This book contains the peer-reviewed papers that were accepted and presented at the 2023 13th International Conference on Environmental Science and Engineering (ICESE 2023), held in Leuven, Belgium, September 8–10, 2023. The conference provides a forum for researchers and practitioners to address advances in the field of environmental science and engineering including problems, solutions, and research directions. The contents of the book cover emerging and diverse topics, including environmental systems approach, clean technologies, environmental restoration and ecological engineering, wastewater and sludge treatment, climate and climatic changes, atmospheric modeling and numerical prediction, waste minimization, recycling and reuse, solid waste management, carbon capture and storage, and sludge treatment and reuse.