Effect of acclimatization factors on reproducibility of biogas production in anaerobic cultures from electrochemically pre-treated or filtered olive mill wastewater

Olive mill wastewater (OMW) is an agro industrial waste with a high organic load produced mainly in the Mediterranean region. Its inherent toxicity to anaerobic microorganisms is attributed to its high content in COD and phenols. Many treatments have been proposed for the remediation of this waste both physicochemical and biological but there is not one that is applicable in all cases. In this work, olive mill wastewater was treated anaerobically at different growth conditions. The waste introduced in the cultures was either filtered or electrochemically pretreated OMW. Two sets of experiments were conducted to evaluate the effect of temperature, HS-Co-M, fatty acids and OMW pretreatment on biogas production efficiency. The thermophilic growth exhibited extended lag phase compared to the mesophilic growth. Biogas production was strongly dependent on growth supplements. Both HS-Co-M and fatty acids enhanced biogas production in the presence of filtered and electrolyzed OMW. In a second set of experiments, the effect of a mixture of fatty acids was investigated in combination with pretreated or raw OMW.