Editing Environmental engineering (section)

== Applications ==

===Water supply and treatment===
Environmental engineers evaluate the water balance within a [[drainage basin|watershed]] and determine the available water supply, the water needed for various needs in that watershed, the seasonal cycles of water movement through the watershed and they develop systems to store, treat, and convey water for various uses.

Water is treated to achieve water quality objectives for the end uses. In the case of a [[potable water]] supply, water is treated to minimize the risk of [[infectious disease]] transmission, the risk of [[Non-communicable disease|non-infectious]] illness, and to create a palatable water flavor. [[Water distribution system]]s<ref name="nap">{{cite book|url=https://www.nap.edu/read/11728/chapter/2|title=Drinking water distribution systems : assessing and reducing risks|date=2006|publisher=National Academies Press|doi=10.17226/11728 |isbn=978-0-309-10306-0|access-date=6 October 2019}}</ref><ref name="kfupm">{{cite web|title=Water Distribution Networks CE370|url=https://faculty.kfupm.edu.sa/CE/abukhari/Courses/CE370/Lectures/Water%20Distribution%20System.pdf|access-date=6 October 2019|website=King Fahd University of Petroleum and Minerals}}</ref> are designed and built to provide adequate water pressure and flow rates to meet various end-user needs such as domestic use, fire suppression, and [[irrigation]].

===Wastewater treatment===
[[File:Wonga wetlands sewage plant.jpg|thumb|220px|left|[[Sewage treatment]] plant, [[Australia]]]]There are numerous [[wastewater treatment]] technologies. A wastewater treatment train can consist of a primary clarifier system to remove solid and floating materials, a secondary treatment system consisting of an [[aeration]] basin followed by [[flocculation]] and [[settling|sedimentation]] or an [[activated sludge]] system and a secondary clarifier, a tertiary biological [[nitrogen]] removal system, and a final [[disinfection]] process. The aeration basin/activated sludge system removes organic material by growing bacteria (activated sludge).  The secondary clarifier removes the activated sludge from the water. The tertiary system, although not always included due to costs, is becoming more prevalent to remove nitrogen and [[phosphorus]] and to disinfect the water before discharge to a surface water stream or ocean outfall.<ref>{{cite book|author= Sims, J.|title= Activated sludge, Environmental Encyclopedia |publisher=Detroit|year=2003}}</ref>

===Air pollution management===

Scientists have developed [[Atmospheric dispersion modeling|air pollution dispersion models]] to evaluate the concentration of a pollutant at a receptor or the impact on overall air quality from vehicle [[Exhaust system|exhausts]] and industrial [[flue gas stack]] emissions. To some extent, this field overlaps the desire to decrease [[carbon dioxide]] and other [[greenhouse gas emissions]] from combustion processes.

===Environmental impact assessment and mitigation===
{{Main|Environmental impact assessment}}[[File:Water pollution.jpg|right|thumbnail|200px|Water pollution]]

Environmental engineers apply scientific and engineering principles to evaluate if there are likely to be any adverse impacts to water quality, air quality, [[habitat (ecology)|habitat]] quality, [[flora (plants)|flora]] and [[fauna (animals)|fauna]], agricultural capacity, [[traffic]], ecology, and noise. If impacts are expected, they then develop mitigation measures to limit or prevent such impacts. An example of a mitigation measure would be the creation of [[wetland]]s in a nearby location to mitigate the filling in of wetlands necessary for a road development if it is not possible to reroute the road.

In the United States, the practice of environmental assessment was formally initiated on January 1, 1970, the effective date of the [[National Environmental Policy Act]] (NEPA). Since that time, more than 100 developing and developed nations either have planned specific analogous laws or have adopted procedure used elsewhere. NEPA is applicable to all federal agencies in the United States.<ref name="McGraw-Hill, Inc">{{cite book|title=McGraw-Hill Encyclopedia of Environmental Science and Engineering|url=https://archive.org/details/mcgrawhillencycl0000unse|url-access=registration|publisher=McGraw-Hill, Inc|year=1993|isbn=9780070513969 |edition=3rd}}</ref>