Effect of alkaline pretreatment on anaerobic digestion of olive mill solid waste

• Published in: Waste management (Elmsford) 2016-12, Vol.58, p.160-168
• Main Authors: Pellera, Frantseska-Maria, Santori, Sofia, Pomi, Raffaella, Polettini, Alessandra, Gidarakos, Evangelos
• Format: Article
• Language: English
• Subjects: Agroindustrial; Anaerobic digestion; Anaerobiosis; Biochemistry; Biodegradability; Biodegradation, Environmental; Biological Oxygen Demand Analysis; Chemical; Dosage; Food-Processing Industry; Hydrogen-Ion Concentration; Kinetics; Lignin - chemistry; Lignin - metabolism; Lignocellulosic; Methane; Methane - metabolism; Models, Theoretical; Olea; Olea - chemistry; Olive; Olives; Pretreatment; Sodium Hydroxide - chemistry; Solid Waste; Solubility; Solubilization; Temperature; Waste Disposal, Fluid - methods
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2016.08.008

•Alkaline pretreatment improved olive pomace solubilization and biodegradability.•Optimum pretreatment durations were found at 16h for 25°C and at 4h for 90°C.•Solubilization was mainly affected by NaOH dosage, followed by temperature.•NaOH dosage and temperature may have joint effects on substrate biodegradability.•Maximum methane yield was obtained for pretreatment at 90°C and 1mmol NaOH/gVS. The present study evaluates the influence of alkaline (NaOH) pretreatment on anaerobic digestion of olive pomace. Batch hydrolysis experiments with different NaOH dosages, process durations and temperatures were conducted, in which the variation of olive pomace solubilization in the liquid phase was investigated. The effect of pretreatment on anaerobic digestion was studied through biochemical methane potential assays. The results demonstrated the effectiveness of the NaOH pretreatment in improving olive pomace solubilization as well as its biodegradability. Maximum specific methane yields were achieved at different NaOH dosages depending on the pretreatment temperature. Consequently, it was concluded that the two operating parameters of the pretreatment stage (NaOH dosage and temperature) may exert a joint effect on substrate biodegradability and methane yields. The highest methane yield (242NmLCH4/gVS) was obtained for the material pretreated at 90°C, at a dosage of 1mmol/gVS (4% of VS).