Environmental engineering is the application of science and engineering principles to protect and utilise natural resources, control environmental pollution, improve environmental quality to enable healthy ecosystems and comfortable habitation of humans. It is based on multiple disciplines including geology, hydrology, biology, chemistry, physics, medicine, engineering, management, economics, law, etc. Environmental engineering involves water supply, pollution control, recycling, waste (solid and liquid) disposal, radiation protection, industrial hygiene, environmental sustainability, and public health. This is an introductory book on environmental engineering and written for undergraduate students in civil and environmental engineering, chemical engineering, environmental science and geography