ETHANOL PULPING AS A STAGE IN THE BIO-REFINERY OF OLIVE TREE PRUNINGS

• Main Authors: Ana Requejo, Alejandro Rodríguez, Zoilo González, Fátima Vargas, Luis Jiménez
• Format: Article
• Language: English
• Published: North Carolina State University 2012-06-01
• Series: BioResources
• Subjects: Biorefinery; Olive Tree Prunings; Pulp; Paper; Bioethanol; Combustion
• Online Access: http://ojs.cnr.ncsu.edu/index.php/BioRes/article/view/BioRes_07_3_3142_Requejo_RGVJ_Ethanol_Pulping_Olive_Prunings/1577

Biomaterials from olive tree pruning are an abundant agricultural residue in various Mediterranean regions. A suggested use of this residue is its separation in a main fraction (trunks and stems with diameter > 1 cm) and a residual fraction (leaves and stems with diameter 1 < cm), using biorefinery procedures. The main fraction is cooked with ethanol, giving rise to a pulp, which can be used either in paper or in bioethanol production if before pulping the main fraction is subjected to a hydrothermal treatment. Pulping with 70% ethanol concentration, 185 °C for 80 min resulted in a pulp with a yield of 46.30% and a content of holocellulose, α-cellulose, and lignin of 77.17%, 62.49%, and 21.73%, respectively. The paper sheets obtained had a breaking length of 1168 m, a burst index of 0.44 kN /g, a tear index of 2.25 mN.m2/g, and a brightness of 43.66%. The pulp converted into bioethanol (by simultaneous hydrolysis and fermentation) achieved a conversion of 70 g bioethanol/100 g potential bioethanol. The residual fraction of olive tree prunings was subjected to combustion to produce thermal energy. The heating value was 18700 kJ/kg, the flame temperature range was 1094 to 2013 ºC, and the dew point temperature range of the flue gases was 47 to 53 °C.