Toxic cyanobacteria in water intended for drinking purpose: improvement of cells and toxins’ analyses and of treatments for their removal

Simonazzi, Mara (2023) Toxic cyanobacteria in water intended for drinking purpose: improvement of cells and toxins’ analyses and of treatments for their removal, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Scienze della terra, della vita e dell'ambiente, 35 Ciclo.
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Massive proliferations of cyanobacteria in freshwaters have recently increased, causing ecological and economic losses. Their ever-increasing presence in water sources destined to potabilization has become a major threat for public health, since several species can produce harmful toxins (cyanotoxin). Therefore, additional specific measures to improve management and treatment of drinking water(s) are required. The PhD thesis investigates toxic cyanobacteria in drinking waters with a special focus on Emilia-Romagna (Italy), throughout three separated chapters, each with different specific objectives. The first chapter aims at improving the fast monitoring of cyanobacteria in drinking water, which was investigated by testing different models of multi-wavelength spectrofluorometers. Inter-laboratories calibrations were conducted using mono-specific cultures and field samples, and both the feasibility and the technical limitations of such tools were illustrated. The second chapter evaluates the effectiveness of drinking water treatments in removing cyanobacterial cells and toxins. Two chlorinated oxidants (sodium hypochlorite and chlorine dioxide) already in use for pre-oxidation during water potabilization, were tested on cultures of the toxic cyanobacterium Microcystis aeruginosa posing a specific focus on toxin removal and revealing that pre-oxidation can cause the release of toxins and unknown metabolites. Innovative treatments based on non-thermal plasma were also tested, observing an effective and rapid inactivation of cyanobacterial cells. The third chapter presents a study on a cyanobacterium isolated from a drinking water reservoir of Emilia-Romagna and investigated by combining biological, chemical, and genomic methods. Although the strain did not produce any known cyanotoxin, high toxicity of water-extract was observed in bioassays and potential implications for drinking water were discussed. Overall, the PhD thesis offers new insights into toxic cyanobacteria management in drinking water, highlighting best practices for drinking water managers regarding their detection and removal. Additionally, the thesis provides new contributions to the understanding of the freshwater cyanobacteria community in the Emilia-Romagna region.

Tipologia del documento
Tesi di dottorato
Simonazzi, Mara
Dottorato di ricerca
Settore disciplinare
Settore concorsuale
Parole chiave
cyanobacteria; cyanotoxin; drinking water; water management; in vivo fluorescence; chlorophyll extraction; intercalibration studies; drinking water treatment; chlorinated oxidants; untargeted LC-HRMS analysis; non-thermal plasma; algal culturing; whole genome sequencing;
Data di discussione
15 Giugno 2023

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