This book focuses on green and innovative wastewater treatment technologies that promote sustainability. It discusses a variety of biological, physical, and chemical treatment technologies. It covers biological processes for recovery of value-added products from wastewater and gives an overview of enzymatic hydrolysis and bioremediation of wastewater using immobilized enzyme and fungus. It offers a case study and future trends of wastewater treatment through membrane bioreactor technologies, describes advanced chemical–physical processes for recalcitrant pollutant, and emphasizes the use of low-cost materials and cost-effective treatment methods.