title: Controlling cyanobacterial blooms through effective flocculation and sedimentation with combined use of flocculants and phosphorus adsorbing natural soil and modified clay.
abstract: Eutrophication often results in blooms of toxic cyanobacteria that hamper the use of lakes and reservoirs. In this paper, we experimentally evaluated the efficacy of a metal salt (poly-aluminium chloride, PAC) and chitosan, alone and combined with different doses of the lanthanum modified bentonite Phoslock(®) (LMB) or local red soil (LRS) to sediment positively buoyant cyanobacteria from Funil Reservoir, Brazil, (22°30'S, 44°45'W). We also tested the effect of calcium peroxide (CaO2) on suspended and settled cyanobacterial photosystem efficiency, and evaluated the soluble reactive P (SRP) adsorbing capacity of both LMB and LRS under oxic and anoxic conditions. Our data showed that buoyant cyanobacteria could be flocked and effectively precipitated using a combination of PAC or chitosan with LMB or LRS. The SRP sorption capacity of LMB was higher than that of LRS. The maximum P adsorption was lowered under anoxic conditions especially for LRS ballast. CaO2 addition impaired photosystem efficiency at 1 mg L(-1) or higher and killed precipitated cyanobacteria at 4 mg L(-1) or higher. A drawback was that oxygen production from the peroxide gave positive buoyancy again to the settled flocs. Therefore, further experimentations with slow release pellets are recommended.
authors.affiliation: Laboratory of Ecology and Physiology of Phytoplankton, Department of Plant Biology, University of Rio de Janeiro State, Rua São Francisco Xavier 524-PHLC Sala 511a, 20550-900, Rio de Janeiro, Brazil. Electronic address: np.noyma@gmail.com.
authors.forename: Natalia Pessoa
authors.initials: NP
authors.lastname: Noyma
authors.affiliation: Laboratory of Ecology and Physiology of Phytoplankton, Department of Plant Biology, University of Rio de Janeiro State, Rua São Francisco Xavier 524-PHLC Sala 511a, 20550-900, Rio de Janeiro, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: de Magalhães
authors.affiliation: Laboratory of Ecology and Physiology of Phytoplankton, Department of Plant Biology, University of Rio de Janeiro State, Rua São Francisco Xavier 524-PHLC Sala 511a, 20550-900, Rio de Janeiro, Brazil.
authors.forename: Luciana Lima
authors.initials: LL
authors.lastname: Furtado
authors.affiliation: Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands.
authors.forename: Maíra
authors.initials: M
authors.lastname: Mucci
authors.affiliation: Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: van Oosterhout
authors.affiliation: Museu Nacional, Federal University of Rio de Janeiro, 20940-040, Rio de Janeiro, Brazil.
authors.forename: Vera L M
authors.initials: VL
authors.lastname: Huszar
authors.affiliation: Laboratory of Ecology and Physiology of Phytoplankton, Department of Plant Biology, University of Rio de Janeiro State, Rua São Francisco Xavier 524-PHLC Sala 511a, 20550-900, Rio de Janeiro, Brazil.
authors.forename: Marcelo Manzi
authors.initials: MM
authors.lastname: Marinho
authors.affiliation: Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands; Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB, Wageningen, The Netherlands.
authors.forename: Miquel
authors.initials: M
authors.lastname: Lürling
mesh_terms: D000458:Cyanobacteria / Q000187:drug effects; D005068:Eutrophication; D005427:Flocculation; D060106:Lakes; D010758:Phosphorus / Q000494:pharmacology*; D012987:Soil
chemical_list: D012987:Soil; D010758:Phosphorus
keywords: Cyanobacteria bloom; Eutrophication control; Geo-engineering in lakes; Lake restoration; Local red soil; Phosphorus mitigation