An assessment of the autotrophic/heterotrophic synergism in microalgae under mixotrophic mode and its contribution in high-rate phosphate recovery from wastewater

Abstract

Dual carbon metabolisms and the synergism contribute to improving nutrient recovery under mixotrophy. However, how synergism influences nutrient recovery has yet to be understood, which is revealed in the current study. Due to dual carbon metabolisms and synergism,the PO4−-P recovery rate under mixotrophy reached 0.34 mg L−1 h−1. Due to the internal cycling of respiratory CO2, the mutualistic index (MI) in terms of synergism helped Scenedesmus accumulate 27.49 % more biomass under mixotrophy than sum of the two controls. In contrast, MI contributed 0.26 g L−1 d−1 to the total modeled mixotrophic productivity of 1.15 g L−1 d−1. To total modeled PO4−-P recovery, mixotrophic-auto, and mixotrophic-hetero shares were 42 % and 58 %. The synergism under mixotrophy contributed 20 % in total PO4−-P recovery. The PO4−-P recovery rate under mixotrophywas comparable to other biological P removal methods. These findings emphasize the potential of synergism in improving productivityand promoting resource recovery for sustainable wastewater treatment.