Roles of Oxygen in Methane-dependent Selenate Reduction in a Membrane Biofilm Reactor : Stimulation or Suppression

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

16 Scopus Citations
View graph of relations

Author(s)

  • Yulu Wang
  • Chun-Yu Lai
  • Mengxiong Wu
  • Yarong Song
  • Shihu Hu
  • Jianhua Guo

Detail(s)

Original languageEnglish
Article number117150
Journal / PublicationWater Research
Volume198
Online published14 Apr 2021
Publication statusPublished - 15 Jun 2021
Externally publishedYes

Abstract

Although methane (CH4) has been proven to be able to serve as an electron donor for bio-reducing various oxidized contaminants (e.g., selenate (SeO42−)), little is known regarding the roles of oxygen in methane-based reduction processes. Here, a methane-based membrane biofilm reactor (MBfR) was established for evaluating the effects of oxygen supply rates on selenate reduction performance and microbial communities. The oxygen supply rate played a dual role (stimulatory or suppressive effect) in selenate reduction rates, depending on the presence or absence of dissolved oxygen (DO). Specifically, selenate reduction rate was substantially enhanced when an appropriate oxygen rate (e.g., 12 to 184 mg/L.d in this study) was supplied but with negligible DO. The highest selenate reduction rate (up to 34 mg-Se/L.d) was obtained under an oxygen supply rate of 184 mg/L.d. In contrast, excessive oxygen supply rate (626 mg/L.d) would significantly suppress selenate reduction rate under DO level of 3 mg/L. Accordingly, though the high oxygen supply rate (626 mg/L.d) would promote the expression of pmoA (5.9 × 109 copies g−1), the expression level of narG (a recognized gene to mediate selenate reduction) would be significantly downregulated (6.1 × 109 copies g−1), thus suppressing selenate reduction. In contrast, the expression of narG gene significantly increased to 2.8 × 1010 copies g−1, and the expression of pmoA gene could still maintain at 1.1 × 109 copies g−1 under an oxygen supply rate of 184 mg/L.d. High-throughput sequencing targeting 16S rRNA gene, pmoA, and narG collectively suggested Methylocystis acts as the major aerobic methanotroph, in synergy with Arthrobacter and Variovorax which likely jointly reduce selenate to selenite (SeO32−), and further to elemental selenium (Se0). Methylocystis was predominant in the biofilm regardless of variations of oxygen supply rates, while Arthrobacter and Variovorax were sensitive to oxygen fluctuation. These findings provide insights into the effects of oxygen on methane-dependent selenate reduction and suggest that it is feasible to achieve a higher selenate removal by regulating oxygen supply rates. © 2021 Elsevier Ltd. All rights reserved.

Research Area(s)

  • Membrane biofilm reactor, Methane, Microbial community structure, Oxygen supply rate, Selenate reduction

Citation Format(s)

Roles of Oxygen in Methane-dependent Selenate Reduction in a Membrane Biofilm Reactor: Stimulation or Suppression. / Wang, Yulu; Lai, Chun-Yu; Wu, Mengxiong et al.
In: Water Research, Vol. 198, 117150, 15.06.2021.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review