Enhancement of landfill methane oxidation using different types of organic wastes

Abstract

Methane (CH4) is a greenhouse gas with a global warming potential that is 25 times higher than car- bon dioxide (CO2). Microbial oxidation of landfill CH4 is about 5 % and it plays a significant role in reducing emissions to the atmosphere. Previous studies have shown that microbial oxidation of CH4 in landfill cover soil can be enhanced using organic matter-rich substrates. This study aims to investigate the CH4 oxidation activity with the addition of different organic wastes in different combina- tions. Batch experiments with different organic wastes for CH4 oxidation activity showed that compost and sawdust required the shortest time to oxidize CH4 compared to empty fruit bunch and black soil. However, other organic wastes (spent yeast, sewage sludge and spent tea leaves) tested in this study produced CH4 instead. Compost and sawdust took 4 days for complete CH4 oxidation. Batch experiments with different combinations of organic waste showed potential CH4 reduction when combined with compost. The combination of 20 % spent yeast ? 80 % compost was able to completely oxidize CH4 at day 16. CH4 was fully oxidized on day 1 by 20 % sewage sludge ? 80 % compost, showing good CH4 oxidation potential; 100 % sawdust fully oxidized CH4 within 4 days, while a combination of 20 % sawdust ? 80 % compost and 40 % sawdust ? 60 % compost took 2 days for complete CH4 oxidation. From this study, it can be concluded that the addition of organic wastes at optimum ratio and combination with compost as landfill cover material will have a significant effect on CH4 emission reduction.