Two stage biohythane productions were evaluated using raw
and fungal pretreated sugarcane top. Raw sugarcane top was used
directly for microbial conversion to evaluate the feasibility of acidogenic
mixed consortia for hydrogen production. Hydrogen yield
of 55 L/kg-VS was obtained (Fig. 3a). This low hydrogen yield was
mainly due to the crystalline structure and presence of lignin barrier
of biomass, which prevents the direct contact of microbes with
substrate. Significant decrease of hydrogen yield was also reported
in the previous work using untreated sugarcane bagasse for hydrogen
production (Kumari and Das, 2015). With the fungal pretreated
sugarcane top, the total hydrogen yield of 77.2 L/kg-VS was
achieved after 14 h of fermentation (Fig. 3a). This improvement
in hydrogen yield was due to removal of lignin barrier after fungal
pretreatment, which enhanced the microbial degradation of biomass
for fermentative hydrogen production. The improvement in
hydrogen yield after fungal pretreatment was also reported by
Zhao et al. (2012). They observed that the hydrogen was immediately
produced after 6 h incubation with no lag phase using fungal
pretreated cornstalk and the maximum hydrogen yield of 80.3 L/kg
pretreated cornstalk was obtained (Zhao et al., 2012).