Conclusions
The present study showed that the aquatic plant duckweed
could be effectively fermented to produce hydrogen. Mild
pretreatment was required to render the duckweed amenable
to fermentation. Among the pretreatment methods that were
studied, acid pretreatment (1% H2SO4 and 85 C for one hour)
was the most effective in improving the efficiency of duckweed
conversion to biohydrogen by fermentation. However,
high sodium concentrations resulting from pH adjustment
after biomass pretreatment were inhibitory to fermentation.
At 35 C and an initial pH of 5.5, the fermentation of acidpretreated
duckweed biomass resulted in a biohydrogen production
of 75.3 mL g1, which is comparable or slightly lower
than yields obtained with commonly studied plant biomass. A
substantially higher biohydrogen production can be expected