This book presents peer-reviewed papers of the 2023 9th International Conference on Environment and Renewable Energy (ICERE 2023), which was held in Hanoi, Vietnam, during February 24-26, 2023, in hybrid mode (both online and in-person). The conference was sponsored by the Hanoi University of Science and Technology, Vietnam, and facilitated exchanging the latest and most advanced information between scientists and engineers in the fields of environment and renewable energy. The book focuses on research related to environmental management; water resources management; ground water remediation; water treatment and reclamation; solar, biomass and wind energy; nuclear energy engineering; renewable energy grids; environmental impact assessment; and renewable energy utilization, among other topics. This volume serves as an excellent reference for researchers and engineers seeking to understand the latest technological developments in these fields.