Carbon-dioxide biofixation and phycoremediation of municipal wastewater using Chlorella vulgaris and Scenedesmus obliquus

The pure cultures of microalgae Chlorella vulgaris ATCC 13482 and Scenedesmus obliquus FACHB 417 were grown in municipal wastewater in 7-L airlift bubble column photobioreactor supplied with 5% CO2/air (v/v). Batch experiments were conducted at 25 °C with 14-h light/10-h dark cycle for a period of 10 days. The CO2 capture efficiencies for both the microalgae were monitored in terms of their respective biomass productivities, carbon contents, and CO2 consumption rates. In the present study, the initial concentration of ammonia (43.7 mg L−1) was decreased to 2.9 and 3.7 mg L−1 by C. vulgaris and S. obliquus, respectively. And, the initial concentration of phosphate (18.5 mg L−1) was decreased to 1.1 and 1.6 mg L−1 by C. vulgaris and S. obliquus, respectively. CO2 biofixation rates by C. vulgaris and S. obliquus, cultivated in municipal wastewater, were calculated to be 140.91 and 129.82 mg L−1 day−1, respectively. The findings from the present study highlight the use of microalgae for wastewater treatment along with CO2 uptake and biomass utilization for pilot scale production of biodiesel, biogas, feed supplements for animals, etc., thus minimizing the production costs.