Advanced oxidation processes (AOPs) are widely used for treating refractory industrial wastewater such as chemical, pharmaceutical, printing and dyeing, and electroplating wastewater. They are also applied in landfill leachate treatment, advanced purification of drinking water, and deep treatment of municipal wastewater for reuse. In addition, AOPs are suitable for medical wastewater, oilfield produced water, RO concentrate treatment, and zero liquid discharge systems. They can effectively remove color, odor, and micro-pollutants, and are also used in swimming pool water circulation and landscape water treatment