Algal cells harvesting using cost-effective magnetic nano-particles

Area of Science:

• Environmental Science
• Materials Science
• Biotechnology

Background:

• Algal harvesting from wastewater is crucial for resource recovery and water purification.
• Developing efficient and cost-effective methods for algal biomass separation remains a challenge.
• Iron-based magnetic nanoparticles (MNPs) present a potential solution due to their magnetic properties and tunable surface chemistry.

Purpose of the Study:

• To synthesize and characterize novel iron-based MNPs for efficient harvesting of single and mixed algal cultures from real wastewater.
• To investigate the optimal operational conditions for algal harvesting using MNPs.
• To evaluate the adsorption behavior and capacity of MNPs for different algal species.

Main Methods:

• Synthesis and characterization of two types of iron-based MNPs (Fe-MNP-I and Fe-MNP-II).
• Algal harvesting experiments using varying concentrations of MNPs, mixing speeds, contact times, and separation times.
• Application of surface response methodology to determine optimal harvesting conditions.
• Adsorption isotherm studies (Langmuir and Freundlich models) to describe algal-MNP interactions.
• Zeta potential measurements to elucidate the adsorption mechanism.
• Recyclability tests of MNPs using an alkaline-ultrasonic regeneration procedure.

Main Results:

• Both Fe-MNP-I and Fe-MNP-II achieved over 95% algae harvesting efficiency (%AHE) under optimized conditions.
• Optimal harvesting conditions were determined for Chlorella vulgaris (C.v) using surface response methodology.
• The Langmuir model best described the adsorption of algae onto Fe-MNP-I, while both Langmuir and Freundlich models fit the adsorption onto Fe-MNP-II.
• Spirulina platensis (SP.PL) exhibited the highest adsorption capacity (18.27 mg DWC/mg particles) on Fe-MNP-I.
• Electrostatic interactions were identified as the primary mechanism for algal-MNP adsorption.
• The synthesized MNPs demonstrated excellent recyclability, with over 10 cycles of regeneration.

Conclusions:

• The developed iron-based MNPs are highly effective for harvesting algal biomass from real wastewater.
• The study provides optimized parameters for efficient algal harvesting, applicable to various algal species.
• The findings highlight the potential of MNPs as a sustainable and reusable solution for wastewater treatment and resource recovery.