Page 351 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Pretreatment of agroindustry waste by ozonolysis for synthesis of biorefinery products 319

Many pretreatment methods have been applied for lignocellulosic biomass, but these
methods may not be suitable for biohydrogen production since it targeted the bioetha-
nol as the final products (Wu et al., 2013b). The main objective of other pretreatment
methods is to separate lignin and hemicellulose within the lignocellulose composite,
which is practically suitable for bioethanol production, since it utilizes just the cellu-
lose, but possibly not for biohydrogen production that utilizes both cellulose and
hemicellulose (Monlau et al., 2013).
Wu et al. (2013b) have investigated the ozone pretreatment to enhance the pro-
duction of biohydrogen from wheat straw. They reported that the wheat straw was
effectively degraded with ozone and increased the delignification with increased
dose of ozone that significantly increased reducing sugar yields. The biohydrogen
was produced by conducting the reaction in a simultaneous enzyme hydrolysis and
dark fermentation, and the results showed that the ozone pretreatment significantly
increased biohydrogen production by a maximum of 158% for ozonated sample at
45 min. Thus it was proven that the biohydrogen production from lignocellulosic
biomass using ozonolysis is technically feasible (Wu et al., 2013b).
Another study from Wu et al (2013b) used barley straw to study the effect of
ozone pretreatment for hydrogen production. The straw lignin was effectively
degraded, and the reducing sugar yield was increased with ozone pretreatment com-
pared to untreated biomass. The hydrogen production increased significantly by a
maximum of 166% at 45 min of straw ozonation (Wu et al., 2013b). In the fermen-
tation experiment the 90 min ozonated samples produced less hydrogen, while the
highest sugar release was found in this group, indicating that the delignification
using ozone does not produce enzyme inhibitor indicating the microorganisms that
were inhibited in the simultaneous dark fermentation with saccharification process.
Besides the ozonolysis process, Hu et al. (2018) worked on the production of
biohydrogen production via dilute acid pretreated sugarcane bagasse through the
detoxification and fermentation strategy. The laccase and NaBH 4 were used to
detoxify the sugarcane bagasse and were washed before the anaerobic degradation
process. The biohydrogen production was found to be increased 10 times higher
when detoxification by washing, compared to the nondetoxified samples.
Meanwhile, the detoxified samples by laccase and NaBH 4 obtained low (below
7 mM) biohydrogen yield. This shows that washing by water proved to be effective
as a detoxification method compared to acid pretreated sugarcane bagasse by lac-
case NaBH 4 for biohydrogen production (Hu et al., 2018).

14.3.3 Levulinic acid
In biomass structure, complex carbohydrate network that linked monosaccharide,
disaccharide, and polysaccharide is presented. Thus the depolymerization of ligno-
cellulosic biomass is required for conversion into chemicals and fuels. The reac-
tions comprise hydrolysis, dehydration, and rehydration, involving a series of
complex reactions and drastic reaction conditions (Tiong et al., 2018). However, in
biomass utilization, the variability of conversion and yield obtained from the bio-
mass materials is depending on the reaction system applied. LA becomes a platform