Systematic formulation of brewery effluent for high-efficiency epuration and food-grade microalgae production

Abstract

Actual (vs. synthetic) effluents were recovered, cost-effectively settled, augmented, and inoculated with Chlorella vulgaris. These minimal modifications ensure ease of process scale-up and economical viability while preserving the food-grade status of the stream. After successful shake flask runs, the process was transferred to 100 and then 500-ml working volume photobioreactors. The achieved performances (biomass production from 0.29 to 0.49 g/L/d - light dose dependent - and removal rates, 24.5 ± 4.3 mg/L/d for PO43−, 6.8 ± 1.6 mg/L/d for SO42−, 107 ± 32 mg/L/d for Total Nitrogen, and 1.30 ± 0.32 mg/L/d for Total Organic Content) are twice as high as the ones reported by other scholars. Cell productivity and illumination were almost perfectly correlated, demonstrating that the process can be easily controlled via adjustment of the illumination. Finally, the produced microalgae exhibit a balanced macronutrient profile and can be deemed food-grade, opening the way to biomass valorization as feed.