Fig. 3 illustrates the change in BHP and BMP of the OFMSW
samples collected during the five months of the year. This behaviour
could be explained by the variable composition of OFMSW
during the sampling campaigns. Higher contents of carbohydrate
rich fractions (BP, F) correspond to higher hydrogen potentials
and lower methane productions, while the opposite is achieved
when the protein and lipid rich fraction (MFC) increases. The
results therefore indicate that the composition of OFMSW plays a
significant role on the variability of data reported in literature for
hydrogen production potentials. Sample compositions and type
of materials are therefore fundamental for use in comparing BHP
data from different OFMSW.
The variability of data on hydrogen potential productions
(Fig. 3), may be moreover related not only to the different types
and origins of the organics in the samples, but also to their rate
of degradation. As reported by Favaro et al. (2013), hydrogen production
may also be enhanced by indigenous microorganisms
present in OFMSW. Accordingly, hydrogen yields could also be
affected by time elapsed between the production and collection
of organic waste, thus reducing the effective yields recorded during
BHP tests.