Industrial pollution, along with domestic sewage, agricultural and urban runoff, contaminates rivers and makes it difficult to treat the water to remove all pollutants. This pollution can affect the quality of rivers, the quality of life of aquatic animals and also affect human health through water consumption. In order to improve water quality, nanotechnology has been studied as an alternative for better removal of pollutants such as heavy metals, separation of oily water and antimicrobial activity. In addition, with the increase of industrialization along with the pollution of rivers, seawater can be an interesting alternative source of drinking water after adequate treatment. Nano-materials are being studied as a possibility to remove salt from seawater and make it drinkable. This book has 5 chapters, including: Chapter I, The Role of Nanotechnology in Industrial Wastewater Treatment;Chapter II, Types of Nanotechnology Applications;Chapter III, Application of Nanotechnology in Industry;Chapter IV, Application of Nano Catalysts in the Purification Industry;Chapter V, Nanotechnology and Economics and its Limitations and References.