In-situ algal control by two-stage nanobubble technology in Taihu Lake: Efficacy and ecological impact

• Published in: Environmental research 2024-12, Vol.263 (Pt 3), p.120077, Article 120077
• Main Authors: Zhu, Lina, Li, Pan, Wang, Chunrong, Hu, Jun, Zhang, Lijuan, Li, Jixiang
• Format: Article
• Language: English
• Subjects: Algal removal; China; Cyanobacteria; Eutrophication; Hydrodynamic cavitation; Hydrodynamics; Lakes - chemistry; Lakes - microbiology; Microbial diversity; Nitrogen - analysis; Odor compounds; Ozone nanobubbles; Phosphorus - analysis
• ISSN: 0013-9351; 1096-0953; 1096-0953
• DOI: 10.1016/j.envres.2024.120077

Hydrodynamic cavitation and ozone nanobubble-coupled hydrodynamic cavitation have demonstrated effective algae control in laboratories, but their in-situ potential, especially impact on nutrient salt degradation and microbial communities remain unclear. This study applied two-stage nanobubble technology, combining hydrodynamic cavitation and ozone nanobubbles, in a 3300 m2 semi-enclosed area of Taihu Lake to address these gaps. Results show that the technology efficiently controls algae, reduces odors, improves anaerobic conditions, and lowers ammonia nitrogen. Over 20 days, chlorophyll-a concentration reduced by 77.46% and cyanobacterial phycocyanin by 89.47%. Additionally, the concentrations of 2-MIB, GSM, and DMTS fell below threshold values. Notably, the relative abundance of Cyanobacteria in sediment dropped from 8.53% in the control area to only 1.59%–3.65% in the experimental area. The technology also achieved a significant reduction in ammonia nitrogen, with removal efficiencies of 78.53% in the water column and 39.17% in sediments, though the removal of total phosphorus was limited. Furthermore, the two-stage nanobubble system enhanced the abundance of nitrogen-cycling microorganisms and genes in the water, while promoting nitrogen- and phosphorus-related microbial communities in sediments and inhibiting the cyanobacteria-associated genus Cyanobium PCC-6307. Thus, Two-stage nanobubble technology can be employed for in-situ algal control in aquatic ecosystems. [Display omitted] •Two-stage nanobubble technology removes more than 90% of the algae.•2-MIB concentration less than 10 ng/L after two-stage nanobubble treatment.•Decrease in ammonia nitrogen concentration after using two-stage nanobubbles.•Increased abundance of functional nitrogen cycle genes when experiment finished.