Decomposable materials were transformed and stabilized to smaller sized materials over the
landfilling period so that bigger FM values could be observed at cLF section. A reasonable decrease of PCB ratio along with waste depth was observed at cLF section (3.91–1.48%) possibly due to difference of decomposition time. This is in accordance that the main components of PCB are cellulose and hemicellulose which can be easily consumed under anaerobic conditions and contribute to the methane yield (Eleazer et al., 1997).