Effect of the characteristics of municipal solid waste on biogas production in landfills

Metagenomic analyses were carried out on municipal solid waste, with samples collected at two different depths (2 and 4 m) and distances (2 and 20 m) from a biogas extraction well. Tests were performed to investigate the hypothesis of oxygen entry in the waste mass through the cover layer. The results indicated the predominance of anaerobic microorganisms (37–51%), whereas the aerobic or aerobic and anaerobic facultative microorganisms presented values of 3–8%. Nevertheless, two-way Permanova analysis highlighted differences between samples with different distances and depths. The distance from the well was the most important variable influencing the community structures, and the most abundant genera were all anaerobic and included Methanobacterium, Methanosarcina, Methanofollis, Desulfosporosinus, Anaerolinea and Clostridium. The results strengthen the hypothesis of oxygen entry in the waste mass through the cover layer affecting the nature of the decomposition process, primarily for shallower depths.