Abstract: “The olive oil represents about 3% from the worldwide production of vegetable oils, but due to high organic content (lipids 0.2-1%, carboxylic acids 0.5-1.5%, sugars 1-8%, polyphenols and pectins 1-1.5%, tannins, polyalcohols, etc.), the wastewaters resulted from olive oil mills are important pollutants, about 30 million tons of wastewaters are produced per year in the world. The biological processes are the most environmentally compatible and least expensive methods for wastewater treatment. The immobilization of whole cells for the degradation of diferent compounds in wastewater can provide several advantages: high activity, yield, operational stability and possible reuse. Considering this, the aim of this paper is the comparative investigation of the lipids biodegradation from olive mill wastewaters using two different bioreactors containing immobilized mixture of Bacillus spp. (Bacillus subtilis, Bacillus megaterium, Bacillus licheniformis and Bacillus ortoliquefaciens in equal rati”

Keywords: lipids, wastewater, Bacillus, bioreactor, diffusion, immobilized cells, effectiveness factor.