OBJECTIVE: Desalination of cheese whey by electrodialysis yields saline wastewater (SWW). The goal was to test this as the basis of a culture medium and to prove experimentally the concept that it was a suitable resource for heterotrophic cultivation of the freshwater green microalga Chlorella vulgaris. RESULTS: Optimization of glucose concentration, nitrogen source and medium salinity for microalgal growth was first carried out in defined medium (DM) and shake flasks. These results were then adopted in shake flask cultivation experiments using pre-treated SWW medium (PSWW). Subsequently, microalgal growth under optimized conditions was tested in bioreactors. Various media such as DM, PSWW and diluted PSWW (DPSWW) were compared. Volumetric biomass productivities decreased in the order DM (0.371 g L-1 h-1, urea) > DPSWW (0.315 g L-1 h-1, soy peptone) > PSWW (0.152 g L-1 h-1, soy peptone). Although biomass productivities in DPSWW and PSWW media were significantly lower than in DM, these media required the addition of only 66 and 33% of DM N sources, respectively. No other added DM component was necessary in (D)PSWW to achieve microalgal growth. CONCLUSIONS: Although the optimized cultivation of freshwater microalgae on alternative medium based on SWW resulted in biomass productivities lower than those on DM, the required addition of N sources was also lower. Potentially lower production costs of Chlorella biomass and the meaningful use of SWW are the main outcomes of this work.

Département de Biologie Faculté des Sciences Biologiques et des Sciences Agronomiques Université Mouloud Mammeri 15000 Tizi Ouzou Algeria

Department of Biotechnology University of Chemistry and Technology Prague Technicka 5 166 28 Prague Czech Republic

Department of Microbiology and Technology Dairy Research Institute Ke Dvoru 12a 160 00 Prague Czech Republic

Unité de Recherche Appliquée en Energies Renouvelables URAER Centre de Développement des Energies Renouvelables CDER 47133 Ghardaïa Algeria

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