Date of Award
Spring 2026
Document Type
Open Access Dissertation
Department
Environmental Health Sciences
First Advisor
Jamie R. Lead
Abstract
Harmful algal blooms (HABs) result from the rapid proliferation of cyanobacteria and microalgae, a phenomenon that has surged globally in recent decades due to nutrient pollution and climate-driven temperature changes. These events pose severe risks to human health, create significant ecological disruptions, and cause extensive economic damage. This dissertation investigates a dual-stage approach to HAB mitigation, specifically the species Cryptomonas ozolini, beginning with the evaluation of nanoparticle-cell interactions in batch settings and culminating in the engineering optimization of a High- Gradient Magnetic Separation (HGMS) flow-through system. The study highlights the transition from laboratory-scale biological removal to the operational constraints of continuous remediation hardware. The first stage of research focused on batch separation to evaluate the efficacy of various nanoparticle coatings. PVP-coated nanoparticles demonstrated the highest versatility, achieving >96% removal in both freshwater and seawater environments. In contrast, chitosan-coated nanoparticles were identified as a sustainable, green alternative due to their biodegradability; however, their performance was highly salinity-dependent, achieving >99% removal in seawater, whereas their performance was lower in freshwater. Kinetic analysis revealed that a 15-minute contact time is the minimum threshold required to allow nanoparticles to successfully associate with algal surfaces for near-total cell depletion. The second stage applied these findings to the engineering of a flow-through HGMS system to define the operational limits of the hardware. Systematic testing identified a slow-flow rate (10 mL/min) as essential for providing the residence time necessary for magnetic forces to overcome hydrodynamic drag. Increasing the flow rate to 20 mL/min resulted in stagnant removal rates, regardless of matrix volume. The density of the steel wool matrix exhibited a non-linear relationship with capture efficiency, with a critical performance threshold identified between 2 g and 4 g and a functional plateau reached at 8 g. This established the definitive mass-to-flow ratio required to optimize magnetic gradient zones within a continuous treatment system. Long- term monitoring over two months confirmed that this magnetic separation approach successfully suppresses the reproductive potential of the bloom. Treated media-maintained cell densities much lower than untreated controls, preventing the rebounding effect common in chemical applications. Collectively, this research provides a scalable framework for HAB remediation, offering a choice between the high-performance universality of PVP and the eco-friendly potential of chitosan for targeted marine applications.
Rights
© 2026, Hamid Reza Esmaili Zand
Recommended Citation
Esmaili Zand, H. R.(2026). Employing Functionalized Magnetic Nanoparticles for the Removal Of Harmful Algal Cells From Freshwater and Seawater Blooms. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/8834