Influence of pH on the Culture of Scenedesmus obliquus in Olive-mill Wastewater

Olive-mill wastewater (OMW), an agro-industrial by-product from olive-oil milling (with the three-phase extraction method), was used experimentally as 5% (v/v) of the medium to culture Scenedesmus obliquus CCAP 276/3A. The characterization of the wastewater indicated a nitrogen deficiency. The highest specific growth rate of S. obliquus mu(m) = 0.022 h(-1) was found when the medium was maintained at a constant pH value of 7.0. The biomass productivity, P-b was determined by the influence of pH on the speciation of the dissolved CO2. The greatest elimination of BOD5 occurred at extreme pH values. The protein and chlorophyll contents presented a maximum value close to pH = 7.0. The highest crude-protein content in the biomass was 25.6%. The polyunsaturated and essential fatty acids presented a clear trend to increase with the pH, at pH 9.0, representing 26.2 and 19.4%, respectively, of the total fatty-acid content of the biomass. (C) KSBB