The microbial composition of olive mill wastewater (OMWW) from six disposal ponds at three localities in North Sinai Governorate, Egypt has been studied. Such OMWW samples contained a variable (but high) number of bacteria, yeasts, and mold. Eighty-one isolates related to 9 bacterial species were recovered, and seven common bacterial species were isolated from Bir al Abd, Al-Arish, and Rafah sites sources namely Enterococcus faecalis, Escherichia coli, Bacillus cereus, B. subtilis, Micrococcus luteus, Pseudomonas aeruginosa, and Klebsiella pneumonia. In addition to these species, Vibrio cholerae and Shigella species were isolated from the Bir al Abd site. One hundred and twenty isolates related to 13 fungal species were recovered. Seven members of different fungal genera (Aspergillus, Penicillium, Fusarium, Paecilomyces, Alternaria, Chaetomium, and Rhizopus) were recorded. Four genera were widely distributed, and they were able to grow efficiently in undiluted OMWW as a sole source of nutrients. Strains of Aspergillus, Penicillium, Fusarium, and Paecilomyces showed a marked capacity for OMWW detoxification. The physicochemical studies further revealed the presence of relatively low levels of sodium, potassium, calcium, magnesium, and iron. Nitrate concentration was relatively high, 70.13 mg/L. The biological oxygen demand (BOD) and the chemical oxygen demand (COD) recorded high values that ranged between 2210-2270 mg/L and 22760-22800 mg/L, respectively. High BOD and COD values are important indicators of high organic and inorganic components of OMWW and possible negative environmental consequences. The presence of fungal and bacterial species implied possible degradation of the effluent.
olive oil- wastewaters- biodegradation- water pollution-phenols- fungi.