Diversity and performance of thermophilic methane oxidizing microbiomes from a full scale manure gas biofilter

Methane emissions from manure management contribute substantially to greenhouse gas release. Compost biofilters offer a sustainable approach for methane mitigation through the activity of methane oxidizing bacteria. However, thermophilic compost biofilters remain poorly characterized compared with mesophilic systems. This study investigated a full-scale thermophilic compost biofilter treating manure derived gas to evaluate the impact of nutrient availability on methane oxidation performance, and the potential for simultaneous removal of organic micropollutants. Batch experiments at 50 °C revealed spatial variation in methane oxidation, with the highest oxidation rates occurring near the gas distribution layer, where microbial biomass and diversity were the highest. Nutrient addition increased methane oxidation by up to 211% in nutrient-limited areas, demonstrating that nutrient availability can constrain biofilter performance. Elemental analyses showed declines of 20%-50% in most nutrients and trace metals, within a year operation, although methane oxidation remained consistently high throughout operation. The compost also degraded several organic micropollutants during methane oxidation, with sulfamethoxazole and benzotriazole achieving up to 78% and 66% removal, respectively, while diclofenac, 2,6-dichlorobenzamide, alachlor-ESA, and dimethyl sulfide showed moderate removal of 8%-28%. Microbial community was highly diverse and metabolically versatile, comprising more than 750 genera. Gas quality profiles yielded strong microbial stratification over time. These findings demonstrate that thermophilic compost biofilters are effective, low-cost systems for simultaneous methane mitigation and removal of selected organic micropollutants, relying on complex microbiomes.