Comparison and optimization of different methods for Microcystis aeruginosa’s harvesting and the role of zeta potential on its efficiency
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This study has compared the harvesting efficiency of four flocculation methods, namely, induced by pH, FeCl3, AlCl3 and chitosan. No changes were observed on M. aeruginosa cells. Flocculation assays performed at pH 3 and 4 have shown the best harvesting efficiency among the pH-induced tests, reaching values above 90% after 8 h. The adjustment of zeta potential (ZP) to values comprised between − 6.7 and − 20.7 mV enhanced significantly the settling rates using flocculant agents, being FeCl3 the best example where increments up to 88% of harvesting efficiency were obtained. Although all the four methods tested have presented harvesting efficiencies above 91% within the first 8 h after the optimization process, the highest performance was obtained using 3.75 mg L−1 of FeCl3, which allowed reaching 92% in 4 h.
KeywordsInduced flocculation Zeta potential Harvesting efficiency Microcystis aeruginosa
This research work was supported by the grants SFRH/BPD/98694/2013 (Bruno Fernandes) and SFRH/BD/52335/2013 (Pedro Geada) from Fundação para a Ciência e a Tecnologia (Portugal). Luís Loureiro is recipient of a fellowship supported by a doctoral advanced training (call NORTE-69-2015-15) funded by the European Social Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the FCT Strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. This study was also supported by the Project UID/Multi/04423/2013, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462), and the project NOVELMAR (reference NORTE-01-0145-FEDER-000035) co-financed by the North Portugal Regional Operational Programme (Norte 2020) under the National Strategic Reference Framework (NSRF) through the ERDF.
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