This book deals with the latest developments regarding urban and industrial wastewaters' adapted treatment with various technologies. It focuses, through valuable publications, on the shifting of the wastewater management paradigm from "treatment and disposal" to "the 4Rs principle: Reduce, Recycle, Reuse, and Recover". The adapted wastewater treatment step will allow (i) the disposal of supplementary water amounts that could be safely reused in order to tackle the water-scarcity problem, and (ii) the preservation of the environment against pollution. Finally, this book will contribute to the achievement of the United Nations Sustainable Development Goals and other international related initiatives.