title: Enhanced oxidation processes by persulfate activation and microfluidics for removal of persistent and emerging contaminants
Creators: name: Dong, Guihua
Publisher: name: Memorial University of Newfoundland
publisherIdentifier: https://ror.org/04haebc03
publisherIdentifierScheme: ROR
Year: 2024

description: The existence of persistent and emerging contaminants (e.g., polycyclic aromatic hydrocarbons, bisphenols) in the aquatic environment is a global issue. These contaminants received growing attention from environmental researchers, practitioners, and policy makers worldwide mainly because of our limited knowledge about their behaviors and adverse impacts on human beings and the environment as well as the lack of efficient treatment methods. Advanced oxidation processes (AOPs) have been regarded as one of the powerful technologies for the removal of recalcitrant organics due to their ability to generate reactive species and indiscriminately convert organics into non/less-toxic small molecules, and eventually into CO₂ and water, if ultimately mineralization can be achieved. There are some commonly used AOPs and enhancement methods, such as photocatalysis, UV/O₃, and persulfate (PS) activation. Although these methods are approved and capable of reducing many organic pollutants to acceptable levels, some challenges have been widely recognized and limited their applications in treating persistent and emerging contaminants, such as relatively low efficiency, high energy consumption, and/or toxic intermediates or residues from incomplete mineralization, as well as the insufficient understanding of reaction mechanisms and transformation pathways. To address the challenges and gaps, the main goal of this dissertation research is, therefore, to develop novel, enhanced AOPs methods for removal of persistent and emerging contaminants and advance knowledge about the associated degradation mechanisms and pathways. The major research achievements are from the following aspects: 1) A comprehensive review on AOP technologies and enhancement methods with – particular focus on PS activation and the rapidly emerging area of environmental microfluidics for the first time – This review offers a valuable insight for the recent advances of AOP enhancement methods and the future trend of AOPs development in environmental field. 2) Development of an enhanced technique of UV/O₃/PS for marine oily wastewater treatment, exploration of its treatment mechanism, and assessment of the associated toxicity. The addition of PS could significantly shorten the treatment time which consequently reduces the energy consumption in the O₃-based AOP. The research provided the scientific evidence and optimal treatment conditions for future scale-up demonstrations and applications. 3) Exploration of the enhanced degradation mechanisms of bisphenol A (BPA) in wastewater by UV/metal oxide activated PS process – The proposed synergetic PS activation process was proved to be a promising method for removal of BPA, a representative emerging contaminant, from wastewater. 4) Development of a new AOP-microreactor system integrated with UV LED-based PS activation by TiO₂/g-C₃N₄ nanosheet for removal of bisphenol S or BPS (a main substitute for BPA) and performance evaluation by comparing the developed microreactor with a conventional batch reactor – The AOP-microreactor system performed in higher efficiency with lower energy consumption than those of batch reactor. The approved AOP-microreactor method as a promising solution for removing emerging contaminants. This dissertation not only helped build a scientific basis for the enhanced AOP methodologies, but also provided powerful techniques for advancement and potential applications in water and wastewater industry.