Recent advances in cathode materials and configurations for upgrading methane in bioelectrochemical systems integrated with anaerobic digestion

Noori, Md. T.; Vu, Mung Thi; Ali, Rana Basit; Min, Booki

doi:10.1016/j.cej.2019.123689

Cited by 106 publications

(24 citation statements)

References 182 publications

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“…The optimization of applied voltage/potential and inoculation method has been broadly investigated to enrich a syntrophically balanced microbiome for MEC-AD systems 2 , 26 . Previous studies also substantiated the importance of persuasive system design 27 – 29 . Particularly, cathode materials with low overpotential, large surface area, and good conductive properties were found to play a deterministic role in MEC-AD performance 3 , 30 – 32 .…”

Section: Introductionmentioning

confidence: 68%

Characterization and significance of extracellular polymeric substances, reactive oxygen species, and extracellular electron transfer in methanogenic biocathode

Zakaria

Dhar

2021

Sci Rep

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The microbial electrolysis cell assisted anaerobic digestion holds great promises over conventional anaerobic digestion. This article reports an experimental investigation of extracellular polymeric substances (EPS), reactive oxygen species (ROS), and the expression of genes associated with extracellular electron transfer (EET) in methanogenic biocathodes. The MEC-AD systems were examined using two cathode materials: carbon fibers and stainless-steel mesh. A higher abundance of hydrogenotrophic Methanobacterium sp. and homoacetogenic Acetobacterium sp. appeared to play a major role in superior methanogenesis from stainless steel biocathode than carbon fibers. Moreover, the higher secretion of EPS accompanied by the lower ROS level in stainless steel biocathode indicated that higher EPS perhaps protected cells from harsh metabolic conditions (possibly unfavorable local pH) induced by faster catalysis of hydrogen evolution reaction. In contrast, EET-associated gene expression patterns were comparable in both biocathodes. Thus, these results indicated hydrogenotrophic methanogenesis is the key mechanism, while cathodic EET has a trivial role in distinguishing performances between two cathode electrodes. These results provide new insights into the efficient methanogenic biocathode development.

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Section: Introductionmentioning

confidence: 68%

Characterization and significance of extracellular polymeric substances, reactive oxygen species, and extracellular electron transfer in methanogenic biocathode

Zakaria

Dhar

2021

Sci Rep

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“…The optimization of applied voltage/potential and inoculation method has been broadly investigated to enrich a syntrophically balanced microbial communities towards developing MEC-AD systems (Villano et al, 2016;Zakaria and Dhar, 2021). Previous studies also substantiated the importance of persuasive system design for effective electro-methanogenesis (Guo et al, 2017;Ma et al, 2017;Noori et al, 2020). Particularly, the selection of cathode electrode with low overpotential, large effective surface area, and good conductive properties was found to play a deterministic role in MEC-AD performance (Choi et al, 2017;De Vrieze et al, 2014;Liu et al, 2017Liu et al, , 2016.…”

Section: Introductionmentioning

confidence: 78%

Characterization and significance of extracellular polymeric substances, reactive oxygen species, and extracellular electron transfer in methanogenic biocathode

Zakaria

Dhar

2020

Preprint

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Carbon-based electrodes have been mostly used as a biocathode material in microbial electrolysis cell assisted anaerobic digestion (MEC-AD) due to their excellent biocompatibility and higher surface area over metal-based electrodes. Here, we report a multifaceted approach combining characterization of microbial communities, extracellular polymeric substances (EPS), redox oxygen species (ROS), and expression of genes associated with extracellular electron transfer (EET) to shed light on mechanisms governing electro-methanogenic activity in different biocathode materials. Carbon fiber and stainless-steel mesh biocathode were tested in MEC-AD systems fed with synthetic glucose medium. Despite the higher specific surface area provided by carbon fiber biocathode, methanogenesis performance was much inferior (100.3 mL CH4) than that obtained from a stainless steel biocathode (179.5 mL CH4). Interestingly, biofilms did not entirely cover the surfaces of carbon fibers, while stainless steel biocathode showed evenly denser biofilms with higher biovolume (30.2±4.2 vs. 13.5±2.8 μm3/μm2). Analyses of microbial communities indicated that the key mechanism for electro-methanogenesis in both reactors was hydrogenotrophic methanogenesis by Methanobacterium species. The redox activity of EPS derived from biocathode, as well as expressions of EET genes, suggested that electro-methanogenesis via direct electron transfer might have occurred to some extent in both biocathodes. Higher abundance of strictly hydrogenotrophic Methanobacterium sp. and homoacetogenic Acetobacterium appeared to play a major role in higher methanogenesis performance from stainless steel biocathode. It was possibly attributed to effective catalysis of hydrogen evolution reaction (HER) on stainless steel biocathode. The most considerable secretion of EPS accompanied by the lowest ROS level in stainless steel biocathode indicated that higher EPS possibly protected cells from harsh metabolic conditions (e.g., unfavorable local pH) induced by faster HER. The results of this study have important significance in the development of effective biocathode for MEC-AD systems.HighlightsStainless-steel mesh outperformed carbon fibers for methanogenic biocathode.Multifaceted characterization of biofilms unveiled underlying mechanisms.The results confirmed H2-utilizing methanogenesis is the dominant pathway.Homoacetogenesis only played a crucial role in the stainless-steel biocathode.Biocathode EPS might be responsible for superior methanogenesis.Graphical Abstract

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“…Generally, the required EV was decided by considering both electrode potential for H 2 evolution, which differs based on the electrode material, and electrode potential at which the reduced products could be harvested [95,96]. For instance, when CH 4 production was implemented using a pure culture of Methanobacterium-like archaeon, attached to graphite cathode, the selected EV was −0.4 V vs. SHE [97].…”

Section: Electrical Energy Input As Tool For Diet Pathway Stimulationmentioning

confidence: 99%

Enhanced Anaerobic Digestion by Stimulating DIET Reaction

Mostafa

Song

et al. 2020

Processes

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Since the observation of direct interspecies electron transfer (DIET) in anaerobic mixed cultures in 2010s, the topic “DIET-stimulation” has been the main route to enhance the performance of anaerobic digestion (AD) under harsh conditions, such as high organic loading rate (OLR) and the toxicants’ presence. In this review article, we tried to answer three main questions: (i) What are the merits and strategies for DIET stimulation? (ii) What are the consequences of stimulation? (iii) What is the mechanism of action behind the impact of this stimulation? Therefore, we introduced DIET history and recent relevant findings with a focus on the theoretical advantages. Then, we reviewed the most recent articles by categorizing how DIET reaction was stimulated by adding conductive material (CM) and/or applying external voltage (EV). The emphasis was made on the enhanced performance (yield and/or production rate), CM type, applied EV, and mechanism of action for each stimulation strategy. In addition, we explained DIET-caused changes in microbial community structure. Finally, future perspectives and practical limitations/chances were explored in detail. We expect this review article will provide a better understanding for DIET pathway in AD and encourage further research development in a right direction.

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Recent advances in cathode materials and configurations for upgrading methane in bioelectrochemical systems integrated with anaerobic digestion

Cited by 106 publications

References 182 publications

Characterization and significance of extracellular polymeric substances, reactive oxygen species, and extracellular electron transfer in methanogenic biocathode

Characterization and significance of extracellular polymeric substances, reactive oxygen species, and extracellular electron transfer in methanogenic biocathode

Characterization and significance of extracellular polymeric substances, reactive oxygen species, and extracellular electron transfer in methanogenic biocathode

Enhanced Anaerobic Digestion by Stimulating DIET Reaction

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