Methane bioconversion to value-added liquid chemicals and in situ applications

Microbial conversion of methane to value-added chemicals is a potential technology for reducing dependence on petroleum-based products in an environmentally friendly manner. However, the poor mass transfer rate of sparingly soluble methane is a major barrier in the successful design and operation of such a process at large-scale.

This sub-project will develop a novel methane fermentation system using gas permeable membranes that will significantly improve the methane transfer rate to microorganisms. We will address a number of issues limiting mass transfer rate and efficiency by optimising methane partial pressure, surface area to volume ratio and recirculation rate.

Recently, we developed a membrane biofilm reactor (MBfR) that can produce volatile fatty acids (VFAs) from methane fermentation under oxygen-limiting conditions. However, the pathway and the key microorganisms involved in methane conversion are still not clear.

This sub-project will develop MBfR technology for high-rate cultivation of methanotrophs for multiple applications, including VFA/solvent production, single cell protein production, and bioremediation of oxidized contaminants such as selenate and perchlorate in groundwater.

Funding

• FL170100086

Project Outcomes

The key purpose of this project is to:

1. Identify key microorganisms and metabolic pathways for conversion of methane to liquid chemicals under micro-aerobic conditions
2. Determine roles of oxygen/nitrate/methane/CO₂ in VFA production
3. Develop biotechnology for methane fermentation, specifically a hybrid MBfR reactor to enable efficient gas transfer
4. Develop applications of methane-based biotechnology
   • Bioremediation of nitrate, nitrite, perchlorate, and selenate from contaminated water
   • Single-cell protein production

Publications

1. Chen, H.; Zhao, L.; Hu, S.; Yuan, Z.; Guo, J., 2018. High-rate production of short-chain fatty acids from methane in a mixed-culture membrane biofilm reactor. Environmental Science & Technology Letters, 5, 662-667.

2. Chen, H.; Luo, J.; Liu, S.; Yuan, Z.; Guo, J., 2019. Microbial methane conversion to short-chain fatty acids using various electron acceptors in membrane biofilm reactors. Environmental science & technology, 53, 12846-12855.

4. Wu M.; Luo J.; Hu S.; Yuan Z.; Guo J., 2019. Perchlorate bio-reduction in a methane-based membrane biofilm reactor in the presence and absence of oxygen. Water Research, 157, 572-578.

3. Chen, H.; Liu, S.; Liu, T.; Yuan, Z.; Guo, J., 2020. Efficient nitrate removal from synthetic groundwater via in situ utilization of short-chain fatty acids from methane bioconversion. Chemical Engineering Journal, 393, 124594.

5. Wang Y.; Lai C.; Wu M.; Song Y.; Hu, S.; Yuan, Z.; Guo, J., 2021. Roles of oxygen in methane-dependent selenate reduction in a membrane biofilm reactor: stimulation or suppression. Water Research, 198, 117150.

6. Zhao L.; Chen H.; Yuan Z.; Guo J., 2021. Interactions of functional microorganisms and their contributions to methane bioconversion to short-chain fatty acids. Water Research, 199, 117184.

7. Wang Y.; Lai C.; Wu M.; Lu X.; Hu, S.; Yuan, Z.; Guo, J., 2022. Copper stimulation on methane-supported perchlorate reduction in a membrane biofilm reactor. Journal of Hazardous Materials, 425, 127917.