Abstract
Atmospheric methane (CH4) concentrations continue to rise rapidly, driven by increased emissions and contributing substantially to global warming. Methanotroph-based CH4 mitigation offers a promising approach at emission sites, but effective reactor designs supporting both efficient CH4 removal and biomass harvest remain underdeveloped. Here, we designed, manufactured, and validated a multi-tray reactor that deploys flat "dry" biofilms of Methylotuvimicrobium buryatense 5GB1C for methane removal from air. Results show continuous CH4 removal from 500 ppm CH4 gas flows using M. buryatense5GB1C and the multi-tray reactor, with either cellulose beads or Whatman papers as the sorbent material for nutrient delivery. Biomass could be harvested without compromising continued CH4 consumption, and regrowth was observed post-harvest. A mathematical model that describes CH4 removal performance with good agreement to experimental results was used to analyze the effect of different biotic and abiotic factors to methane removal. Finally, we deployed the reactor at a closed landfill that emits CH4. This field study demonstrated continuous CH4 removal from landfill gas for three weeks, with fluctuating inlet CH4 concentrations (200-4000 ppm) and varying ambient temperatures. The inlet CH4 concentration strongly correlated with CH4 removal performance, while temperature showed no significant influence. Together, these results establish the multi-tray reactor encompassing M. buryatense 5GB1C biofilms as a prospective platform for methanotroph-based CH4 mitigation.