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Microbial Methane Conversion to Short-Chain Fatty Acids Using Various Electron Acceptors in Membrane Biofilm Reactors
journal contribution
posted on 2019-10-18, 20:29 authored by Hui Chen, Jinghuan Luo, Shuai Liu, Zhiguo Yuan, Jianhua GuoGiven
our vast methane reserves and the forecasted shortage of
crude oil in the not too distant future, the conversion of methane
into value-added liquid chemicals or fuels would be beneficial. The
generated chemicals or fuels could augment the petroleum-dominated
chemical market, and also satisfy the increasing demand for transportation
fuels. While methane bioconversion to liquid chemicals has just been
reported recently, there is limited understanding of the process.
This study aims to clarify the potential electron acceptors that could
support the process. Here we operated four membrane biofilm reactors
(MBfRs) fed with nitrate, nitrite, oxygen at a relatively low rate,
and oxygen at a relatively high rate, respectively, to study if they
can support methane bioconversion to short-chain fatty acids (SCFAs)
and the associated microbiological features. All tested electron acceptors
facilitated methane bioconversion to SCFAs (ranging from 1.1 to 36.7
mg acetate L–1 d–1, or 3.4 to
114.6 mg acetate d–1 m–2 of biofilm).
The carbon efficiency was estimated to be 7.9 ± 1.4% to 148.5
± 1.3%, with an efficiency higher than 100%, suggesting the assimilation
of other carbon, very likely CO2, into the products. A
low oxygen supply rate of 46.4 ± 2.3 mg O2 d–1 m–2 was found to be the most favorable among all
the electron conditions provided according to the SCFAs production
rate and also the carbon utilization efficiency. Microbial characterization
revealed that completely different communities evolved in the respective
reactors, suggesting diverse microbial pathways exist for methane
bioconversion into value-added chemicals.