Process Optimization of UV-Based Advanced Oxidation Processes in VOC Removal Applications

Air pollution is a major concern in developed countries due to its hazardous health effects. Recent studies by the WHO (World Health Organization) estimate that urban air pollution causes a number of diseases of the respiratory tract and is associated with 150,000 deaths each year. Volatile organic compounds (VOCs) are among the major pollutants affecting the outdoor air quality. Given that industrial processes are the main source of atmospheric VOC emissions, national and international authorities have issued regulations to limit such emissions. However, traditional removal technologies such as incineration, have low energy efficiency and high investment costs. AOPs (advanced oxidation processes) offer a promising alternative in which very reactive conditions can be achieved at room temperature, thus greatly increasing energy efficiency. However, this is still not a mature technology due to challenges that limit the range of applications. This thesis focuses on two types of UV-based AOP: photocatalysis and UV-ozone. The goal is to improve VOC conversion and achieve a process that is competitive with traditional technologies. The research on photocatalysis presents an innovative UV reactor design that is closer to industrial conditions and has the ability to effectively screen different samples. Effort was put into finding a metallic support for the photocatalyst without using additional adhesives. Several electrochemical treatments were performed on metals to restructure the surface. One treatment proved to be superior when it came to stabilizing the TiO2 coating, especially when compared with the traditional ceramic support. Research on UV-ozone AOPs focused on reactor modelling, developing a numerical and a fluid dynamics model. The goal was to gain a deep understanding of the governing phenomena of UV-ozone reactors so as to optimize the reactor configuration. The numerical model created described the UV irradiation and the reaction kinetics accurately, while a computational fluid dynamics (CFD) simulator modelled the fluid a larger scale, simulating two prototypes. The work resulted in general guidelines for the design of UV-ozone UV reactors as well as for full-scale units. QC 20180820