Book excerpt: This book presents comprehensive reviews on the latest developments of nanotechnologies to detect and remove pollutants in water, air and food. Polymer nanocomposites, nanoparticles from microbes and the application of nanotechnologies for desalination and agriculture are also discussed. Pollution of water and air by contaminants and diseases is a major health issue leading globally to millions of deaths yearly according to the World Health Organization. Such issue requires advanced methods to clean environmental media.