Date of Award

2026

Keywords

fouling, microplastics, nanoplastics, surface modification, ultrafiltration membranes

Document Type

Thesis

Publisher

Edith Cowan University

Degree Name

Doctor of Philosophy

School

School of Engineering

First Supervisor

Masoumeh Zargar

Second Supervisor

Michael Johns

Third Supervisor

Mehdi Khiadani

Fourth Supervisor

Amir Razmjou

Abstract

Occurrence of microplastics (MPs) and nanoplastics (NPs) in aquatic environments has become a major environmental concern due to their persistence, widespread distribution, and growing detection in water and wastewater systems. While membrane-based processes are among the most effective technologies for removing these small plastic particles from water streams, MPs/NPs pose significant challenges to membrane operation. These challenges arise from the dual role of MPs/NPs in membrane processes, where they must be removed from water streams while also acting as foulants that reduce permeability, accelerate performance decline, increase cleaning requirements, and shorten membrane lifespan. Although membrane systems are increasingly applied to control these emerging particulate pollutants, most commercial systems were originally developed for conventional foulants rather than emerging pollutants such as MPs/NPs that not only have highly variable sizes but also diverse surface functionalities and aggregation behaviour. This challenge highlights the need to re-evaluate and optimise membrane surfaces for MP/NP fouling control, targeting improved fouling reversibility and enhanced long-term operational stability.

In response to this need, this thesis investigated how tuning membrane surface properties, particularly hydrophilicity, surface charge, and interfacial structure, can be used to control MP/NP fouling and fouling reversibility. This was achieved through a series of studies conducted across both ultrafiltration (UF) and forward osmosis (FO) membrane platforms. In the UF studies, commercial poly(ethersulfone) membranes were modified through plasma induced grafting using monomers with distinct surface chemistries, including carboxyl-and amine-functional groups, as well as zwitterionic and mixed-charge chemistries. To extend the work beyond pressure-driven systems, a thin-film nanocomposite FO membrane was also developed by incorporating engineering metal-organic frameworks to examine the contribution of interfacial nanocomposite design to MP antifouling behaviour.

Overall, this thesis shows that effective control of MP/NP fouling depends not only on retaining plastic particles but on engineering membrane surfaces that regulate adhesion, deposition, and cleaning efficiency. By linking surface chemistry with fouling behaviour across different membrane platforms, this work provides a clearer framework for designing more resilient membranes for emerging particulate contaminants in water treatment systems.

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Access to this thesis is embargoed until 12th August 2027 

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Link to publisher version (DOI)

10.25958/r5d2-xr02