The book reviews advanced methods of wastewater treatments. Included are oxidation processes for the degradation of organic molecules; applications of nanomaterials and nanocomposites in membrane-based processes; design of adsorption columns; photocatalytic degradation processes; and the removal of dyes, pesticides and pharmaceutical compounds. Keywords: Degradation of Organic Molecules, Nano Filtration, Ultrafiltration, Microfiltration, Nanomaterial-based Membranes, Adsorption Columns, Nano Carbon Cage, Photocatalytic Degradation, Dyes, Pesticides, Pharmaceutical Compounds, Advanced Oxidation Processes, Complex Organic Molecules, Perfluorooctanoic Acid, Hydrolytic Acidification, Levofloxacin Degradation, Catalytic Degradation, Energy Storage.