In the experiment to
select the solvent, the digestion was conducted with different
concentration of volatile solids (VS) ranging from 0.5 to 2%.
In the optimization study, two percent of VS of the untreated
and pretreated peels were placed in 120mL glass bottle. The
total volume of the mixture was 30mL including 20mL of
inoculumand the rest was orange peel and water.The reactors
were then flushed with amixed gas containing 80%ofN2 and
20% of CO2 for 2min. The reactors were incubated at 55∘C
for 33 days. Reactors containing only water and inoculum
were used as a blank.