Microalgae-mediated bioremediation and valorization of cattle wastewater previously digested in a hybrid anaerobic...

Scenedesmus obliquus (ACOI 204/07) microalgae were cultivated in cattle wastewater in vertical alveolar flat panel photobioreactors, operated in batch and continuous mode, after previous digestion in a hybrid anaerobic reactor. In batch operation, removal efficiencies ranges of 65 to 70% of COD, 98 to 99% of NH₄⁺ and 69 to 77.5% of PO₄^-3 after 12days were recorded. The corresponding figures for continuous flow were from 57 to 61% of COD, 94 to 96% of NH₄⁺ and 65 to 70% of PO₄^-3 with mean hidraulic retention time of 12days. Higher rates of CO₂ fixation (327-547mgL^-1d^-1) and higher biomass volumetric productivity (213-358mgL^-1d^-1) were obtained in batch mode. This microalgae-mediated process can be considered promising for bioremediation and valorization of effluents produced by cattle breeding yielding a protein-rich microalgal biomass that could be eventually used as cattle feed.