4. Conclusions
OP and OMW are two agro-food refuses derived from olive oil
production which can be used for bioethanol generation through
anaerobic fermentation. OP is a semi-solid waste with high concentrations
of lignin and cellulose, both recalcitrant substances that
need to be hydrolysed, through anaerobic processes, to degrade
them into ethanol. OMW has a high content of polyphenols, which
inhibit the microbial metabolism and, consequently, the conversion
of the substrates into ethanol. The different pretreatments tested in
this work were able to improve the hydrogen and bioethanol produced
from a mixture of OP and OMW. It was noted that the PCa test
increased the bioethanol production from the OP-OMW mixture to
a concentration of almost 5.00 g/L by reducing the inhibiting
polyphenol concentration from 197.98 mg gallic acid/L (NP Test) to
79.20 mg/L (Table 2). The best pretreatment was BP, which had
several positive effects: it reduced the polyphenol content in the
reaction medium, but above all it contributed to the hydrolysis of
cellulose into glucose, which resulted in an increase in the ethanol
concentration in the reaction medium from 2.50 g/L, when no
pretreatment was used, to almost 10.00 g/L, thus improving the
process 2.33- fold