Model-based evaluation of thermal and operational strategies for methane oxidation biosystems in cold regions

Methane oxidation biosystems (MOBs), engineered within landfill covers to promote microbial methane (CH₄) oxidation, offer a sustainable approach for mitigating CH₄ emissions. However, their performance in cold regions has not been systematically assessed, leaving uncertainty about their effectiveness under subzero ambient temperatures. Winter operation may be improved through external heating and aeration, but the conditions warranting their use and full-scale feasibility remain uncertain. This study developed and validated GEGCSim, a numerical model coupling multicomponent gas transport, two-phase flow, CH₄ oxidation, biological and waste heat generation, and heat transfer, to evaluate cold-region MOB performance and potential interventions. Validation against laboratory and field studies confirmed GEGCSim's ability to reproduce MOBs' thermal, gas, and oxidation dynamics. Simulations showed that passive MOBs' became inactive when ambient temperatures fell below -10°C. Strategies were evaluated to improve MOBs' winter operation. Increasing the oxidation capacity improved performance but did not sustain activity at ambient temperatures near -20°C. External heating restored winter performance, although temperatures in lower layers increased above the optimal range for methanotrophs. Active aeration eliminated oxygen (O₂) limitation and achieved complete oxidation at temperatures down to -5°C. At colder temperatures, higher CH₄ loading was required to generate sufficient heat from oxidation. However, this generated excess heat that reduced MOB efficiency in summer. Seasonal CH₄ loading could help balance winter heat generation and summer overheating in active MOBs. While these simulated strategies show potential, their long-term effectiveness at full-scale landfills, practical feasibility, costs, and environmental benefits, including external energy consumption, require further evaluation.