Cheese whey, the major by-product of the dairy industry, poses an environmental challenge due to its high organic load but simultaneously represents a nutrient-dense matrix suitable for biotechnological valorization. This review synthesizes recent advances positioning whey as (i) a fermentation substrate for lactic acid bacteria, yeasts/fungi, and microalgae, enabling the production of functional biomass, organic acids, bioethanol, exopolysaccharides, enzymes, and wastewater bioremediation; (ii) a platform for postbiotic generation, supporting cell-free preparations with functional activities; and (iii) a food-grade encapsulating material, particularly through whey proteins (β-lactoglobulin, α-lactalbumin), which can form emulsions, gels, and films that protect biotics and bioactive compounds during processing, storage, and gastrointestinal transit. We analyze key operational variables (whey type and pretreatment, supplementation strategies, batch and continuous cultivation modes), encapsulation routes (spray drying, freeze-drying, and hybrid protein–polysaccharide systems), and performance trade-offs relevant to industrial scale-up. Finally, we outline future directions, including precision fermentation, mixed-culture processes with in situ lactase activity, microfluidics-enabled encapsulation, and life-cycle assessment, to integrate product yields with environmental performance. Collectively, these strategies reframe whey from a high-impact waste into a circular bioeconomy resource for the food, nutraceutical, and environmental sectors.

Microalgae offer a sustainable alternative for wastewater treatment by simultaneously removing pollutants and producing biomass of potential value. This study evaluated five species—Haematococcus pluvialis, Chlorella vulgaris, Chlamydomonas sp., Anabaena variabilis, and Scenedesmus sp.—in three undiluted food and beverage industry effluents from Mexico: nejayote (alkaline wastewater generated during corn nixtamalization for tortilla production), tequila vinasses (from tequila distillation), and cheese whey (from cheese making). Strains were adapted through UV mutagenesis and gradual acclimatization to grow without freshwater dilution. Bioremediation efficiency was assessed via reductions in chemical oxygen demand (COD), total nitrogen (TN), and total phosphates (TPO₄). C. vulgaris achieved complete TN and TPO₄ removal and 90.2% COD reduction in nejayote, while A. variabilis reached 81.7% COD and 79.3% TPO₄ removal in tequila vinasses. In cheese whey, C. vulgaris removed 55.5% COD, 53.0% TN, and 35.3% TPO₄. These results demonstrate the feasibility of microalgae-based systems for treating complex agro-industrial wastewaters, contributing to sustainable and circular wastewater management.