Influence of hydrodynamic stress in the growth of Scenedesmus obliquus using a culture medium based on olive-mill wastewater

The wastewater from olive oil elaboration (OMW) constitutes a major environmental problem in producing countries of olive oil. OMW from the three-phase system is harmful due to its high organic load and the presence of phytotoxic phenolic compounds. The culture medium was constituted with 5% OMW. The effects of mechanical agitation and aeration rates on the microalga Scenedesmus obliquus growth, in a batch photobioreactor were studied. A maximum specific growth rate, μm = 0.031 h−1, was obtained using a rotational impeller speed around 350 rpm without aeration and was greater than that found in the absence of stirring 0.024 h−1. The chlorophyll contents were independent of the stress and light intensity in the cultures, but did boost the nutrient concentration in the medium. The stress induced by stirring or by aeration of the cultures did not alter the final cell-protein and carbohydrate content, 18% and 48% as mean value, respectively.