A. C. Marques, L. Santos, M. N. Costa et al.

Scientific Reports • 2015

Abstract Electrochemically active bacteria (EAB) have the capability to transfer electrons to cell exterior, a feature that is currently explored for important applications in bioremediation and biotechnology fields. However, the number of isolated and characterized EAB species is still very limited regarding their abundance in nature. Colorimetric detection has emerged recently as an attractive mean for fast identification and characterization of analytes based on the use of electrochromic materials. In this work, WO 3 nanoparticles were synthesized by microwave assisted hydrothermal synthesis and used to impregnate non-treated regular office paper substrates. This allowed the production of a paper-based colorimetric sensor able to detect EAB in a simple, rapid, reliable, inexpensive and eco-friendly method. The developed platform was then tested with Geobacter sulfurreducens , as a proof of concept. G. sulfurreducens cells were detected at latent phase with an RGB ratio of 1.10 ± 0.04 and a response time of two hours.

Daichi Yoshizu, Soranosuke Shimizu, Miyu Tsuchiya et al.

Microorganisms • 2024

Studies have used anaerobic-digester sludge and/or effluent as inocula for bioelectrochemical systems (BESs), such as microbial fuel cells (MFCs), for power generation, while limited studies have isolated and characterized electrochemically active bacteria (EAB) that inhabit anaerobic digesters. In the present work, single-chamber MFCs were operated using the anaerobic-digester effluent as the sole source of organics and microbes, and attempts were made to isolate EAB from anode biofilms in MFCs by repeated anaerobic cultivations on agar plates. Red colonies were selected from those grown on the agar plates, resulting in the isolation of three phylogenetically diverse strains affiliated with the phyla Bacillota, Campylobacterota and Deferribacterota. All these strains are capable of current generation in pure-culture BESs, while they exhibit different electrochemical properties as assessed by cyclic voltammetry. The analyses of their cell-free extracts show that cytochromes are abundantly present in their cells, suggesting their involvement in current generation. The results suggest that anaerobic digesters harbor diverse EAB, and it would be of interest to examine their ecological niches in anaerobic digestion.

Justin Biffinger, Meghann Ribbens, Bradley Ringeisen et al.

Biotechnology and Bioengineering • 2009

Abstract Metal reduction assays are traditionally used to select and characterize electrochemically active bacteria (EAB) for use in microbial fuel cells (MFCs). However, correlating the ability of a microbe to generate current from an MFC to the reduction of metal oxides has not been definitively established in the literature. As these metal reduction assays may not be generally reliable, here we describe a four‐ to nine‐well prototype high throughput voltage‐based screening assay (VBSA) designed using MFC engineering principles and a universal cathode. Bacterial growth curves for Shewanella oneidensis strains DSP10 and MR‐1 were generated directly from changes in open circuit voltage and current with five percent deviation calculated between each well. These growth curves exhibited a strong correlation with literature doubling times for Shewanella indicating that the VBSA can be used to monitor distinct fundamental properties of EAB life cycles. In addition, eight different organic electron donors (acetate, lactate, citrate, fructose, glucose, sucrose, soluble starch, and agar) were tested with S. oneidensis MR‐1 in anode chambers exposed to air. Under oxygen exposure, we found that current was generated in direct response to additions of acetate, lactate, and glucose. Biotechnol. Bioeng. 2009;102: 436–444. © 2008 Wiley Periodicals, Inc.

Atsumi Hirose, Takuya Kasai, Motohide Aoki et al.

Nature Communications • 2018

Abstract Electrochemically active bacteria (EAB) receive considerable attention for their utility in bioelectrochemical processes. Although electrode potentials are known to affect the metabolic activity of EAB, it is unclear whether EAB are able to sense and respond to electrode potentials. Here, we show that, in the presence of a high-potential electrode, a model EAB Shewanella oneidensis MR-1 can utilize NADH-dependent catabolic pathways and a background formate-dependent pathway to achieve high growth yield. We also show that an Arc regulatory system is involved in sensing electrode potentials and regulating the expression of catabolic genes, including those for NADH dehydrogenase. We suggest that these findings may facilitate the use of EAB in biotechnological processes and offer the molecular bases for their ecological strategies in natural habitats.

Yana Mersinkova, Hyusein Yemendzhiev

Journal of Advances in Biology & Biotechnology • 2020

Aims: This study aims to define criteria for the main physical and chemical characteristics of the environmental niches populated with electrochemically active microorganisms, capable to perform anaerobic respiration and potentially used in Bio-electrochemical systems such as Microbial Fuel Cells. 
 Study Design: In this study, specific parameters of the environment in water bodies (such as lakes, streams etc.) and their bottom layers are analyzed. The main parameters of interest include the concentration of dissolved oxygen in the water column, the organic matter content in the sediments and the presence of alternative electron acceptors (such as iron and manganese ions) to support anaerobic respiration. Sediment microorganisms are characterized for their electrochemical and biodegradation activity.
 Place and Duration of Study: The tested sediment and water samples were collected from "Poda" Protected Site located on the outfall of Lake “Uzungeren”, south of City of Burgas, Bulgaria.
 Methodology: The samples were analyzed employing TGA, ICP and microbiological methods focusing on chemical, physical and biological conditions available for anaerobic respiration in this ecological niche.
 Results: The results show very low concentrations of dissolved oxygen (from 1.4 to 2.2 mg/dm3 in the various locations). The conductivity and the pH values ​​measured were relatively high and the mean values obtained are 5230 μS/cm and 8.2 respectively. The sediment samples demonstrated very high organic matter content (22.5% of the dry mass) and relatively high levels of iron and manganese.
 Microbial fuel cell powered by mixed bacterial culture isolated from the tested sediment samples demonstrated stable performance reaching power density of 3.5 W/m2 and the COD removal rate of 42 mgO2/dm3 per day.
 Conclusion: The result confirms the initial hypothesis that electrochemically active microorganisms are available in environments with high concentration of organic matter, iron and manganese in combination with low availability of dissolved oxygen. Mixed culture of anaerobic bacteria isolated from the tested sediment sample was successfully implemented to power Microbial Fuel Cell.

Qi Deng, Xiaoyi Huangyang, Xin Zhang et al.

Advanced Energy Materials • 2022

The low electrocatalytic activity of pristine graphite felt (GF) electrodes toward V(II)/V(III) and V(IV)/V(V) redox couples is a major concern in vanadium redox flow batteries (VRFBs). For overcoming this challenge, herein a novel composite electrode is proposed comprising of two components: multidimensional frame carbon (MFC) derived from edge‐rich carbon and GF that serves as the frame for the in situ growth of MFC. The high electrocatalytic activity, rapid charge migration, and reduced local current emanating from the 0D, 2D, and 3D coexistent structures of the MFC material, respectively, enhance the performance of the GF. Consequently, the battery assembled using the MFC GF electrode achieves a maximum current density of 500 mA cm−2, along with high stability and preeminent energy efficiency at a current density of 200 mA cm−2 for over 400 cycles. For the first time via density functional theory analysis on VRFBs, this study reveals that the edge‐rich carbon atoms possess higher electrocatalytic activity in both positive and negative electrolytes than the plane carbon atoms and heteroatoms. Therefore, this study is of immense significance in guiding and promoting the application of edge‐rich carbon in the battery‐based energy storage industry.

Yanping Wang, Xusen Cheng, Ke Liu et al.

ACS Applied Materials & Interfaces • 2022

Microbial fuel cells (MFCs) are promising ecofriendly techniques for harvesting bioenergy from organic and inorganic matter. Currently, it is challenging to design MFC anodes with favorable microorganism attachment and fast extracellular electron transfer (EET) rate for high MFC performance. Here we prepared N-doped carbon nanotubes (NCNTs) on carbon felt (CF) and used it as a support for growing hierarchical Co8FeS8-FeCo2O4/NCNTs core-shell nanostructures (FeCo/NCNTs@CF). We observed improved wettability, specific areal capacitance, and diffusion coefficient, as well as small charge transfer resistance compared with bare CF. MFCs equipped with FeCo/NCNTs@CF displayed a power density of 3.04 W/m2 and COD removal amount of 221.0 mg/L/d, about 47.6 and 290.1% improvements compared with that of CF. Biofilm morphology and 16s rRNA gene sequence analysis proved that our anode facilitated the enrichment growth of exoelectrogens. Flavin secretion was also promoted on our hierarchical elelctrode, effectively driving the EET process. This work disclosed that hierarchical nanomaterials modified electrode with tailored physicochemical properties is a promising platform to simultaneously enhance exoelectrogen attachment and EET efficiency for MFCs.

Tonni Agustiono. Kurniawan, M. Othman, Xue Liang et al.

Sustainability • 2022

Currently, access to electricity in the cities of the Global South is so limited that electrification remains low in rural areas. Unless properly tackled, one-third of the world’s cities will suffer from energy scarcity. The emergence of microbial fuel cell (MFC) technology accelerates the deployment of decentralized and sustainable energy solutions that can address the looming energy shortage. This review consolidates scattered knowledge into one article about the performance of MFC in optimizing electricity generation from phosphorus (P)-laden wastewater, while removing the target nutrient from wastewater simultaneously. It is obvious from a literature survey of 108 published articles (1999–2022) that the applications of MFC for building a self-powered municipal water treatment system represents an important breakthrough, as this enables water treatment operators to generate electricity without affecting the atmospheric balance of CO2. Using a pyrite-based wetland MFC, about 91% of P was removed after operating 180 days, while generating power output of 48 A/m2. Unlike other techniques, MFCs utilize bacteria that act as micro-reactors and allow substrates to be oxidized completely. The Earth’s tiniest inhabitants can efficiently transform the chemical energy of organic matter in unused wastewater either into hydrogen gas or electricity. This facilitates wastewater treatment plants powering themselves in daily operation or selling electricity on the market. This MFC technology radically changes how to treat wastewater universally. By exploring this direction along the water–energy–food nexus, MFC technology could transform wastewater treatment plants into a key sustainability tool in the energy sector. This suggests that MFCs provide a practical solution that addresses the need of global society for clean water and electricity simultaneously.

Lei Xu, Guoquan Zhang, Guang'en Yuan et al.

RSC Advances • 2015

In this study, an aerobic membrane bioreactor (MBR) equipped with anthraquinone–disulphonate/polypyrrole (AQDS/PPY) composite modified polyester (PT) flat membrane serving as the cathode of a dual-chamber microbial fuel cell (MFC) was developed for wastewater treatment, energy recovery and membrane fouling mitigation. Various physicochemical characteristic parameters were investigated to determine the surface properties of the AQDS/PPY/PT membrane. During most of the operation period, the chemical oxygen demand and NH4+–N removal efficiencies of this novel MFC–MBR coupled system averaged 92.5% and 70.6%, respectively. Over the hydraulic retention time of 11.58 h and the external resistance of 1000 Ω, a maximum power density of 0.35 W m−3 and a current density of 2.62 A m−3 were obtained, meanwhile, the membrane fouling mitigation achieved the best status the H2O2 concentration in membrane effluent also reached the highest value of 2.1 mg L−1. The effective membrane fouling mitigation was attributed mainly to the continuous self-generated bio-electricity of MFC, which not only accelerates the back-diffusion of negative charged foulants away from the membrane surface through the electrostatic repulsion, but also realizes membrane chemical cleaning through the in situ electrogenerated H2O2 and even ˙OH radicals on the membrane surface and/or inside the membrane pore from the self-sustainable heterogeneous electro-Fenton process. Though the electricity recovery of the MFC–MBR coupled system was much lower than other high-output MFC systems, this study provided a new insight into the membrane anti-fouling mechanism and will arouse extensive interests to explore more high-efficiency catalytic membrane materials to maximize power output and minimize membrane fouling.

Yihua Li, Jiaqi Sun, Lifen Liu et al.

Environmental Science: Nano • 2017

In this study, a photocatalytic composite membrane (PCM) coated with CoFe2O4(–rGO) and polyvinylidene fluoride (PVDF) on a carbon fiber cloth was firstly prepared by inclusion of nanoparticles in a PVDF casting solution. The PCM with CoFe2O4(–rGO) functioned as the cathode membrane in a photocatalysis-assisted MFC-MBR system. Comparison tests with four types of MFe2O4 photo-catalysts (M = Ni, Fe, Co, Zn) in PCM indicated that CoFe2O4 had the highest oxygen reduction reaction (ORR) activity. Upon compositing with reduced graphene oxide (rGO), the CoFe2O4–rGO greatly improved the catalytic activity. Photocatalysis in the cathode greatly promoted both power generation and contaminant removal. The maximum power density of 942 mW m−3 (versus anode volume) was achieved using this PCM with CoFe2O4–rGO, under visible-light irradiation, and the removal of tetracycline hydrochloride antibiotics in a photocatalysis-assisted MFC-MBR system was higher than that without irradiation. By efficiently decomposing recalcitrant substances, the photocatalysis-assisted MFC-MBR system exhibits better and broader application potential in wastewater treatment than a conventional MFC-MBR system. The beneficial effects of nanoparticles on flux and conductivity in the PVDF casting solution were also evaluated.

Shaojun Zhang, W. Tong, Mingyu Wang

Ferroelectrics • 2021

Abstract Improving the power output and other power generation performance is the technical bottleneck restricting the industrial application of microbial fuel cell (MFC). Modification of the anode using nanomaterials can significantly increase the power output of MFC. The negatively charged characteristics of Rhodopseudomonas palustris was utilized to propose electroplating of graphene on the surface of biochar, and preparation of polyaniline (PANI) modified biochar electrode by in situ polymerization. Thus, a graphene oxide/polyaniline modified biochar (GO/PANI@Biochar) anode was prepared. Thus, compared the effects of GO/PANI@Biochar, biochar, traditional carbon cloth (CC), and graphite felt (GF) anodes on the power generation performance of MFC. The results showed that the contact angle θ of the new anode was as low as 0°. The biocompatibility is good, and a large number of electricity-producing microorganisms adhere to the surface of the anode material. The maximum power density of GO/PANI@Biochar anode MFC reached to 2025 mW/m2, which was 72.12% higher than that of unmodified biochar, and it was 3.5, 4.39 times that of traditional GF and CC. The maximum output voltage was 6.12% higher than before modification, 15.56% and 23.8% higher than traditional GF and CC anodes. GO/PANI@Biochar anode utilized the advantages of GO conductivity and biochar high biocompatibility effectively. The synergism of them can significantly improve the current and power density of MFC.

Liping Fan, Junyi Shi, Yaobin Xi

Membranes • 2020

Low power production and unstable power supply are important bottlenecks restricting the application of microbial fuel cells (MFCs). It is necessary to explore effective methods to improve MFC performance. By using molasses wastewater as fuel, carbon felt as an electrode, and the mixture of K3[Fe(CN)6] and NaCl as a catholyte, an MFC experimental system was set up to study the performance of MFCs with three different proton exchange membranes. A Nafion membrane was used as the basic material, and polyvinylidene fluoride (PVDF) and acetone-modified PVDF were used to modify it, respectively. The experimental results show that a PVDF-modified membrane can improve the water absorption effectively and, thus, make the MFC have greater power generation and better wastewater treatment effect. The acetone-modified PVDF can further improve the stability of output power of the MFC. When the acetone-modified PVDF was used to modify the Nafion membrane, the steady output voltage of the MFC was above 0.21 V, and the Chemical Oxygen Demand (COD) removal rate for molasses wastewater was about 66.7%, which were 96.3% and 75.1% higher than that of the MFC with the ordinary Nafion membrane. Membrane modification with acetone-modified PVDF can not only increase the output voltage of the MFC but also improve the stability of its output electrical energy.

Jian-sheng Huang, Yong Guo, Ping Yang et al.

Water Science and Technology • 2014

In order to study the performance and bacterial communities of an anaerobic fluidized bed microbial fuel cell (AFB-MFC) system, the 16S rDNA gene sequencing was applied, and high-strength synthetic wastewater was treated by the AFB-MFC system. The high-strength synthetic wastewater, in which the concentrations of chemical oxygen demand (COD), nitrite nitrogen, and nitrate nitrogen were above 19,000, 2,516–3,871 and 927–1,427 mg/L, was treated by the AFB-MFC system. The removal efficiency of COD, nitrite nitrogen, and nitrate nitrogen reached 70–89, 98 and 98%, while the maximum voltage was 394 mV. The bacteria analysis revealed the presence of Alistipes putredinis, Carnobacterium sp., Victivallis vadensis, Klebsiella pneumoniae, Thauera sp., Parabacteroides merdae, Parvimonas micra, Parabacteroides sp., and Desulfomicrobium baculatum in the anode chamber. In addition, the Klebsiella pneumoniae was observed to have the capability of organic degradation and electricity generation, while the Thauera sp. has the capability of denitrification.

Tolera G. Degefa, Marek Łukasz Płaczek, Grzegorz Kokot

Applied Sciences • 2022

MFC (Microfiber composite) piezoelectric transducers are one of the smart composite materials used among others in alternative energy sources and autonomous wireless sensors which exploit vibrational energy. This work presents the theoretical and experimental investigations of the integration of MFC piezoelectric transducers on epoxy glass fiber composite material and explores the capacity of power generation based on a variety of ambient temperatures and frequencies. The study examined the use of ambient vibrational energy to power small electronic devices of wireless sensor networks which eliminates the need for external power, periodic battery replacement costs, and chemical waste from conventional batteries. The test was conducted using a laboratory stand equipped with a thermal chamber and an Instron ElectroPulse waveform generator which induces a concentric cyclic load to the laminated beam. Laminated MFC was loaded with a low–frequency range, controlled displacement under different moderate temperatures. The test was conducted at temperatures ranging from 25 to 60 degrees Celsius and at frequencies ranging from 5 to 25 Hz. The results show that the voltage generated by the transducer is highly affected by both temperature and frequency of excitation.

C. Turick, S. Shimpalee, P. Satjaritanun et al.

Applied Microbiology and Biotechnology • 2019

Real-time electrochemical monitoring in bioprocesses is an improvement over existing systems because it is versatile and provides more information to the user than periodic measurements of cell density or metabolic activity. Real-time electrochemical monitoring provides the ability to monitor the physiological status of actively growing cells related to electron transfer activity and potential changes in the proton gradient of the cells. Voltammetric and amperometric techniques offer opportunities to monitor electron transfer reactions when electrogenic microbes are used in microbial fuel cells or bioelectrochemical synthesis. Impedance techniques provide the ability to monitor the physiological status of a wide range of microorganisms in conventional bioprocesses. Impedance techniques involve scanning a range of frequencies to define physiological activity in terms of equivalent electrical circuits, thereby enabling the use of computer modeling to evaluate specific growth parameters. Electrochemical monitoring of microbial activity has applications throughout the biotechnology industry for generating real-time data and offers the potential for automated process controls for specific bioprocesses.

Azwar Muhammad Yahya, M. Hussain, Ahmad Khairi Abdul Wahab

International Journal of Energy Research • 2015

An integrated modeling, optimization, and control approach for the design of a microbial electrolysis cell (MEC) was studied in this paper. Initially, this study describes the improvement of the mathematical MEC model for hydrogen production from wastewater in a fed‐batch reactor. The model, which was modified from an already existing model, is based on material balance with the integration of bioelectrochemical reactions describing the steady‐state behavior of biomass growth, consumption of substrates, hydrogen production, and the effect of applied voltage on the performance of the MEC fed‐batch reactor. Another goal of this work is to implement a suitable control strategy to optimize the production of biohydrogen gas by selecting the optimal current and applied voltage to the MEC. Various simulation tests involving multiple set‐point changes, disturbance rejection, and noise effects were performed to evaluate the performance where the proposed proportional–integral–derivative control system was tuned with an adaptive gain technique and compared with the Ziegler–Nichols method. The simulation results show that optimal tuning can provide better control effect on the MEC system, where optimal H2 gas production for the system was achieved. Copyright © 2014 John Wiley & Sons, Ltd.

Xuee Wu, F. Zhao, N. Rahunen et al.

Angewandte Chemie International Edition • 2011

Herein we have demonstrated a DET mechanism used by D. desulfuricans; where the periplasmic cytochromes and hydrogenases play an important role, and Pd nanoparticles bound to the microbes may participate in the electron transfer process. The present work is of importance not only for the fundamental studies of electron transfer processes in microbial physiology and ecology, but also for increased understanding and improvement of the performance of bioelectrochemical techniques e.g. precious metals are extensively used and important catalysts, and therefore present in many industry processing wastewaters. Bio-nanoparticles can oxidize in situ metabolites e.g. H2, formate and ethanol in the anode chambers, while also acting as cathodic catalysts for the oxygen reduction reaction[23]. In addition, this study indicates the feasibility of using bioelectrochemical systems for metal immobilization, recovery or detoxification

Pengyi Yuan, Younggy Kim

Biotechnology for Biofuels • 2017

BackgroundMicrobial electrolysis cells (MECs) use bioelectrochemical reactions to remove organic contaminants at the bioanode and produce hydrogen gas at the cathode. High local pH conditions near the cathode can also be utilized to produce struvite from nutrient-rich wastewater. This beneficial aspect was investigated using lab-scale MECs fed with dewatering centrate collected at a local wastewater treatment plant. The main objective was to improve phosphorus recovery by examining various cathode configurations and electric current conditions.ResultsThe stainless steel mesh (SSM) cathode was relatively inefficient to achieve complete phosphorus recovery because struvite crystals were smaller (a few to tens of micrometers) than the open space between mesh wires (80 µm). As a result, the use of multiple pieces of SSM also showed a limited improvement in the phosphorus recovery up to only 68% with 5 SSM pieces. Readily available organic substrates were not sufficient in the dewatering centrate, resulting in relatively low electric current density (mostly below 0.2 A/m2). The slow electrode reaction did not provide sufficiently high pH conditions near the cathode for complete recovery of phosphorus as struvite. Based on these findings, additional experiments were conducted using stainless steel foil (SSF) as the cathode and acetate (12 mM) as an additional organic substrate for exoelectrogens at the bioanode. With the high electric current (>2 A/m2), a thick layer of struvite crystals was formed on the SSF cathode. The phosphorus recovery increased to 96% with the increasing MEC operation time from 1 to 7 days. With the high phosphorus recovery, estimated energy requirement was relatively low at 13.8 kWh (with acetate) and 0.30 kWh (without acetate) to produce 1 kg struvite from dewatering centrate.ConclusionsFor efficient phosphorus recovery from real wastewater, a foil-type cathode is recommended to avoid potential losses of small struvite crystals. Also, presence of readily available organic substrates is important to maintain high electric current and establish high local pH conditions near the cathode. Struvite precipitation was relatively slow, requiring 7 days for nearly complete removal (92%) and recovery (96%). Future studies need to focus on shortening the time requirement.

Faiz Miran, M. Mumtaz, H. Mukhtar et al.

Frontiers in Bioengineering and Biotechnology • 2021

The microbial fuel cell (MFC) is emerging as a potential technology for extracting energy from wastes/wastewater while they are treated. The major hindrance in MFC commercialization is lower power generation due to the sluggish transfer of electrons from the biocatalyst (bacteria) to the anode surface and inefficient microbial consortia for treating real complex wastewater. To overcome these concerns, a traditional carbon felt (CF) electrode modification was carried out by iron oxide (Fe3O4) nanoparticles via facile dip-and-dry methods, and mixed sulfate-reducing bacteria (SRBs) were utilized as efficient microbial consortia. In the modified CF electrode with SRBs, a considerable improvement in the bioelectrochemical operation was observed, where the power density (309 ± 13 mW/m2) was 1.86 times higher than bare CF with SRBs (166 ± 11 mW/m2), suggesting better bioelectrochemical performance of an SRB-enriched Fe3O4@CF anode in the MFC. This superior activity can be assigned to the lower charge transfer resistance, higher conductance, and increased number of catalytic sites of the Fe3O4@CF electrode. The SRB-enriched Fe3O4@CF anode also assists in enhancing MFC performance in terms of COD removal (>75%), indicating efficient biodegradability of tannery wastewater and a higher electron transfer rate from SRBs to the conductive anode. These findings demonstrate that a combination of the favorable properties of nanocomposites such as Fe3O4@CF anodes and efficient microbes for treating complex wastes can encourage new directions for renewable energy–related applications.

R. Mateos, A. Sotres, Raúl M. Alonso et al.

Energies • 2019

Bioelectrochemical systems (BESs) is a term that encompasses a group of novel technologies able to interconvert electrical energy and chemical energy by means of a bioelectroactive biofilm. Microbial electrosynthesis (MES) systems, which branch off from BESs, are able to convert CO2 into valuable organic chemicals and fuels. This study demonstrates that CO2 reduction in MES systems can be enhanced by enriching the inoculum and improving CO2 availability to the biofilm. The proposed system is proven to be a repetitive, efficient, and selective way of consuming CO2 for the production of acetic acid, showing cathodic efficiencies of over 55% and CO2 conversions of over 80%. Continuous recirculation of the gas headspace through the catholyte allowed for a 44% improvement in performance, achieving CO2 fixation rates of 171 mL CO2 L−1·d−1, a maximum daily acetate production rate of 261 mg HAc·L−1·d−1, and a maximum acetate titer of 1957 mg·L−1. High-throughput sequencing revealed that CO2 reduction was mainly driven by a mixed-culture biocathode, in which Sporomusa and Clostridium, both bioelectrochemical acetogenic bacteria, were identified together with other species such as Desulfovibrio, Pseudomonas, Arcobacter, Acinetobacter or Sulfurospirillum, which are usually found in cathodic biofilms. Moreover, results suggest that these communities are responsible of maintaining a stable reactor performance.

Leifeng Chen, Leifeng Chen, Pier-Luc Tremblay et al.

Journal of Materials Chemistry A • 2016

Microbes can reduce CO2 into multicarbon chemicals with electrons acquired from the cathode of a bioelectrochemical reactor. This bioprocess is termed microbial electrosynthesis (MES). One of the main challenges for the development of highly productive MES reactors is achieving efficient electron transfer from the cathode to microbes. Here, carbon cloth cathodes modified with reduced graphene oxide functionalized with tetraethylene pentamine (rGO-TEPA) were readily self-assembled in the cathodic chamber of a MES reactor. Electroactive biofilms with unique spatial arrangement were subsequently formed with Sporomusa ovata at the surface of rGO-TEPA-modified electrodes resulting in a more performant MES process. The acetate production rate from CO2 was increased 3.6 fold with the formation of dense biofilms when wild type S. ovata was combined with rGO-TEPA. An improvement of 11.8 fold was observed with a highly structured biofilm including multiple spherical structures possibly consisting of bioinorganic networks of rGO-TEPA and bacterial cells from a novel strain of S. ovata adapted to reduce CO2 faster. The three dimensional biofilms observed in this study enabled highly effective electric interactions between S. ovata and the cathode, demonstrating that the development of dense cathode biofilms is an effective approach to improve MES productivity.

Xiaofang Yan, Danyang Liu, Johannes B. M. Klok et al.

Environmental Science & Technology • 2023

Bioelectrochemical systems (BESs) are considered to be energy-efficient to convert ammonium, which is present in wastewater. The application of BESs as a technology to treat wastewater on an industrial scale is hindered by the slow removal rate and lack of understanding of the underlying ammonium conversion pathways. This study shows ammonium oxidation rates up to 228 ± 0.4 g-N m–3 d–1 under microoxic conditions (dissolved oxygen at 0.02–0.2 mg-O2/L), which is a significant improvement compared to anoxic conditions (120 ± 21 g-N m–3 d–1). We found that this enhancement was related to the formation of hydroxylamine (NH2OH), which is rate limiting in ammonium oxidation by ammonia-oxidizing microorganisms. NH2OH was intermediate in both the absence and presence of oxygen. The dominant end-product of ammonium oxidation was dinitrogen gas, with about 75% conversion efficiency in the presence of a microoxic level of dissolved oxygen and 100% conversion efficiency in the absence of oxygen. This work elucidates the dominant pathways under microoxic and anoxic conditions which is a step toward the application of BESs for ammonium removal in wastewater treatment.

Putty Ekadewi, M. Hardhi, Putri Anggun Puspitarini et al.

E3S Web of Conferences • 2018

Denitrification is the conversion process of nitrate to gaseous nitrogen forms carried out by bacteria commonly referred to as denitrifiers. Microbial Electrolysis Cell (MEC) is a type of bioelectrochemical system (BES) that is connected to external power source to aid the reactions. This research investigates the effect of applied voltage value on denitrification by nitrate removal efficiency of two model denitrifying species from the genus Pseudomonas in single-chambered MEC. Pseudomonas aeruginosa and Pseudomonas nitroreducens exhibited native removal efficiency at 70.62% and 68.20%, respectively. These values respectively reached up to 89.67% and 88.58% at 1.20 V, the upper limit of this study. Pseudomonas aeruginosa displayed better performance in MEC based off its produced current stability (mA) across the 0.35-1.20 V range. The effect of applied voltage on nitrate removal efficiency and setup performance was more prominent on known exoelectrogenic species of Pseudomonas such as Pseudomonas aeruginosa compared to Pseudomonas nitroreducens. Operating applied voltages of 0.35 V and 0.70 V was recommended for the application of the system based on technical and economical considerations. Further studies are needed to determine the response of the bacteria on wider range of applied voltages in MEC as well as elucidating these effects on autotrophic systems.

K. So, S. Kawai, Y. Hamano et al.

Physical Chemistry Chemical Physics • 2014

The fructose/dioxygen biofuel cell, one of the direct electron transfer (DET)-type bioelectrochemical devices, utilizes fructose dehydrogenase (FDH) on the anode and multi-copper oxidase such as bilirubin oxidase (BOD) on the cathode as catalysts. The power density in the literature is limited by the biocathode performance. We show that the DET-type biocathode performance is greatly improved, when bilirubin or some related substances are adsorbed on electrodes before the BOD adsorption. Several data show that the substrate modification induces the appropriate orientation of BOD on the electrode surface for the DET. The substrate-modification method has successfully been applied to air-breathing gas-diffusion-type biocathodes. We have also optimized the conditions of the FDH adsorption on carbon cryogel electrodes. Finally, a one-compartment DET-type biofuel cell without separators has been constructed, and the maximum power density of 2.6 mW cm(-2) was achieved at 0.46 V of cell voltage under quiescent (passive) and air atmospheric conditions.

Q. Fu, Yoshihiro Kuramochi, N. Fukushima et al.

Environmental Science & Technology • 2015

The use of thermophilic microorganisms as biocatalysts for electromethanogenesis was investigated. Single-chamber reactors inoculated with thermophiles and operated at 55 °C showed high CH4 production rates (max. 1103 mmol m(–2) day(–1) at an applied voltage of 0.8 V) with current-capture efficiencies >90%, indicating that thermophiles have high potential as biocatalysts. To improve the electromethanogenic activity, the developed biocathode was transferred to a two-chamber reactor and operated at a poised potential of −0.5 V vs SHE. The CH4 production rates of the biocathode were enhanced approximately 6-fold in 160 h of poised-potential incubation, indicating that the acclimation of the biocathode resulted in performance improvement. Compositional alteration of the cathodic microbiota suggested that a Methanothermobacter-related methanogen and synergistetes- and thermotogae-related bacteria were selected during the acclimation. Cyclic voltammetry of the “acclimated” biocathode showed an augmented cathodic catalytic wave with a midpoint potential at ca. −0.35 V vs SHE. Moreover, the biocathode was able to catalyze electromethanogenesis at −0.35 V vs SHE. These results suggested that the ability of the biocathode to catalyze electromethanogenesis via direct electron transfer was enhanced by the acclimation. This study provides new technological and fundamental information on electromethanogenic bioelectrochemical systems (BESs) that may be extended to other BESs.

Ke Chen, Chunling Ma, Xiaolei Cheng et al.

Bioresources and Bioprocessing • 2023

Abstract It is of great significance to utilize CO 2 as feedstock to synthesize biobased products, particularly single cell protein (SCP) as the alternative food and feed. Bioelectrochemical system (BES) driven by clean electric energy has been regarded as a promising way for Cupriavidus necator to produce SCP from CO 2 directly. At present, the key problem of culturing C. necator in BES is that reactive oxygen species (ROS) generated in cathode chamber are harmful to bacterial growth. Therefore, it is necessary to find a solution to mitigate the negative effect of ROS. In this study, we constructed a number of C. necator strains displayed with superoxide dismutase (SOD), which allowed the decomposition of superoxide anion radical. The effects of promoters and signal peptides on the cell surface displayed SOD were analyzed. The proteins displayed on the surface were further verified by the fluorescence experiment. Finally, the growth of C. necator CMS incorporating a pBAD-SOD-E-tag-IgAβ plasmid could achieve 4.9 ± 1.0 of OD 600 by 7 days, equivalent to 1.7 ± 0.3 g/L dry cell weight (DCW), and the production rate was 0.24 ± 0.04 g/L/d DCW, around 2.7-fold increase than the original C. necator CMS (1.8 ± 0.3 of OD 600 ). This study can provide an effective and novel strategy of cultivating strains for the production of CO 2 -derived SCP or other chemicals in BES. Graphical Abstract

Li-hua Huang, Xiu-fen Li, Yueping Ren et al.

PubMed • 2017

Microbial fuel cell (MFC) technology has potential in recovering bioelectricity from different types of waste, which attracts more and more attention in the field of environment and energy. However, low power density, high cost and low substrate degradation rate, closely associated with anode performance, limit its practical application. In this study, proportional polyaniline (PANI) together with graphene was chosen to obtain the PANI dopped graphene composite. The as-received composite was modified onto the surface of glassy carbon electrode. The results of electrochemical analysis showed that the optimal mass ratio of graphene was 20% for cyclic voltammetry (CV) and linear sweep voltammetry (LSV) analysis. The anodes with 5% graphene produced a peak power density of (831±45) mW·m-2, which was 1.2, 1.3, 1.3, 1.5, 1.8 times of those with 20% graphene, 1% graphene, graphene, PANI and carbon cloth, respectively. Moreover, 5% graphene reactors showed the maximum values in output voltage, open-circuit voltage (OCV), chemical oxygen demand (COD) removal rate, coulombic efficiency (CE), and biomass density. The polarization resistance was only (24±2)Ω in 5% graphene reactors,which was 19.8% of that of carbon cloth. The results of electrochemical analysis were not consistent with those of bioelectrochemical analysis, demonstrating that the biocompatibility of electrode was one of the important factors affecting MFC performance. 5% graphene anode showed full advantages of graphene and PANI, which improved the performance of MFC.

Hoang Dung Nguyen, T. Dao, Nguyen Xuan Que Vo

IOP Conference Series: Earth and Environmental Science • 2024

Microbial fuel cells (MFCs) present promising technology for sustainable wastewater treatment and energy generation. In this study, we operated an algae-MFC system to investigate its performance in terms of electricity generation and wastewater treatment capacity. The MFC reactor, with the support of a separate algae vessel providing oxygen-rich water to the cathode chamber, was continuously operated with varying organic loading rates to the anode with the synthetic wastewater. Results showed that the algae-MFC achieved a stable electricity generation, reaching a maximum power density of 840 mW m−3 at the highest chemical oxygen demand (COD) loading rate (0.30 kg m−3 h−1). Furthermore, the system could remove 75% of COD at a short HRT of 4 h. Coulombic efficiency was unexpectedly low, from 0.35% to 0.70%, indicating the need of energy recovery improvement from wastewater. A challenge of internal resistance increase over time was identified and discussed. Future prospects were discussed including the algae integrating directly into the cathode chamber to enhance the nitrogen removal and to explore the co-cultivation possibility of microalgae and autotrophic bacteria for a simultaneous removal of organic substances and nutrients. Overall, this study demonstrated the application potential of algae-MFC systems for sustainable wastewater treatment and energy production.

M. Ghasemi, A. Nassef, M. Al-Dhaifallah et al.

International Journal of Energy Research • 2020

The current work introduces an enhancement in the performance of the microbial fuel cell through estimating the optimal set of controlling parameters. The maximization of both power density (PD) and the percentage of chemical oxygen demand (COD) removal were considered as the enhancement in the cell's performance. Three main parameters in terms of performance as well as commercialization are the system's inputs; the Pt which takes the range of 0.1‐0.5 mg/cm2, the degree of sulphonation in sulfonated‐poly‐ether‐ether‐ketone that changes in the range of 20‐80%, and the rate of aeration of cathode which varies between 10 and 150 mL/min. From the experimental dataset, two robust adaptive neuro‐fuzzy inference system models based on the fuzzy logic technique have been constructed. The comparisons between the models' outputs and the experimental data showed well‐fitting in both training and testing datasets. The mean squared errors of the PD model, for testing and whole datasets, were found 2.575 and 0.909 while for the COD model it showed 19.242 and 6.791, respectively. Then, based on the two fuzzy models, a Particle Swarm Optimization algorithm has been used to determine the best parameters that maximize both of the PD and the COD removal of the cell. The optimization process was utilized for single and multi‐object optimization processes. In the single optimization, the resulting maximums of the PD and the COD removal were found 62.844 (mW/m2) and 99.99 (%), respectively. Whereas, in the multi‐object optimization, the values of 61.787 (mW/m2) and 96.21 (%) were reached as the maximums for the PD and COD, respectively. This implies that, in both cases of optimization processes, the adopted methodology can efficiently enhance the microbial fuel cell performances than the previous work.

Siti Mariam Daud, Mimi Hani Abu Bakar, W. R. Wan Daud et al.

Energy Science & Engineering • 2021

A proton exchange membrane (PEM) is one of the most critical and expensive components in a dual‐chamber microbial fuel cell (MFC) that separates the anode and cathode chambers. The novel macroporous kaolin earthenware coated with polybenzimidazole (NKE‐PBI) fabricated in this study could become an alternative to PEM membranes. Briefly, PBI powder was dissolved in dimethylacetamide. Thereafter, NKE was fabricated at different porosities (10%, 20%, and 30%) using different starch powder volumes, which acted as pore‐forming agents. The NKE‐PBI with 30 vol% starch powder content produced the highest power output of 2450 ± 25 mW m−2 (10.50 A m−2) and internal resistance of 71 ± 19 Ω under batch mode operation. The MFC–PEM reactor generated the lowest power output at the highest internal resistance of up to 1300 ± 15 mW m−2 (3.7 A m−2) and 313 ± 16 Ω, respectively. In this study, the nonselective porous NKE coated with PBI membranes improved proton conduction activity and displayed comparable power performance with that of Nafion 117 in a dual‐chambered MFC. Therefore, a porous earthenware membrane coated with a proton conductor could become a potential separator in a scaled‐up MFC system for commercialization.

M. S. Bhagat, A. K. Mungray, A. Mungray

Environmental Technology • 2023

ABSTRACT This study explored the effect of a solenoid magnetic field (SOMF) as a pre-treatment on anaerobic sewage sludge (ASS) before using it in an osmotic microbial fuel cell (OMFC) as an inoculant. The ASS efficiency in terms of colony-forming unit (CFU) was improved ten times by applying SOMF compared to the control conditions. The obtained highest power density, current density, and water flux in the OMFC were 32.70 ± 5 mW·m−2, 135.13 ± 15 mA·m−2, and 4.24 ± 0.11 L·m−2h−1 respectively, for 72 h at 1 mT magnetic field. The coulombic efficiency (CE) and chemical oxygen demand (COD) removal efficiency were increased to 40–45% and 4–5% respectively, compared to un-treated ASS. Also, the start-up time of the ASS-OMFC system was almost reduced to 1–2 days based on open circuit voltage data. On the other hand, increasing the pre-treatment intensity of SOMF with time, it decreased the performance of OMFC. Also, the low intensity with increased pre-treatment time up to a specific limit enhanced the performance of OMFC. GRAPHICAL ABSTRACT

Pankaj Kumar Dubey, Bindeshwar Singh, Varun Kumar

• 2022

Fuel cells are used in many applications, from personal use to energy generation stations. The fuel cell 2 The entire system is efficient at maximum and half load, scales to a variety of sizes, is eco-friendly and has potentially comparable initial costs to conventional technologies. Portable electricity, mobility, cogeneration in buildings, and distributed electricity for utilities are promising applications for fuel cells. The vital barriers to the money orientation of fuel cells are pricing and longevity. We will talk about fuel cells, the classification of fuel cells, fuel cell problems, and how artificial intelligence can help improve the performance of fuel cells.

Qiuhong Jia, Caizhi Zhang, Bin Deng et al.

Journal of Fuel Cell Science and Technology • 2015

In a proton exchange membrane fuel cell (PEMFC), the hydrogen feed into the anode in a periodical pressure swing, so-called hydrogen pressure pulsation feed (HPPF), significantly affects the transport phenomena of hydrogen and water in the anode flow field. HPPF could adjust the distribution of the back diffusion water and the hydrogen partial pressure along the anode flow channels, improve hydrogen mass transfer in the anode flow field, and enhance the diffusion of hydrogen in the porous medium (anode diffusion layer). On the other hand, HPPF technique could mitigate the anode flooding issue caused by water back diffusion from the cathode, improve the fuel cell performance. In this work, the principle of HPPF technique was introduced and analyzed by a mathematic approach. Some of the important parameters used in HPPF technique, such as amplitude of pulsation pressure, pulsating frequency, etc., were experimentally investigated on dead-end mode PEMFC stack. The experimental results showed that the amplitude of pressure pulsation, pulsating frequency, and position applied for HPPF highly affected the performance of the PEMFC stack. It can be seen that higher the frequency and/or amplitude of pressure pulsation, the better the performance of PEMFC stack.

K. Rani, P. Sobha Rani, N. Chaitanya et al.

International Journal of Intelligent Engineering and Systems • 2022

Currently, modern electrical distribution networks (EDNs) are experiencing high demand with emerging electric vehicle loads and are being planned for specific load requirements such as agricultural loads. In this connection, characterization and optimization of their performance become essential in planning studies. In this paper, optimal reactive power compensation using a distribution-static synchronous compensator (D-STATCOM) is proposed with the aim of loss reduction, voltage profile improvement and voltage stability enhancement different types of loads including agricultural and electric vehicle loads. A recent efficient meta-heuristic approach, improved bald eagle search (IBES), is implemented for solving the proposed optimization problem considering different operational and planning constraints. The simulation results are performed on IEEE 33-bus for different types of load modelling. The computational efficiency of IBES is compared with basic BES and other literature works. From the results, IBES has shown superior computational characteristics than all compared works. On the other hand, the optimal location and size of D-STATCOM caused significant loss reduction, voltage profile improvement and voltage stability enhancement for kinds of loads as experiencing in the modern EDNs.

H. Zou, L. Chu, Yan Wang

Archives of Environmental Protection • 2023

Azo dye wastewater treatment is urgent necessary nowadays. Electrochemical technologies commonly enable more effi cient degradation of recalcitrant organic contaminants than biological methods, but those rely greatly on the energy consumption. A novel process of biofi lm coupled with electrolysis, i.e., bioelectrochemical system (BES), for methyl orange (MO) dye wastewater treatment was proposed and optimization of main infl uence factors was performed in this study. The results showed that BES had a positive effect on enhancement of color removal of MO wastewater and 81.9% of color removal effi ciency was achieved at the optimum process parameters: applied voltage of 2.0 V, initial MO concentration of 20 mg/L, glucose loads of 0.5 g/L and pH of 8.0 when the hydraulic retention time (HRT) was maintained at 3 d, displaying an excellent color removal performance. Importantly, a wide range of effective pH, ranging from 6 to 9, was found, thus greatly favoring the practical application of BES described here. The absence of a peak at 463 nm showed that the azo bond of MO was almost completely cleaved after degradation in BES. From these results, the proposed method of biodegradation combined with electrochemical technique can be an effective technology for dye wastewater treatment and may hopefully be also applied for treatment of other recalcitrant compounds in water and wastewater. Azo dye wastewater treatment in a novel process of biofi lm coupled with electrolysis 39 wastewater by using BES in this study. In the BES designed here, a stainless steel column was used as the cathode, where an activated carbon fi ber (ACF) was attached to the surface of cathode to enrich microorganisms. The performance of BES was assessed in terms of color removal effi ciency of MO. The effect of applied voltage, MO concentration, carbon source content and pH on MO denitrifi cation rate was investigated to optimize the operation on BES. Moreover, to investigate the change of molecular and structural characteristics during the MO treatment, UV/Visible absorption spectra with reaction time was further analyzed. These results obtained from this study, BES linking biological with electrochemical process, may serve as a new suggestion for the treatment of dye wastewaters or non-biodegradable industrial wastewaters. Material and methods Experimental setup The BES was made from polyvinyl chloride with a single-chamber cylinder and Figure 1 shows the schematic diagram of BES adopted in this study. The BES had a total and working volume of 4.0 L and 3.0 L respectively with an internal diameter of 16 cm and 20 cm in height. The BES consisted of an ACF (Shanghai Zhaokuo, Co., Ltd, China) wrapped around the stainless steel column (6 cm internal diameter × 12 cm height × 0.15 cm wall thickness) as the cathode electrode and a high-purity graphite rod (2 cm diameter × 13 cm length) as the anode electrode. An adjustable direct current regulated power supply (PS-305DM; Dongguan Longwei Electronic Technology, Co., Ltd, China) was connected with anode and cathode to provide voltage. Besides, an automatic stirrer (OS20; Beijing Dragon Laboratory Instruments Limited, China) was installed at the top of the BES to provide well-mixed environment. Experimental design After construction, the experiments were carried out for 167 days. Activated sludge (1 L, 1 g/L of MLSS), i.e., seed sludge, was collected from an oxidation ditch confi guration (Fengyang Municipal Wastewater Treatment Plant, Anhui, China) and immediately washed three times using deionized water to remove soluble carbon sources. And then, it was inoculated in the BES reactor to accelerate the biofi lm development onto the surface of ACF cathode, including three stages: fi rstly, from day 0 to day 20, a single synthetic wastewater was fed to the BES to promote the rapid growth of microorganisms; secondly, after that, a 1:1 (vol/vol) mixture of synthetic wastewater and azo dyes wastewater containing 30 mg/L MO was fed for 15 days to gradually enrich the specifi c microorganisms; fi nally, from day 36, it was intensively enriched by feeding the only MO wastewater for 30 days. In order to investigate the effect of process parameters on MO color removal in BES, the applied voltage, MO concentration, carbon source content and pH were gradually increased respectively (see Table 1) after biofi lm formation. During the experimental period, the hydraulic retention time (HRT) was maintained at 3 d according to the preliminary test. The synthetic wastewater consisted of organic carbon, nutrients and buffer solution and its composition is as follows: 40 mg/L KH2PO4, 40 mg/L (NH4)2SO4, 3 mg/L CaCl2, 45 mg/L MgSO4∙7H2O and 1 mL/L of nutrient solution (1200 mg/L FeCl3∙6H2O, 130 mg/L H3BO3, 25 mg/L CuSO4∙5H2O, 160 mg/L KI, 100 mg/L MnCl2∙4H2O, 50 mg/L Na2MoO4∙2H2O, 110 mg/L ZnSO4∙7H2O, 130 mg/L CoCl2∙6H2O and 800 mg/L EDTA). In addition, glucose and MO were added into the synthetic wastewater according to the experimental arrangement, which was used as the carbon source. The other compositions acted as nutrient and buffer solution for microbial growth. Analytical methods Samples of effl uents were fi ltered through a 0.22 μm-pore-size syringe fi lter prior to analysis. MLSS analysis was performed according to the standard methods (APHA, 2005). pH was measured by a pH meter analyzer (S20, Mettler-Toledo, Switzerland). Absorbance was analyzed by measuring the adsorption at 463 nm using an UV-3600 (Shimadzu, Japan). Fig. 1. Schematic diagram of BES 40 H. Zou, L. Chu, Y. Wang Results and discussion Effect of applied voltage on color removal The performance of color removal in BES at different applied voltages (HRT: 3 d; applied voltage: 0, 0.6, 0.8, 1.0, 1.4, 1.8, 2.2, 2.5 and 3.0) are shown in Figure 2. MO concentration of infl uent was maintained at 20 mg/L. It is clearly observed from Figure 2 that color removal effi ciency increased with the increasing voltage applied from 0 V to 2.5 V, displaying the promoting effect of applied voltage on color removal. The BES is totally related to the current density and it was enhanced with the increasing voltage applied, providing suitable conditions for microorganism on the biofi lm and electrochemical reaction (Chen et al. 2015). The highest color removal effi ciency (80.5%) was observed in BES at an applied voltage of 2.5 V. The reason might be that the presence of current density was more conductive to the bacteria growth and electrochemical reaction. At 3.0 V, it was declined to 77.2%. This can be due to the fact that high concentrations of intermediate products would be formed in solution at an excessive applied voltage. There exists an inevitable comparison for electron between the further degradation of intermediate products and the rupture of –N=N– at the cathode’s surface (Liu et al. 2015), leading to the decline in current effi ciency. Notably, the color removal effi ciency was 68.9% at 1.8 V signifi cantly higher than that at 1.4 V (53.5%) in BES. This may be attributed to the oxidative electrolysis of water and reduction of protons (Thrash and Coates 2008), thus producing more oxygen at anode and hydrogen at cathode, which were utilized by microorganisms as electron acceptor and electron. Table 1. Experimental design used here Process parameters Set value Applied voltage 0, 0.6, 0.8, 1.0, 1.4, 1.8, 2.2, 2.5 and 3.0 V MO concentration 5, 10, 20, 40, 60, 80, 100 mg/L Carbon source content 0, 0.1, 0.3, 0.5, 0.7, and 1.0 g/L pH 3, 4, 5, 6, 7, 8, 9, 10, and 11 Fig. 2. Color removal effi ciency at different applied voltages in BES Fig. 3. Color removal effi ciency with different dye concentration of infl uent in BES As the BES was controlled under no electric fi led, i.e., applied voltage of 0 V, exhibiting only a typical biological reaction, the color removal effi ciency was rather low (21.2%). Dye wastewater is well known to be of low biodegradability, which was hard to be treated by using only a single biological treatment method. And then, it was sharply increased up to 36.8% at 0.6 V, suggesting that micro-current fl owing through the biofi lm on the cathodic surface had positive effect on the microbial metabolism due to the electric fi eld stimulation. Effect of dye concentration on color removal The effects of different MO concentration of infl uent (5, 10, 20, 40, 60, 80, 100 mg/L) on color removal performance are shown in Figure 3. During the treatment process, BES was operated at the same condition (HRT: 3 d; applied voltage: 2.0 V). Color removal effi ciency gradually decreased from 90.2% to 42.8% with the increase of initial MO concentration ranging from 5 mg/L to 100 mg/L, displaying a negative effect of initial dye loading on BES, which may be most likely due to the toxicity of the dye metabolites (such as aromatic amines) produced during dye reduction at high dye concentrations (Pearce et al. 2003). Similar results were also found in a report (Sponza and Işik 2005) that increase in Direct Black 38 concentration caused a decrease in color removal effi ciency in an anaerobic/aerobic sequential reactor responsible for dye wastewater treatment. These results suggested that the biomass inhibition effect could occur in BES when the dye concentration exceeded a proper range. Effect of carbon source content on color removal Figure 4 shows the effect of different carbon source content (0, 0.1, 0.3, 0.5, 0.7, and 1.0 g/L), glucose used here, on the color removal performance in BES. The other operation conditions were listed as follows: HRT=3 d, applied voltage=2.0 V, initial MO concentration=20 mg/L. It was observed that glucose displayed an obvious promotion on color removal effi ciency in BES. The color removal effi ciency was only 36.2% without addition of carbon source and it increased signifi cantly up to 59.5% with the addition of 0.1 mg/L of glucose. This result was consistent with other studies (Al-Amrani et al. 2013, Murali et al. 2013), where co-subs

Vijay Babu Pamshetti, Wei Zhang

2024 IEEE 4th International Conference on Sustainable Energy and Future Electric Transportation (SEFET) • 2024

The objective of this study is to assess the optimal design and operational strategy for multi-microgrids (MMGs) within an active distribution network, with the aim of enhancing supply security and reliability. In accordance with this perspective, the paper introduces a three-layer coordinated operational planning framework for MMG planning. This framework considers various elements, including distributed generation (DGs) such as wind, biomass, and solar production, distributed reactive power sources (DRSs), and battery energy storage (BES). The primary goal of the provided framework is to minimize power exchange between MMGs and the anticipated energy not served, ultimately leading to an enhancement in supply security and reliability. Furthermore, the study explores the impact of conservation voltage reduction (CVR). To address the unpredictability of load consumption and renewable energy generation, scenario modeling was implemented. A backward scenario reduction technique was then employed to strike a balance between model accuracy and computational efficiency. To validate the proposed framework, it was implemented on an IEEE 33 bus distribution system. Comparative analysis against conventional planning schemes revealed a significant improvement, with a 58.37% reduction in supply exchange between MMGs and a 63.91 % decrease in energy not served achieved by the proposed MMG formulation. These test results underscore the superior efficacy of the proposed framework in enhancing both supply security and reliability when compared to conventional planning approaches.

D. H. Wang, D. H. Wang, Do Youb Kim et al.

Angewandte Chemie International Edition • 2011

This research was supported by Future-based Technology Development Program (Nano Fields, 2010-0029321) and the WCU (World Class University) program (R32-2008-000-10142-0) through the NRF of Korea funded by the MEST. J. H. Park acknowledges the support from NRF of Korea funded by the MEST (NRF-2009- C1AAA001-2009-0094157, 2011-0006268). Research at UCSB was supported by the US Army General Technical Services (LLC/GTS-S- 09-1-196) and by the Department of Energy (BES-DOE- ER46535).

Yew Weng Kean, A. Ramasamy, S. Sukumar et al.

International Journal of Power Electronics and Drive Systems (IJPEDS) • 2018

This paper presents a stand-alone hybrid renewable energy system (SHRES) consisting of solar photovoltaic (PV), wind turbine (WT) and battery energy storage (BES) in an effort reduce the dependence on fossil fuels. The renewable energy sources have individual inverters and the PV inverter of the SHRES is operated using active and reactive power control. The PV inverter have two main control structures which are active power control and reactive power control and each contain a proportional integral (PI) controller. Accurate control of the PV inverter’s active power is essential for PV curtailment applications. Thus, this paper aims to enhance the performance of the SHRES in this work by optimizing the performance of the PV inverter’s active power PI controller parameters through the design of adaptive controllers. Therefore, an adaptive controller and an optimized adaptive controller are proposed in this paper. The performances of the proposed controllers are evaluated by minimizing the objective function which is the integral of the time weighted absolute error (ITAE) criterion and this performance is then compared with a controller that is tuned by the traditional trial and error method. Simulation results showed that the optimized adaptive controller is better as it recorded an error improvement of 42.59%. The dynamic optimized adaptive controller is more adept at handling the fast changes of the SHRES operation.

P. Kirmizakis, R. Doherty, C. Mendonça et al.

Environmental Science and Pollution Research • 2019

Here, we show the electrical response, bacterial community, and remediation of hydrocarbon-contaminated groundwater from a gasworks site using a graphite-chambered bio-electrochemical system (BES) that utilizes granular activated carbon (GAC) as both sorption agent and high surface area anode. Our innovative concept is the design of a graphite electrode chamber system rather than a classic non-conductive BES chamber coupled with GAC as part of the BES. The GAC BES is a good candidate as a sustainable remediation technology that provides improved degradation over GAC, and near real-time observation of associated electrical output. The BES chambers were effectively colonized by the bacterial communities from the contaminated groundwater. Principal coordinate analysis (PCoA) of UniFrac Observed Taxonomic Units shows distinct grouping of microbial types that are associated with the presence of GAC, and grouping of microbial types associated with electroactivity. Bacterial community analysis showed that β-proteobacteria (particularly the PAH-degrading Pseudomonadaceae) dominate all the samples. Rhodocyclaceae- and Comamonadaceae-related OTU were observed to increase in BES cells. The GAC BES (99% removal) outperformed the control graphite GAC chamber, as well as a graphite BES and a control chamber both filled with glass beads.

Jamal Faraji, M. Babaei, Navid Bayati et al.

Electronics • 2019

Extreme weather events lead to electrical network failures, damages, and long-lasting blackouts. Therefore, enhancement of the resiliency of electrical systems during emergency situations is essential. By using the concept of standby redundancy, this paper proposes two different energy systems for increasing load resiliency during a random blackout. The main contribution of this paper is the techno-economic and environmental comparison of two different resilient energy systems. The first energy system utilizes a typical traditional generator (TG) as a standby component for providing electricity during the blackouts and the second energy system is a grid-connected microgrid consisting of photovoltaic (PV) and battery energy storage (BES) as a standby component. Sensitivity analyses are conducted to investigate the survivability of both energy systems during the blackouts. The objective function minimizes total net present cost (NPC) and cost of energy (COE) by considering the defined constraints of the system for increasing the resiliency. Simulations are performed by HOMER, and results show that for having almost the same resilience enhancement in both systems, the second system, which is a grid-connected microgrid, indicates lower NPC and COE compared to the first system. More comparison details are shown in this paper to highlight the effectiveness and weakness of each resilient energy system.