Performance of different microalgae-based technologies in nutrient removal and biogas upgrading in response to various GR24 concentrations

Abstract

Microalgae-based technology is an emerging strategy for the simultaneous purification of nutrients in biogas slurry and CO2 in biogas. To evaluate effects of synthetic analogue of strigolactone (GR24) concentration on removal efficiency, mono-cultivation of microalgae and co-cultivation of algae with fungus or activated sludge were performed in a photobioreactor. The GR24 concentration of 10−9 M was contributed to the optimum growth characteristics, photosynthetic performance and purification effects in the co-cultivation system of Chlorella vulgaris with activated sludge. The optimal growth rate and mean daily productivity for Chlorella vulgaris were 0.419 ± 0.04 d−1 and 0.342 ± 0.029 g L−1 d−1, respectively. The photosynthetic performance parameters Fv/Fm, PIABS, ΨO, and ΦEO were 0.89 ± 0.08, 6.89 ± 0.62, 0.97 ± 0.09, and 0.69 ± 0.06, respectively, indicating that GR24 with a concentration of 10−9 M was more helpful for photosynthesis of microalgae. Moreover, the maximum removal rate of chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and CO2 were obtained by the induction of 10−9 M of GR24, which were 77.33 ± 7.25%, 78.86 ± 7.51%, 78.12 ± 7.57% and 69.33 ± 6.86%, respectively. This research therefore provides an effective strategy for wastewater bioremediation and high-quality biogas energy acquisition.