Title:Combined Filtration and Flocculation for Chlorella vulgaris Harvesting
Volume: 15
Issue: 1
Author(s): Lisendra Marbelia*, Muhammad R. Bilad, Pieter Rens and Ivo Vankelecom
Affiliation:
- Chemical Engineering Department, Faculty of Engineering, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia
- Membrane Technology Group, Division cMACS, Faculty of Bioscience Engineering, KU Leuven, Leuven 3001,
Belgium
Keywords:
Microalgae, membrane, filtration, flocculation, harvesting, efficiency.
Abstract:
Background: The present study aims to explore the feasibility of using flocculation combined
with filtration for microalgae harvesting, i.e., Chlorella vulgaris. This is important because microalgae
have small sizes and its broth is stable, which makes it difficult to be harvested. The aforementioned
facts cause the harvesting cost to be relatively high and become the bottleneck of microalgae
processes.
Objective: The objective of this research is to find the relation between microalgae concentration, chitosan
dosing as a flocculant, and its filterability on membranes.
Methods: Research was performed by first cultivating the microalgae in a lab-scale photobioreactor,
followed by jar test, flocculation, and filtration experiment. Jar test flocculation was performed using
chitosan and microalgae with different concentrations, by simply mixing it in a 100 mL bottle and analyzing
the results with UV Vis Spectroscopy. Filtration experiments were performed using lab-made
polyvinylidene fluoride membrane, in a 100 mL dead-end filtration cell and in a 5 L tank for submerged
filtration. During both filtration tests, filtration flux and fouling were monitored and compared.
Results: Results showed that the chitosan concentration needed as a flocculant depends on the microalgae
biomass concentration. For the filterability tests, the results proved that flocculation with chitosan
enhanced the filterability of the microalgae broth both in dead-end and submerged filtration
mode. For the used biomass concentration of around 400 mg/L, the filterability test showed an optimum
concentration of chitosan at 7.5 to 10 mg/L, which resulted in a higher filtration flux and lower
irreversible fouling in the dead-end filtration and a higher critical flux in the submerged filtration setup.
Conclusion: This increased filterability allowed higher fluxes to be operated, thus resulting in a more
efficient harvesting process.
