Mechanistic investigation of toxicological change in ZnO and TiO2 multi-nanomaterial systems during anaerobic digestion and the microorganism response

Zheng, Lei; Zhang, Zhaoxi; Tian, Liyan; Zhang, Lingling; Cheng, Shikun; Li, Zifu; Cang, Daqiang

doi:10.1016/j.bej.2019.03.017

Cited by 29 publications

(15 citation statements)

References 45 publications

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“…The lowest ROS level was observed for cathode biofilms formed on stainless steel, while ROS levels were very similar in anode/cathode biofilms developed on carbon fibers. Recent studies reported ROS accumulation in anaerobic digesters 21 , 72 , while ROS is usually thought to be produced during aerobic metabolism. It has been suggested that unfavorable metabolic conditions (e.g., inhibition by toxicants, pH changes) could lead to ROS accumulation in digesters 21 , 72 .…”

Section: Resultsmentioning

confidence: 99%

“…Recent studies reported ROS accumulation in anaerobic digesters 21 , 72 , while ROS is usually thought to be produced during aerobic metabolism. It has been suggested that unfavorable metabolic conditions (e.g., inhibition by toxicants, pH changes) could lead to ROS accumulation in digesters 21 , 72 . ROS accumulation may suppress metabolic activities, leading to the deterioration of digester performance.…”

Section: Resultsmentioning

confidence: 99%

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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: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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 lowest ROS level was observed for cathode biofilms on stainless steel surface, while very similar ROS levels were found in anode/cathode biofilms developed on carbon fibers. Recent studies reported ROS accumulation in the anaerobic digestion process (Tian et al, 2019; Zheng et al, 2019), while ROS is usually thought to be produced during aerobic metabolism. It has been suggested that unfavorable metabolic conditions (e.g., inhibition by toxicants, pH changes) could lead to ROS accumulation in digesters (Tian et al, 2019; Zheng et al, 2019).…”

Section: Resultsmentioning

confidence: 99%

Section: Ros Levelsmentioning

confidence: 99%

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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“…Chen et al [16] observed that the performance and the microbial activity were enhanced by the supplementation of nano-carbon powder and nano-aluminium oxide whereas the use of nano-ZnO and nano-CuO appreciably reduce the microbial action in addition to the performance of the anaerobic fermentation process. Zheng et al [17] observed a reduced performance in the AD process by using the ZnO nanoparticle but the performance was found identical to the control group when the combination of ZnO and TiO 2 was used as the multi engineered nanoparticle material. Zhang et al [18] identi ed a higher accumulation of volatile fatty acid by adding ZnO nanomaterial compared to the control sample mainly due to the effect of Zn 2+ during the AD of waste activated sludge.…”

Section: Introductionmentioning

confidence: 97%

Effect of Various Potential Additives on Hydrogen Fermentation During the Co-Digestion of Food Waste and Cow Dung

Deheri¹,

Acharya²

2020

Preprint

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The effect of calcium peroxide (CaO2), zinc oxide (ZnO), copper oxide (CuO), and calcium carbonate (CaCO3) as additives during the anaerobic co-digestion of food waste and cow dung is experimentally investigated to enhance the hydrogen fermentation. The maximum concentration of hydrogen in the generated gas is found to be 26.43%, 21.67%, 17.64%, and 20.84% while the cumulative yield of hydrogen remains 114.1, 109.27, 104.87, and 107.38 mL g− 1 Total Solid (TS) with CaO2, ZnO, CuO, and CaCO3 respectively. The sample in which no additive is used (control) exhibits a maximum hydrogen concentration of 17% and a cumulative hydrogen generation of 101.57 mL g− 1 TS in the produced gas. Result reveals an enhancement in the hydrogen concentration up to 9.43% whereas the cumulative hydrogen yield is increased up to 11% with additives compared to the control sample. Overall the hydrogen fermentation can be significantly enhanced with the additives through the anaerobic co-digestion process.

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Mechanistic investigation of toxicological change in ZnO and TiO2 multi-nanomaterial systems during anaerobic digestion and the microorganism response

Cited by 29 publications

References 45 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

Effect of Various Potential Additives on Hydrogen Fermentation During the Co-Digestion of Food Waste and Cow Dung

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