Feasibility of methane bioconversion to methanol by acid-tolerant ammonia-oxidizing bacteria

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

12 Scopus Citations
View graph of relations

Author(s)

  • Junji Zhang
  • Zhetai Hu
  • Tao Liu
  • Zhiyao Wang
  • Jianhua Guo
  • Min Zheng

Detail(s)

Original languageEnglish
Article number117077
Journal / PublicationWater Research
Volume197
Online published21 Mar 2021
Publication statusPublished - 1 Jun 2021
Externally publishedYes

Abstract

Bioconversion of biogas to value-added liquids has received increasing attention over the years. However, many biological processes are restricted under acidic conditions owing to the excessive carbon dioxide (CO2, 30–40% v/v) in biogas. Here, using an enriched culture dominated by acid-tolerant ammonia-oxidizing bacteria (AOB) ‘Candidatus Nitrosoglobus’, this study examined the feasibility of producing methanol from methane in the CO2-acidified environment (i.e. pH of 5.0). Within the tested dissolved methane range (0.1–0.9 mM), methane oxidation by the acid-tolerant AOB culture followed first-order kinetics, with the same rate constant (i.e. 0.43 (L/(g VSS‧h)) between pH 7.0 and 5.0. The acidic methane oxidation showed robustness against high dissolved concentrations of CO2 (up to 4.06 mM) and hydrogen sulfide (H2S up to 0.11 mM), which led to a high methanol yield of about 30–40%. As such, the raw biogas containing toxic CO2 and H2S can directly serve for methanol production by this acid-tolerant AOB culture, economizing a conventionally costly biogas upgradation process. Afterwards, two batch reactors fed with methane and oxygen intermittently both obtained a final concentration of 1.5 mM CH3OH (equal to 72 mg chemical oxygen demand/L) in the liquid, suggesting it is a useful carbon source to enhance denitrification in wastewater treatment systems. In addition, ammonia availability was identified to be critical for a higher rate of this AOB-mediated methanol production. Overall, our results for the first time demonstrated the capability of a novel acid-tolerant AOB culture to oxidize methane, and also illustrated the technical feasibility to utilize raw biogas for methanol production at acidic conditions. © 2021 Elsevier Ltd. All rights reserved.

Research Area(s)

  • Ammonia-oxidizing bacteria (AOB), Biogas utilization, Candidatus ‘Nitrosoglobus’, Low pH, Methane bioconversion to methanol

Citation Format(s)

Feasibility of methane bioconversion to methanol by acid-tolerant ammonia-oxidizing bacteria. / Zhang, Junji; Hu, Zhetai; Liu, Tao et al.
In: Water Research, Vol. 197, 117077, 01.06.2021.

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