Advanced oxidation processes (AOPs) use chemical treatment to remove contaminants from water by oxidation with hydroxyl radicals. These hydroxyl radicals can be produced using UV light, ozone or hydrogen peroxide, but recently reactions have been developed that use persulfates as the radical source. Persulfates are strong oxidants with flexible in situ activation characteristics, including activation with heat, alkali conditions, electricity, ultrasonic treatment, transition metals, carbon and even organics. Persulfate activation can generate sulfate radicals as well as other reactive species. These reactive species, especially the sulfate radical, can degrade most organic pollutants making them valuable in the fields of water purification, soil remediation, disinfection, sludge dewatering, and other important applications in environmental systems. Describing recent developments in persulfate-based AOPs, this book aims to provide a summary of environmental applications for persulfate-based AOPs and to guide the reader, in a comprehensive way, through various advanced oxidation processes in environmental applications. Topics include new activation methods, activation mechanisms, and advanced materials for use in activating persulfate-based AOPs for different environmental applications.