Environmental engineering

Environmental engineering is a professional engineering discipline that applies scientific and technical principles to protect human health, preserve ecological integrity, and enhance the quality of the environment. Drawing upon fields such as chemistry, biology, ecology, geology, hydraulics, hydrology, microbiology and mathematics, it seeks to develop sustainable solutions for managing pollution, conserving resources and improving environmental conditions. The discipline is closely connected to civil and chemical engineering, with sanitary engineering forming a significant historical component within the civil engineering tradition.
Environmental engineers address challenges related to waste management, water and air pollution control, recycling, public health, and hazardous-waste treatment. Their role includes designing water purification and wastewater treatment systems, developing strategies to prevent waterborne diseases, evaluating hazardous-waste management practices and implementing environmental regulations. They also assess the environmental impact of construction projects and study environmental problems at local and global scales, including acid rain, global warming, ozone depletion and emissions from transport and industry. Many jurisdictions require environmental engineers to hold professional licences or registration.

Etymology

The term environmental derives from the late nineteenth-century French word environ, meaning ‘to encircle’ or ‘to surround’. The English noun environment was first used in 1827 to refer to the conditions in which a person or object exists, and later adopted in the ecological sense in the mid-twentieth century.The word engineer has roots in the Latin ingenium and entered mediaeval French as engignour, referring to designers of military machinery such as catapults and siege engines. Its association with public works and civil infrastructure developed during the sixteenth century, gaining wider usage in the era of John Smeaton.

Historical Development

Ancient civilisationsAlthough the formal discipline is modern, environmental engineering reflects practices that date back thousands of years. As early societies recognised the connection between environmental conditions and public health, they constructed systems to improve sanitation and water management.
The Indus Valley Civilisation developed sophisticated water infrastructure between 3300 and 1300 BCE, including wells, baths, storage tanks, drinking-water systems and a city-wide sewage network. Civilisations in Mesopotamia, Egypt, Crete and early settlements in Scotland established drainage and sanitation systems between 4000 and 2000 BCE. Greek engineers constructed aqueducts and sewerage systems that reused rainwater for irrigation and fertilisation. The Romans further advanced water infrastructure, building aqueducts from 312 BCE onwards for irrigation and drinking water, and developing underground sewers as early as the seventh century BCE to drain marshes and carry waste to the River Tiber.
Modern eraProgress in environmental engineering stagnated after the fall of the Roman Empire until the nineteenth century. As industrialisation intensified and urban populations expanded, public health problems became acute. Modern environmental engineering took shape in London during the mid-nineteenth century, particularly following the Great Stink of 1858. Joseph Bazalgette designed an extensive sewerage system to divert sewage away from the River Thames, which at that time also supplied drinking water. The resulting improvements dramatically reduced cholera and other waterborne diseases.
By the mid-twentieth century, environmental engineering emerged as a distinct academic and professional field. Concerns over pollution, ecological degradation and technological impacts led to new legislation and environmental programmes. Rachel Carson’s Silent Spring (1962), which highlighted the ecological dangers of the pesticide DDT, is often regarded as the catalyst for the modern environmental movement and reinforced the societal demand for environmental engineering expertise.

Education and Training

Environmental engineering programmes are offered by universities around the world, typically within civil or chemical engineering departments. Students in civil engineering-oriented programmes focus on hydrology, water resources management, water and wastewater treatment design and bioremediation. Those in chemical engineering-oriented programmes study environmental chemistry, separation processes and advanced treatment technologies. Related fields include natural resources engineering, agricultural engineering and environmental technology.
Training extends across several broad course categories:

• Mechanical engineering applications, such as the design of treatment facilities, pumping stations and solid-waste handling systems.
• Environmental engineering systems, covering infrastructure design, site development and ecological protection.
• Environmental chemistry and chemical engineering, examining chemical behaviour, pollutants, mining effluents and biochemical processes.
• Environmental technology, focusing on monitoring, measurement, modelling and control of environmental impacts, including renewable-energy systems and electronic monitoring equipment.

A typical curriculum incorporates subjects such as mass and energy transfer, environmental chemistry, nuclear chemistry, population dynamics, resource consumption, economic growth, risk assessment, water pollution and hydrological modelling, air-quality science, atmospheric dispersion modelling, pollution control, global climate processes, solid-waste management, recycling and life-cycle assessment.

Key Applications

Water supply and treatmentEnvironmental engineers analyse water availability within drainage basins and design systems to ensure reliable supplies for domestic, agricultural and industrial use. This includes the design and operation of treatment facilities that remove contaminants and safeguard public health.
Wastewater treatmentWastewater treatment systems are engineered to remove solids, organic matter, nutrients, pathogens and chemical pollutants before effluent is released into the environment. Engineers design primary, secondary and tertiary treatment stages and develop technologies for industrial effluent control.
Air-pollution controlEnvironmental engineers address emissions from industrial, commercial and residential sources. They apply principles of atmospheric chemistry and dispersion modelling to design pollutant-control systems, evaluate risks and comply with regulatory standards.
Solid-waste managementThe field encompasses waste minimisation, collection, transfer, recycling, resource recovery and the design of landfills and waste-to-energy systems. Life-cycle assessment tools help determine the environmental impacts of waste-management strategies.
Environmental impact assessmentEnvironmental engineers evaluate the potential effects of new developments on ecosystems, air and water quality, noise levels and public health. This involves modelling, risk analysis and recommending mitigation measures to reduce adverse impacts.
Global environmental challengesEngineers contribute to understanding and managing global issues such as climate change, ocean acidification, rising temperatures and stratospheric shifts. They also study emissions from transportation and develop technologies and policies to reduce their environmental footprint.