Enhancement of landfill methane oxidation using different types of organic wastes

Methane (CH₄) is a greenhouse gas with a global warming potential that is 25 times higher than carbon 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 combinations. 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.