Maximizing resource efficiency with dairy and municipal wastewater as nutrient media for Chlorella vulgaris with simultaneous CO2 sequestration

Abstract Addressing critical environmental challenges such as greenhouse gas emissions, global warming, and eutrophication demands urgent and innovative solutions. In recent years, microalgae have emerged as a promising avenue for addressing these pressing issues. In this study, the combination of dairy and municipal wastewater is proposed as a culture medium for cultivating microalgae strains capable of sequestering atmospheric CO 2 . Specifically, the growth of Chlorella vulgaris was investigated using Bold's basal medium, along with varying concentrations of municipal and dairy wastewater, both with and without CO 2 supplementation, to assess their CO 2 capture potential. Concurrently, the efficiency of chemical oxygen demand (COD), total nitrogen, potassium, and phosphate removal from the wastewater was evaluated. Additionally, the combination of wastewater media with CO 2 supplementation yielded the highest CO 2 uptake rates, indicating the feasibility of simultaneous CO 2 capture during microalgae cultivation. Media composition with 25% municipal wastewater: 75% dairy wastewater supplemented with CO 2 demonstrated superior COD elimination with a higher percentage of nutrient removal from wastewater compared to other wastewater proportions. The nutrient removal capacity of aforementioned media also comes in line with high CO 2 sequestration rate (13.57 mg L −1 h −1 ). These findings underscore the potential of utilizing wastewater from diverse sources as a viable culture medium for microalgae cultivation, facilitating concurrent CO 2 capture and wastewater treatment.