H2SO4 (2 N) was the condition that yielded more sugars without
originating high concentrations of harmful compounds (all below
2.5% g g dw1). These represent the main reasons for the choice
of this acid concentration for the pre-treatment of Sc biomass.
3.2.1.3. Biomass loading effect. In order to optimize the sugars concentration
in the final hydrolysate, regarding their utilization for
fermentations processes, Scenedesmus biomass loading concentrations
ranging from 20 to 500 g L1 were extracted using H2SO4
(2 N, since it was considered previously as the best concentration
for the sugar extraction). The sugar extraction efficiency from the
biomass to the supernatant seem to decrease with the increase
of biomass concentration, being 50 g L1 the optimum biomass
concentration, corresponding to 28.6% g eqglu g dw1 (89.9%) of
total sugars (Tables 1 and 2), while for 500 g L1 of biomass, total
sugar recovery was 23.3% g eqglu g dw1 (73.1%), which reveals
that there may be a retention of sugars in the biomass due to the
higher hydrolysate viscosity.
Also in Table 2 it is shown that the type of monosaccharide extracted
was not affected with the loading of biomass, since the glucose
concentration remained almost constant, with an
approximate value of 63% of all monosaccharide’s extracted. This
result shows that the acid was enough to attack the polysaccharides
regardless of the biomass’ concentration.
Focusing on the sugar yield, biomass concentration of 500 g L1
allowed a sugar concentration on the supernatant above 100 g L1,
the desired concentration to carry out an alcoholic fermentation