The second volume in a new two-volume set on applied water science, this book provides understanding, occurrence, identification, toxic effects and control of water pollutants in an aquatic environment using green chemistry protocols. The high rate of industrialization around the world has led to an increase in the rate of anthropogenic activities which involve the release of different types of contaminants into the aquatic environment. This generates high environmental risks, which could affect health and socio-economic activities if not treated properly. There is no doubt that the rapid progress in improving water quality and management has been motivated by the latest developments in green chemistry. Over the past decade, sources of water pollutants and the conventional methods used for the treatment of industrial wastewater treatment have flourished. Water quality and its adequate availability have been a matter of concern worldwide particularly in developing countries. According to a World Health Organization (WHO) report, more than 80% of diseases are due to the consumption of contaminated water. Heavy metals are highly toxic and are a potential threat to water, soil, and air. Their consumption in higher concentrations gives hazardous outcomes. Water quality is usually measured in terms of chemical, physical, biological, and radiological standards. The discharge of effluent by industries contains heavy metals, hazardous chemicals, and a high amount of organic and inorganic impurities that can contaminate the water environment, and hence, human health. Therefore, it is our primary responsibility to maintain the water quality in our respective countries. This book provides understanding, occurrence, identification, toxic effects and control of water pollutants in an aquatic environment using green chemistry protocols. It focuses on water remediation properties and processes including industry-scale water remediation technologies. This book covers recent literature on remediation technologies in preventing water contamination and its treatment. Chapters in this book discuss remediation of emerging pollutants using nanomaterials, polymers, advanced oxidation processes, membranes, and microalgae bioremediation, etc. It also includes photochemical, electrochemical, piezoacoustic, and ultrasound techniques.