Interference of extracellular soluble algal organic matter on flocculation-sedimentation harvesting of Chlorella sp

Sanjaya Lama; Michaela Pappa; Nathalia Brandão Watanabe; Cécile Formosa-Dague; Wouter Marchal; Peter Adriaensens; Dries Vandamme

doi:10.1016/j.biortech.2024.131290

Interference of extracellular soluble algal organic matter on flocculation-sedimentation harvesting of Chlorella sp

Bioresour Technol. 2024 Nov:411:131290. doi: 10.1016/j.biortech.2024.131290. Epub 2024 Aug 15.

Authors

Sanjaya Lama¹, Michaela Pappa², Nathalia Brandão Watanabe³, Cécile Formosa-Dague⁴, Wouter Marchal⁵, Peter Adriaensens⁶, Dries Vandamme⁷

Affiliations

¹ Analytical and Circular Chemistry, Institute for Materials Research (imo-imomec), Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: [email protected].
² Analytical and Circular Chemistry, Institute for Materials Research (imo-imomec), Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: [email protected].
³ Analytical and Circular Chemistry, Institute for Materials Research (imo-imomec), Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium; Chemical Engineering Department, Escola Politécnica of the University of São Paulo, São Paulo, Brazil. Electronic address: [email protected].
⁴ Toulouse Biotechnology Institute, Université de Toulouse, INSA, INRAE, CNRS, Toulouse, France. Electronic address: [email protected].
⁵ Analytical and Circular Chemistry, Institute for Materials Research (imo-imomec), Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: [email protected].
⁶ Analytical and Circular Chemistry, Institute for Materials Research (imo-imomec), Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: [email protected].
⁷ Analytical and Circular Chemistry, Institute for Materials Research (imo-imomec), Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: [email protected].

PMID: 39153690
DOI: 10.1016/j.biortech.2024.131290

Abstract

Extracellular soluble algal organic matter (AOM) significantly interferes with microalgae flocculation. This study investigated the effects of various AOM fractions on Chlorella sp. flocculation using ferric chloride (FeCl₃), sodium hydroxide (NaOH), and chitosan. All flocculants achieved high separation efficiency (87-99 %), but higher dosages were required in the presence of AOM. High molecular weight (>50 kDa) AOM fraction was identified as the primary inhibitor of flocculation across different pH levels, whereas low/medium molecular weight (<3 and <50 kDa) AOM had minimal impact. Compositional analysis revealed that the inhibitory AOM fraction is a glycoprotein rich in carbohydrates, including neutral, amino, and acidic sugars. The significance of this study is in identifying carboxyl groups (-COOH) from acidic monomers in >50 kDa AOM that inhibit flocculation. Understanding AOM composition and the interaction dynamics between AOM, cells, and flocculants is crucial for enhancing the techno-economics and sustainability of flocculation-based microalgae harvesting.

Keywords: Biomass; Dewatering; Heteropolysaccharides; Microalgae; Ultrafiltration.

MeSH terms

Chitosan / chemistry
Chitosan / pharmacology
Chlorella* / metabolism
Extracellular Space / chemistry
Flocculation* / drug effects
Hydrogen-Ion Concentration
Microalgae / metabolism
Molecular Weight
Organic Chemicals / pharmacology
Solubility*

Substances

Organic Chemicals
Chitosan