Green engineering creates options that enable sustainability by developing chemicals, processes, value-added products, and systems that are environmentally preferable, energy and resource efficient, and often cost-effective. The present book focuses on these aspects including production of eco-friendly biodiesel, anaerobic digestion of pharmaceutical effluent, mass production of microalgae for industrial applications, waste mediated synthesis of inorganic nanomaterials for wastewater treatment, and the role of phytoremediation. It also covers biotechnological tools and techniques required for sustainable development.