Stimulating effects of glycerol on the growth, phycoremediation and biofuel potential of Chlorella pyrenoidosa cultivated in wastewater

Chlorella pyrenoidosa is one of the potential microalgae to build sustainable processes for biofuel production alongside the phycoremediation of wastewater. However, low lipid content and impaired lipid quality are major reasons that make the produced microalgal-biofuel uneconomic. Here, we show supplementation of glycerol, a byproduct of biodiesel industry, at a concentration of 3 gL(-1) in synthetic wastewater (SWW) can enhance up to 133.74% lipid accumulation (30.76 +/- 0.93% dry wt. basis) in C. pyrenoidosa, as compared to control, without glycerol (13.16 +/- 0.25% dry wt. basis). Further, the glycerol supplementation improved the biodiesel quality, as evident from the fatty acid profiling. The glycerol supplementation stimulated the microalgal growth also, both under shake flasks and reactor scale studies. Besides, the glycerol supplementation improved the phycoremediation potential with up to 96.35, 47.22 and 79.88% removal in phosphate, nitrate and chemical oxygen demand (COD) within 15 days of microalgal growth period. Synergistically, up to 457.80 +/- 1.11 mgL(-1) exopolysaccharides production was attained in the microalgal culture. Such an attempt forwards a stepping-stone for developing sustainable future energy and wastewater treatment infrastructure. (C) 2021 The Authors. Published by Elsevier B.V.

Automated summary

The addition of glycerol in synthetic wastewater can significantly enhance lipid accumulation and biodiesel quality of Chlorella pyrenoidosa, while also promoting microalgal growth and wastewater purification.