Cultivation of a naturally resilient Chlorella sp.: A bioenergetic strategy for valorization of cheese whey for high nutritional biomass production

This study investigated Chlorella's capacity to treat cheese whey (CW) effluent and produce a high-nutritional value biomass, by using a systematic sequential experimental design. Physicochemical analysis of CW revealed its high pollution load, characterized by elevated levels of lactose, phosphorus, and nitrogen, as well as high turbidity due to the presence of whey solids. Screening experiments demonstrated that trace mineral addition and continuous air supply are essential factors for Chlorella biomass production in CW (>800 mg·mL−1). Furthermore, whey solids did not hinder Chlorella growth, with notable biomass production observed even in undiluted CW, demonstrating this microalga's ability to adapt metabolically to the complex environment. Laboratory-scale photobioreactor experiments confirmed Chlorella's ability to produce biomass in CW, outperforming controls (>800 mg·mL−1). Bioremediation potential assessment exhibited significant reductions in organic pollutants (>14 g·L−1 COD), nitrogen (>400 mg·L−1), phosphorus (>140 mg·L−1) and sodium (>650 mg·L−1). CW solids were also removed with Chlorella harvesting (>99 %). Harvested algal biomass was enriched with proteins (>40 g·100 g−1), polyunsaturated fatty acids (>9 % TFA) and pigments, offering potential applications in nutraceutical and pharmaceutical industries. Overall, this study highlights Chlorella's efficacy in CW treatment and biomass valorization, offering a sustainable solution for dairy wastewater management while producing valuable resources. [Display omitted] •A systematic sequential experimental design was developed for algal cultivation in CW.•Chlorella can produce biomass in CW with trace mineral addition and air supply.•Chlorella could remove significant amounts of lactose from CW.•Mixotrophy led to high yields of biomass.•Chlorella cultivation in CW increased the nutritional value of the whey solid fraction.