Principles of Environmental Engineering is an introductory environmental engineering textbook for first year students. It provides a background in fundamental science and engineering principles of environmental engineering for students who may or may not become environmental engineers. Principles places more emphasis on scientific principles, ethics and safety, and focuses less on engineering design. The text exposes students to a broad range of environmental topics including risk management, water quality and treatment, air pollution, hazardous waste, solid waste, and ionizing radiation as well as discussing relevant regulations and practices. The book also uses mass and energy balance as a tool for understanding environmental processes and solving environmental engineering problems.