Aerobic and anaerobic biotreatment of olive oil mill wastewater in Lebanon

Abstract

Olive oil mill wastewater (OMW), known in Lebanon as Zibar, is one of the two by-products obtained during olive oil extraction. OMW represents a serious environmental pollution problem especially for underground and surface water. Aerobic and anaerobic OMW biotreatment processes were developed and improved and showed promising success. A bacterial mixture of 10 strains (Aquaspirillum dispar, Bacillus cereus/thuringiensis, Brevibacterium otitidis, Klebsiella pneumoniae, Proteus penneri/vulgaris, Pseudomonas fluorescence biotype F, Pseudomonas marginalis, Pseudomonas mendonica, Pseudomonas sp. and Pseudomonas viridilivida) and five yeast cultures (Candida boidini, Candida memodendra, Candida mogii, Pichia haplophia and Sacharomyces ludwigii) were isolated from OMW, purified and reused in OMW aerobic biotreatment. Pilot- (5,000 L) and industrial-scale (25,000 L) biotreatments were performed. After 14 days of pilot-scale biotreatment, a 69.6% in biochemical oxygen demand (BOD) and a 68.3% reductions in chemical oxygen demand (COD) values were achieved, while a 71.0% BOD and a 66.9% COD reduction were scored after 31 days of industrial-scale biotreatment. Anaerobic OMW biotreatment done at the experimental laboratory scale using omasomal juice as microbial starter achieved a reduction of 67.4% BOD and 65.9% COD with 37.2 L of biogas production per liter of Zibar after six weeks of incubation. The employed aerobic and anaerobic OMW biotreatment processes, developed at the LAU Biotechnology Labs, that achieved acceptable BOD and COD reduction rates and produced biogas, are low cost technologies and suitable for possible application in small rural olive mills in Lebanon and in the Middle East.