Assessment of Ozone Nanobubble Technology to Reduce Freshwater Algae

Algal blooms can lead to low dissolved oxygen and fluctuating pH, and the toxins produced by some species can be toxic to aquatic animals. In this study, we assessed the potential of ozone nanobubble technology for reducing a diatom species, Nitzschia sp., commonly found in freshwater ponds in Hong Kong. This study suggests that ozone at a low dose of 0.025 ± 0.003 ppm was sufficient to reduce algae by 66.4% within 5 minutes of treatment. An even higher killing effect (68.2%) was observed when ozone was delivered using nanobubbles for 9 minutes. A 24-hour delayed effect was also detected, with a further reduction of approximately 10% of the algae for both ozone treatments (macro and nanobubble delivery methods). In addition to controlling algae, applying ozone at a level that is not detrimental to fish may also benefit the dissolved oxygen levels in pond systems. © 2023 Pok Him Ng et al.