Clean Water and Sanitation (SDG 6), Climate Action (SDG 13)
Ozonation as an effective emerging treatment for cyanobacterial blooms in a changing climate Nikoletta Tsiarta, Efthymia Chatziathanasiou, Andreas Hadjicosti, Maria G. Antoniou * Department of Chemical Engineering, Cyprus University of Technology, 3036 Lemesos, Cyprus. E-mail: maria.antoniou@cut.ac.cy Cyanobacterial blooms, intensified by climate change [1] and nutrient enrichment from human activities, pose a growing threat to freshwater ecosystems and clean water access, aligning with the challenges outlined in SDG6 (Clean Water and Sanitation). These blooms produce toxic cyanotoxins, including microcystins and anatoxins, which contaminate drinking water sources [2] and cause significant health risks, including liver damage, gastrointestinal issues, and neurological symptoms. In addition, they disrupt recreational activities, fisheries, and overall aquatic ecosystem health [3] . As part of efforts to mitigate the impacts of climate change on water quality, effective and sustainable treatment strategies are essential. Ozonation has shown promise in addressing these issues by disrupting cyanobacterial cells and degrading toxins [4] simultaneously. This study investigates ozone’s impact on three cyanobacteria species ( Microcystis sp., Aphanizomenon sp., and Cylindrospermopsis sp.) and a green alga ( Scenedesmus obliquus ) across four ozone concentrations (0.5–4 mg/L) at 20°C. Results indicated that cyanobacteria are more sensitive to ozone than green algae, with a 4 mg/L dose effectively disrupting cyanobacterial biomass without recovery. Additionally, cell age influenced response to ozone, with younger cultures exhibiting increased resilience at lower doses. Keywords: freshwater cyanobacteria, cyanotoxins, ozonation, photosynthetic vitality. References 1. Paerl, H. W., & Huisman, J. (2008). Blooms like it hot. Science, 320(5872), 57–58. 2. World Health Organization (WHO). (2018). Cyanobacterial toxins: Microcystin-LR in drinking-water. 3. Hudnell, H. K. (2008). The state of U.S. freshwater harmful algal blooms assessments, policy and legislation. Toxicon, 52(2), 344–352. 4. Zamyadi, A., MacLeod, S. L., Fan, Y., McQuaid, N., Dorner, S., & Sauvé, S. (2017). Impact of ozonation on the removal of microcystin toxins from drinking water sources. Water Research, 124, 477–485.here
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