Self-fermentation: Innovative pretreatment for use high concentration of olive mill wastewater in anaerobic digestion plant

This study aimed to evaluate the impact of self fermentation on methane production as biological pretreatment of olive mill wastewater (OMW). The self-fermentation was carried out at room temperature without mixing and at natural light cycle. The batch assays were performed at the influent substrate concentration of 36.7 g VS/l (OMW 100%), 18,4 g VS/l (OMW 50%) and 9.2 g VS/l (OMW 25%). The methane production was performed at 37°C in mixing condition. The results of methane production were compared with those obtained using untreated OMW. The results of this study showed that the self fermentation process is a very effective pretreatment to produce methane. Only the self-fermented samples have produced methane from undiluted OMW and a maximum cumulative methane production of 7583 ± 138 mlCH4/L and a yield of 246 ± 10 mlCH4/ gVS were obtained. A yield increase of +13.5% at OMW dilution of 50% was also achieved as compared to untreated OMW results. Interestingly, in the anaerobic digestion of untreated OMW, high hydrogen yields, with an average value of 46.8 ± 1.9 mlH2/gVS, were obtained. Moreover a depletion around 20% v/v of polyphenols was recorded for all experimental set. © 2016 ETA-Florence Renewable Energies.