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Title: Alkaline flocculation of Phaeodactylum tricornutum induced by brucite and calcite

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 (>7.5 mM). Zeta potential measurements suggest that brucite precipitation caused flocculation by charge neutralization. When calcium concentration was 12.5 mM, flocculation was also observed at a pH of 10. Furthermore, zeta potential remained negative up to pH 11.5, suggesting that precipitated calcite caused flocculation by a sweeping coagulation mechanism.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [2] ;  [1] ;  [2]
  1. KU Leuven Kulak, Kortrijk (Belgium)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. KU Leuven, Leuven (Belgium)
Publication Date:
OSTI Identifier:
1236222
Report Number(s):
SAND--2015-6106J
Journal ID: ISSN 0960-8524; 615250
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Bioresource Technology
Additional Journal Information:
Journal Volume: 196; Journal Issue: C; Journal ID: ISSN 0960-8524
Publisher:
Elsevier
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Biomass Program (EE-2E)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES coagulation; marine algae; enmeshment; biomass; autoflocculation