Discover insights from thousands of peer-reviewed papers on microbial electrochemical systems
André Gemünde, Nils‐Lennart Ruppert, Dirk Holtmann
ChemElectroChem · 2024
Abstract Cupriavidus necator , despite lacking direct electron transfer capabilities, demonstrates efficient reduction of various redox mediators in oxygen‐free cultivation within bioelectrochemical systems. This study investigates the reduction site of ferricyanide through inhibition and expression rate analysis of oxygen and nitrate respiration chain complexes, comparing aerobic cultivation conditions with fructose as carbon and electron donor to autotrophic (CO 2 /H 2 /O 2 ) and anodic cultivation conditions (fructose/anode). Azide inhibition identified cytochrome c oxidase as the primary complex facilitating electron transfer to ferricyanide, with a secondary role proposed for nitrite reductase NirS, demonstrating a 3.9±1.1‐fold higher expression when exposed to anodic conditions. The 2.9±0.6‐fold increase in the expression of the natural porin OmpA under anodic conditions implies its potential involvement in ferricyanide uptake. Additionally, chemically permeabilizing cell membranes with cetyltrimethylammonium bromide doubles ferricyanide reduction rates without an anode present, offering insights for optimizing redox mediation in C. necator based bioelectrochemical systems. This study opens up new possibilities for the targeted optimization of mediated electron transfer in C. necator and other organisms.
Huimin Zhao, Jianqiang Zhao, Fenghai Li et al.
Frontiers in Microbiology · 2016
Microbial fuel cell (MFC) with nitrite as an electron acceptor in cathode provided a new technology for nitrogen removal and electricity production simultaneously. The influences of influent nitrite concentration and external resistance on the performance of denitrifying MFC were investigated. The optimal effectiveness were obtained with the maximum total nitrogen (TN) removal rate of 54.80±0.01 g m-3 d-1. It would be rather desirable for the TN removal than electricity generation at lower external resistance. Denaturing gradient gel electrophoresis suggested that Proteobacteria was the predominant phylum, accounting for 35.72%. Thiobacillus and Afipia might benefit to nitrite removal. The presence of nitrifying Devosia indicated that nitrite was oxidized to nitrate via a biochemical mechanism in the cathode. Ignavibacterium and Anaerolineaceae was found in the cathode as a heterotrophic bacterium with sodium acetate as substrate, which illustrated that sodium acetate in anode was likely permeated through proton exchange membrane to the cathode .
Daobo Li, Xiaodan Zheng, Yonggang Yang et al.
Microorganisms · 2025
Extracellular electron transport (EET) supports the survival of specific microorganisms on the Earth’s surface by facilitating microbial respiration with diverse electron acceptors. A key aspect of EET is the organization of electron relays, i.e., multi-heme c-type cytochromes (MHCs), within the periplasmic space of microbial cells. In this study, we investigated the mobility of periplasmic electron relays in Shewanella oneidensis MR-1, a model strain capable of EET, using in vivo protein crosslinking to the MHCs. First, we established that crosslinking efficiency correlates with the spatial proximity and diffusion coefficient of protein molecules through in vitro tests. Based on these findings, we identified distinct molecular behaviors of periplasmic MHCs, showing that the tetraheme flavocytochrome FccA, which also serves as a periplasmic fumarate reductase, forms protein complexes with limited motility, while the small tetraheme c-type cytochrome CctA remains discrete and mobile. Both MHCs contribute to EET for bioelectrochemical nitrate and nitrite reduction. These findings reveal dual mechanisms for organizing periplasmic electron relays in EET, advancing our understanding of microbial extracellular respiration.
Maria Presutti, Geremia Sassetto, Angela Marchetti et al.
Journal of Chemical Technology & Biotechnology · 2026
Abstract BACKGROUND Chlorinated aliphatic hydrocarbons such as trichloroethylene ( TCE ) are persistent groundwater contaminants due to improper disposal and low biodegradability. This work presents an innovative bioelectrochemical system for the integrated reductive/oxidative removal of TCE from contaminated water, implemented in a single tubular reactor. Unlike previous approaches relying on sequential reactor configurations, this study optimizes a three‐electrode setup that enables both anaerobic and aerobic dechlorination processes to occur simultaneously within the same unit. The system features a mixed metal oxide ( MMO ) anode that facilitates oxygen evolution and supports oxidative degradation, and a graphite cathode for TCE reduction under anaerobic conditions. The reactor's configuration promotes the coexistence of both anaerobic and aerobic microbial communities, enabling complete dechlorination of TCE and minimization of toxic by‐products RESULTS After characterizing the system from a fluid‐dynamic point of view, continuous‐flow galvanostatic runs at +15, +30, and +20 mA achieved removal efficiencies above 97%. By‐product profiles confirmed the progression toward full mineralization. The most effective performance was obtained at +30 mA, with a removal rate of 38.6 μmol/L d −1 . Coulombic efficiency and energy consumption were also evaluated, highlighting the feasibility of low‐energy operation. CONCLUSION This single‐reactor strategy represents a significant advancement in the design of compact and efficient systems for in situ groundwater remediation, reducing operational complexity while enhancing treatment performance. © 2026 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley Sons Ltd on behalf of Society of Chemical Industry (SCI).
Hafiz Abdul Kareem, Mohd Faheem Khan
International Journal of Molecular Sciences · 2026
Soil contamination by per- and polyfluoroalkyl substances (PFAS) represents a pressing environmental and public health concern due to the exceptional persistence of carbon–fluorine bonds, which prevent natural attenuation and limit the effectiveness of conventional remediation. Agricultural and industrial soils serve as long-term sinks for PFAS, continuously releasing these pollutants into groundwater and facilitating their transfer through the food chain. Conventional chemical and physical remediation methods are often costly, energy-intensive, and yield incomplete removal, underscoring the need for sustainable and biologically driven alternatives. Microbial consortia have emerged as a promising solution due to their metabolic complementarities, cross-feeding interactions, and ecological resilience, which together enable PFAS transformation and partial defluorination under complex soil and subsurface conditions. Key enzymes such as oxygenases, reductive dehalogenases, and hydrolases are often operating within co-metabolic networks, which play central roles in these processes. Advances in metagenomics, CRISPR-based functional screening, and metabolic modelling are rapidly uncovering novel PFAS-degrading microbes and pathways. Integration of machine learning with multi-omics and environmental datasets further enables the prediction of degradation mechanisms, identification of keystone degraders, and rational design of synthetic consortia. Emerging sustainable strategies, including biochar- and nutrient-amended soil microcosms, plant–microbe partnerships for coupled soil–groundwater phytoremediation, and bioelectrochemical systems that offer new avenues for enhancing PFAS biodegradation in situ. This review synthesises recent research progress and provides critical perspectives on the mechanistic, ecological, and engineering dimensions of PFAS bioremediation, proposing an integrated conceptual framework linking microbial consortia dynamics, enzymatic pathways, and environmental engineering interventions to guide scalable field applications and sustainable management of PFAS-contaminated soil–groundwater ecosystems.
Uwe Schröder, Falk Harnisch, Elizabeth Heidrich et al.
Frontiers in Science · 2026
Global wastewater production exceeds 359 billion m 3 annually, of which only 52% is treated, mostly in expensive and resource-consuming processes. Microbial electrochemical technologies (METs) offer a transformative approach to sustainable wastewater management by converting waste into valuable resources such as energy, clean water, and nutrients. They present a viable solution to the United Nations’ Sustainable Development Goal 6 (to ensure access to water and sanitation for all) by enhancing both sanitation and resource recovery. METs, including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs), harness electrogenic microorganisms to oxidize organic matter, generating electric energy or producing energy carriers like hydrogen and methane. METs also enable recovery of nutrients, such as ammonium and phosphates, which are essential for agriculture, thereby closing resource loops in a circular economy. Despite their potential, challenges remain in scaling up METs for widespread application. Pilot-scale MFCs and MECs have demonstrated feasibility, achieving up to 90% chemical oxygen demand removal and producing electric power, methane, or hydrogen from wastewater. However, high capital costs, material limitations, and energy efficiency barriers hinder commercialization. Innovations in electrode design, modular configurations, and integration with existing wastewater treatment processes (e.g., anaerobic digestion, membrane bioreactors, or constructed wetlands) are advancing METs toward higher technology readiness levels (TRLs 4–8). Field applications, like a system for urine-based electricity generation in underserved regions, highlight METs adaptability and societal impact. The transition from laboratory to real-world implementation requires scaling, process integration, and further optimization to reduce costs and improve performance. By aligning with circular economy principles, METs can transform wastewater into a resource, contributing to energy security, environmental sustainability, and global sanitation goals. Future research should focus on scalable designs, economic viability, and interdisciplinary collaboration alongside understanding and optimizing the microbial “black box” to enable METs to transform previously unused wastewater streams into valuable resources with targeted applications.
Zheng Ge, Zhen He
Environmental Science: Water Research & Technology · 2016
Microbial fuel cells (MFCs) have been intensively studied at a bench scale and the further development of this technology requires system scaling up and understanding of their performance under non-laboratory conditions. In this study, a 200 L modularized MFC system consisting of 96 MFC modules was developed and operated in a local wastewater treatment plant for treating primary effluent. During more than 300 days' operation, the MFC system removed more than 75% of the total chemical oxygen demand and 90% of the suspended solids, despite significant fluctuations in treatment performance affected by wastewater quality and operational factors. It achieved 68% removal of ammonia nitrogen, but phosphorous and the nitrate accumulated due to nitrification needs further disposal. The frequency of the catholyte recirculation exerted a strong effect on the energy consumption of the MFC system. Through both parallel and serial electric connections, the MFC system generated power of ∼200 mW that was extracted by a power management system to drive a 60 W DC pump for catholyte recirculation. Over 60% of the material cost of the MFCs was due to the cation exchange membrane, and the capital cost of the MFC system could be comparable to that of small wastewater treatment facilities. The results of this study encourage the further development of MFC technology with reduced costs and improved performance towards sustainable wastewater treatment.
Joanna Rodziewicz, Artur Mielcarek, Wojciech Janczukowicz et al.
Applied Sciences · 2022
Soilless tomato cultivation wastewater, with typically low COD, high concentrations of phosphorus, and oxidized forms of nitrogen, may be effectively treated in a rotating electrochemical disk contactor (RECDC) and in a bioelectrochemical reactor (BER), such as a rotating electrobiological disk contactor (REBDC). The aim of this study was to determine the technological parameters of both reactors, i.e., electric current density (J) and hydraulic retention time (HRT), depending on the effluent quality requirements. The study was conducted with four one-stage RECDCs and with four one-stage REBDCs, at four hydraulic retention times, i.e., 4, 8, 12, and 24 h, and electric current densities of 0.63, 1.25, 2.50, 5.00, and 10.00 A/m2. It was demonstrated that soilless tomato cultivation wastewater could be effectively treated in electrochemical and electrobiological disk contactors, and then discharged to sewage system facilities. In a RECDC, the highest denitrification (53.4%) and dephosphatation (99.8%) performance was achieved at J = 10.0 A/m2 and HRT = 24 h. If the effluents are to be discharged to natural reservoirs, their effective treatment is only feasible in a REBDC. The bioelectrochemical disk contactor ensured over 90% dephosphatation effectiveness. At HRT = 24 h and all electric current densities studied, the concentrations of pollutants in the effluent met requirements set for industrial wastewater discharged into natural waters and the ground. By applying J = 2.5 A/m2 and HRT = 24 h in the REBDC, it was possible to achieve a phosphorus concentration below 3.0 mg P/L and concentrations of ammonia nitrogen and nitrites lower than the permissible levels for treated industrial wastewater introduced to waters and to the ground. Given the nitrate concentration (exceeding 30 mg N/L), an external carbon source is recommended to aid a treatment process that uses a technological system with a REBDC. Technological schemes were proposed for wastewater treatment plants (WWTPs) with a RECDC and a REBDC, for discharging treated wastewater to natural waters, the ground, and sewage systems.
Yifan Yu, Jafari Ali, Yuesuo Yang et al.
Energies · 2022
Applying microbial fuel cell (MFC) technology for eco-remediation of Cr(VI) pollution from a subsurface environment has great scientific value and practical significance due to its promising advantages of pollutant remediation and renewable energy generation. The aim of the current review is to summarize the migration characteristics of Cr(VI) in a subsurface soil/water environment and investigate the factors affecting the MFC performance for synchronous Cr(VI) remediation and power generation, and sequentially highlight diverse challenges of MFC technology for in situ remediation of subsurface groundwater and soils. The critical review put forward that Cr(VI) removal efficiency and energy production of MFC can be improved by enhancing the adjustability of cathode pH, setting potential, modifying electrode, and incorporating other technologies into MFC. It was recommended that designing typical large-scale, long-term continuous flow MFC systems, adding electron shuttle media or constructing artificial electron according to actual groundwater/soil and Cr(VI) pollution characteristics, site geology, and the hydrogeology condition (hydrochemical conditions, colloid type, and medium) are essential to overcome the limitations of the small size of the laboratory experiments and improve the application of technology to in situ Cr(VI) remediation. This review provided reference and ideas for future research of MFC-mediated onsite Cr(VI) remediation.
H. T. Dinh, Hiromi Kambara, Yoshiki Harada et al.
Microbes and Environments · 2021
The present study investigated bioelectrical methane production from CO2 without organic substances. Even though microbial methane production has been reported at relatively high electric voltages, the amount of voltage required and the organisms contributing to the process currently remain unknown. Methane production using a biocathode was investigated in a microbial electrolysis cell coupled with an NH4+ oxidative reaction at an anode coated with platinum powder under a wide range of applied voltages and anaerobic conditions. A microbial community analysis revealed that methane production simultaneously occurred with biological denitrification at the biocathode. During denitrification, NO3– was produced by chemical NH4+ oxidation at the anode and was provided to the biocathode chamber. H2 was produced at the biocathode by the hydrogen-producing bacteria Petrimonas through the acceptance of electrons and protons. The H2 produced was biologically consumed by hydrogenotrophic methanogens of Methanobacterium and Methanobrevibacter with CO2 uptake and by hydrogenotrophic denitrifiers of Azonexus. This microbial community suggests that methane is indirectly produced without the use of electrons by methanogens. Furthermore, bioelectrical methane production occurred under experimental conditions even at a very low voltage of 0.05 V coupled with NH4+ oxidation, which was thermodynamically feasible.
Yamini Jangir, Sarah French, Lily M. Momper et al.
bioRxiv (Cold Spring Harbor Laboratory) · 2016
Abstract Continental subsurface environments can present significant energetic challenges to the resident microorganisms. While these environments are geologically diverse, potentially allowing energy harvesting by microorganisms that catalyze redox reactions, many of the abundant electron donors and acceptors are insoluble and therefore not directly bioavailable. Extracellular electron transfer (EET) is a metabolic strategy that microorganisms can deploy to meet the challenges of interacting with redox-active surfaces. Though mechanistically characterized in a few metal-reducing bacteria, the role, extent, and diversity of EET in subsurface ecosystems remains unclear. Since this process can be mimicked on electrode surfaces, it opens the door to electrochemical techniques to enrich for and quantify the activities of environmental microorganisms in situ . Here, we report the electrochemical enrichment of microorganisms from a deep fractured-rock aquifer in Death Valley, California, USA. In experiments performed in mesocosms containing a synthetic medium based on aquifer chemistry, four working electrodes were poised at different redox potentials (272, 373, 472, 572 mV vs. SHE) to serve as electron acceptors, resulting in anodic currents coupled to the oxidation of acetate during enrichment. The anodes were dominated by Betaproteobacteria from the families Comamonadaceae and Rhodocyclaceae. A representative of each dominant family was subsequently isolated from electrode-associated biomass. The EET abilities of the isolated Delftia strain (designated WE1–13) and Azonexus strain (designated WE2–4) were confirmed in electrochemical reactors using working electrodes poised at 522 mV vs. SHE. The rise in anodic current upon inoculation was correlated with a modest increase in total protein content. Both genera have been previously observed in mixed communities of microbial fuel cell enrichments, but this is the first direct measurement of their electrochemical activity. While alternate metabolisms (e.g. nitrate reduction) by these organisms were previously known, our observations suggest that additional ‘hidden’ interactions with external electron acceptors are also possible. Electrochemical approaches are well positioned to dissect such extracellular interactions that may be prevalent in the subsurface.
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.
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.
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
Samrat MVV Naga, Rao K Kesava, Bernardo Ruggeri et al.
bioRxiv (Cold Spring Harbor Laboratory) · 2017
Abstract The sea contains various microbes which have an ability to reduce and oxidize substances like iron, sulphur, and nitrate. Most of these processes happen in the seawater, but can also be applied for purification of wastewater. In the present work, a consortium of seawater bacteria has been used for the first time in a microbial fuel cell to reduce nitrate in synthetic water samples and produce electricity by oxidizing organic matter. The concentrations of and were reduced to well below their permissible limits. Moreover, the growth of the bacterial consortium at cathode causes an increased electricity production in the cell because of the increased bacterial activity. The performance of the cell with a bicarbonate buffered solution (BBS) at the cathode was superior to that obtained with the commonly used phosphate buffered solution (PBS). As BBS is the natural buffering agent found in the sea, the use of BBS is eco-friendly. The same seawater bacterial consortium could be used at both the anode and the cathode, confirming their adaptability to different environments. Unfortunately, denitrification was accompanied by the generation of high concentrations of at the anode and the cathode, probably because of the use of N 2 gas for sparging the anolyte. This aspect merits further investigation.
Bo Dong, Yurong Li, Xinyue Li et al.
Journal of New Materials for Electrochemical Systems · 2022
Compared with a microbial fuel cell (MFC) of single flora, the MFC of mixed flora provide much better denitrification and electricity generation performance. Therefore, in-depth analysis of the kinetic features such as the structures of various types of microflora in MFCs is of important theoretical and practical significance. There is little existing research on the electricity generation and pollutant removal process of cathode microorganisms and the functions of microbial flora. To this end, this paper constructs an MFC anaerobic-aerobic coupled denitrification system and studies its performance enhancement method. First, the basic principle of MFC biological denitrification was expounded, the kinetics was introduced into the analysis of the reaction between the MFC microorganisms and pollutants, and the migration and transformation occurring in the reaction process and the mechanism of transformation speed changes were revealed. Then, the analysis and calculation methods for the electrochemical parameters and microbial diversity index in MFC were explained in detail, and the experimental results and analysis conclusions were given.
Xiaodong Zhao, Xiaorui Qin, Xiuqing Jing et al.
Biotechnology for Biofuels and Bioproducts · 2023
Abstract Background Soil microbial fuel cells (MFCs) can remove antibiotics and antibiotic resistance genes (ARGs) simultaneously, but their removal mechanism is unclear. In this study, metagenomic analysis was employed to reveal the functional genes involved in degradation, electron transfer and the nitrogen cycle in the soil MFC. Results The results showed that the soil MFC effectively removed tetracycline in the overlapping area of the cathode and anode, which was 64% higher than that of the control. The ARGs abundance increased by 14% after tetracycline was added (54% of the amplified ARGs belonged to efflux pump genes), while the abundance decreased by 17% in the soil MFC. Five potential degraders of tetracycline were identified, especially the species Phenylobacterium zucineum, which could secrete the 4-hydroxyacetophenone monooxygenase encoded by EC 1.14.13.84 to catalyse deacylation or decarboxylation. Bacillus , Geobacter , Anaerolinea , Gemmatirosa kalamazoonesis and Steroidobacter denitrificans since ubiquinone reductase (encoded by EC 1.6.5.3), succinate dehydrogenase (EC 1.3.5.1), Coenzyme Q-cytochrome c reductase (EC 1.10.2.2), cytochrome-c oxidase (EC 1.9.3.1) and electron transfer flavoprotein-ubiquinone oxidoreductase (EC 1.5.5.1) served as complexes I, II, III, IV and ubiquinone, respectively, to accelerate electron transfer. Additionally, nitrogen metabolism-related gene abundance increased by 16% to support the microbial efficacy in the soil MFC, and especially EC 1.7.5.1, and coding the mutual conversion between nitrite and nitrate was obviously improved. Conclusions The soil MFC promoted functional bacterial growth, increased functional gene abundance (including nitrogen cycling, electron transfer, and biodegradation), and facilitated antibiotic and ARG removal. Therefore, soil MFCs have expansive prospects in the remediation of antibiotic-contaminated soil. This study provides insight into the biodegradation mechanism at the gene level in soil bioelectrochemical remediation.
M. R. Arredondo
· 2019
Nitrogen removal from wastewaters is necessary to prevent the pollution of receiving water bodies. At the same time, nitrogen is an essential nutrient for plants, so it is used in the production of fertilizers. Both the conventional removal of nitrogen compounds from wastewater and their production are energy intensive. For this reason, recovering nitrogen directly from wastewater, instead of removing it, can result in reduced energy consumption associated with both its production and removal processes. The use of electrochemical systems (ES) and bioelectrochemical systems (BES) for the recovery of ammonia from wastewaters has been investigated over the past few years. These systems have been proposed as a sustainable alternative to conventional processes because they have the potential to recover energy (in the form of electricity or H2) from wastewaters while recovering ammonia. From all the domestic wastewater streams, urine contains most of the nitrogen (around 80%), and represents only 1% of the volume. Urine can be collected by the use of urine-diverting toilets or waterless urinals, preventing the dilution of the nutrients with high volumes of potable water. In this thesis, we evaluated the use of (bio)electrochemical systems for the recovery of total ammonia nitrogen (TAN) from urine. Our focus was on improving the understanding and performance of the system in terms of TAN recovery. This was needed to get the technology closer to application as, at the start of this research, the proof-of-principle had just been demonstrated, and the highest TAN recoveries were around 30%. The feasibility of BES as a technology for energy-efficient TAN recovery was evaluated in Chapter 2. It was shown that BESs can become economically feasible if, on top of electricity or hydrogen production, the benefits of TAN removal are taken into account. According to our analysis, when TAN removal is taken into account, BESs can still be economic at high internal resistances (200 mΩ.m2), which makes it easier for the application of the system at a bigger scale. The need to develop and test a method to effectively extract ammonia from the catholyte solution was identified as one of the main limiting factors of the system. One of the main conclusions from Chapter 2 was that it was crucial to couple an effective TAN stripping system to the BES to increase TAN recovery. This was addressed in Chapter 3, and followed up in Chapters 4 and 5. Finally, it was determined that to improve TAN recovery in BES, the interactions between the factors affecting the recovery of TAN in BES (such as current density, catholyte pH, TAN concentration, etc.) should be studied in more detail. In Chapter 3, we demonstrated that an ES with an integrated gas-permeable hydrophobic membrane unit can effectively recover TAN from urine. Furthermore, the relationship between current density and TAN loading rate was studied in more detail. It was shown that the relationship between the applied current density and the TAN loading, here called the load ratio, is essential to assess the TAN removal efficiency and energy input of (B)ESs. The load ratio is useful to find the conditions in which a (B)ES for the recovery of TAN can be operated optimally, but it does not take into account other parameters essential to assess the performance of (B)ESs. These limitations are discussed throughout the thesis and in Chapter 6. In Chapter 4, a hydrogen-recycling electrochemical system (HRES) was developed to minimize the energy input of electrochemical systems for the recovery of TAN. In this technology, the hydrogen gas produced at the cathode is reused as the electron donor in the anode, allowing for ammonia recovery at high rates and relatively low energy input. This technology can be applied to recover TAN from wastewaters that do not contain enough organic matter to be treated in a BES. Furthermore, it lowers the risk of chloride oxidation, which typically occurs in electrochemical systems treating wastewaters with high concentrations of chloride, such as urine. Chloride oxidation can result in the formation of harmful compounds such as chlorine gas, chlorination byproducts and adsorbable organic halides (AOX). At a load ratio of 1.2-1.3, the system accomplished TAN removal efficiencies of 73-82% and recoveries of 60-73%. Additional hydrogen needed to be supplied by a supporting electrolyzer, which accounted for 4-9% of the total energy demand of the system. Finally, in Chapter 5, we tested the concept of load ratio in a BES. The load ratio can be manipulated either by changing the current density or the TAN loading rate. In a BES the current density cannot be controlled as easily as in an electrochemical system, because it depends on the oxidation of organic matter by microorganisms. At the same time, manipulating the TAN loading rate would directly affect the organic loading rate, and therefore the current density. We ran the BES coupled to a gas-permeable hydrophobic membrane on synthetic urine and urine. Both influents were fed at different dilutions, flow rates and certain modifications (such as removing TAN from urine prior to feeding it to the cell) in order to obtain a variety of load ratios. We found out that there was a clear increasing trend in TAN removal efficiency with respect to load ratio for both human and synthetic urine. We did not obtain load ratios higher than 0.8, which means that the current was not enough to transport all the TAN across the membrane. This resulted in overall low removal efficiencies (2 to 47%, with 3 exceptions from 52- 61%). In Chapter 6, we discuss what may cause these low current densities. In this last chapter, we also focus on the reasons why (B)ESs have not been applied at larger scales yet, and give future perspectives and recommendations to bring this promising technology closer to application.
Jing Cai, Ping Zheng, Mahmood Qaisar et al.
Journal of Industrial Microbiology and Biotechnology · 2014
Abstract The effect of operating modes on the simultaneous sulfide and nitrate removal were studied in two-chamber microbial fuel cells (MFCs). The batch and continuous operating modes were compared and evaluated in terms of substrate removal and electricity generation. Upon gradual increase in the influent sulfide concentration from 60 to 1,020 S mg L−1, and the hydraulic retention time decrease from 17.2 to 6 h, the MFC accomplished a good substrate removal efficiency whereby nitrogen and sulfate were the main end products. The removal efficiency of the MFC in the continuous mode was much higher than that in the batch mode, and its current densities in the continuous mode were more stable and higher than in the batch mode, which could be explained by the linear relationship between electrons released by the substrates and accepted on the electrodes. The electricity output in the continuous mode of the MFC was higher than that in the batch mode. MFC's operation in the continuous mode was a better strategy for the simultaneous treatment of sulfide and nitrate.
Sanath Kondaveeti, Dae-Hyeon Choi, Md Tabish Noori et al.
Energies · 2022
Ammonia removal from wastewater was successfully achieved by simultaneous nitrification and denitrification (SND) in a double-chamber microbial electrolysis cell (MEC). The MEC operations at different applied voltages (0.7 to 1.5 V) and initial ammonia concentrations (30 to 150 mg/L) were conducted in order to evaluate their effects on MEC performance in batch mode. The maximum nitrification efficiency of 96.8% was obtained in the anode at 1.5 V, followed by 94.11% at 1.0 V and 87.05% at 0.7. At 1.5 V, the initial ammonia concentration considerably affected the nitrification rate, and the highest nitrification rate constant of 0.1601/h was determined from a first-order linear regression at 30 mg/L ammonium nitrogen. The overall total nitrogen removal efficiency was noted to be 85% via the SND in the MEC operated at an initial ammonium concentration of 50 mg/L and an applied cell voltage of 1.5 V. The MEC operation in continuous mode could remove ammonia (50 mg/L) in a series of anode and cathode chambers at the nitrogen removal rate of 170 g-N/m3.d at an HRT of 15. This study suggests that a standalone dual-chamber MEC can efficiently remove ammonia via the SND process without needing additional organic substrate and aeration, which makes this system viable for field applications.
Urania Michaelidou, Annemiek ter Heijne, Gerrit Jan W. Euverink et al.
Applied and Environmental Microbiology · 2011
ABSTRACT Four types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended with Geobacter sulfurreducens strain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, to Geobacter sulfurreducens strain PCA. Other bacterial species were also detected in the system, such as a Propionicimonas -related species that was dominant in the anodic liquid and Pseudomonas -, Clostridium -, Desulfovibrio -, Azospira -, and Aeromonas -related species.
Narcís Pous, Maria Dolors Balaguer, Jesús Colprim et al.
Microbial Biotechnology · 2018
Summary Groundwater pollution is a serious worldwide concern. Aromatic compounds, chlorinated hydrocarbons, metals and nutrients among others can be widely found in different aquifers all over the world. However, there is a lack of sustainable technologies able to treat these kinds of compounds. Microbial electro‐remediation, by the means of microbial electrochemical technologies ( MET ), can become a promising alternative in the near future. MET can be applied for groundwater treatment in situ or ex situ , as well as for monitoring the chemical state or the microbiological activity. This document reviews the current knowledge achieved on microbial electro‐remediation of groundwater and its applications.
Afaf Abdel Razik Mohamed, Ali El-Dissouky Ali, Mohamed Salah El-Din Hassouna et al.
Applied Water Science · 2025
Abstract Ammonia presence in water has many negative impacts including eutrophication. So, the major objective of this research was to evaluate the efficiency of microbial fuel cell (MFC) and electrochemical (ECS) systems for their removal and/or recovery from wastewater at different levels of ammonia (500 ppm, 1000 ppm, and 1500 ppm). Additionally, a novel approach was tested by using nanomaterial prepared from pomegranate peel as a coating material for the electrodes as it is abundant in many countries. Two systems were tested: Group (A) with a non-coated graphite plate anode (MFC1 and ECS1) and Group (B) which was coated with nano-graphene oxide made from pomegranate peels (MFC2 and ECS2). Results revealed that MFC1 gave the best ammonia removal efficiency reaching 96.2% when the initial concentration was 500 ppm after 13 days, and MFC2 gave maximum removal efficiency of 94.4% and 99.4% for 1000 and 1500 ppm after 19 and 25 days, respectively. COD results coincided with the removal efficiency. Electrochemical ammonia removal was carried out using two external electrical currents, 40 and 80 mA. Results showed that ECS2 gave the highest ammonia removal efficiency of 95.08% at 80 mA in case of 500 ppm, and the maximum for recovery was 80% when 1000 ppm was tested at 80 mA along with an increase in pH in the cathode chamber. Furthermore, ECS2 consumed less energy than ECS1 for ammonia recovery. ECS2 efficiently treated slaughterhouse wastewater reaching almost 100% ammonia removal; however, the maximum recovery of 44.7% occurred after 6 h, but consuming less energy than ECS1. It was evidenced that using an anode coated with nanographene oxide provided dual benefits of quickness and effective ammonia removal and/or recovery and provisioning energy requirements.
Irene Bavasso, Daniele Montanaro, Elisabetta Petrucci et al.
Sustainability · 2018
In this work, the feasibility of the Shortcut Biological Nitrogen Removal (SBNR) in the anodic chamber of a Microbial Fuel Cell (MFC) was investigated. Thirty day experiments were carried out using synthetic wastewaters with a Total Organic Carbon vs. nitrogen ratio (TOC/N) ranging from 0.1 to 1. Ammonium, nitrite, nitrate, pH, and TOC were daily monitored. Results showed that microaerobic conditions in the anodic chamber favored the development of nitritation reaction, due to oxygen transfer from the cathodic chamber through the membrane. Nitritation was found to depend on TOC/N ratio: at TOC/N equal to 0.1 an ammonium removal efficiency of up to 76% was observed. Once the oxygen supply to the cathodic chamber was stopped, denitritation occurred, favored by an increase of the TOC/N ratio: a nitrite removal of 80.3% was achieved at TOC/N equal to 0.75. The presence of nitrogen species strongly affected the potential of the electrochemical system: in the nitritation step, the Open Circuit Voltage (OCV) decreased from 180 mV to 21 mV with the decrease of the TOC/N ratio in the investigated range. Lower OCV values were observed in the denitritation steps since the organic carbon acted as the energy source for the conversion of nitrite to nitrogen gas. A kinetic analysis was also performed. Monod and Blackman models described the ammonium and the organic carbon removal processes well during the nitritation step, respectively, while Blackman-Blackman fitted experimental results of the denitritation step better.
Krishnaveni Venkidusamy, M. Megharaj
Frontiers in Microbiology · 2016
Electrode respiring bacteria (ERB) possess a great potential for many biotechnological applications such as microbial electrochemical remediation systems (MERS) because of their exoelectrogenic capabilities to degrade xenobiotic pollutants. Very few ERB have been isolated from MERS, those exhibited a bioremediation potential toward organic contaminants. Here we report once such bacterial strain, Stenotrophomonas maltophilia MK2, a facultative anaerobic bacterium isolated from a hydrocarbon fed MERS, showed a potent hydrocarbonoclastic behavior under aerobic and anaerobic environments. Distinct properties of the strain MK2 were anaerobic fermentation of the amino acids, electrode respiration, anaerobic nitrate reduction and the ability to metabolize n-alkane components (C8–C36) of petroleum hydrocarbons (PH) including the biomarkers, pristine and phytane. The characteristic of diazoic dye decolorization was used as a criterion for pre-screening the possible electrochemically active microbial candidates. Bioelectricity generation with concomitant dye decolorization in MERS showed that the strain is electrochemically active. In acetate fed microbial fuel cells (MFCs), maximum current density of 273 ± 8 mA/m2 (1000 Ω) was produced (power density 113 ± 7 mW/m2) by strain MK2 with a coulombic efficiency of 34.8%. Further, the presence of possible alkane hydroxylase genes (alkB and rubA) in the strain MK2 indicated that the genes involved in hydrocarbon degradation are of diverse origin. Such observations demonstrated the potential of facultative hydrocarbon degradation in contaminated environments. Identification of such a novel petrochemical hydrocarbon degrading ERB is likely to offer a new route to the sustainable bioremedial process of source zone contamination with simultaneous energy generation through MERS.
Rachchanon Yodrach, Purita Rattanabundan, Pimprapa Chaijak
Journal of Degraded and Mining Lands Management · 2025
Mature coconut water (MCW) is a by-product of various coconut industries. It is produced in large quantities annually. If untreated, this waste can pollute groundwater systems upon discharge. In this study, MCW was used as a low-cost medium for bacterial nanocellulose (BNC) production. The effects of exogenous carbon and nitrogen sources were studied under static conditions. Suitable conditions were then selected for use in a microbial fuel cell (MFC) to generate electrical energy from BNC fermentation. Subsequently, the BNC was immobilized with silver nanoparticles (AgNPs) and used against the pathogenic bacteria Escherichia coli and Staphylococcus aureus. The results showed that the system generated maximum current density (CD) and power density (PD) of 54.250 ± 0.180 mA/m² and 5.886 ± 0.039 mW/m², respectively. The AgNPs-immobilized BNC film effectively inhibited the growth of both Gram-negative E. coli and Gram-positive S. aureus with inhibition zones measuring 26.0 ± 0.3 mm and 30.1 ± 0.2 mm, respectively. This study provides new insights into producing electrical energy during BNC synthesis fermentation.
Marco Hartl
· 2020
The objective of this work was the improvement and control of wastewater treatment using constructed wetlands operated as Microbial Fuel Cells (CW-MFCs) and Microbial Electrolysis Cells (CW-MECs). For this purpose, eight meso-scale experimental systems were constructed. The first experiment investigated the use of CW-MFC as a bioindicator, showing that it could be used as a qualitative alarm tool for sudden COD increases. The following three experiments investigated the removal of conventional contaminants as well as organic micropollutants (OMPs) using duplicates of CW-MEC, closed-circuit CW-MFC, open-circuit CW-MFC and conventional CW-control. Results showed that CW-MEC and CW-MFC+ increased the removal of COD (7-13%) and ammonium (18-22%) when compared to the control systems. Regarding OMPs, carbamazepine, diclofenac and naproxen removal was increased by 10-17% in CW-MFC+ and CW-MEC when compared to the control, while ibuprofen removal was similar amongst treatments. Additionally, a microbial activity analysis showed that activity was 4-34% higher in CW-MFC+ as compared to CW-control, and a microbial community analysis indicated that anode and cathode communities in CW-MEC were significantly different tq other treatments, seemingly due to the effects of electrolysis. In CW-MFC+ only cathode communities were different. probably due to sampling issues at the anodes. El objetivo de esta tesis es la mejora de la eficiencia y control del tratamiento de aguas residuales mediante humedales construidos operados como sistemas bioelectroquímicos (CW-BES), tanto en su configuración de celdas microbianas de combustible (CW-MFC) como en configuración de celdas microbianas electrolíticas (CW-MEC). Para este propósito, ocho CW-BES a escala experimental de mesocosmo fueron construidos. Durante el primer experimento se investigó el uso de CW-BES operados como celdas CW-MFC como herramienta de bioindicación de la carga orgánica. En los subsiguientes experimentos se abordó el estudio de la mejora del tratamiento de contaminantes convencionales y microcontaminantes mediante la operación de CW-BES y CW-MFC y se comparó con la eliminación de los mismos con sistemas de humedales control (CW-Control). Los resultados mostraron que los CW-MEC y los CW-MFC incrementaban la eficiencia de tratamiento entre un 7-13% y entre el 18-22% respectivamente a la eliminación de la materia orgánica y el amonio. En relación a la eliminación de microcontaminantes, la eliminación de carbamacepina, diclofenaco y naproxeno mejoró entre un 1 O y un 17% en los CW-BES comparado con los sistemas control, mientras que la eliminación de ibuprofeno no mostró diferencias. El estudio de la actividad microbiana en los sistemas experimentales mostró que ésta aumenta entre un 4 y un 34% en los CW-BES. El estudio de las comunidades microbianas en los sistemas experimentales mostró diferencias significativas tanto en zona anódica como catódica de los CW-BES, comparado con los sistemas experimentales control.
Mariana Rodríguez Arredondo, Philipp Kuntke, Annemiek ter Heijne et al.
Journal of Chemical Technology & Biotechnology · 2019
Abstract BACKGROUND The load ratio is a crucial parameter to optimize the current driven recovery of total ammonia nitrogen (TAN) from urine. The load ratio is the ratio between the current density and the TAN loading rate. It is currently not known if the load ratio concept applies to a bioelectrochemical system (BES) because the current density and TAN loading rate cannot be controlled independently. RESULTS We found a clear increasing trend in TAN removal efficiency with respect to load ratio in the BES for both human and synthetic urine. The maximum TAN removal efficiency was 60.9% at a load ratio of 0.7, corresponding to a TAN transport rate of 119 gN m −2 day −1 at an electrical energy input of 1.9 kWh kgN −1 (synthetic urine). Low load ratios (<1) were obtained, indicating that the current was not enough to transport all the TAN across the membrane. CONCLUSIONS BES and ES show the same general relationship between TAN removal efficiency and load ratio. Therefore, given a stable current density, the concept of load ratio can also predict the TAN removal efficiency in BES. Higher current densities, and insights into the factors limiting current, are needed to increase the load ratio and therefore the TAN removal efficiency. © 2019 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Narcis Pous, Sebastià Puig, M. Dolors Balaguer et al.
Environmental Science: Water Research & Technology · 2017
This paper evaluates the influence of HRT and nitrate content on denitrifying BES.
M. L. Di Franca, B. Matturro, S. Crognale et al.
Frontiers in Microbiology · 2022
Chlorinated solvents still represent an environmental concern that requires sustainable and innovative bioremediation strategies. This study describes the microbiome composition of a novel bioelectrochemical system (BES) based on sequential reductive/oxidative dechlorination for complete perchloroethylene (PCE) removal occurring in two separate but sequential chambers. The BES has been tested under various feeding compositions [i.e., anaerobic mineral medium (MM), synthetic groundwater (SG), and real groundwater (RG)] differing in presence of sulfate, nitrate, and iron (III). In addition, the main biomarkers of the dechlorination process have been monitored in the system under various conditions. Among them, Dehalococcoides mccartyi 16S rRNA and reductive dehalogenase genes ( tceA , bvcA , and vcrA ) involved in anaerobic dechlorination have been quantified. The etnE and etnC genes involved in aerobic dechlorination have also been quantified. The feeding composition affected the microbiome, in particular when the BES was fed with RG. Sulfuricurvum , enriched in the reductive compartment, operated with MM and SG, suggesting complex interactions in the sulfur cycle mostly including sulfur oxidation occurring at the anodic counter electrode (MM) or coupled to nitrate reduction (SG). Moreover, the known Mycobacterium responsible for natural attenuation of VC by aerobic degradation was found abundant in the oxidative compartment fed with RG, which was in line with the high VC removal observed (92 ± 2%). D. mccartyi was observed in all the tested conditions ranging from 8.78E + 06 (with RG) to 2.35E + 07 (with MM) 16S rRNA gene copies/L. tceA was found as the most abundant reductive dehalogenase gene in all the conditions explored (up to 2.46 E + 07 gene copies/L in MM). The microbiome dynamics and the occurrence of biomarkers of dechlorination, along with the kinetic performance of the system under various feeding conditions, suggested promising implications for the scale-up of the BES, which couples reductive with oxidative dechlorination to ensure the complete removal of highly chlorinated ethylene and mobile low-chlorinated by-products.
Bruna Matturro, Marco Zeppilli, Agnese Lai et al.
Frontiers in Microbiology · 2021
Bioelectrochemical systems (BES) are attractive and versatile options for the bioremediation of organic or inorganic pollutants, including trichloroethylene (TCE) and Cr(VI), often found as co-contaminants in the environment. The elucidation of the microbial players’ role in the bioelectroremediation processes for treating multicontaminated groundwater is still a research need that attracts scientific interest. In this study, 16S rRNA gene amplicon sequencing and whole shotgun metagenomics revealed the leading microbial players and the primary metabolic interactions occurring in the biofilm growing at the biocathode where TCE reductive dechlorination (RD), hydrogenotrophic methanogenesis, and Cr(VI) reduction occurred. The presence of Cr(VI) did not negatively affect the TCE degradation, as evidenced by the RD rates estimated during the reactor operation with TCE (111±2 μeq/Ld) and TCE/Cr(VI) (146±2 μeq/Ld). Accordingly, Dehalococcoides mccartyi , the primary biomarker of the RD process, was found on the biocathode treating both TCE (7.82E+04±2.9E+04 16S rRNA gene copies g −1 graphite) and TCE/Cr(VI) (3.2E+07±2.37E+0716S rRNA gene copies g −1 graphite) contamination. The metagenomic analysis revealed a selected microbial consortium on the TCE/Cr(VI) biocathode. D. mccartyi was the sole dechlorinating microbe with H 2 uptake as the only electron supply mechanism, suggesting that electroactivity is not a property of this microorganism. Methanobrevibacter arboriphilus and Methanobacterium formicicum also colonized the biocathode as H 2 consumers for the CH 4 production and cofactor suppliers for D. mccartyi cobalamin biosynthesis. Interestingly, M. formicicum also harbors gene complexes involved in the Cr(VI) reduction through extracellular and intracellular mechanisms.
Daniele Cecconet, Fabrizio Sabba, Matyas Devecseri et al.
Preprints.org · 2019
Groundwater contamination is an ever-growing environmental issue, that has attracted much and undiminished attention for the past half century. Groundwater contamination originates from anthropogenic (e.g. hydrocarbons), natural compounds (e.g. nitrate and arsenic), or both; to tackle these contaminants different technologies have been tested during the years. Recently, bioelectrochemical systems (BESs) have emerged as a potential treatment for groundwater contamination, with in situ applications reported, that showed promising results. Nitrate and hydrocarbons (toluene, phenanthrene, benzene, BTEX and light PAHs) have been successfully removed, due to the interaction of microbial metabolism with poised electrodes, other than physical migration due to the electric field generated in BES. The selection of proper BESs relies on several factors and problems such as complexity of the groundwater, scale-up and energy requirements that need to be taken into account. Modelling efforts could help predict case scenarios and choose an ideal design and approach to solve these issues. In this review, we critically analyze in situ BES applications for groundwater remediation, focusing in particular on the different setups proposed, and we identify and discuss the existing research gaps in the field.
G. Pillot, O. Amin Ali, S. Davidson et al.
bioRxiv (Cold Spring Harbor Laboratory) · 2020
Abstract Deep-sea hydrothermal vents are extreme and complex ecosystems based on a trophic chain. We are still unsure of the identities of the first colonizers of these environments and their metabolism, but they are thought to be (hyper)thermophilic autotrophs. Here we investigate whether the electric potential observed across hydrothermal chimneys could serve as an energy source for these first colonizers. Experiments were performed in a two-chamber microbial electrochemical system inoculated with deep-sea hydrothermal chimney samples, with a cathode as sole electron donor, CO 2 as sole carbon source, and nitrate, sulfate, or oxygen as electron acceptors. After a few days of culture, all three experiments showed growth of electrotrophic biofilms consuming the electrons (directly or indirectly) and producing organic compounds including acetate, glycerol, and pyruvate. Within the biofilms, the only known autotroph species retrieved were members of Archaeoglobales . Various heterotrophic phyla also grew through trophic interactions, with Thermococcales growing in all three experiments as well as other bacterial groups specific to each electron acceptor. This electrotrophic metabolism as energy source driving initial microbial colonization of conductive hydrothermal chimneys is discussed.
Xiaojun Jin, Nuan Yang, Dake Xu et al.
Frontiers in Bioengineering and Biotechnology · 2024
Bioelectrochemical systems are sustainable and potential technology systems in wastewater treatment for nitrogen removal. The present study fabricated an air-cathode denitrifying microbial fuel cell (DNMFC) with a revisable modular design and investigated metabolic processes using nutrients together with the spatiotemporal distribution characteristics of dominated microorganisms. Based on the detection of organics and solvable nitrogen concentrations as well as electron generations in DNMFCs under different conditions, the distribution pattern of nutrients could be quantified. By calculation, it was found that heterotrophic denitrification performed in DNMFCs using 56.6% COD decreased the Coulombic efficiency from 38.0% to 16.5% at a COD/NO3 −-N ratio of 7. Furthermore, biological denitrification removed 92.3% of the nitrate, while the residual was reduced via electrochemical denitrification in the cathode. Correspondingly, nitrate as the electron acceptor consumed 16.7% of all the generated electrons, and the residual electrons were accepted by oxygen. Microbial community analysis revealed that bifunctional bacteria of electroactive denitrifying bacteria distributed all over the reactor determined the DNMFC performance; meanwhile, electroactive bacteria were mainly distributed in the anode biofilm, anaerobic denitrifying bacteria adhered to the wall, and facultative anaerobic denitrifying bacteria were distributed in the wall and cathode. Characterizing the contribution of specific microorganisms in DNMFCs comprehensively revealed the significant role of electroactive denitrifying bacteria and their cooperative relationship with other functional bacteria.
Xiaoou Wang, Ming Xue, Zhaoyu Wang et al.
Water · 2024
This study designed integrated constructed wetland–microbial fuel cell (CW–MFC) systems using activated carbon (AC) as both CW substrates and MFC anodes and investigated the structure-activity relationship of six kinds of commercial columnar AC, as well as the organics and nitrogen removal, microbial activity and diversity of CW–MFCs. Results showed that the nitrogen adsorption by AC tended to be a linear process in which physical adsorption played a leading role and micropores made great contributions. A higher specific surface area, developed mesopores, and oxygen functionalities were conducive to the capacitance properties of AC, while a higher specific surface area and developed micropores were conducive to reduce material resistance and improve ion permeability. Coconut-shell-based AC had both excellent nitrogen adsorption capacity and electrochemical properties, making it ideal as both CW substrates and MFC anodes for CW–MFCs. The electricity generation, coulombic efficiency, internal resistance, and organics and nitrogen removal of CW–MFCs were positively correlated with the total depth of AC anodes. The total depth of AC anodes can be determined based on the influent organics/nitrogen loadings and organics/nitrogen removal load of AC, and a relatively smaller depth of a single AC anode (5 cm) was recommended. The MFC effectively improved the enzymatic activity (by 10.33% dehydrogenase, 8.72% catalase, and 7.35% ammonia monooxygenase), nitrification/denitrification intensity (by 9.53%/6.68%), and microbial diversity (by 1.64–4.07%) of AC (MFC anodes) in CW–MFCs, while the depth of a single AC anode barely influenced the microbial activity and diversity. MFCs increased COD and NH3-N removal in CW–MFCs by 11.60% and 3.4%, respectively. The increased total adsorption capacity of AC with the increase of its total depth narrowed the difference in COD removal resulting from the promotion of MFCs on organics degradation. MFCs increased TN removal in CW–MFCs by 5.29% through promoting denitrification in cathodes and enhancing NH3-N assimilation in anodes. The phyla of EAB (Proteobacteria, Bacteroidetes, Firmicutes, and Acidobacteria) and genera of EAB (Citrobacter, Geobacter, and Pseudomonas) accounted for 85–86% and 15.58–16.64% of the microbial community on AC anodes in CW–MFCs, respectively.
Wei Li, Xiaohong Chen, Linshen Xie et al.
Water · 2019
Due to the deficiency of fresh water resources and the deterioration of groundwater quality worldwide, groundwater remedial technologies are especially crucial for preventing groundwater pollution and protecting the precious groundwater resource. Among the remedial alternatives, bioelectrochemical systems have unique advantages on both economic and technological aspects. However, it is rare to see a deep study focused on the information mining and visualization of the publications in this field, and research that can reveal and visualize the development trajectory and trends is scarce. Therefore, this study summarizes the published information in this field from the Web of Science Core Collection of the last two decades (1999–2018) and uses Citespace to quantitatively visualize the relationship of authors, published countries, organizations, funding sources, and journals and detect the research front by analyzing keywords and burst terms. The results indicate that the studies focused on bioelectrochemical systems for groundwater remediation have had a significant increase during the last two decades, especially in China, Germany and Italy. The national research institutes and universities of the USA and the countries mentioned above dominate the research. Environmental Science & Technology, Applied and Environmental Microbiology, and Water Research are the most published journals in this field. The network maps of the keywords and burst terms suggest that reductive microbial diversity, electron transfer, microbial fuel cell, etc., are the research hotspots in recent years, and studies focused on microbial enrichment culture, energy supply/recovery, combined pollution remediation, etc., should be enhanced in future.
Chen Yang, Yiheng Cao, Chuanping Feng
Water · 2025
Excessive nitrogen fertilizer use has resulted in growing nitrate contamination of groundwater. In this study, an in situ bioelectrochemical reactor (isBER) reinforced with woodchips was developed for the treatment of actual nitrate-contaminated groundwater. During the 75-day experiment, the denitrification performance, grid permeability, and microbial community structure were investigated under different flow rates and current densities. The reactor achieved a remarkable nitrate removal efficiency of 97.6% ± 0.4% and a rate of 2.09 ± 0.14 mg-N/(L·h). These results were obtained at a temperature of 18.5 ± 0.8 °C, a current density of 350 mA/m2, and a flow rate of 10 cm/d. Notably, the reactor can adapt to a wide flow-rate range of 5~20 cm/d and the operation proceeded smoothly without any blockages. Furthermore, the cathode module demonstrated enrichment of hydrogen autotrophic denitrifying bacteria (Pseudomonas, Stenotrophomonas) and heterotrophic denitrifying bacteria (Brucella, Enterobacteriaceae). Conversely, the anode module exhibited relatively high enrichment levels of aerobic microorganisms and lignin-degrading bacteria (Cellvibrio). The research results can provide novel insights and technical support for in situ remediation of groundwater nitrate contamination.
Joanna Rodziewicz, Artur Mielcarek, Kamil Bryszewski et al.
Energies · 2022
An attempt was undertaken to determine indicators of energy consumption in bio-electro reactors (BERs) i.e., an aerobic rotating electrobiological disc contactor (REBDC) and an anaerobic sequencing batch biofilm reactor (SBBR), during contaminant removal from soilless tomato cultivation wastewater having a specific composition, i.e., high nitrate and phosphorus concentrations and low COD. Because of this specificity, the energy consumption during the treatment process was characterized by a cumulative indicator for simultaneous removal of phosphorus and nitrates—EEINUTRIENTSrem (electric energy consumption per unit of removed nutrient load, expressed as kWh/kgNUTRIENTSrem). Four values of direct current density were tested: 0.63, 1.25, 2.5, and 5.0 A/m2. The indicator values were compared at a hydraulic retention time (HRT) of 24 h. The study demonstrated that the values of electric energy consumption per unit of removed nutrient load determined in the anaerobic SBBR ranged from 30 to 464 kWh/kg NUTRIENTSrem and were lower than the values obtained in the aerobic REBCD, i.e., 80–1380 kWh/kg NUTRIENTSrem.
Anup Gurung, Bhim Sen Thapa, Seong-Yun Ko et al.
Energies · 2023
Nitrate (NO3−-N) and nitrites (NO2−-N) are common pollutants in various water bodies causing serious threats not only to aquatic, but also to animals and human beings. In this study, we developed a strategy for efficiently reducing nitrates in microbial fuel cells (MFCs) powered by a granular activated carbon (GAC)-biocathode. GAC was developed by acclimatizing and enriching denitrifying bacteria under a redox potential (0.3 V) generated from MFCs. Thus, using the formed GAC-biocathode we continued to study their effect on denitrification with different cathode materials and circulation speeds in MFCs. The GAC-biocathode with its excellent capacitive property can actively reduce nitrate for over thirty days irrespective of the cathode material used. The stirring speed of GAC in the cathode showed a steady growth in potential generation from 0.25 V to 0.33 V. A rapid lag phase was observed when a new carbon cathode was used with enriched GAC. While a slow lag phase was seen when a stainless-steel cathode was replaced. These observations showed that effective storage and supply of electrons to the GAC plays a crucial role in the reduction process in MFCs. Electrochemical analysis of the GAC properties studied using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and zeta potential showed distinct properties with different abiotic and biocathode conditions. We found that the enrichment of electrotrophic bacteria on GAC facilitates the direct electron transfer in the cathode chamber for reducing NO3−-N in MFCs as observed by scanning electron microscopy.
Xiaofei Wang, Antonin Prévoteau, K. Rabaey
Environmental Science & Technology · 2021
Nitrate contamination is a common problem in groundwater around the world. Nitrate can be cathodically reduced in bioelectrochemical systems using autotrophic denitrifiers with low energy investment and without chemical addition. Successful denitrification was demonstrated in previous studies in both microbial fuel cells and microbial electrolysis cells (MECs) with continuous current flow, whereas the impact of intermittent current supply (e.g., in a fluidized-bed system) on denitrification and particularly the electron-storing capacity of the denitrifying electroactive biofilms (EABs) on the cathodes have not been studied in depth. In this study, two continuously fed MECs were operated in parallel under continuous and periodic polarization modes over 280 days, respectively. Under continuous polarization, the maximum denitrification rate reached 233 g NO3--N/m3/d with 98% nitrate removal (0.6 mg NO3--N/L in the effluent) with negligible intermediate production, while under a 30 s open-circuit/30 s polarization mode, 86% of nitrate was removed at a maximum rate of 205 g NO3--N/m3/d (4.5 mg NO3--N/L in the effluent) with higher N2O production (6.6-9.3 mg N/L in the effluent). Conversely, periodic polarization could be an interesting approach in other bioelectrochemical processes if the generation of chemical intermediates (partially reduced or oxidized) should be favored. Similar microbial communities dominated byGallionellaceaewere found in both MECs; however, swapping the polarization modes and the electrochemical analyses suggested that the periodically polarized EABs probably developed a higher ability for electron storage and transfer, which supported the direct electron transfer pathway in discontinuous operation or fluidized biocathodes.