This book covers the fundamental principles of "systems" and "sustainability", and introduces the methodology of "new systems thinking," which comprises system modeling, mapping, integration, analysis, and sustainability assessment. The application of this new systems thinking approach is demonstrated through practical case studies, including waste management systems, food-energy-water nexus, and biorefinery systems. This is an excellent reference for academics, undergraduate and postgraduate students, professional engineers, and policymakers across various disciplines including: chemical and process engineering, environmental science, environmental engineering, and environmental management.