Improved methane elimination by methane-oxidizing bacteria immobilized on modified oil shale semicoke

Methane is a greenhouse gas with significant global warming potential. The methane-oxidizing bacteria (MOB) immobilized on biocarrier could perform effectively and environmentally in methane elimination. To further improve the efficiencies of MOB immobilization and methane elimination, the surface biocompatibility of biocarrier needs to be improved. In this work, the oil shale semicoke (SC) was chemically modified by sodium p-styrenesulfonate hydrate (SS) and 2-(methacryloyloxy)ethyltrimethylammonium chloride (DMC) to promote surface hydrophilicity and positive charge, respectively. Results revealed that, under methane concentrations of ~10% (v/v) and ~0.5% (v/v), the MOB immobilized on semicoke modified with 1.0 mol L^-1 of SS permitted improved methane elimination capacities (ECs), which were 15.02% and 11.11% higher than that on SC, respectively. Additionally, under methane concentrations of ~10% (v/v) and ~0.5% (v/v), the MOB immobilized on semicoke modified with 0.4 mol L^-1 of DMC held superior ECs, which were 17.88% and 11.29% higher than that on SC, respectively. The qPCR analysis indicated that the MOB abundance on modified semicoke were higher than that on SC. In consequence, the surface biocompatibility of semicoke could be promoted by SS and DMC modifications, which potentially provided methods for other biocarriers to improve surface biocompatibility.