DOI: https://doi.org/10.15368/theses.2020.71
Available at: https://digitalcommons.calpoly.edu/theses/2207
Date of Award
6-2020
Degree Name
MS in Civil and Environmental Engineering
College
College of Engineering
Advisor
Rebekah Oulton
Advisor Department
Civil and Environmental Engineering
Advisor College
College of Engineering
Abstract
This study reviews catalytic ozonation AOPs and traditional ozone-based AOPs to compare their efficiency for degradation of ozone-recalcitrant compounds. With the world’s population increasing and water becoming a scarce resource, it is important to improve current water recycling methods. Recycling water will play a large role in accommodating the increasing demand, but it will also be necessary to be improve the level of treatment in order to account for emerging contaminants (ECs) such as pharmaceuticals and personal care products. Advanced oxidation processes (AOPs) have been developed to degrade ECs that are not effectively removed by conventional wastewater treatment. The goal of implementing AOPs is to promote the formation of hydroxyl radicals (•OH), which are stronger oxidants than ozone, to degrade recalcitrant compounds. Current AOPs under investigation include ozonation of metal and carbon-based catalysts, known as catalytic ozonation. Traditional ozone-based AOPs currently in use include UV combined with ozone (UV/O3) and hydrogen peroxide combined with ozone (H2O2/O3).
Seventeen studies were reviewed to analyze the effectiveness of multiple carbon- and metal oxide-catalytic ozonation AOPs, compared to traditional AOPs. These studies varied in reactor type, water source, pH, catalyst pretreatment, inclusion of competitor species, and flow regime. The variety of testing conditions made comparison difficult, so all studies were compared based on contaminant removal efficiency and degradation rate, as well as general EC degradation and removal of TOC. The addition of metal oxides during ozonation consistently increased rate of removal and in some cases, even doubled the reaction rate. Catalytic ozonation consistently decreased total organic carbon (TOC) levels amongst multiple studies, even in the presence of competitor species. Future work should study the formation and subsequent breakdown of reaction intermediates, role of competitor species, and impact of sorption to the ozonation catalyst.