Influence of industrial olive mill wastewater pre-treatment on the Scenedesmus obliquus growth

Industrial olive mill wastewater (OMW) is one of the more problematic wastewaters to treat by the conventional biological process since it has a high organic load expressed as high values for chemical oxygen demand (COD) and total organic carbon (TOC). In addition, to other inhibitory compounds such as phenolic compounds. High values for maximum specific growth rate and volumetric biomass productivity are mandatory to success in the industrial microalgal culture. In this work, three operating units, flocculation, artificial photolysis, and microfiltration before the microalga Scenedesmus obliquus culture were established. All experiments were carried out on a laboratory scale in stirred batch tank photobioreactors using different dilutions of OMW as culture medium (5% to 100% of OMW, v/v). The highest value of the maximum specific growth rate for Scenedesmus obliquus, $\mu_{\mathrm{m}}=0.0836\mathrm{h}^{-1}$, was determined in the culture medium at 100% of OMW. However, at the lowest concentration of OMW, 5% of OMW (v/v), in the culture medium was determined the highest biomass productivity, 0.587, mg/(Lh). Regarding the treated water quality, the COD removal (93.7%) was registered during the application of the pre-treatment units plus algal culture when 100% of OMW was used. The resulting treated water can be reused in irrigation.