Alba Ceballos‐Escalera, Narcís Pous, Paola Chiluiza-Ramos et al.

Water Research • 2020

The coexistence of different pollutants in groundwater is a common threat. Sustainable and resilient technologies are required for their treatment. The present study aims to evaluate microbial electrochemical technologies (METs) for treating groundwater contaminated with nitrate (NO 3 - ) while containing arsenic (in form of arsenite (As(III)) as a co-contaminant. The treatment was based on the combination of nitrate reduction to dinitrogen gas and arsenite oxidation to arsenate (exhibiting less toxicity, solubility, and mobility), which can be removed more easily in further post-treatment. We operated a bioelectrochemical reactor at continuous-flow mode with synthetic contaminated groundwater (33 mg N-NO 3 - L -1 and 5 mg As(III) L -1 ) identifying the key operational conditions. Different hydraulic retention times (HRT) were evaluated, reaching a maximum nitrate reduction rate of 519 g N-NO 3 - m 3 Net Cathodic Compartment d -1 at HRT of 2.3 h with a cathodic coulombic efficiency of around 100 %. Simultaneously, arsenic oxidation was complete at all HRT tested down to 1.6 h reaching an oxidation rate of up to 90 g As(III) m -3 Net Reactor Volume d -1 . Electrochemical and microbiological characterization of single granules suggested that arsenite at 5 mg L -1 did not have an inhibitory effect on a denitrifying biocathode mainly represented by Sideroxydans sp. Although the coexistence of abiotic and biotic arsenic oxidation pathways was shown to be likely, microbial arsenite oxidation linked to denitrification by Achromobacter sp. was the most probable pathway. This research paves the ground towards a real application for treating groundwater with widespread pollutants.

Barbara Lamolinara, Amaury Pérez-Martínez, Estela Guardado-Yordi et al.

Waste Management • 2022

Ana Paula Faria, Liliana P. L. Gonçalves, João M. Peixoto et al.

Journal of Cleaner Production • 2016

The increasing food demand and the exhaustion of non-renewable fuels provide new market opportunities in the agro-farming sector. Biological systems designed to add value to useless organic sub-products and to generate off-grid electricity may be one of the most interesting outcomes. Therefore, the capacity of some microorganisms to transfer electrons generated during organic carbon oxidation directly to an anode in a so-called microbial fuel cell (MFC) might be an asset in a sustainable management context. In this regard, the main goal of the present work was to evaluate the performance of a continuous MFC applied in a dairy industry. A maximum voltage of 576 mV was produced during continuous operation, corresponding to a power density of 92.2 mW m−2 or 1.9 W m−3. MFC was able to remove 1298 ± 617 mg L−1 of chemical oxygen demand (COD) at a hydraulic retention time of 8.4 h, and the maximum COD removal (63 ± 5%) was achieved after 20 days of continuous operation. In addition, the coulombic efficiency average was around 10.5 ± 10% with a maximum of 24.2 ± 1.5%. In average, the MFC was able to extract a specific energy of 8.95 × 10−2 kW h kg−1 COD with a maximum output of 20.53 × 10−2 kW h kg−1 COD. In conclusion, the MFC technology is a valuable option for simultaneous wastewater treatment and energy recovery and deserves to be tested and scaled-up in the dairy industry.

Carolina Cruz Viggi, Serena Simonetti, Enza Palma et al.

Biotechnology for Biofuels • 2017

Collectively, these results of this study suggest that for biochar addition in anaerobic digester operation, the screening and identification of the most suitable biochar material should be based on EDC determination, via simple electrochemical tests.

Leo A. Kucek, Jiajie Xu, Mytien Nguyen et al.

Frontiers in Microbiology • 2016

To convert wastes into sustainable liquid fuels and chemicals, new resource recovery technologies are required. Chain elongation is a carboxylate-platform bioprocess that converts short-chain carboxylates (SCCs) (e.g., acetate [C2] and n-butyrate [C4]) into medium-chain carboxylates (MCCs) (e.g., n-caprylate [C8] and n-caproate [C6]) with hydrogen gas as a side product. Ethanol or another electron donor (e.g., lactate, carbohydrate) is required. Competitive MCC productivities, yields (product vs. substrate fed), and specificities (product vs. all products) were only achieved previously from an organic waste material when exogenous ethanol had been added. Here, we converted a real organic waste, which inherently contains ethanol, into MCCs with n-caprylate as the target product. We used wine lees, which consisted primarily of settled yeast cells and ethanol from wine fermentation, and produced MCCs with a reactor microbiome. We operated the bioreactor at a pH of 5.2 and with continuous in-line extraction and achieved a MCC productivity of 3.9 g COD/L-d at an organic loading rate of 5.8 g COD/L-d, resulting in a promising MCC yield of 67% and specificities of 36% for each n-caprylate and n-caproate (72% for both). Compared to all other studies that used complex organic substrates, we achieved the highest n-caprylate-to-ncaproate product ratio of 1.0 (COD basis), because we used increased broth-recycle rates through the forward membrane contactor, which improved in-line extraction rates. Increased recycle rates also allowed us to achieve the highest reported MCC production flux per membrane surface area thus far (20.1 g COD/m 2 -d). Through microbial community analyses, we determined that an operational taxonomic unit (OTU) for Bacteroides spp. was dominant and was positively correlated with increased MCC productivities. Our data also suggested that the microbiome may have been shaped for improved MCC production by the high broth-recycle rates. Comparable abiotic studies suggest that further increases in the broth-recycle rates could improve the overall mass

Jingxin Zhang, Kai‐Chee Loh, Jonathan T.E. Lee et al.

Scientific Reports • 2017

A novel compact three-stage anaerobic digester (HM3) was developed to combine the advantages of high solids anaerobic digestion (AD) and wet AD for co-digestion of food waste and horse manure. By having three separate chambers in the three-stage anaerobic digester, three different functional zones were created for high-solids hydrolysis, acidogenesis and wet methanogenesis. The results showed that the functionalized partitioning in HM3 significantly accelerated the solubilization of solid organic matters and the formation of volatile fatty acids, resulting in an increase of 11~23% in methane yield. VS reduction in the HM3 presents the highest rate of 71% compared to the controls. Pyrosequencing analysis indicated that different microbial communities in terms of hydrolyzing bacteria, acidogenic bacteria and methanogenic archaea were selectively enriched in the three separate chambers of the HM3. Moreover, the abundance of the methanogenic archaea was increased by 0.8~1.28 times compared to controls.

Vafa Ahmadi, Carlos Dinamarca, Nabin Aryal

Journal of Hazardous Materials Advances • 2024

• Iron-assisted electron transfer was stimulated on cathode. • Consistent 92–95 % CH 4 in biogas with heat-treated stainless-steel cathode. • Methanobacterium and Methanosarcina dominated on cathode. • Mass loss of cathode was controlled at low voltage. • Maximum 59 % soluble organic matter removal was achieved. A key factor in biogas production via bioelectrochemical systems (BES) is the stability of electrodes in long-term operation, especially under limited applied energy and varying levels of organic and inorganic carbon content during wastewater treatment. Heat-treated stainless-steel (HTSS) has emerged as a potent cathode for methane (CH 4 ) production in BES for scaling up the technology. In this study, a BES reactor with HTSS electrodes was operated in on-off voltage conditions at different carbon levels in wastewater to evaluate CH 4 evolution through bioelectrosynthesis and controlled microbial corrosion on cathode. Results demonstrated that a low cathodic potential enriched the biofilm with hydrogenotrophic methanogens as Methanobacterium and Methanosarcina . Despite low current generation at lower applied cathodic voltage, biogas with 92–95 % CH 4 content was achieved. Electrochemical impedance spectroscopy test indicated an increased biofilm capacitance, supporting enhanced carbon dioxide (CO 2 ) reduction to CH 4 . The mass loss rate of cathode reached 3.1·10 −14 mg·cm −2 ·d −1 after 133 days of operation, confirming the durability of HTSS cathode. Controlled microbial corrosion showed positive effect on CH 4 production due to iron mediated electron transfer in energy-limited conditions. These findings strengthen the potential of HTSS cathode as a durable and efficient cathode in scaling up BES reactors for CH 4 production.

Antonin Prévoteau, Frederik Ronsse, Inés Cid et al.

Scientific Reports • 2016

Biochars have gathered considerable interest for agronomic and engineering applications. In addition to their high sorption ability, biochars have been shown to accept or donate considerable amounts of electrons to/from their environment via abiotic or microbial processes. Here, we measured the electron accepting (EAC) and electron donating (EDC) capacities of wood-based biochars pyrolyzed at three different highest treatment temperatures (HTTs: 400, 500, 600 °C) via hydrodynamic electrochemical techniques using a rotating disc electrode. EACs and EDCs varied with HTT in accordance with a previous report with a maximal EAC at 500 °C (0.4 mmol(e(-)).gchar(-1)) and a large decrease of EDC with HTT. However, while we monitored similar EAC values than in the preceding study, we show that the EDCs have been underestimated by at least 1 order of magnitude, up to 7 mmol(e(-)).gchar(-1) for a HTT of 400 °C. We attribute this existing underestimation to unnoticed slow kinetics of electron transfer from biochars to the dissolved redox mediators used in the monitoring. The EDC of other soil organic constituents such as humic substances may also have been underestimated. These results imply that the redox properties of biochars may have a much bigger impact on soil biogeochemical processes than previously conjectured.

Rahul Kandpal, Safdar Ali, Shaikh Ziauddin Ahammad

Chemical Engineering Journal • 2025

Ravi Kumar Parihar, Pappu Kumar Burnwal, Satyendra P. Chaurasia et al.

Reviews in Environmental Science and Bio/Technology • 2024

Mónica Reig, Sandra Casas, Oriol Gibert et al.

Desalination • 2016

Modupe S. Ayilara, Olubukola Oluranti Babalola

Frontiers in Agronomy • 2023

The growing rate of urbanization and industrialization has led to an increase in several types of pollution caused by the release of toxic chemicals to the environment. This is usually perpetuated by the manufacturing industry (e.g. detergent and dye), agricultural sectors (e.g. fertilizers and pesticides), mining industry (e.g. cyanide and sulphuric acid) and construction companies (e.g. cement and metals). These pollutants have adverse effects on the health of plants, animals, and humans. They also lead to the destruction of the microbial population in both aquatic and the terrestrial regions, and hence, have necessitated the need for remediation. Although different remediation methods, such as the physical and chemical methods, have been adopted for years, however, the drawbacks and challenges associated with them have promoted the use of an alternative which is bioremediation. Bioremediation involves using biological agents such as plants and microbes to remove or lessen the effects of environmental pollutants. Of the two, microbes are more utilized primarily because of their rapid growth and ability to be easily manipulated, thus enhancing their function as agents of bioremediation. Different groups of bacteria, fungi and algae have been employed to clean up various environmental pollutants. This review discusses the types, mechanisms, and factors affecting microbial bioremediation. It also recommends possible steps that could be taken to promote the use of microbes as bioremediation agents.

Mon Oo Yee, Oona Snoeyenbos-West, Bo Thamdrup et al.

Frontiers in Energy Research • 2019

Direct electron uptake by prokaryotes is a recently described mechanism with a potential application for energy and CO2 storage into value added chemicals. Members of Methanosarcinales, an environmentally and biotechnologically relevant group of methanogens, were previously shown to retrieve electrons from an extracellular electrogenic partner performing Direct Interspecies Electron Transfer (DIET) and were therefore proposed to be electroactive. However, their intrinsic electroactivity has never been examined. In this study, we tested two methanogens belonging to the genus Methanosarcina, M. barkeri and M. horonobensis, regarding their ability to accept electrons directly from insoluble electron donors like other cells, conductive particles and electrodes. Both methanogens were able to retrieve electrons from Geobacter metallireducens via DIET. Furthermore, DIET was also stimulated upon addition of electrically conductive granular activated carbon (GAC) when each was co-cultured with G. metallireducens. However, when provided with a cathode poised at -400 mV (vs. SHE), only M. barkeri could perform electromethanogenesis. In contrast, the strict hydrogenotrophic methanogen, Methanobacterium formicicum, did not produce methane regardless of the type of insoluble electron donor provided (Geobacter cells, GAC or electrodes). A comparison of functional gene categories between the two Methanosarcina showed differences regarding energy metabolism, which could explain dissimilarities concerning electromethanogenesis at fixed potentials. We suggest that these dissimilarities are minimized in the presence of an electrogenic DIET partner (e.g. Geobacter), which can modulate its surface redox potentials by adjusting the expression of electroactive surface proteins.

Anna Vilajeliu-Pons, Sebastià Puig, Inmaculada Salcedo-Dávila et al.

Environmental Science Water Research & Technology • 2017

Evaluation of different electrode materials in stacked scaled-up MFCs for swine manure treatment to move the technology towards application.

Bo Wang, Wenzong Liu, Yifeng Zhang et al.

Water Research • 2020

Michael S. Guzman, Karthikeyan Rengasamy, Michael M. Binkley et al.

Nature Communications • 2019

Extracellular electron uptake (EEU) is the ability of microbes to take up electrons from solid-phase conductive substances such as metal oxides. EEU is performed by prevalent phototrophic bacterial genera, but the electron transfer pathways and the physiological electron sinks are poorly understood. Here we show that electrons enter the photosynthetic electron transport chain during EEU in the phototrophic bacterium Rhodopseudomonas palustris TIE-1. Cathodic electron flow is also correlated with a highly reducing intracellular redox environment. We show that reducing equivalents are used for carbon dioxide (CO 2 ) fixation, which is the primary electron sink. Deletion of the genes encoding ruBisCO (the CO 2 -fixing enzyme of the Calvin-Benson-Bassham cycle) leads to a 90% reduction in EEU. This work shows that phototrophs can directly use solid-phase conductive substances for electron transfer, energy transduction, and CO 2 fixation.

Marta Coma, Ramiro Vilchez‐Vargas, Hugo Roume et al.

Environmental Science & Technology • 2016

Acetate and ethanol can be converted to caproic acid by microorganisms through reverse β-oxidation. There is limited insight into the versatility of chain elongation in view of different starting substrates, including even- and odd-carbon carboxylates and alcohols other than ethanol. Thermodynamic analyses show that most elongation pathways are energetically feasible. Through incubations of microbial communities with different substrate-pair combinations, we established that ethanol and propanol were both highly suitable for chain elongation. As an electron acceptor, acetate, propionate, and butyrate readily elongated with ethanol, whereas an adaptation period was necessary for formate. Isobutyrate and longer-chained fatty acids above butyrate were not elongated. The microbial communities converged, and consistent enrichment of Clostridium spp. was observed, independent of the supplied alcohol or carboxylate, with a strain related to Clostridium kluyveri dominating the enrichments. Community analysis also showed phylotypes related to Bacteroidaceae and Microbacteriaceae families in all tests that are capable of converting the base substrates to useful intermediates. These organisms were mainly enriched with methanol or formate. Our overall conclusion is thus that multiple substrates can be used for chain elongation and that this process is carried out by highly similar organisms for direct chain elongation irrespective of the substrate.

Gabriele Beretta, Andrea Filippo Mastorgıo, Lisa Pedrali et al.

Reviews in Environmental Science and Bio/Technology • 2019

Some studies show how exposure to fields can enhance or reduce cell activity, with possible applicative consequences in the field of biotechnology, including biological techniques for depollution. In order to identify full-scale conditions that are suitable and potentially applicable for use in electromagnetic fields to stimulate and accelerate bioremediation processes, this paper offers an examination of the scientific literature that is available on the effects of fields on microorganisms, and a critical analysis of it. The biological effects at times contrast with each other.

Stefano Campanaro, Laura Treu, Panagiotis Kougias et al.

Biotechnology for Biofuels • 2016

This study is a pioneer research on the phylogenetic and functional characterization of the microbial community populating biogas reactors. By applying for the first time high-throughput sequencing and a novel binning strategy, the identified genes were anchored to single genomes providing a clear understanding of their metabolic pathways and highlighting their involvement in anaerobic digestion. The overall research established a reference catalog of biogas microbial genomes that will greatly simplify future genomic studies.

Athmakuri Tharak, S. Venkata Mohan

ACS Sustainable Chemistry & Engineering • 2024

Gas fermentation using homoacetogenic consortia to convert CO2 into sustainable fuels and chemicals has emerged as a promising biotechnological route toward carbon neutrality. However, a significant challenge is the low gas–liquid mass transfer rates due to the limited solubility of C1 gases. This study investigates CO2 fermentation enhancement using a high-pressure gas fermentation (HPGF) reactor embedded with electrodes, effectively overcoming CO2 solubility barriers and addressing sustainability through an innovative approach. CO2 fermentation with H2 as the electron donor was conducted in pressurized fermenters (PFs) at varying partial pressures (pCO2-2, -3, and -5 bar), while pressured electro-fermentation (PEF) used electrodes to replace H2. The pCO2-PEF-5 condition achieved the highest acetic acid productivity of 2.8 g/L, followed by pCO2-PEF-3 at 2.65 g/L, representing 1.2 and 1.18 times higher yields than the best condition of PFs (pCO2-PF-3, 2.1 g/L), respectively. Additionally, PEF systems enhanced solventogenic activity, with ethanol production reaching 1.4 g/L in pCO2-PEF-5. The substitution of H2 with electrodes in CO2 fermentation improved fixation and conversion rates (pCO2-PEF-5: 67 mg/L/h, 77%), demonstrating a viable strategy for enhanced CO2 conversion. The thermodynamic analysis indicated more spontaneous synthesis of acetic acid and ethanol in PEF systems compared with PF systems. Bioelectrochemical assessments revealed higher charge transfer rates, with a faradaic efficiency of 48% in pCO2-PEF-5, further supporting CO2 conversion. Especially, key genes in the Wood–Ljungdahl pathway (WLP) were upregulated in PEF systems, confirming that electro-fermentation influences metabolic pathways favoring carbon fixation and solvent production. A life cycle assessment (LCA) highlighted a net emission reduction of −7 kg CO2 equiv in PEF-5 and lower impact across endpoint categories, highlighting the carbon-negative potential of this approach. From a planetary boundary framework perspective, this process operates within the Holocene state by reducing CO2 emissions, helps in maintaining biosphere integrity, reduces atmospheric CO2, and contributes minimally to nitrogen and phosphorus flows. This study signifies the sustainability of the PEF strategy for scaling CO2 conversion processes. The integration of electro-fermentation not only addresses mass transfer limitations but also enhances carbon fixation efficiency and metabolic productivity.

Yun Chen, Xie Jiang, Keke Xiao et al.

Water Research • 2017

Hans Schneider, Bin Lai, Jens O. Krömer

Advances in biochemical engineering, biotechnology • 2022

Mohamad Afiq Mohd Asrul, Mohd Farid Atan, Hafizah Abdul Halim Yun et al.

International Journal of Hydrogen Energy • 2025

Qing Liang, Huichuan Zhuang, Miaojia Lu et al.

Journal of Hazardous Materials • 2018

Venkatesh Chaturvedi, Pradeep Verma

Bioresources and Bioprocessing • 2016

Today we are witnessing a global energy crisis due to huge energy demands and limited resources. Non-renewable energy sources are depleting and renewable energy sources are not properly utilized. There is an immediate need for search of alternate routes for energy generation. Microbial fuel cell (MFC) technology, which uses microorganisms to transform chemical energy of organic compounds into electricity is considered a promising alternative. Extensive studies have corroborated new insights into MFC, which show that a wide array of carbon sources including wastes can be employed using a variety of microbes. Consequently, microbial transformation of wastes using novel bioremediation strategies such as MFC for energy generation is considered as an efficient and environmentally benign approach. This paper deals with critical review of different classes of xenobiotics and wastes that can be employed for bioenergy generation, microorganisms involved, power output, major benefits, challenges and pit holes of MFC technology.

Bo Wang, Wenzong Liu, Yifeng Zhang et al.

Water Research • 2020

Hans Priks, Ivar Zekker, Antonio Ivan Manuell Nava et al.

Environmental Science and Pollution Research • 2024

Micaela Brandão Lavender, John Steller, Dandan Liu et al.

Journal of Power Sources • 2024

A 17 L scale up methane producing bioelectrochemical system (BES) for power-to-gas application was built taking into account: (1) use of granular activated carbon as cathode material to provide a large surface area for the reaction to take place; (2) a commercially available tubular membrane separating the anaerobic cathodic reaction from the anodic oxygen production; (3) an hexagonal prism design that can be further up-scaled in modules, specially avoiding the hurdle of producing electrodes in non-commercially available sizes. The BES was operated for 470 days with step wise increase in applied current density between −6 and −125 A m −3 BES , with resulting methane production rates between 10 NL m −3 BES d −1 and 280 NL m −3 BES d −1 and faradaic efficiency ranging between 80% and 100%. A stable performance was observed after a start-up period of around 70 days. Furthermore, changes in the electrolyte composition and anode dimensions were made in order to decrease losses associated to the electrolyte and anode reaction, respectively. The distribution of the voltage losses is assessed in this paper and for the majority of the experimental time the energy efficiency ranged around 40%, specifically when operating with an electrolyte with / carbonate/bicarbonate concentrations of 0.2 M, 0.4 M and 0.6 M and with an anode surface area equal to or larger than 0.02 m 2 . Besides the BES itself, the reactor line-up included a bubble column, an oxygen stripping unit and an interchange vessel, all of which essential for its operation. • A 17 L methane producing BES with GAC as cathode material was built. • Stable performance was observed for 400 days with an energy efficiency of around 40%. • Methane production rates up to 280 NL m −3 BES d −1 were achieved.

Ka Yu Cheng, Tharanga Weerasinghe Mohottige, Maneesha P. Ginige et al.

Hydrometallurgy • 2023

Alumina is typically produced from bauxite ores using the Bayer process, in which the ores are mixed with alkaline liquor under elevated temperatures. Australian bauxite ore contains a wide range of organics, which detrimentally affect the Bayer process. Therefore, the removal of organic compounds from the alkaline Bayer process liquor is critical in maintaining process efficiency and alumina quality. Oxalate (C2O42−) is a key organic impurity in the Bayer process liquors that requires removal as it increases in concentration in the processing circuit as the Bayer liquor is continually recycled. Compared to conventional physiochemical or physical methods (e.g., chemical precipitation, wet-oxidation, liquor burning), microbial bioreactor treatment processes have the potential to be more economical and environmentally sustainable for oxalate removal. Some Australian alumina refineries have implemented full-scale bioreactors such as moving bed biofilm reactors (MBBRs) and aerobic suspended growth bioreactors (ASGB). While these bioreactors are robust and effective in removing oxalate, they have some limitations, such as the need for pre-acidification of influent and the loss of ammonia (nutrient) through volatilization. Therefore, this study aimed to provide an overview of the fundamentals and recent advances in biotechnical processes for the treatment of alkaline oxalate-containing liquor. Laboratory-scale studies on promising new biotreatment concepts, such as the use of bioelectrochemical systems to facilitate concurrent oxalate degradation and caustics recovery, as well as the utilization of nitrogen-fixing microorganisms to obviate the requirement for external nutrient dosage, are discussed. Perspectives for further research on oxalate-containing waste streams are also proposed.

Sanju Sreedharan, Renu Pawels

International Journal of Environmental Science and Technology • 2021

Daniele Molognoni, Marian Garcia, Pablo Sánchez-Cueto et al.

Journal of Environmental Management • 2024

Hongrui Cao, Qing Feng, Jin Sun et al.

SSRN Electronic Journal • 2022

Muhammad Ibrahim, Deqiang Chen, Hafsat Alhassan Danjaji et al.

Total Environment Research Themes • 2022

A bioelectrochemical system is a form of bioengineering technology that has been popularly employed in treating wastewater and energy recovery. However, most of the recent studies in the field of bioelectrochemical technology have mainly focused on scalable architectural designs of the system, while research on the selection of a suitable biocatalyst for the improvement of bioelectrochemical cleanup of pollutants has been given insufficient consideration. The three major limitations of improving bioelectrochemical cleanup technology are time consumption, high cost, and non-nature-based catalyst. In this study, a new bioelectrochemical compartment (BC) incorporating a biochar-based catalyst was fabricated to determine the upscaling effect on the cleanup of nitrate (NO3) and ammonia (NH3) from an aqueous solution. The two different bioelectrochemical reactors used in this experiment were denoted as System 1 (control), and System 2 (experimental), which were later expressed as S1 and S2, and the wastewater sample used was activated sludge. The highest cleanup efficiency of NO3 (99%) was achieved in S2 when the BC was operated with a biochar-based catalyst compared to that of the which was 95%. However, the cleanup efficiencies of NH3 were 96% and 67% in S1 and S2, respectively. This outcome indicated that the highest cleanup efficiency of NH3 was achieved in S1. In addition, we monitored biogas generation in each BC and recovered a significant quantity of CO2, N2O, and CH4. Sporosarcina, Tissierala from the species of Firmicutes, and Pseudomonas of phylum Proteobacteria were the most abundant bacteria that supported the cleanup of pollutants in this study.

Chengyan Liu, Hao-Yi Cheng, Siyuan Zhai et al.

Chemical Engineering Journal • 2023

Anand Govind More, Sunil Kumar Gupta

Journal of Bioscience and Bioengineering • 2018

Diana Y. Alvarez Esquivel, Robert K. Brown, Stefan Knohl et al.

ChemElectroChem • 2020

Abstract This study details, in‐depth, the development of graphite paper as electrodes, specifically anodes, for microbial electrochemical technologies. Processed natural graphite powders were used as an active filler substance in paper composites. Mechanical and electrical properties were balanced during development. Graphite papers with 80 wt% natural graphite content had tear lengths of 730±58 m and resistivities of 0.014±0.001 Ω cm. Electrochemically active biofilms on these materials, cultivated from biomass taken from the bioanodes of an already running bioelectrochemical reactor, were fed with acetate and yielded an average maximum current density of 0.855±0.135 as well as 0.489±0.148 mA cm −2 with a complex substrate mixture. All anodes exhibited similar performance to commonly used carbonaceous electrodes fed the same substrates. This places them as flexible and cheap electrode materials suitable for large‐scale microbial electrochemical technologies.

Xianshu Liu, Jie Ding, Nanqi Ren et al.

International Journal of Environmental Research and Public Health • 2016

In this study, the high-production-volume chemical benzothiazole (BTH) from synthetic water was fully degraded into less toxic intermediates of simple organic acids using an up-flow internal circulation microbial electrolysis reactor (UICMER) under the hydraulic retention time (HRT) of 24 h. The bioelectrochemical system was operated at 25 ± 2 °C and continuous-flow mode. The BTH loading rate varied during experiments from 20 g·m -3 ·day -1 to 110 g·m -3 ·day -1 . BTH and soluble COD (Chemical Oxygen Demand) removal efficiency reached 80% to 90% under all BTH loading rates. Bioluminescence based Shewanella oneidensis strain MR-1 ecotoxicity testing demonstrated that toxicity was largely decreased compared to the BTH wastewater influent and effluent of two control experiments. The results indicated that MEC (Microbial Electrolysis Cell) was useful and reliable for improving BTH wastewater treatment efficiency, enabling the microbiological reactor to more easily respond to the requirements of higher loading rate, which is meaningful for economic and efficient operation in future scale-up.

Jordan R Day, Elizabeth Heidrich, Toby S. Wood

Chemosphere • 2021

Mathematical modelling can reduce the cost and time required to design complex systems, and is being increasingly used in microbial electrochemical technologies (METs). To be of value such models must be complex enough to reproduce important behaviour of MET, yet simple enough to provide insight into underlying causes of this behaviour. Ideally, models must also be scalable to future industrial applications, rather than limited to describing existing laboratory experiments. We present a scalable model for simulating both fluid flow and bioelectrochemical processes in microbial fuel cells (MFCs), benchmarking against an experimental pilot-scale bioreactor. The model describes substrate transport through a two-dimensional fluid domain, and biofilm growth on anode surfaces. Electron transfer is achieved by an intracellular redox mediator. We find significant spatial variations in both substrate concentration and current density. Simple changes to the reactor layout can greatly improve the overall efficiency, measured in terms of substrate removal and total current generated.

Melanie T. Knoll, Nikolai Jürgensen, Janek Weiler et al.

Bioresource Technology Reports • 2023

Microbial electrolysis systems (MES) facilitate the process of using waste for efficient production of hydrogen thus resulting in lower energy costs compared to conventional hydrogen production. However, the stability and robustness of anode-respiring biofilms often limit long-term MES application. In this study, a 10 L rotating disc bioelectrochemical reactor was used to analyze the anodic biofilm under rapidly changing processing conditions, including changes in anode potential and shear force. A low complexity biofilm formed by Shewanella oneidensis and Geobacter sulfurreducens was studied to determine the boundary conditions for achievable current density and species interaction in large-scale applications. Demonstrating its robustness to the applied changes, the biofilm produced a stable current density of 1.2 A m−2 over 1.5 months. Furthermore, a mathematical model was developed to predict the behavior of the system in terms of current output, which may allow automatic user-defined control of sub-processes in MES reactors in the future.

Vitor Cano, Julio Cano, Sabrina C. Nunes et al.

Renewable and Sustainable Energy Reviews • 2020