Algal cells harvesting using cost-effective magnetic nano-particles

• Published in: The Science of the total environment Vol. 720; p. 137621
• Main Author: Almomani, Fares
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10-06-2020
• Subjects: Adsorption; Algae recovery; Biomass concentration; Chlorella vulgaris; Cost-Benefit Analysis; Intact cells; Magnetic Phenomena; Magnetics; Magnetite Nanoparticles; Optimization methodology; Magnetite nanoparticles; Optimization methodology; Intact cells; Algae recovery; Biomass concentration
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.137621

Innovative iron-based nanoparticles were synthesized, characterized and tested for the first time for harvesting single and mixed algal culture from real wastewater. The tailor-made magnetic nanoparticles (MNPs; Fe-MNP-I and Fe-MNP-II) achieved a percentage algae harvesting efficiency (%AHE) higher than 95% using a concentration of MNPs (CMNP) of 25 ± 0.3 (std. dev = 0.08) mg.L−1, mixing speed (Mspeed) of 120 ± 2 (std. dev = 0.10) rpm, short contact time (Ct) of 7 ± 0.1 (std. dev = 0.05) min and separation time (SPt) of 3 ± 0.1 (std. dev = 0.09) min. The optimum operational conditions for harvesting of Chlorella vulgaris (C.v) were determined at (CMNP = 40 ± 0.4 (std. dev = 0.5) gMNPs.L−1, SPt = 2.5 ± 0.4 (std. dev = 0.1) min, Mspeed = 145 ± 3 (std. dev = 1.50) rpm and Ct = 5 ± 0.3 (std. dev = 0.10) min using surface response methodology. Langmuir model describes better the adsorption behavior of algae-Fe-MNP-I system, while both Langmuir and Freundlich fit well the adsorption behavior of algae-Fe-MNP-II. The maximum adsorption capacity of Spirulina platensis (SP.PL) (18.27 ± 0.07 (std. dev = 0.19) mgDWC.mgparticles−1) was higher than that for Chlorella vulgaris (C.v) (11.52 ± 0.01 (std. dev = 0.34) mgDWC.mgparticles−1) and mixed algal culture (M.X) (17.20 ± 0.07 (std. dev = 0.54) mgDWC.mgparticles−1) over Fe-MNP-I. Zeta potential measurements revealed that the adsorption mechanism between MNPs and algal strains is controlled by electrostatic interaction. The synthesized MNPs were recycled 10 times using alkaline-ultrasonic regeneration procedure.
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•Innovative nanoparticles were prepared and use to harvest single and mixed algae cells.•Algae harvesting efficiency of Chlorella vulgaris reached above 95% within 5 min.•Nanoparticles can be reused up to 10 times without significant efficiency loss.•Surface response methodology was used to identified optimum harvesting conditions.•Magnetic separation provides great potential to save time and energy during algal harvesting.