K. Wang, Pui Vun Chai
Water deterioration has become increasingly severe due to industrialization and the growth of human populations. Different types of emerging pollutants have also created immense stress on the environment, with some showing strong resistance to conventional biological treatment systems. As a result, more sophisticated water and wastewater treatment technologies are required to ensure safe and reliable water supplies. Advanced oxidation processes (AOPs) have proven effective by generating strong reactive oxygen species, such as hydroxyl radicals, that can degrade highly resistant pollutants. These radicals may be produced through ultraviolet radiation, ultrasound, or electric power in the presence of appropriate catalysts. Incorporating nanotechnology as a catalyst in AOPs offers significant advantages, as nanomaterials exhibit high stability, large surface area, strong reactivity, and recyclability. Such properties not only enhance the purification of water for human and environmental health but also reduce the reliance on chemical additives, improve energy efficiency, and promote the sustainable use of resources. Collectively, these advances contribute to cleaner water access, more responsible treatment practices, and a lower environmental footprint that supports both ecosystem protection and climate resilience.