Reformation of dairy effluent-a phycoremediation approach

Microalgae are a unique renewable resource utilized since ages, serving as a reservoir for the production of various metabolites. In this study, dairy waste water (DWW) is used as the nutrient media for the cultivation of microalgae. This study focuses on the phycoremediation process of converting rich nutrients in the effluent into biomass and removing contaminants using microalgae. The specific growth rate reached the maximum of 0.55 day^-1 in Desmococcus olivaceous, followed by 0.39 day^-1 for Scenedesmus dimorphus, 0.23 day^-1 in DCS (consortia composing all three strains in equal ratio), and lastly 0.22 day^-1 in Chlorella vulgaris. The biomass productivity was 1.44 g L^-1 day^-1, 1.06 g L^-1 day^-1, 0.88 g L^-1 day^-1, and 0.65 g L^-1 day^-1 in D. olivaceous, S. dimorphus, C. vulgaris, and DCS, respectively. The COD and BOD removal percentage was 82.85% and 45.40% in D. olivaceous, 81.98% and 44.25% in C. vulgaris, 80.73% and 53.45% in S. dimorphus, and 80.10% and 43.10% in DCS, respectively. These results emphasize the promising role of algae in dairy effluent treatment, highlighting the effluent as a suitable medium for microalgae cultivation. It verifies the circular bio-economy concept where the treated wastewater is converted into value-added products.