Environmental engineering is the branch of engineering which applies scientific and engineering principles to:

protect human health and infrastructure from environmental dangers;
protect environments, both local and global, from natural and human threats, including control of waste;
improve environmental quality.Environmental engineers devise feasible solutions for waste water management, air pollution control, recycling, waste disposal, radiation protection, industrial hygiene, animal agriculture, environmental sustainability, and public health. They design municipal water supply and industrial wastewater treatment systems, and design plans to prevent waterborne diseases and improve sanitation in urban, rural and recreational areas. They evaluate hazardous-waste management systems to evaluate the severity of such hazards, advise on treatment and containment, and develop regulations to prevent mishaps. They implement environmental engineering law, as in assessing the environmental impact of proposed construction projects.
Environmental engineers study the effect of technological advances on the environment, addressing local and worldwide environmental issues such as acid rain, global warming, ozone depletion, water pollution and air pollution from automobile exhausts and industrial sources.Many universities offer environmental engineering programs at either the department of civil engineering or chemical engineering. Environmental "civil" engineers focus on hydrology, water resources management, bioremediation, and water treatment plant design. Environmental "chemical" engineers, on the other hand, focus on environmental chemistry, advanced air and water treatment technologies and separation processes. Some subdivision of environmental engineering include natural resources engineering and agricultural engineering.
Engineers increasingly acquire specialized training in law (J.D.) and help to formulate and implement environmental engineering law.Most jurisdictions impose licensing and registration requirements for qualified environmental engineers.