Boosted Biomass Production of Single and Co-Cultures of Microalgae Grown in Whey Supplemented Media: a Sustainable...

Whey is a major by-product of the dairy industry characterized by its high nitrogenous loads and organic content, presenting significant environmental challenges, if it is not valorized properly. This study investigates the potential of microalgae single and co-cultures as a sustainable approach for whey valorisation and valuable biomass production. Different combinations of four-species-comprising Scenedesmus sp. (SC), Tetradesmus obliquus (TO), Chlorella vulgaris Beijerinck (CVB), and Chlorella vulgaris CCAP 211/19 (CV)-were cultivated in casein whey-based media to assess cell proliferation and biomass yield. Nitrogen assimilation was also investigated during this study. Results revealed that TO achieved the highest biomass yield (1.3 g/L) in whey medium, while the co-culture of Chlorella vulgaris strains exhibited synergistic growth, outperforming single cultures and the mixed culture of all four species (MIX). Flow cytometry showed that the pattern of the cell population of algae for whey containing media was different from those for standard medium (BBM), the cells were larger with reduced chlorophyll content. The highest cell counts were related to TO and the consortium culture (MIX). This observation could be linked to the results obtained by biomass weight, which showed that TO had the highest biomass weight, as this microalgae exhibited larger cells sizes and cell counts. Interestingly, nitrogen assimilation studies demonstrated that co-cultures of microalgae enhanced nitrate and ammonia removal, significantly. The removal performance was particularly improved in whey-supplemented media, underscoring the potential of co-cultures for efficient and sustainable nitrogen removal. Up to 99% of protein and 90% of nitrate could be successfully removed from whey solution after three weeks. This research emphasizes the dual benefits of microalgae co-cultures in nitrogen removal and simultaneously high-value biomass production using media based on whey. The results of nitrogen assimilation using co-cultures offered an improved sustainable solution to nitrogen removal problem in the food industry. The findings provide a foundation for precision consortium design in dairy waste valorization, paving the way for cost-effective and environmentally friendly solutions in the dairy industry.