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by the interaction between moisture content and reaction time. The ozonolysis,
when run under the optimum conditions, yielded lignin degradation at 84.7 wt.%
and TRS at 99.9%.
Wu et al. (2013a) studied biohydrogen production from the barley straw using a
semibatch reactor and the ozonolysis process. The straw lignin was effectively
degraded while reducing sugar yield increased. Compared to the untreated samples,
the ozonated samples produced significantly higher yield of hydrogen by up to
166%, proving that the ozone pretreatment could enhance the production of biohy-
drogen from barley straw. Another study by Wu et al. (2013b) worked on ozonoly-
sis of wheat straw in a semibatch reactor to enhance the production of biohydrogen.
It found that the wheat straw lignin was effectively degraded and the delignification
increased as the ozone consumption increased (Wu et al., 2013b). The reducing
sugar yield increased and the biohydrogen production also significantly increased
compared to the untreated samples. Hence, the biohydrogen production is consid-
ered technically feasible by utilizing lignocellulosic biomass using ozonolysis.
The fixed-bed reactor has been studied by Travaini et al. (2016a) for its effect of
ozonolysis pretreatment in terms of the ozone consumption, sugar release, and etha-
nol production yield from sugarcane bagasse. The statistical analysis showed that
the ozone concentration significantly affected reaction time and sugar release after
enzymatic hydrolysis. The longer reaction time and reduction of ozone flow
resulted in small differences of ozone consumptions. Around 80% of ethanol yields
were obtained by the hydrolysate experiments. Garcı ´a-Cubero et al. (2012) investi-
gated rye and wheat straw in a fixed-bed reactor via ozonolysis and found that the
insoluble lignin reduction was about 50%. The untreated raw straw’s glucose yields
were 10% that can be considered lower. The yield of monosaccharides decreased as
ozonation time increased due to side reactions.
Cesaro and Belgiorno (2013) investigated anaerobic digestion of solid organic
waste by applying two types of pretreatment that are sonolysis and ozonation in a
Drechsel trap reactor and a bubble column reactor. The experimental results showed
that the bubble column reactor was more effective, giving lower residual ozone and
higher ozone interaction with the substrate compared to the Drechsel trap reactor.
Heiske et al (2013) studied ozonolysis via plasma-assisted pretreatment (PAP) to
improve the anaerobic digestion of wheat straw. The ozone was generated by
dielectric barrier discharge operating at atmospheric pressure and room temperature.
This method has shown to be efficient for decomposing lignin and hence facilitating
microbial access to cellulose and hemicellulose.
On the other hand, the Japanese cedar has been used in a rotary reactor to
improve enzymatic saccharification by combining wet disk milling with ozonolysis
(Miura et al., 2012). The results showed that the ozone treatment mainly removes
lignin but also removes hemicellulose by regulating the ozone consumption. The
matrix polymers in the cell walls are partially removed by the ozonolysis process,
thus increasing the sugar yield.
Based on these studies on ozonolysis, it can be safely stated that ozonolysis has
a huge potential to be utilized as a significant pretreatment method for biomass con-
version process. Researchers have developed and studied many types of reactors to