Environmental engineering

Environmental engineering is the application of science and engineering principles to protect and enhance the quality of our environment—air, water, and land resources—to sustain the health of humans and other living organisms. It combines conservation measures, pollution remediation, and waste reduction with public education and government policy.

In the U.S., minimum education requirements for environmental engineers typically include a Bachelor's Degree in environmental (or civil) engineering from an accredited college.

Environmental engineering emphasizes several areas: process engineering, environmental chemistry, water and wastewater treatment (sanitary engineering), waste reduction/management, and pollution prevention/cleanup.

Some consider 'Environmental Engineering' to include the development of sustainable processes.

Development of environmental engineering

Ever since people first recognized that their health and well-being are related to the quality of their environment, they have applied thoughtful principles to attempt to improve environmental quality. For instance, the engineers of ancient Rome constructed aqueducts to combat drought and create a healthful water supply for the Roman metropolis. In the fifteenth century, Bavaria created laws restricting the development and degradation of alpine country that constituted the region's water supply.

Modern environmental engineering began in the nineteenth century, when cities such as London and Paris instituted laws decreeing the construction of sewer systems for the proper collection and disposal of sewage, and facilities to treat drinking water. Consequently, waterborne diseases such as cholera, which were leading causes of death, dropped in incidence and became rarities.

Conservation measures to protect the environment were also pursued. For example, in the early twentieth century, the national park system was created in the United States.

With the growth of societies, many actions intended to benefit those societies had longer-term impacts that reduced the quality of the environment. One example is the widespread application of DDT to control agricultural pests in the years following World War II. The agricultural benefits of using DDT were outstanding, as crop yields increased dramatically and world hunger was substantially reduced. In addition, malaria was controlled better than it had ever been. On the other hand, various species were brought to the verge of extinction due to the impact of DDT on their reproductive cycles—a story told vividly in Rachel Carson's Silent Spring. Consequently, the modern environmental movement began, and the field of environmental engineering was pursued with renewed vigor.

Scope of environmental engineering

Environmental engineering undertakes to prevent and clean up all kinds of pollutants—chemical, biological, thermal, radioactive, and even mechanical. To meet its goals, environmental engineering incorporates elements from various disciplines, including chemistry, biology, ecology, geology, civil engineering, chemical engineering, mechanical engineering, and public health.

There are several divisions in the field of environmental engineering.

Environmental impact assessment and mitigation

This division is a decision-making tool. Engineers and scientists assess the impacts of a proposed project on environmental conditions. They apply scientific and engineering principles to evaluate the project's impacts on:

the quality of air, water, habitat;
flora and fauna;
agricultural capacity;
traffic; and
social needs and customs.

They also consider such factors as noise levels and visual (landscape) impacts.

If adverse impacts are expected, they then develop measures to limit or prevent such impacts. For example, to mitigate the filling-in of a section of wetlands during a proposed road development, they may plan for the creation of wetlands in a nearby location.

Water supply and treatment

Engineers and scientists work to secure water supplies for potable and agricultural use. They examine a watershed area and evaluate the water balance in terms of such factors as the availability of water for various needs and the seasonal cycles of water in the watershed. In addition, they develop systems to store, treat, and convey water for various uses. For example, for potable water supplies, water is treated to minimize the risk of diseases 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 needs, such as domestic use, fire suppression, and irrigation.

Wastewater conveyance and treatment

Most urban and many rural areas no longer discharge human waste directly to the land through outhouse, septic, and/or honey bucket systems, but rather deposit such waste into water and convey it from households via sewer systems. Engineers and scientists develop collection and treatment systems to carry this waste material away from where people live and produce the waste and discharge it into the environment. In developed countries, substantial resources are applied to the treatment and detoxification of this waste before it is discharged into a river, lake, or ocean system. Developing nations are striving to obtain the resources to develop such systems so that they can improve water quality in their surface waters and reduce the risk of water-borne infectious disease.

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.

See: Remediation

Air quality management

Engineers apply scientific and engineering principles to the design of manufacturing and combustion processes to reduce air emissions to acceptable levels. Scrubbers, precipitators, after-burners, and other devices are utilized to remove particulates, nitrogen oxides, sulfur oxides, and reactive organic gases from vapors prior to allowing their emission to the atmosphere. This field is beginning to overlap with energy efficiency and the desire to reduce carbon dioxide and other greenhouse gas emissions from combustion processes. Scientists develop dispersion models to evaluate the concentration of a pollutant at a receptor source or the impact on overall air quality and smog production from vehicle and flue gas stack emissions.

See: Remediation

Additional applications

Contaminated land management and site remediation
Risk assessment
Environmental policy and regulation development
Solid waste management
Hazardous waste management
Environmental health and safety
Natural resource management
Noise pollution
Geographic information system (GIS)

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