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Interactions between nanoscale zero valent iron and extracellular polymeric substances of anaerobic sludge.

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Title: Interactions between nanoscale zero valent iron and extracellular polymeric substances of anaerobic sludge.
Authors: He, Chuan-Shu1 (AUTHOR), Ding, Rong-Rong1 (AUTHOR), Chen, Jia-Qi1 (AUTHOR), Li, Wen-Qiang1 (AUTHOR), Li, Qi1 (AUTHOR), Mu, Yang1 (AUTHOR) yangmu@ustc.edu.cn
Source: Water Research. Jul2020, Vol. 178, pN.PAG-N.PAG. 1p.
Subjects: Bioelectrochemistry, Anaerobic digestion, Iron, Wastewater treatment, Charge exchange, Vitamin B2
Abstract: The effects on the activity of anaerobic digestion (AD) of interactions between extracellular polymeric substances (EPS), a protective barrier of microorganisms towards toxic compounds, and nanoscale zero valent iron (nZVI) remain incompletely understood. In this work, EPS induced a dosage-dependent dispersion of nZVI clusters due to their effective accumulation on the nZVI surface. The small size of nZVI clusters and the formation of stable Fe-EPS complex promoted the dissolution of nZVI with a final increase of 15–20% H 2 yield. Further characterizations of EPS demonstrated the presence of some semiquinones, like riboflavin, which may work as a sink to accept electrons from nZVI. This likely explains the EPS dosage-related reduction of H 2 release rate in the initial stage and the possible decrease in nZVI reducibility responsible for disrupting cell integrity. Interactions between nZVI and EPS could improve the electrochemical activity of EPS, favoring microbial extracellular electron transfer. Therefore, the presence of EPS at relatively higher concentrations may 1) reduce the inhibition of nZVI to AD process by avoiding the fast accumulation of H 2 and restricting damage to cell integrity; 2) benefit the methanogenesis process by providing more exogenous H 2 from complete nZVI dissolution with higher electrochemical activity of EPS. This study provides insight into the interactions between EPS and nanoparticles with strong reducibility in biological wastewater treatment systems. Image 1 • Effective surface-coating of EPS enhanced the dispersion of nZVI clusters. • Interactions between nZVI and EPS resulted in complete corrosion of nZVI. • Semiquinones present in EPS could accept nZVI electrons to reduce H 2 release rate. • Interactions between nZVI and EPS improved the electrochemical activity of EPS. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:The effects on the activity of anaerobic digestion (AD) of interactions between extracellular polymeric substances (EPS), a protective barrier of microorganisms towards toxic compounds, and nanoscale zero valent iron (nZVI) remain incompletely understood. In this work, EPS induced a dosage-dependent dispersion of nZVI clusters due to their effective accumulation on the nZVI surface. The small size of nZVI clusters and the formation of stable Fe-EPS complex promoted the dissolution of nZVI with a final increase of 15–20% H 2 yield. Further characterizations of EPS demonstrated the presence of some semiquinones, like riboflavin, which may work as a sink to accept electrons from nZVI. This likely explains the EPS dosage-related reduction of H 2 release rate in the initial stage and the possible decrease in nZVI reducibility responsible for disrupting cell integrity. Interactions between nZVI and EPS could improve the electrochemical activity of EPS, favoring microbial extracellular electron transfer. Therefore, the presence of EPS at relatively higher concentrations may 1) reduce the inhibition of nZVI to AD process by avoiding the fast accumulation of H 2 and restricting damage to cell integrity; 2) benefit the methanogenesis process by providing more exogenous H 2 from complete nZVI dissolution with higher electrochemical activity of EPS. This study provides insight into the interactions between EPS and nanoparticles with strong reducibility in biological wastewater treatment systems. Image 1 • Effective surface-coating of EPS enhanced the dispersion of nZVI clusters. • Interactions between nZVI and EPS resulted in complete corrosion of nZVI. • Semiquinones present in EPS could accept nZVI electrons to reduce H 2 release rate. • Interactions between nZVI and EPS improved the electrochemical activity of EPS. [ABSTRACT FROM AUTHOR]
ISSN:00431354
DOI:10.1016/j.watres.2020.115817