Circular biovalorization of tofu whey wastewater using cocultured microalgae for producing high value feed and nutrition fortified laying hen products.

This study developed a fed-batch coculture of Schizochytrium sp. and Chlorella vulgaris in tofu whey wastewater (SC-CC-TW) to simultaneously bioremediate wastewater, co-produce lipid- and protein-rich biomass, and generate a functional feed additive for producing nutrient-fortified eggs. SC-CC-TW system achieved the high co-production yields of lipid (20.09 g/L) and protein (8.39 g/L). Concurrently, this system exhibited efficient wastewater bioremediation, achieving removal efficiencies of 97.60% for chemical oxygen demand, 97% for total nitrogen, and 93.55% for total phosphorus, thereby qualifying for discharge. The resulting SC-CC-TW biomass qualified as a premium feed additive characterized by more comprehensive fatty acid and amino acid profiles, whilst strictly complying with safety regulations for pathogens and heavy metals. Furthermore, dietary inclusion of SC-CC-TW in laying hens significantly elevated whole egg docosahexaenoic acid deposition by 184.36 mg/whole egg and optimized the n-6/n-3 fatty acid ratio to 4.01. Moreover, the whole egg exhibited the elevated contents of essential (EAA, 1561.61 m g/whole egg) and total (TAA, 3472.55 mg/whole egg) amino acids, alongside favorable EAA/TAA (0.45) and EAA/NEAA (0.82) ratios. These findings underscored the feasibility of valorizing waste food processing wastewater into nutrient-enriched poultry feed and products using a synergistic microalgal coculture system.