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.^[1]
  

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,^[2][3] 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.^[4][5][6][7]

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.^{[citation needed]} 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.^{[citation needed]}

Most jurisdictions impose licensing and registration requirements for qualified environmental engineers.

Development[edit]

Ever since people first recognized that their health is related to the quality of their environment, they have built systems to improve it. The ancient Indian Harappan civilization (the Indus Valley Civilization) had advanced control over their water resources more than 5000 years ago. The public work structures found at various sites in the area include wells, public baths, storage tanks, a drinking water system, and a city-wide sewage collection system. They also had an early canal irrigation system enabling large-scale agriculture.^[8] The Romans constructed aqueducts for irrigation and safe urban water supply, including the metropolis of Rome. In the 15th century, Bavaria created laws restricting the development and degradation of alpine country that gathered the region's water supply.

The modern era included increasing efforts in public health engineering.^[9] Modern environmental engineering began in London in the mid-19th century when Joseph Bazalgette designed the first major sewerage system that reduced the incidence of waterborne diseases such as cholera. The introduction of drinking water treatment and sewage treatment in industrialized countries reduced waterborne diseases from leading causes of death to rarities.^[10] The field emerged as a separate academic discipline during the middle third of the 20th century in response to widespread public concern about water and air pollution and other environmental degradation.

As society and technology grew more complex, they increasingly produced unintended effects on the natural environment. One example is the widespread application of the pesticide DDT to control agricultural pests in the years following World War II. While the agricultural benefits were outstanding and crop yields increased dramatically, reducing world hunger, and malaria was controlled better than ever before, the pesticide brought numerous bird species to the edge of extinction due to its impact on their reproductive cycle. The story of DDT as vividly told in Rachel Carson's Silent Spring (1962) is considered to be the birth of the modern environmental movement, which led to the modern field of "environmental engineering."^[11]

Scope[edit]

The following topics typically make up a curriculum in environmental engineering:^[12]

1. 
   Mass and Energy transfer
   


2. 
   Environmental chemistry
   
   
   
   1. Inorganic chemistry
   
   
   2. Organic Chemistry
   
   
   3. Nuclear Chemistry
   
   
   
   


3. 
   Growth models
   
   
   
   1. Resource consumption
   
   
   2. Population growth
   
   
   3. Economic growth
   
   
   
   


4. 
   Risk assessment
   
   
   
   1. Hazard identification
   
   
   2. 
      Dose-response Assessment
   
   
   3. Exposure assessment
   
   
   4. Risk characterization
   
   
   5. Comparative risk analysis
      
   
   
   
   


5. 
   Water pollution
   
   
   
   1. 
      Water resources and pollutants
      
   
   
   2. Oxygen demand
   
   
   3. Pollutant transport
      
   
   
   4. 
      Water and waste water treatment
      
   
   
   
   


6. 
   Air pollution
   
   
   
   1. Industry, transportation, commercial and residential emissions
   
   
   2. Criteria and toxic air pollutants
      
   
   
   3. Pollution modelling (e.g. Atmospheric dispersion modeling)
   
   
   4. Pollution control
   
   
   5. Air pollution and meteorology
      
   
   
   
   


7. 
   Global change
   
   
   
   1. 
      Greenhouse effect and global temperature
      
   
   
   2. 
      Carbon, nitrogen, and oxygen cycle
      
   
   
   3. 
      IPCC emissions scenarios
      
   
   
   4. Oceanic changes (ocean acidification, other effects of global warming on oceans) and changes in the stratosphere (see Physical impacts of climate change)
   
   
   
   


8. 
   Solid waste management and resource recovery
   
   
   
   1. Life cycle assessment
   
   
   2. Source reduction
   
   
   3. 
      Collection and transfer operations
   
   
   4. Recycling
   
   
   5. 
      Waste-to-energy conversion
   
   
   6. Landfill
   
   
   
   

Environmental impact assessment and mitigation[edit]

Scientists have air pollution dispersion models to evaluate the concentration of a pollutant at a receptor or the impact on overall air quality from vehicle 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.
They apply scientific and engineering principles to evaluate if there are likely to be any adverse impacts to water quality, air quality, habitat quality, flora and fauna, agricultural capacity, traffic impacts, social impacts, ecological impacts, noise impacts, visual (landscape) impacts, etc. 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 wetlands 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.^[13]

Water supply and treatment[edit]

Sewage treatment plant, Australia

Engineers evaluate the water balance within a 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-infectious illness, and to create a palatable water flavor. Water distribution systems 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[edit]

Water pollution

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 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.^[14]

Air pollution management[edit]

Scientists have developed air pollution dispersion models to evaluate the concentration of a pollutant at a receptor or the impact on overall air quality from vehicle 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 Protection Agency[edit]

The U.S. Environmental Protection Agency (EPA) is one of the many agencies that work with environmental engineers to solve key issues. An important component of EPA's mission is to protect and improve air, water, and overall environmental quality in order to avoid or mitigate the consequences of harmful effects.

Ecological engineering for sustainable agriculture in arid and semiarid West African regions^[15][edit]

Ecological engineering offers new alternatives for the management of agricultural systems that are more tailored to the ever-changing social and environmental necessities in these regions. This requires managing the complexity of agrosystems, while striving to mimic the functioning of natural ecosystems of West African drylands and taking advantage of traditional practices and local know-how resulting from a long process of adaptation to environmental constraints.

1. Acting on biodiversity. Biodiversity is essential to the productivity of ecosystems and their temporal stability under the impact of external disturbances. Several ecological processes related to biodiversity may be intensified for the benefit of agrosilvopastoral systems: promoting diversity and soil microorganism activity to benefit plants, associating and utilizing the mutual benefits of plants


2. Utilizing organic matter and nutrient cycles. The productivity of agrosystems with low chemical input use in dryland regions is primarily based on efficient organic resource management, and in turn on the nutrient and energy flows they induce. It is thus possible to intervene at several levels: enhancing crop-livestock farming integration to preserve natural resources, restoring the biological activity of soils via specific organic inputs, supplying nutrients to plants locally.


3. Enhancing available water use. Water supplies are limited and irregular in dryland areas. Current management of these supplies—which involves capturing rainwater and surface runoff—could be improved in several ways: adapting to erratic rainfall or drought risks by focusing on: (i) the organization of the farm and community (farm plot patterns in association with the random rainfall distribution, etc.), and on (ii) cropping techniques to reduce crop water needs (plant choices, weeding, etc.), preserving water in crop fields by hampering runoff, accounting for the essential role of trees regarding soil and water in drylands.


4. Managing landscapes and associated ecological processes. Ecological crop pest regulation by their natural enemies is one ecosystem service provided by biodiversity. Better pest management could be considered in association with promoting biodiversity at different scales, e.g. from the plant to the landscape.

Education[edit]

Courses aimed at developing graduates with specific skills in environmental systems or environmental technology are becoming more common and fall into broad classes:

• 
  Mechanical engineering courses oriented towards designing machines and mechanical systems for environmental use such as water treatment facilities, pumping stations, garbage segregation plants and other mechanical facilities;


• 
  Environmental engineering or environmental systems courses oriented towards a civil engineering approach in which structures and the landscape are constructed to blend with or protect the environment;


• 
  Environmental chemistry, sustainable chemistry or environmental chemical engineering courses oriented towards understanding the effects (good and bad) of chemicals in the environment. Focus on mining processes, pollutants and commonly also cover biochemical processes;


• 
  Environmental technology courses oriented towards producing electronic or electrical graduates capable of developing devices and artifacts able to monitor, measure, model and control environmental impact, including monitoring and managing energy generation from renewable sources.

Prominent environmental engineers[edit]

• G. D. Agrawal


• Braden Allenby


• Ashraf Choudhary


• Marc Edwards


• Robert A. Gearheart


• Alfred Stowell Jones


• Sudhakar Kesavan


• Joseph Lstiburek


• Daniel Oerther


• George Pinder


• Ellen Swallow Richards


• Paul V. Roberts


• Daniel A. Vallero


• Abel Wolman

See also[edit]

• American Academy of Environmental Engineers and Scientists


• Association of Environmental Engineering and Science Professors


• Association of Environmental Professionals


• Atmospheric dispersion modeling


• Biofiltration


• Confederation of European Environmental Engineering Societies


• Ecological sanitation


• Engineering geology


• Environmental design


• Environmental engineering law


• Environmental engineering science


• Environmental health


• Environmental impact assessment


• Environmental management


• Environmental restoration


• Environmental science


• Environmental studies


• Civil engineering


• Geoprofessions


• Hydraulic engineering


• Hydrology


• Institute of Environmental Management and Assessment


• List of environmental degrees


• List of environmental engineers


• Society of Environmental Engineers


• Water purification


• Water quality modeling

References[edit]

• Davis, M. L. and D. A. Cornwell, (2006) Introduction to environmental engineering (4th ed.) McGraw-Hill
  ISBN 978-0072424119
  

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