Oluwatosin Obata, M.J. Salar-García, John Greenman et al.

Journal of Environmental Management • 2020

The Microbial fuel cell (MFC) technology harnesses the potential of some naturally occurring bacteria for electricity generation. Digested sludge is commonly used as the inoculum to initiate the process. There are, however, health hazards and practical issues associated with the use of digested sludge depending on its origin as well as the location for system deployment. This work reports the development of an efficient electroactive bacterial community within ceramic-based MFCs fed with human urine in the absence of sludge inoculum. The results show the development of a uniform bacterial community with power output levels equal to or higher than those generated from MFCs inoculated with sludge. In this case, the power generation begins within 2 days of the experimental set-up, compared to about 5 days in some sludge-inoculated MFCs, thus significantly reducing the start-up time. The metagenomics analysis of the successfully formed electroactive biofilm (EAB) shows significant shifts between the microbial ecology of the feeding material (fresh urine) and the developed anodic biofilm. A total of 21 bacteria genera were detected in the urine feedstock whilst up to 35 different genera were recorded in the developed biofilm. Members of Pseudomonas (18%) and Anaerolineaceae (17%) dominate the bacterial community of the fresh urine feed while members of Burkholderiaceae (up to 50%) and Tissierella (up to 29%) dominate the anodic EAB. These results highlight a significant shift in the bacterial community of the feedstock towards a selection and adaptation required for the various electrochemical reactions essential for survival through power generation.

Lili Tian, Xuejun Yan, Dongbin Wang et al.

Water Research • 2022

Tian‐shun Song, Hongkun Zhang, Haixia Liu et al.

Bioresource Technology • 2017

Caroline Rivalland, Fatima Radouani, Silvina Gonzalez‐Rizzo et al.

Bioelectrochemistry • 2021

Tom J. Zajdel, Moshe Baruch, Gábor Méhes et al.

Scientific Reports • 2018

Microbial electrochemical systems provide an environmentally-friendly means of energy conversion between chemical and electrical forms, with applications in wastewater treatment, bioelectronics, and biosensing. However, a major challenge to further development, miniaturization, and deployment of bioelectronics and biosensors is the limited thickness of biofilms, necessitating large anodes to achieve sufficient signal-to-noise ratios. Here we demonstrate a method for embedding an electroactive bacterium, Shewanella oneidensis MR-1, inside a conductive three-dimensional poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) matrix electropolymerized on a carbon felt substrate, which we call a multilayer conductive bacterial-composite film (MCBF). By mixing the bacteria with the PEDOT:PSS precursor in a flow-through method, we maintain over 90% viability of S. oneidensis during encapsulation. Microscopic analysis of the MCBFs reveal a tightly interleaved structure of bacteria and conductive PEDOT:PSS up to 80 µm thick. Electrochemical experiments indicate S. oneidensis in MCBFs can perform both direct and riboflavin-mediated electron transfer to PEDOT:PSS. When used in bioelectrochemical reactors, the MCBFs produce 20 times more steady-state current than native biofilms grown on unmodified carbon felt. This versatile approach to control the thickness of bacterial composite films and increase their current output has immediate applications in microbial electrochemical systems, including field-deployable environmental sensing and direct integration of microorganisms into miniaturized organic electronics.

Markus Stöckl, Natascha Caroline Teubner, Dirk Holtmann et al.

ACS Applied Materials & Interfaces • 2019

Bioelectrochemical systems (BESs) are hybrid systems using electroactive bacteria and solid electrodes, which serve as electron donor or acceptor for microorganisms. When forming a biofilm on the electrode, bacteria secrete extracellular polymeric substances (EPSs). However, EPS excretion of electroactive biofilms in BES has been rarely studied so far. Consequently, the aim of this study is to develop a routine including the electrochemical cultivation, biofilm harvesting, fractionation, and biochemical analysis of the EPS secreted by Geobacter sulfurreducens under electroactive conditions. G. sulfurreducens was cultivated in microbial fuel cell mode on graphite-based electrodes polarized to +400 mV versus Ag/AgCl for 8 d. A maximum current density of 172 ± 29 μA cm -2 was reached after 7 d. The EPS secreted from the biofilms were harvested and fractioned into soluble, loosely bound, and tightly bound EPS and biochemically analyzed. Electroactive cultures secreted significantly more EPSs compared to cells grown under standard heterotrophic conditions (fumarate respiration). With 116 pg per cell, the highest amount of EPSs was measured for the soluble EPS fraction of G. sulfurreducens using anodic respiration, followed by the tightly bound (18 pg cell -1 ) and loosely bound (11 pg cell -1 ) fractions of the EPS. Proteins were found to dominate all EPS fractions of the biofilms grown under electrochemical conditions. To the best of the authors' knowledge, these experiments are the first approach toward a complete analysis of the main EPS components of G. sulfurreducens under anode-respiring conditions.

José Roberto González-Paz, Karina Becerril-Varela, Claudia Guerrero–Barajas

Archives of Microbiology • 2022

Lijie Zhou, Fei Wu, Pingxiang Ou et al.

Water Research • 2024

Tao Wang, Lilin Zhou, Chuanlin Cai et al.

Journal of Water Process Engineering • 2023

Constructed wetland–microbial fuel cells (CW–MFC) and aeration technology are typically used for the treatment of mariculture wastewater with a low carbon/nitrogen ratio and high-salinity. However, salt inhibition limits their efficiency. Here, based on CW–MFC, an electroactive bacteria–algae biofilm and siphon aeration technology were employed in a pilot study to validate their technical and economic feasibility. The system yielded average removal efficiencies of 80.99 % ± 1.3 %, 92.59 % ± 3.13 %, 94.03 % ± 5.11 %, 97.38 % ± 3.62 %, and 95.95 % ± 2.59 %, respectively, for chemical oxygen demand, total phosphorus, total nitrogen, sulfamethoxazole, and Cu2+, with an average voltage of 354 ± 23 mV. Nitrification and denitrification bacteria Vicingus (12.52 %), Marinobacter (7.93 %), Muricauda (10.86 %), and Xanthomarina (13.62 %); extracellular respiratory bacteria Geobacteraceae (9.47 %) and Pseudomonas (2.54 %); and microalgae bacteria Pseudooceanicola (12.45 %) and Hoeflea (7.45 %) were significantly enriched. The energy consumption per ton of sewage treatment was 0.0045 kWh·m−3, representing 47.87 % lower costs than those related to traditional aeration. These results proved the feasibility of CW–MFC coupled with electroactive bacteria–algae biofilm and siphon aeration tidal flow technology for mariculture wastewater treatment.

Wang Gai, Qiong Bo, Donghua Yang et al.

Energy Sources Part A Recovery Utilization and Environmental Effects • 2019

A highly efficient electrode material is required to explore and apply to microbial electrolysis cell (MEC) with high hydrogen evolution reaction (HER) efficiency. Pt/C was one of the most efficient catalysts for hydrogen production in current lab research, but it was expensive and some chemicals in wastewater were prone to Pt poisoning, which was a great limitation in application. Thus, a cheap and effective nickel(II) Oxide/Y (NiO/Y) material was prepared by using Y zeolites as carrier loaded with NiO in this study, which was used in MEC to evaluate the hydrogen evolution performance in comparison with Pt/C. The results indicated that NiO/Y composites showed a competitive HER performance to Pt/C. The linear sweep voltammetry (LSV) tests and Tafel plots showed that the NiO/Y composites exhibited the best catalytic activity for HER. In the MEC tests, the NiO/Y composites cathode was comparable with the Pt/C cathode in terms of current densities and energy efficiency. The coulombic efficiency, cathodic energy efficiency rate and hydrogen production rate obtained with NiO/Y cathode MEC was 85.88 ± 6.5%, 228.39 ± 3.2% and 0.83 ± 0.05 m3/m3d under, respectively, which were slightly higher than those obtained with the Pt/C cathode MEC. It was concluded that even with the cheap Y zeolites as the supports, the NiO/Y materials showed the superior performance, which was attributed to a good dispersing of the active component of NiO on the large specific surface area of Y zeolites and the fast escape of hydrogen bubbles from microporous and mesoporous structure of Y zeolites.

Naufila Mohamed Ashiq, Alreem Ali Juma Al Rahma Aldarmaki, M. AlKetbi et al.

Sustainability • 2025

Microbial electrolysis cells (MECs) are bioreactors that utilize electroactive microorganisms to catalyze the oxidation of organic substrates in wastewater, generating electron flow for hydrogen production. Despite the concept, a persistent performance gap exists where metabolically active anodic biofilms frequently fail to achieve expected current densities by the flow of electrons to produce hydrogen. This review examines the multiple causes that lead to the disconnect between robust biofilm development, electron transfer, and hydrogen production. Factors affecting biofilm generation (formation, substrate selection, thickness, conductivity, and heterogeneity) are discussed. Moreover, factors affecting electron transfer (electrode configuration, mass transfer constraints, key electroactive species, and metabolic pathways) are discussed. Also, substrate diffusion limitations, proton accumulation causing inhibitory pH gradients in stratified biofilms, elevated internal resistance, electron diversion to competing processes like hydrogenotrophic methanogenesis consuming H2, and detrimental biofilm aging, impacting hydrogen production, are studied. The critical roles of electrode materials, reactor configuration, and biofilm electroactivity are analyzed, emphasizing advanced electrochemical (CV, EIS, LSV), imaging (CLSM, SEM, AFM), and omics (metagenomics, transcriptomics, proteomics) techniques essential for diagnosing bottlenecks. Strategies to enhance extracellular electron transfer (EET) (advanced nanomaterials, redox mediators, conductive polymers, bioaugmentation, and pulsed electrical operation) are evaluated for bridging this performance gap and improving energy recovery. The review presents an integrated framework connecting biofilm electroactivity, EET kinetics, and hydrogen evolution efficiency. It highlights that conventional biofilm metrics may not reflect actual electron flow. Combining electrochemical, microelectrode, and omics insights allows precise evaluation of EET efficiency and supports sustainable MEC optimization for enhanced hydrogen generation.

Aida Afify, A. Abd El Gwad, N. Abd EL Rahman

Journal of Agricultural Chemistry and Biotechnology • 2017

Microbial electrolysis cells (MECs) were used for production of bio-hydrogen (Bio-H2)by Enterobacter aerogenes DSM 30053 from domestic wastewater at three volumes of anode chamber in MECs 300ml, 400 ml and 500 ml were applied. Power supply of 0.4 V, 0.6 V and 0.8 V was used applied to MECs using a regulated external voltage. The highest volume of Bio-H2 112.83 cm3 production was obtained from domestic wastewater without addition of bacteria at the anode chamber 500 ml with power supply 0.8 V. While the highest volume of Bio-H2 316 cm3 production was obtained by Enterobacter aerogenes DSM 30053 at the anode chamber 500 ml with power supply 0.4 V from domestic wastewater.

Ling Dai, Chunguang Jia, Bowen Liu et al.

Sustainable Energy & Fuels • 2022

The Ru/CoP nanohybrids was developed as potential cathode catalyst of microbial electrolysis cell for H 2 generation.

Pilar Sánchez‐Peña, Jesús Rodríguez, Juan Antonio Baeza et al.

International Journal of Hydrogen Energy • 2024

Despite its high cost, Pt is the usual catalyst for hydrogen production in the cathode of Microbial Electrolysis Cells (MECs). Its effectiveness depends not only on the amount deposited but also on the availability and distribution of Pt nanoparticles on the cathode surface. This work provides a comprehensive study of the effectiveness of the Pt coating with five deposition techniques: spray, electrospray, brush painting, doctor blade and sputtering. The performance of the cathodes was studied with different Pt loadings by monitoring the current intensity and H 2 production in MECs. Furthermore, cathodes were characterized morphologically using scanning electron microscopy together with energy-dispersive X-ray spectroscopy to study their Pt surface distribution and composition. Sputtering was initially discarded due to Pt detachment. When using the same amount of Pt (0.50 mg Pt cm −2 ), the highest current density was obtained for electrospray (2.0 mA cm −2 ), followed by spray (1.9 mA cm −2 ), brush painting (1.6 mA cm −2 ) and doctor blade (1.2 mA cm −2 ). Hence, electrospray improved 20 % the results obtained by the default method of brush painting. Electrospray and spray provided better performance because of the direct deposition of Pt on the carbon fibres creating a compact Pt layer on the electrode surface. Furthermore, it was observed that the cell performance decreased significantly with decreasing amount of Pt per cm 2 , observing the best performance with the highest Pt load tested (0.5 mg Pt cm −2 ) regardless of the deposition technique. • Different Pt deposition methods were studied to produce MEC cathodes. • Brush painting, doctor blade, electrospray, spray, and sputtering were compared. • The spraying techniques showed the best long.-term performance >2 m 3 H 2 m −3 d −1 . • Sputtering led to Pt detachment and to a failure in the long-term operation. • MEC performance relies on Pt amount and accessibility (on dispersion technique).

Peerawat Khongkliang, Prawit Kongjan, Bussakorn Utarapichat et al.

International Journal of Hydrogen Energy • 2017

Edson Baltazar Estrada‐Arriaga, Raúl Montero-Farías, Cornelio Morales-Morales et al.

Bioprocess and Biosystems Engineering • 2024

Raphaël Rousseau, Luc Etcheverry, Emma Roubaud et al.

Applied Energy • 2019

Aida Afify, A. Abd El Gwad, N. Abd El-Rahman

Journal of Agricultural Chemistry and Biotechnology • 2023

Green technology for bio-hydrogen production refers to the use of electrochemical systems and electroactive bacteria. Microbial electrolysis cells (MECs) are one of these systems. Among the electroactive bacteria were used in this study Escherichia coli NRRL B-3008 and Enterobacter aerogenes DSM 30053. Water from Al-Salam Canal was also used as a substrate according to chemical structure (H2O) of water as cheap source to produce hydrogen gas by using microorganisms i.e bacteria. The result obtained were indicate that Escherichia coli NRRL B-3008 gave the highest values of bio-hydrogen production rates (Bio-HPR = 102.7 cm3) and hydrogen yield (YH2 = 57.19 %) was obtained from MEC (anode 500ml) and an applied voltage 0.8V. Enterobacter aerogenes DSM 30053 gave the highest values of Bio-HPR = 132.57 cm3 and YH2 = 70.13 % was obtained from MEC (anode 500ml) and an applied voltage 0.4V. While, the highest volume of Bio-H2 without bacteria was 51.1 cm3 and YH2 = 31.18 % with an applied voltage 0.8 V (anode 500ml). Therefore, the bacterial electrolysis are very important biological process for highest hydrogen yield by bio-hydrogen production.

Vikash Kumar, Malaya Prasad Behera, Yifan Lv et al.

Materials & Design • 2024

• Interdigitated and spiral electrode configurations manufactured by SLM of SS316L and Al-Si10-Mg are evaluated for MECs for the first time. • The SLM SS316L anodes with controlled porosities were also pyrrole coated for the first time, targeting better cell performance. • The voltage outputs across 1 kΩ are 0.49 V and 0.61 V and full acclimation times are 26 and 12 days for Al-and Ppy-SS anode based MFCs respectively. • Pyrrole-coated stainless-steel (Ppy-SS) anodes resulted in denser biofilms compared to the spiral Al-Si10-Mg anodes. • The MEC based on the Ppy-SS spiral electrode scored the best with an overall efficiency 88.74%, compared to other cases reported so far. • The current density 322.01 ± 17.68 A/m 3 and hydrogen evolution 2.89 ± 0.18 m 3 d -1 m 3 achieved are the second and third highest values respectively. In the ever-increasing quest for alternative energy sources, hydrogen emerged as a promising green option, but efficient and economical production and management have been the primary constraints. Converting wastewater into H 2 and other forms of energy attracted significant attention in terms of simultaneously and sustainably managing both the wastewater and the energy generation problems. Microbial Electrolysis Cells (MEC) evolved recently as promising options for converting wastewater into H 2 and electricity but with serious constraints on scalability. The current research aims to explore design and manufacturing solutions to build structurally strong and electrochemically effective electrodes that can also lead to scalable MEC. Two designs based on the interdigitated and spiral electrode architectures are proposed and evaluated. The added design freedom with additive manufacturing by selective laser melting of specific alloys of choice is effectively utilised in physically prototyping the interdigitated and spiral electrode forms designed with controlled porosity constraints. Microstructural, electrochemical, and cell performance characterisations led to the understanding that the spiral electrode configuration with polypyrrole-coated stainless steel 316L anode is a promising design option for both longitudinal and lateral scale-up of the MEC.

Huankai Li, Hui Liu, Weizhong Lin et al.

Journal of environmental chemical engineering • 2022

Kexin Zhao, Yan Zhou, N. Tan et al.

Energy Conversion and Management X • 2023

The efficiency of hydrogen production from waste activated sludge (WAS) through combining anaerobic digestion and microbial electrolysis cell (AD-MEC) systems has been increasing. With advancements in materials science, the cost of MEC anode materials has decreased, making this technology potentially economically viable. By analyzing data from 3611 centralized wastewater treatment plants (WWTPs) in 276 prefecture-level cities in China, theoretical application scenarios and environmental benefits of hydrogen production in these WWTPs via AD-MEC were evaluated. Additionally, a theoretical economic model is constructed to validate the economic feasibility of AD-MEC technology. The key findings suggested that the theoretical potential for hydrogen production from WAS in China is 152,610.5 tons/year. The amount of CO2 emitted by natural gas, fuel diesel buses, or power electric public transportation could reduce approximately 1.51, 3.2, and 2.4 million tons/year, respectively, through utilizing hydrogen instead of the above energy sources. Due to the broader temperature adaptability of hydrogen fuel cells, this emission reduction effect was more pronounced in colder, high-latitude regions. Economic analysis revealed that, considering sludge reduction, the AD-MEC system could achieved a return on investment of 13%. This study demonstrated that with the rapid progression in urbanization, AD-MEC systems could contribute to reducing WAS treatment costs and providing clean hydrogen for carbon emission reductions in urban areas.

Lea Ouaknin Hirsch, Bharath Gandu, Abhishiktha Chiliveru et al.

Polymers • 2024

The bacterial anode of microbial electrolysis cells (MECs) is the limiting factor in a high hydrogen evolution reaction (HER). This study focused on improving biofilm attachment to a carbon-cloth anode using an alginate hydrogel. In addition, the modified bioanode was encapsulated by a filter bag that served as a physical barrier, to overcome its low mechanical strength and alginate degradation by certain bacterial species in wastewater. The MEC based on an encapsulated alginate bioanode (alginate bioanode encapsulated by a filter bag) was compared with three controls: an MEC based on a bare bioanode (non-immobilized bioanode), an alginate bioanode, and an encapsulated bioanode (bioanode encapsulated by a filter bag). At the beginning of the operation, the Rct value for the encapsulated alginate bioanode was 240.2 Ω, which decreased over time and dropped to 9.8 Ω after three weeks of operation when the Geobacter medium was used as the carbon source. When the MECs were fed with wastewater, the encapsulated alginate bioanode led to the highest current density of 9.21 ± 0.16 A·m -2 (at 0.4 V), which was 20%, 95%, and 180% higher, compared to the alginate bioanode, bare bioanode, and encapsulated bioanode, respectively. In addition, the encapsulated alginate bioanode led to the highest reduction currents of (4.14 A·m -2 ) and HER of 0.39 m 3 ·m -3 ·d -1 . The relative bacterial distribution of Geobacter was 79%. The COD removal by all the bioanodes was between 62% and 88%. The findings of this study demonstrate that the MEC based on the encapsulated alginate bioanode exhibited notably higher bio-electroactivity compared to both bare, alginate bioanode, and an encapsulated bioanode. We hypothesize that this improvement in electron transfer rate is attributed to the preservation and the biofilm on the anode material using alginate hydrogel which was inserted into a filter bag.

R. García-Amador, Universidad Autónoma Metropolitana, Sergio Hernández et al.

Revista Mexicana de Ingeniería Química • 2018

The use of biomass for alternative energy production has experienced a boom because of the low cost of raw material and the high added value of the product as far as hydrogen is concerned. Steam explosion is used as pretreatment of lignocellulosic biomass to increase the accessibility of sugars. An approach based on sustainability and development of biorefineries allows proposing the integrated use of agave bagasse pretreatment fractions to produce bio-hydrogen. In this work, hydrolysates from steam-explosion pretreated agave bagasse were used as substrate in microbial electrolysis cells (MEC). Hydrolysates were evaluated at concentrations of 20 %, 40 % and 100 % (v/v). Besides, the use of hydrolysates was compared by analyzing two inoculum sources, compost leachate and granular sludge. The highest hydrogen production was 8.5 mL L-1 d-1, which was achieved using 20 % hydrolysate, 10 % compost leachate at the anodic potential of 0.8 V/Ag/AgCl in a two-chamber microbial electrolysis cell.

A. Yağmur Gören, Ahmet Faruk Kilicaslan, İbrahim Dinçer et al.

Renewable Energy • 2024

Membraneless microbial electrolysis cells (MECs) are potentially considered to produce biohydrogen (bioH 2 ) in a green manner and simultaneously minimize agricultural and wastewater facility wastes. However, effective, sustainable, and cost-effective system configuration and improvement of operating variables, working at ambient conditions, are needed to make the MEC a sustainable process. Therefore, this study investigates the bioH 2 production from poplar leaves and anaerobic sludge mixture by incorporating nanomaterials comprising Al 2 O 3 , MgO, and Fe 2 O 3 metal oxides at various dosages. Moreover, the effects of applied cell voltage (0.5–1.5 V) and inoculum amount (20–40 mL) on bioH 2 production and organic matter removal performance are evaluated. The maximum bioH 2 production value is 417 mL at an applied voltage of 1.5 V with a chemical oxygen demand (COD) removal efficiency of 37.6 % under operating times of 5 min using 40 ml of inoculum. The bioH 2 production of the MEC system is reduced with the decrease in inoculum amount. The highest bioH 2 production of 828 mL is obtained at improved conditions in the presence of 1 g of Fe 2 O 3 metal oxide. Overall, this study provides the potentiality of simultaneous waste minimization and bioH 2 production under ambient conditions that highlight the waste-to-energy pathway for membraneless and green bioelectrochemical process.

Daniel A. Moreno-Jimenez, Yamini Kumaran, Harry Efstathiadis et al.

ACS ES&T Engineering • 2023

Microbial electrolysis cells (MECs) can electrochemically produce green hydrogen from waste streams. However, cathode materials have been a bottleneck for the practical application of MECs due to difficulties in scale-up and high costs. To overcome current drawbacks, we have examined a novel flowable cathode in MECs, where nickel-loaded activated carbon (Ni/AC) powders were suspended in a buffering solution as a cathode without electrode fabrication processes. The Ni/AC flow cathode with higher Ni content and minimum Ni/AC loading (4 Ni-atom% and 0.125 wt-AC.%, Ni4/AC0.125) demonstrated the highest catalytic activities (−0.86 V vs Ag/AgCl at −10 A/m2) among Ni/AC flow cathodes tested. This result indicates that pseudocapacitive behavior toward Faradaic reactions can be promoted by increasing Ni loadings on Ni/AC particles. The MEC with a Ni4/AC0.125 flow cathode produced comparable hydrogen production rates (1.62 ± 0.15 L-H2/Lreactor-day) to the Pt control (1.64 ± 0.09 L-H2/L-day) and 40% higher than the blank (only current collector without Ni/AC, 1.29 ± 0.02 L-H2/L-day) at a 4 h cycle. The impacts of carbon black blending remain unclear; there was a 10% increase in hydrogen production rates with the lowest carbon black content (0.06 wt %) in the Ni/AC flow cathode, but hydrogen production rates were not further improved as carbon black content increased.

Ting Zhao, Zhihong Liu, Zhengtong Guo et al.

Journal of Environmental Management • 2025

Anwar Ahmad, Alaya Said Senaidi, Sajjala Sreedhar Reddy

Journal of Environmental Health Science and Engineering • 2023

Oscar Guerrero‐Sodric, Juan Antonio Baeza, Albert Guisasola

Chemical Engineering Journal • 2025

Microbial electrolysis cells (MECs) are considered a breakthrough technology in the water-energy nexus frame due to the good results obtained at lab-scale conditions: organic matter degradation with low sludge production and energy recovery as hydrogen. However, the scaling-up of these systems has found significant hurdles and the lab-scale performance has not been achieved at a higher scale. This study comprehensively details the design, construction, and operation of a 1 m 3 MEC pilot plant integrated into an urban wastewater treatment plant (WWTP) and fed with primary effluent. The experimental trials conducted showcased the MEC performance under varying operational conditions, achieving a maximum organic matter removal efficiency of 51 % and continuous hydrogen production at a maximum rate of 8.59 L m −2 d −1 (0.094 m 3 m −3 d −1 ) with synthetic wastewater and 7.29 L m −2 d −1 (0.042 m 3 m −3 d −1 at full capacity, 15 cassettes) with real urban primary effluent. These results are comparable to those obtained in pilot MEC at smaller scales (~100 L), demonstrating a good scalability of the proposed prototype. A techno-economic assessment was performed to evaluate the commercial potential of the pilot MEC, considering factors such as revenue from hydrogen production, electricity consumption costs and capital expenses. The outcomes of this study represent a significant advancement in the scale-up of MECs, offering valuable insights into the challenges and opportunities associated with real-world implementation. Further improvements should focus on minimizing material costs, hydrogen leakages and voltage losses to enhance scalability, as well as exploring the applicability of MECs in niches other than urban WWTP. • A 1 m 3 microbial electrolysis cell (MEC) produced hydrogen at low voltage. • MEC produced 8.59 and 3.45 L H₂ m −2 d −1 with synthetic and real wastewater. • MEC removed 51 % COD with a 2-day hydraulic retention time (HRT). • MEC feasibility depends on reducing material and capital costs for scaling up. • High MEC costs require innovations in materials to improve commercial viability.

Gerard Pérez-Pi, Jorge Luque-Rueda, Pau Bosch‐Jimenez et al.

Nanomaterials • 2024

High-performance and cost-efficient electrocatalysts and electrodes are needed to improve the hydrogen evolution reaction (HER) for the hydrogen (H 2 ) generation in electrolysers, including microbial electrolysis cells (MECs). In this study, free-standing carbon nanofiber (CNF) films with supported cobalt phosphide nanoparticles have been prepared by means of an up-scalable electrospinning process followed by a thermal treatment under controlled conditions. The produced cobalt phosphide-supported CNF films show to be nanoporous (pore volume up to 0.33 cm 3 g -1 ) with a high surface area (up to 502 m 2 g -1 ) and with a suitable catalyst mass loading (up to 0.49 mg cm -2 ). Values of overpotential less than 140 mV at 10 mA cm -2 have been reached for the HER in alkaline media (1 M KOH), which demonstrates a high activity. The high electrical conductivity together with the mechanical stability of the free-standing CNF films allowed their direct use as cathodes in a MEC reactor, resulting in an exceptionally low voltage operation (0.75 V) with a current density demand of 5.4 A m -2 . This enabled the production of H 2 with an energy consumption below 30 kWh kg -1 H 2 , which is highly efficient.

Robert K. Brown, Ulrike Christiane Schmidt, Falk Harnisch et al.

Journal of Power Sources • 2017

Suman Bajracharya, Mohita Sharma, Gunda Mohanakrishna et al.

Renewable Energy • 2016

Wenzong Liu, Yongjian Piao, Fugui Zhang et al.

Environmental Science Water Research & Technology • 2018

GeoChips based on mcrA and cytochrome genes to evaluate community structure variety of methanogens and electron transfer process.

Ling Dai, Lijuan Xiang, Mengtian Zhang et al.

ChemElectroChem • 2022

Abstract The development of highly efficient cathodes for hydrogen production that can operate in a suitable pH condition is a daunting challenge in microbial electrolysis cells (MECs). Herein, an asymmetric neutral‐alkaline double‐chamber microbial electrolysis cells (AMECs) by using conventional carbon brush with microorganism attached as neutral anode and the Ru/CNTs electrode as alkaline cathode, respectively, was proposed. To implement this, a hybrid with ruthenium nanoparticles loaded on conductive carbon nanotubes (Ru/CNTs) was prepared by a reduction deposition method, which exhibited comparable electrocatalytic performance to the expensive benchmark Pt/C catalysts for hydrogen evolution reaction (HER). Compared to the traditional MECs running in symmetric neutral electrolyte, the as‐developed AMEC displayed a higher current density of 17.13 A m −2 and hydrogen production rate of 0.167 m 3 m −2 d −1 . The present AMEC provides an energy‐saving and cost‐effective process technology for electrolysis H 2 generation.

Ibdal Satar, Mimi Hani Abu Bakar, Wan Ramli Wan Daud et al.

International Journal of Energy Research • 2020

The low cost, low over-potential loss, good catalytic properties for hydrogen evolution reaction (HER), high corrosion stability, commercially available, and could be applied in pH-neutral solution and ambient temperature are important properties for the cathode materials when it is applied in microbial electrolysis cell (MEC) technology. This study has two-pronged objectives: the first is to investigate the feasibility of titanium (Ti) and graphite felt (GF) coated with nickel (Ni), and the second is to generate hydrogen from the fermentation effluent (FE). The electrodeposition (ED) method was used to deposit Ni catalyst onto Ti (Ni/Ti) and GF (Ni/GF) surfaces. The scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were used to characterize the cathode morphology and element composition. The catalytic properties of Ni/Ti and Ni/GF could be evaluated using the linear sweep voltammetry tests. The maximum volumetric H2 production rates of MEC using Ni/Ti and Ni/GF cathodes were obtained at 0.39 ± 0.01 and 0.33 ± 0.03 m3 H2 m−3 d−1 respectively. The Ni/Ti and Ni/GF cathodes could be used as alternative cathodes while producing hydrogen from FE.

Rahul Gautam, Robert Steinberger Wilckens, Uttam Kumar Ghosh

ACS Sustainable Resource Management • 2024

To counter energy scarcity and geopolitical tensions, sustainable fuels are the need of the hour. The current study has explored a noble combination of hydrogen production in a single-chambered microbial electrolysis cell and then its reactor effluent was used for algal biomass production to promote maximum resource recovery. A heat-pretreated sugarcane bagasse fed MEC resulted in 2.1 ± 0.02 m3 of hydrogen/m3/day at an applied voltage of 0.8 V, with a coulombic efficiency of 57.6 ± 0.5 % and an electrical energy efficiency of 70.16 ± 2%. A high current density of 48 A/m2 due to effective biofilm and a corresponding COD removal efficiency of 69.1 ± 2% were reported, and hydrogen production rates (HPR) for the MEC were reported as 1.85 ± 0.02 m3/m2/d on the basis of cathode surface area. Further, the MEC reactor digestate was separated in solid and liquid digestate fractions, supplied to the algal growth batch reactor, and resulted in significant biomass growth. The solid feed digestate residue produced a biomass productivity of 0.95 g/L, and liquid feed digestate filtrate produced a biomass productivity of 0.65 g/L of dry algal biomass. The study proposes maximum energy extraction and reactor digestate valorization for a circular economy and a sustainable environment.

Muhammad Zia Ur Rahman, Mohsin Rizwan, Rabia Liaquat et al.

International Journal of Hydrogen Energy • 2023

Ana Baía, Alonso I. Arroyo-Escoto, Nuno V. Ramos et al.

Energies • 2025

This study explores the feasibility of producing biohydrogen from winery wastewater using a dual-chamber microbial electrolysis cell (MEC). A mixed microbial consortium pre-adapted to heavy-metal environments and enriched with Geobacter sulfurreducens was anaerobically cultivated from diverse waste streams. Over 5000 h of development, the MEC system was progressively adapted to winery wastewater, enabling long-term electrochemical stability and high organic matter degradation. Upon winery wastewater addition (5% v/v), the system achieved a sustained hydrogen production rate of (0.7 ± 0.3) L H2 L−1 d−1, with an average current density of (60 ± 4) A m−3, and COD removal efficiency exceeding 55%, highlighting the system’s resilience despite the presence of inhibitory compounds. Coulombic efficiency and cathodic hydrogen recovery reached (75 ± 4)% and (87 ± 5)%, respectively. Electrochemical impedance spectroscopy provided mechanistic insight into charge transfer and biofilm development, correlating resistive parameters with biological adaptation. These findings demonstrate the potential of MECs to simultaneously treat agro-industrial wastewaters and recover energy in the form of hydrogen, supporting circular resource management strategies.

Tunç Çatal, Eke Pasaoglu, Dilan Akagunduz et al.

International Journal of Energy Research • 2021

Mevastatin is one of the common pharmaceuticals found in wastewaters, and its biodegradation is still an environmental problem due to its recalcitrant properties. Although various biological, chemical and physical methods have been investigated for the removal of mevastin, microbial electrolysis cells (MECs) have not been examined, yet. MECs are new generation biotechnological tools used in hydrogen energy production. In this study, the effects of mevastatin on hydrogen production in MECs were investigated for the first time. MECs produced hydrogen gas in the presence of mevastatin, and an increase in hydrogen production was observed. Over 90% of the mevastatin were removed in MECs. These results also showed that the fermentation process associated with carbon dioxide production can favor hydrogen production with mevastatin. In conclusion, the efficiency of hydrogen production in microbial cells can be increased by the use of wastewaters contaminated with mevastatin.

Shmuel Rozenfeld, Bharath Gandu, Lea Ouaknin Hirsch et al.

International Journal of Energy Research • 2021

Yuxue Wang, Yu Zhao, Ailian Wu et al.

International Journal of Electrochemical Science • 2018

Microbial electrolysis cells (MECs) utilize microorganisms to decompose organic matter in wastewater and produce hydrogen at the cathode. Thus, a low-cost and highly active cathode material is of great important in such system. In this study, electrodeposited Ni, Co, and Ni/Co on carbon paper (CP) were prepared as cathode to replace platinum. At an applied voltage of 0.7 V, the Ni MEC cathode produced most gas of 11.40 mL at current density of 15.31 A m−2, which was 73.24% higher than that of bare CP electrode (3.05 mL). Linear sweep voltammetry and Cyclic voltammetry measurements showed that the hydrogen evolution performance of the Ni cathode was significantly better than Co and Ni/Co cathodes. The tafel plots proved that the hydrogen evolution overpotential of Ni cathode (59.89 mV decade−) was lower than that of bare CP electrode (99.22 mV decade−). Owing to the improved current density, hydrogen recovery rate and low hydrogen evolution overpotential, the developed electrodeposited Ni on CP materials possessed much higher catalytic activity than bare CP. Thus, electrodeposited Ni on CP are promising electrocatalysts for hydrogen evolution reaction and low-cost cathode materials in MECs.