The Effects of Nanobubble-Assisted Oxygen Supersaturation on the Growth of Chlorella vulgaris

Algal blooms caused by excessive growth of microalgae pose serious environmental threats to aquatic ecosystems and water quality management in rivers and lakes. Oxygen saturation is important to microalgal productivity. However, effective and controllable methods to control algae growth remain a challenge in practice. In this study, we explored the effects of oxygen enrichment mediated by air and oxygen nanobubble systems on the growth of Chlorella vulgaris. The results revealed that oxygen enrichment treatment delayed early-stage algal growth compared to the control. With daily gas infusion, the oxygen nanobubble group with approximate dissolved oxygen concentration ~12 mg/L showed a significant reduction in final cell density (p < 0.01, ANOVA two-factor with replication, n = 3), ~2/3 of the control. Our results suggest that the reduced microalgal growth is associated with dissolved oxygen concentrations. The findings provide preliminary support for the potential applications in aquatic environments.