ISBN: 9781260548020 is an International Student Edition of Principles of Environmental Engineering & Science 4th Edition by Mackenzie L Davis, Susan J Masten This ISBN 9781260548020 is Textbook only. It will not come with online access code. Online Access code (should only be purchased when required by an instructor ) sold separately at other ISBN. The content of of this title on all formats are the same. 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.