Independent of direct interspecies electron transfer: Magnetite-mediated sulphur cycle for anaerobic degradation of benzoate under low-concentration sulphate conditions

The aim of this study was to investigate the primary mechanism of magnetite promoting anaerobic degradation of aromatic compounds under the low-concentration sulphate conditions. Under influent conditions of benzoate at 50 mM-chemical oxygen demand (COD) and sulphate at 15 mM, magnetite promoted ben...

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Published in:Journal of hazardous materials 2022-02, Vol.423 (Pt A), p.127051-127051, Article 127051
Main Authors: Li, Yang, Dong, Chunlei, Li, Yuan, Nie, Wenqi, Wang, Mingwei, Sun, Cheng, Liang, Lianfu, Zhao, Zhiqiang, Zhang, Yaobin
Format: Article
Language:English
Subjects:
Anaerobiosis
Benzoate Degradation
Benzoates
Electrons
Ferric Compounds
Ferrosoferric Oxide
Magnetite
Oxidation-Reduction
Sulfates
Sulfur
Sulphate Reduction
Sulphur Cycle
Sulphur Disproportionation
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Summary:The aim of this study was to investigate the primary mechanism of magnetite promoting anaerobic degradation of aromatic compounds under the low-concentration sulphate conditions. Under influent conditions of benzoate at 50 mM-chemical oxygen demand (COD) and sulphate at 15 mM, magnetite promoted benzoate degradation (77.1% vs 56.3%), while the effluent sulphate concentration was slightly higher than that without magnetite (1.6 mM vs 0.7 mM), inconsistent with functional gene prediction that both sulphate respiration and sulphur compound respiration were relatively more active in the presence of magnetite. Remarkably, X-ray diffraction showed that, signal related to Fe3O4 faded away and finally was replaced by FeSO4 and FeS, indicating that magnetite participated in benzoate degradation coupled to sulphate reduction via dissimilatory Fe(III) reduction. Further X-ray photoelectron spectroscopy showed that, signal related to S0 was only detected with magnetite, suggesting the possibility of re-oxidation of sulphide to elemental sulphur coupled to Fe(III) reduction. This was further supported by the increase in abundance of Desulfuromonas acetexigens capable of growing on Fe(III). In addition, magnetite specially enriched the chemolithotrophic sulphur-disproportionating microbes, Desulfovibrio aminophilus, which might proceed the disproportionation of elemental sulphur to sulphate and sulphide to achieve a sulphur cycle for benzoate degradation. [Display omitted] •Magnetite enhanced benzoate degradation under low-concentration sulphate conditions.•Signal related to magnetite in X-ray diffraction spectra was no longer detected.•Elemental sulphur was dominant reduced sulphur species in presence of magnetite.•Both sulphate/Fe(III)-reducing and sulphur-disproportionating microbes were enriched.•Magnetite mediated a sulphur cycle rather than direct interspecies electron transfer.
ISSN:0304-3894
1873-3336
DOI:10.1016/j.jhazmat.2021.127051