Showing papers on "Microbial electrolysis cell published in 2015"
TL;DR: In this article, a batch test was conducted to investigate the bioelectrochemical enhancement of methane production from the high-solid anaerobic digestion of waste sludge in the microbial electrolysis cells (MEC) with iron-graphite electrode.
182 citations
TL;DR: Glycerol and starch as substrates in MEC could not avoid the complete proliferation of hydrogen scavengers, even under low hydrogen retention time conditions induced by continuous nitrogen sparging, and hydrogen production was only sustained with milk as a single substrate.
158 citations
TL;DR: An integrated dark fermentation and microbial electrochemical cell (MEC) process was evaluated for hydrogen production from sugar beet juice, and the overall hydrogen production was 25% of initial COD (equivalent to 6 mol H2/mol hexoseadded).
140 citations
TL;DR: Microbial electrolysis cell (MECs) were investigated as a promising technology to manage waste activated sludge (WAS) reduction and bio-methane generation and the effect of WAS concentration on the MECs performance was discussed.
137 citations
TL;DR: The application of the biocathode for hydrogen production in a Microbial Electrolysis Cell (MEC) is a promising alternative to precious metal catalysts but further studies are necessary for an acute and experimental comprehension of the transfer of electrons and the energy conservation mechanism involved.
Abstract: The application of the biocathode for hydrogen production in a Microbial Electrolysis Cell (MEC) is a promising alternative to precious metal catalysts. However, biocathodes are still in the improvement and development stages and require a deep understanding of the bioelectrochemical mechanisms involved. In this review, the results of biocathode MEC experiments and studies in the literature on biocathode development methods were summarised; furthermore, used carbon sources and substrates in biocathodic compartments and microbial communities on the biocathode were characterised. Based on the respective articles that were examined, biocathode MEC may be developed and initiated in one of three categories: (I) half biological two-chambered biocathode MEC; (II) full biological two-chambered biocathode MEC; (III) full biological single-chambered biocathode MEC. In addition, various mixed cultures capable of producing hydrogen were identified, and predominant species were detected. Desulfovibrio paquesii, Desulfovibrio G11 and Geobacter sulfurreducens were also successfully tested as pure cultures in biocathode MECs. Further studies are necessary for an acute and experimental comprehension of the transfer of electrons and the energy conservation mechanism involved in the biocathode MEC, which may provide a cost-effective and practical implementation of this technology.
132 citations
TL;DR: This study assesses the ability of two twin membraneless MEC units (that are part of a modular pilot-scale MEC) to treat dWW, and finds that MECs performance deteriorated significantly during the continuous tests.
128 citations
19 Jan 2015
TL;DR: In this article, the authors present an economic and energy analysis of ammonium recovery in bioelectrochemical systems and compare it with existing nitrogen removal technologies, and present an estimation of the conditions needed to achieve maximum nitrogen recovery in both a microbial fuel cell and a microbial electrolysis cell.
Abstract: Removal of nitrogen compounds from wastewater is essential to prevent pollution of receiving water bodies (i.e. eutrophication). Conventional nitrogen removal technologies are energy intensive, representing one of the major costs in wastewater treatment plants. For that reason, innovations in nitrogen removal from wastewater focus on the reduction of energy use. Bioelectrochemical systems (BESs) have gained attention as an alternative to treat wastewater while recovering energy and/or chemicals. The combination of electrodes and microorganisms has led to several methods to remove or recover nitrogen from wastewater via oxidation reactions, reduction reactions and/or transport across an ion exchange membrane. In this study, we give an overview of nitrogen removal and recovery mechanisms in BESs based on state-of-the-art research. Moreover, we show an economic and energy analysis of ammonium recovery in BESs and compare it with existing nitrogen removal technologies. We present an estimation of the conditions needed to achieve maximum nitrogen recovery in both a microbial fuel cell (MFC) and a microbial electrolysis cell (MEC). This analysis allows for a better understanding of the limitations and key factors to take into account for the design and operation of MFCs and MECs. Finally, we address the main challenges to overcome in order to scale up and put the technology in practice. Overall, the revenues from removal and recovery of nitrogen, together with the production of electricity in an MFC or hydrogen in an MEC, make ammonium recovery in BESs a promising concept.
127 citations
TL;DR: In this article, the electron transfer mechanisms of bio-electrochemical methane production by mixed cultures were investigated, and at a cathode potential of -0.7?V vs. normal hydrogen electrode (NHE), average current density was 2.9 A m-2 cathode and average methane production rate was 1.8 M-2 m-1 cathode per day.
Abstract: BACKGROUND In a methane-producing bioelectrochemical system (BES) microorganisms grow on an electrode and catalyse the conversion of CO2 and electricity into methane. Theoretically, methane can be produced bioelectrochemically from CO2 via direct electron transfer or indirectly via hydrogen, acetate or formate. Understanding the electron transfer mechanisms could give insight into methods to steer the process towards higher rate. RESULTS In this study, the electron transfer mechanisms of bioelectrochemical methane production by mixed cultures were investigated. At a cathode potential of -0.7?V vs. normal hydrogen electrode (NHE), average current density was 2.9 A m-2 cathode and average methane production rate was 1.8 mole e- eq m-2 cathode per day (5.2?L CH4 m-2 cathode per day). Methane was primarily produced indirectly via hydrogen and acetate. Methods to steer towards bioelectrochemical hydrogen and acetate production to further improve the performance of a methane-producing BES are discussed. CONCLUSION At cathode potentials equal to or lower than -0.7?V vs. NHE and using mixed cultures, methane was primarily produced indirectly via hydrogen and acetate. (Bio)electrochemical hydrogen and acetate production rate could be increased by optimizing the cathode design and by enriching the microbial community. Consequently, the production rate of CO2-neutral methane in a BES could be increased. © 2014 Society of Chemical Industry
106 citations
TL;DR: In this paper, a statistical method, namely grey relational analysis, was exploited to evaluate hydrogen evolution performance of eight different non-precious metal alloy cathodes, including stainless steel alloys 304, 316, 420, A286, and nickel alloys 201, 400, 625 with Ni HX in comparison to precious metal of Pt (platinum).
98 citations
TL;DR: These results provide for the first time a noteworthy alternative for the treatment of saline effluents and continuous production of H2, and an important enrichment in the anodic biofilm with five main bacterial groups.
95 citations
TL;DR: The results demonstrate the potential of the pyrolysis-microbial electrolysis process as a sustainable and efficient route for production of renewable hydrogen with significant implications for hydrocarbon production from biomass.
TL;DR: The MEC H2 production demonstrated in this study is an alternative to the currently used process of reforming natural gas to supply H2 needed to upgrade bio-oils to stable hydrocarbon fuels.
Abstract: Furanic and phenolic compounds are problematic byproducts resulting from the breakdown of lignocellulosic biomass during biofuel production. The capacity of a microbial electrolysis cell (MEC) to produce hydrogen gas (H2) using a mixture of two furanic (furfural, FF; 5-hydroxymethyl furfural, HMF) and three phenolic (syringic acid, SA; vanillic acid, VA; and 4-hydroxybenzoic acid, HBA) compounds as the substrate in the bioanode was assessed. The rate and extent of biotransformation of the five compounds and efficiency of H2 production, as well as the structure of the anode microbial community, were investigated. The five compounds were completely transformed within 7-day batch runs and their biotransformation rate increased with increasing initial concentration. At an initial concentration of 1200 mg/L (8.7 mM) of the mixture of the five compounds, their biotransformation rate ranged from 0.85 to 2.34 mM/d. The anode Coulombic efficiency was 44-69%, which is comparable to that of wastewater-fed MECs. The H2 yield varied from 0.26 to 0.42 g H2-COD/g COD removed in the anode, and the bioanode volume-normalized H2 production rate was 0.07-0.1 L/L-d. The biotransformation of the five compounds took place via fermentation followed by exoelectrogenesis. The major identified fermentation products that did not transform further were catechol and phenol. Acetate was the direct substrate for exoelectrogenesis. Current and H2 production were inhibited at an initial substrate concentration of 1200 mg/L, resulting in acetate accumulation at a much higher level than that measured in other batch runs conducted with a lower initial concentration of the five compounds. The anode microbial community consisted of exoelectrogens, putative degraders of the five compounds, and syntrophic partners of exoelectrogens. The MEC H2 production demonstrated in this study is an alternative to the currently used process of reforming natural gas to supply H2 needed to upgrade bio-oils to stable hydrocarbon fuels.
TL;DR: In this article, a non-noble metal electroformed Ni mesh cathode alternatives to typical cathode material (Pt/CC) was intensively examined in a single-chamber membrane-free MEC.
TL;DR: In this article, an innovative Bioelectro-Fenton system capable of alternate switching between microbial electrolysis cell (MEC) and microbial fuel cells (MFC) mode of operation was developed to meet the challenges.
TL;DR: It is indicated that adding select antibiotics to the mixed species community in MECs could be a suitable method to enhance hydrogen production efficiency.
TL;DR: This study demonstrates the feasibility of H2 production on abiotic cathodes using enriched bioanode at low current densities using cold rolling and casting methods.
TL;DR: In this article, the organic matter consumption and hydrogen production rate were evaluated in a two-chamber microbial electrolysis cell (MEC), and three chemical oxygen demand (COD) concentration levels (400, 600 and 1200 ǫmg/L) were tested.
Abstract: The organic matter consumption and hydrogen production rate were evaluated in a two-chamber microbial electrolysis cell (MEC). Three chemical oxygen demand (COD) concentration levels (400, 600 and 1200 mg/L) were tested. The COD was composed of a mixture of volatile fatty acids (VFAs) present in the effluent of a dark fermentation process. The two levels of voltage studied were 350 and 550 mV. The performance of the MEC was evaluated using either an anionic (AEM) or cationic exchange membrane (CEM). The robustness of the MEC was tested using two dark fermentation effluents, one with VFAs and another containing 1100 mg/L glucose. The highest production rates (81 mL/L/day) were obtained with 550 mV, and 85 % COD consumption was attained. No considerable differences in the hydrogen production rate were observed when the COD was increased from 400 to 1200 mg/L using 550 mV. However, maximal hydrogen production rates were obtained with the lower COD concentration using 350 mV. Neither the employment of AEM and CEM nor the change from synthetic substrate to real substrate resulted in remarkable changes in MEC performance. The substrate containing glucose was more slowly degraded because glucose was first transformed into VFAs, and then the VFAs were consumed to produce hydrogen. In this case, methane and carbon dioxide were detected.
TL;DR: In this article, a two-stage process (fermentative+biocatalyzed electrolysis) was proposed to reduce the organic load of an industrial waste stream (cheese whey) in parallel with hydrogen production.
TL;DR: Experimental data rebuts different hypothesis and shows that methanogenesis at high BES concentration was likely due to the capacity of some Archaea (hydrogen-oxidizing genus Methanobrevibacter) to resist high B ES concentration up to 200 mM.
TL;DR: Improved performance of the EAD is thought to be achieved by direct oxidation of the short-chain fatty acids at the bioanode as well as indirect contribution of low acetic acid concentration to enhancing beta-oxidation.
TL;DR: It is revealed that acetate could be easily oxidized by anode respiring bacteria in MEC, while butyrate and propionate could not be oxidized to the same degree.
TL;DR: A methane-producing microbial electrolysis cell was continuously fed at the anode with a synthetic solution of soluble organic compounds simulating the composition of the soluble fraction of a municipal wastewater and revealed a high diversity in the anodic bacterial community with the presence of both fermentative and aerobic microorganisms.
Abstract: A methane-producing microbial electrolysis cell (MEC) was continuously fed at the anode with a synthetic solution of soluble organic compounds simulating the composition of the soluble fraction of a municipal wastewater. The MEC performance was assessed at different anode potentials in terms of chemical oxygen demand (COD) removal efficiency, methane production, and energy efficiency. As a main result, about 72-80% of the removed substrate was converted into current at the anode, and about 84-86% of the current was converted into methane at the cathode. Moreover, even though both COD removed and methane production slightly decreased as the applied anode potential decreased, the energy efficiency (i.e., the energy recovered as methane with respect to the energy input into the system) increased from 54 to 63%. Denaturing gradient gel electrophoresis (DGGE) analyses revealed a high diversity in the anodic bacterial community with the presence of both fermentative (Proteiniphilum acetatigenes and Petrimonas sulphurifila) and aerobic (Rhodococcus qingshengii) microorganisms, whereas only two microorganisms (Methanobrevibacter arboriphilus and Methanosarcina mazei), both assignable to methanogens, were observed in the cathodic community.
TL;DR: In this article, real-field acidogenic effluents rich in short chain carboxylic acids/volatile fatty acids (VFA) were obtained from bio-hydrogen (H 2 ) producing reactor operated with spent wash as substrate.
TL;DR: In this article, a spiral wound electrode was used to construct a microbial electrolysis cell for wastewater treatment and methane (CH4) production, which achieved high energy efficiency and high COD removal rate.
TL;DR: Pre-fermentation with a 3-day solids retention time (SRT) led to the maximum generation of VFAs, with or without pretreatment of the PS through pulsed-electric-fields (PEF), and using pre-fermented centrate led to successful performance in terms of Coulombic efficiency, Coulombics recovery, and COD-removal efficiency.
TL;DR: The power output of the MFC was sufficient to meet the requirement of the ESC and MEC, and the "self-sustained metal reduction" was achieved in this hybrid system.
TL;DR: In this article, the authors used Artificial Neural Networks (ANNs) for the modelling of bio-hydrogen yield in microbial electrolysis cells (MECs) by using a committee of five ANNs.
Abstract: The enhancement of hydrogen yield in microbial electrolysis cells (MECs) requires a robust process model that accurately relates the effect of anodic physicochemical input variables to the process output. Artificial neural networks (ANNs) have been used for the modelling of complex and non-linear processes. This paper reports the modelling of biohydrogen yield in MECs by using a committee of five ANNs. A topology of 6–(6, 8, 11, 12, 14)–1 was adopted, corresponding to the number of neurons of inputs, hidden (varied) and output layers. The ANN inputs were substrate type, substrate concentration, pH, temperature, applied voltage and reactor configuration. Model development was carried out with 50 data points from 15 published studies. The coefficients of determination (R2) between the experimental and predicted hydrogen yields for the five models were as follows: 0.90, 0.81, 0.85, 0.70 and 0.80. Model validation on new MEC processes showed a strong correlation between the observed and predicted hydrogen yie...
TL;DR: In this article, a new microbial electrolysis cell (MEC) system for hydrogen generation that was composed of a microbial fuel cell and a bio-photo-electrochemical cell (BPEC) was reported.
Abstract: Here, we report a new microbial electrolysis cell (MEC) system for hydrogen generation that was composed of a microbial fuel cell (MFC) and a bio-photoelectrochemical cell (BPEC). The BPEC consisted of a photocathode and a microbially-catalyzed anode. In the new MEC system, hydrogen was produced by the BPEC photocathode when it was illuminated with visible light, with the voltage for electrolysis supplied by the MFC. The electrons produced from the MFC anode were transferred to the BPEC photocathode through an external circuit and then photogenerated holes captured some of the electrons emitted by the MFC anode under visible light. This prevented the recombination of the photogenerated hole and electron pairs, leaving more photogenerated electrons available for hydrogen evolution reactions. This also allowed the remaining electrons from the MFC anode to participate in hydrogen evolution reactions. Under visible light, hydrogen was continuously produced from the new MEC system, with a maximum current density of 0.68 A m−2 and an average hydrogen-production rate of 1.35 ± 0.15 mL h−1.
TL;DR: In this article, the performance of graphite felt cathode for Co(II) reduction and hydrogen production in microbial electrolysis cells (MECs) was compared. And the results provided the first assessment of these materials for Co-II reduction with simultaneous hydrogen evolution, and SSM as the most promising inexpensive alternative to the others.
TL;DR: In this paper, a modified biocathode with PANI (Polyaniline)/MWCNT (Multi-Walled Carbon Nanotube) composites was used to improve hydrogen production in single-chamber, membrane-free biOCathode MECs.