the electrode can provide detailed information about the kinetics of adsorption 1,2 , biomembrane reorganization phenomena and electron transfers through the film 3 . In this communication the application of EIS to bioelectrochemical interfaces is illustrated by studying examples of the two kinds of electrode interfaces. The adsorption of adenine, one of the DNA bases, on single crystal Au(111) electrode is presented as an example of a Gibbs adsorption electrode interface, in which the adsorbate is present in the metal and the electrolyte phases, while the study of modified electrodes with phospholipid films exemplifies the electrochemical behavior of organized biomembrane coating the metal with the polar heads of the lipidic chains directed towards the electrolyte solution part of the interface. The experimental procedures In the case of the two kinds of interfaces have to be designed in order to avoid interference of surface reconstruction phenomena (in the case of the work with single crystal electrodes) or film reorganization phenomena (in the case of phospholipids modified electrodes). The results about adenine adsorption as a function of the pH of the solution allow us to evaluate the kinetics of the adsorption and their correlation with results previously obtained by the authors using FT-IR-spectro-electrochemical methods 1,2 . The results about phospholipids film coated electrodes allows us to conclude about the stability of the film as a function of the electric field and to analyze the plausible electron transfer through them, when adding electroactive compounds to the solution phase. [1].- M. Rueda, F. Prieto, A. Rodes, J.M. Delgado, Electrochim. Acta, 82 (2012) 534 [2].- J. Alvarez-Malmagro, F. Prieto, M. Rueda, A. Rodes, Electrochim. Acta, 140 (2014) 476 [3].- M. Rueda, F. Prieto, I. Navarro, R. Romero, J. Electroanal. Chem. 649 (2010) 42

Annemiek ter Heijne, Dandan Liu, Mira Sulonen et al.

Journal of Power Sources • 2018

Peng Cheng, Yingchuan Zhang, Nianfang Ma et al.

Bioresource technology • 2022

Microbial fuel cell (MFC) exhibits huge potentials in disposing wastewater and extra energy consumption. Exploring useful microorganisms for MFC is the crucial section. Herein, the electrochemical mechanism of extracellular anaerobic respiration in MFC inoculated with gram-positive Rhodococcus pyridinivorans HR-1, was first revealed. The MFC exhibited rapid recovery of currents on anode, and could recover to maximum output within one hour, with redox peaks near -0.38 and -0.18 V through electron transfer between the biofilm and anode. When the biofilm-based pathway was blocked by wrapping the anode with Millipore filter membrane, HR-1 inoculated MFC could still generate electricity within a longer recovery period (∼35 h) during anolyte exchange. This was proposed as a self-secreted electron shuttle pathway for electron transfer in R. pyridinivorans HR-1. Cyclic voltammetry analysis revealed that the biofilm-based and self-secreted electron shuttle-based pathways co-existed in R. pyridinivorans HR-1 inoculated MFC, which could play synergistic roles in electricity generation.

Mustapha Omenesa Idris, Mohamad Nasir Mohamad Ibrahim, Nur Asshifa Md Noh et al.

Chemosphere • 2022

Naphthalene is a very common and hazardous environmental pollutant, and its biodegradation has received serious attention. As demonstrated in this study, naphthalene-contaminated wastewater can be biodegraded using a microbial fuel cell (MFC). Furthermore, the potential of MFC for electricity generation appears to be a promising technology to meet energy demands other than those produced from fossil fuels. Nowadays, efforts are being made to improve the overall performance of MFC by integrating biowaste materials for anode fabrication. In this study, palm kernel shell waste was used to produce palm kernel shell-derived graphene oxide (PKS-GO) and palm kernel shell-derived reduced graphene oxide (PKS-rGO), which were then fabricated into anode electrodes to improve the system's electron mobilization and transport. The MFC configuration with the PKS-rGO anode demonstrated greater energy production potential, with a maximum power density of 35.11 mW/m2 and a current density of 101.76 mA/m2, compared to the PKS-GO anode, which achieved a maximum power density of 17.85 mW/m2 and a current density of 72.56 mA/m2. Furthermore, there is simultaneous naphthalene biodegradation with energy production, where the biodegradation efficiency of naphthalene with PKS-rGO and PKS-GO is 85.5%, and 79.7%, respectively. In addition, the specific capacitance determined from the cyclic voltammetry curve revealed a value for PKS-rGO of 2.23 × 10-4 F/g, which is also higher than the value for PKS-GO (1.57 × 10-4 F/g) on the last day of operation. Anodic microbial analysis shows that electrogens thrive in the MFC process. Finally, a comparison with previous literature and the future prospects of the study are also presented.

Yaniv Shlosberg, Ailun Huang, Tünde N Tóth et al.

ACS biomaterials science & engineering • 2023

In recent years, extensive scientific efforts have been conducted to develop clean bioenergy technologies. A promising approach that has been under development for more than a hundred years is the microbial fuel cell (MFC) which utilizes exoelectrogenic bacteria as an electron source in a bioelectrochemical cell. The viability of bacteria in soil MFCs can be maintained by integrating plant roots, which release organic materials that feed the bacteria. In this work, we show that rather than organic compounds, roots also release redox species that can produce electricity in a biofuel cell. We first studied the reduction of the electron acceptor Cytochrome C by green onion roots. We integrate green onion roots into a biofuel cell to produce a continuous bias-free electric current for more than 24 h in the dark. This current is enhanced upon irradiation of the onion's leaves with light. We apply cyclic voltammetry and 2D-fluorescence measurements to show that NADH and NADPH act as major electron mediators between the roots and the anode, while their concentrations in the external root matrix are increased upon irradiation of the leaves. Finally, we show that roots can contribute to energy storage by charging a supercapacitor.

Kun Dai, Yang Yan, Qing-Ting Wang et al.

Applied microbiology and biotechnology • 2021

The electricity production via psychrophilic microbial fuel cell (PMFC) for wastewater treatment in cold regions offers an alternative to avoid the unwanted methane dissolution of traditional anaerobic fermentation. But, it is seldom reported by mixed-culture, especially closed to 0 °C. Thus, a two-chamber mixed-culture PMFC at 4 °C was successfully operated in this study using acetate as an electron donor. The main results demonstrated a good performance of PMFC, including the maximum voltage of 513 mV at 1000 Ω, coulombic efficiency of 53%, and power density of 689 mW/m2. The cyclic voltammetry curves of enriched biofilm showed a direct electron transfer pathway. These good performances of mixed-culture PMFC were due to the high psychrophilic activity of enriched biofilm, including exoelectrogens genera of Geobacter (6.1%), Enterococcus (17.5%), and Clostridium_sensu_stricto_12 (3.8%). Consequently, a mixed-culture PMFC provides a reasonable strategy to enrich exoelectrogens with high activity. For low-temperature regions, the mixed-culture PMFC involved biotechnologies shall benefit energy generation and valuable chemical production in the future. KEY POINTS: • PMFC showed a maximum voltage of around 513 mV under a resistance of 1000 Ω. • The coulombic efficiency was 53% and the max power density was 689 mW/m2. • Geobacter, Enterococcus, and Clostridium_sensu_stricto_12 were key exoelectrogens.

Verjesh Kumar Magotra, Sunil Kumar, T W Kang et al.

Scientific reports • 2020

The acute problem of eutrophication increasing in the environment is due to the increase of industrial wastewater, synthetic nitrogen, urine, and urea. This pollutes groundwater, soil and creates a danger to aquatic life. Therefore, it is advantageous to use these waste materials in the form of urea as fuel to generate power using Microbial Fuel Cell (MFC). In this work, we studied the compost soil MFC(CSMFC) unlike typical MFC with urea from the compost as fuel and graphite as a functional electrode. The electrochemical techniques such as Cyclic Voltammetry, Chronoamperometry are used to characterise CSMFC. It is observed that the CSMFC in which the compost consists of urea concertation of 0.5 g/ml produces maximum power. Moreover, IV measurement is carried out using polarization curves in order to study its sustainability and scalability. Bacterial studies were also playing a significant role in power generation. The sustainability study revealed that urea is consumed in CSMFC to generate power. This study confirmed that urea has a profound effect on the power generation from the CSMFC. Our focus is to get power from the soil processes in future by using waste like urine, industrial wastewater, which contains much amount of urea.

Xiaoling Li, Ruiyu Zheng, Xuwu Zhang et al.

Journal of environmental management • 2018

In the past decades, the microbial fuel cell (MFC) technology has caught the attention of the scientific community for its potential in transforming petroleum hydrocarbon (PHC) pollutants directly into electricity through microbial catalyzed anodic. The microbe was one of the most important factors that both influence MFCs and PHC degradation. Here we aimed to identify new microbes to expand the list of microbial species which are both electrogenic and diesel hydrocarbon degrading. In this text, we depicted a strain of microbe named E2, isolated from on the anode surface of MFC, and using diesel as sole carbon source. E2 exhibited electrochemical activity in cyclic voltammetry curve, implicating that it had electrogenic ability. E2 degraded about 50% diesel (3.26 g/L) in maximum during 8 days. Pyrosequencing of 16S rRNA gene of E2 revealed E2 was a sub-strain of Vibrio. Corresponding to salt and alkali tolerant properties of vibrio, the optimal condition for E2 in degrading diesel was 3%-4% in salinity, and pH 8-9 in mineral medium. Collectively, as a member of Gammaproteobacteria class, E2 was novel marine microbe both electricity generation and diesel degradation, which may attract its future application toward artificial microbial community construction in MFC in promoting the PHC pollution removal.