title: Alkaline flocculation of Phaeodactylum tricornutum induced by brucite and calcite.
abstract: Alkaline flocculation holds great potential as a low-cost harvesting method for marine microalgae biomass production. Alkaline flocculation is induced by an increase in pH and is related to precipitation of calcium and magnesium salts. In this study, we used the diatom Phaeodactylum tricornutum as model organism to study alkaline flocculation of marine microalgae cultured in seawater medium. Flocculation started when pH was increased to 10 and flocculation efficiency reached 90% when pH was 10.5, which was consistent with precipitation modeling for brucite or Mg(OH)2. Compared to freshwater species, more magnesium is needed to achieve flocculation (>7.5mM). Zeta potential measurements suggest that brucite precipitation caused flocculation by charge neutralization. When calcium concentration was 12.5mM, flocculation was also observed at a pH of 10. Zeta potential remained negative up to pH 11.5, suggesting that precipitated calcite caused flocculation by a sweeping coagulation mechanism.
authors: KU Leuven Kulak, Laboratory Aquatic Biology, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium. Electronic address: dries.vandamme@kuleuven-kulak.be.
authors: Dries
authors: D
authors: Vandamme
authors: Sandia National Laboratories, Albuquerque, NM, USA.
authors: Philip I
authors: PI
authors: Pohl
authors: KU Leuven Kulak, Laboratory Aquatic Biology, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium.
authors: Annelies
authors: A
authors: Beuckels
authors: KU Leuven Kulak, Research Unit Food & Lipids, Department of Molecular and Microbial Systems Kulak, Etienne Sabbelaan 53, B-8500 Kortrijk, Belgium; Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
authors: Imogen
authors: I
authors: Foubert
authors: Sandia National Laboratories, Albuquerque, NM, USA.
authors: Patrick V
authors: PV
authors: Brady
authors: Sandia National Laboratories, Albuquerque, NM, USA.
authors: John C
authors: JC
authors: Hewson
authors: KU Leuven Kulak, Laboratory Aquatic Biology, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium.
authors: Koenraad
authors: K
authors: Muylaert
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry*; D017377:Diatoms / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D005427:Flocculation; D008276:Magnesium Hydroxide / Q000737:chemistry*
chemical_list: D002119:Calcium Carbonate; D008276:Magnesium Hydroxide
keywords: Autoflocculation; Biomass; Coagulation; Enmeshment; Marine algae