abstract
Bioethanol is one of the most promising renewable energy sources, and it can be used as an alternative to
petroleum-derived products. Agro-food residues are the substrates most frequently used for bioethanol
production through anaerobic fermentation. The cultivation of olive trees and olive oil production are
important economic activities throughout all Mediterranean countries. The wastes derived from olive oil
production include a liquid waste, known as Olive Mill Wastewater (OMW), and a semi-solid waste,
called Olive Pomace (OP), which is rich is lignin and cellulose materials. The aim of this work is to
evaluate the quantity of hydrogen and bioethanol that could be extracted from an OMW-OP mixture after
Saccharomyces cerevisiae anaerobic fermentation. In addition, different pretreatments (ultrasonic pretreatment,
basic pretreatment, and calcium carbonate addition) have been tested to increase the glucose
concentration and, consequently, the bioethanol and hydrogen production in the reaction medium and to
decrease the content of inhibiting polyphenols which are mainly present in the OMW. All of the pretreatments
were shown to have improved the hydrogen and bioethanol concentration at the end of the
fermentation. The basic and ultrasonic pretreatments resulted in the best bioethanol and hydrogen
production. These two pretreatments contributed to the hydrolysis of the lignin and cellulose and to
increasing the soluble sugars (in particular glucose) content in the reaction mixture. Calcium carbonate
addition decreased the polyphenol concentration; the polyphenols inhibit the fermentation mediated by
S. cerevisiae.