This book looks at the recent developments in the area of photocatalytic degradation of dyes using photocatalytic techniques, for example by means of various nanoparticles, heterogeneous, and hybrid systems. Dyes are one of the major groups of water pollutants and are widely used in a diverse range of industries. The toxic effects of organic dyes in wastewater can have a great environmental impact, therefore there is significant interest and need to remove these dyes effectively and efficiently during wastewater treatment. This volume covers a plethora of basics on the photochemistry of dyes and provides information on technological perspectives including reactor designs and process intensification. Since many industries release a significant amount of colored effluents, which are toxic and difficult to remove by conventional methods, the comprehensive studies herein will contribute to helping reduce the impact of colored effluents in wastewater on the environment.