10 Breakthroughs in Environmental Engineering

Main Highlights

Environmental engineering is now a formal academic discipline, but its origins date back to ancient times when humans first began altering their surroundings to fulfill their needs. This field combines scientific and engineering principles to address how we use and affect natural resources. Today, environmental engineers tackle challenges such as pollution mitigation, energy efficiency, soil erosion, water purification, and waste disposal to safeguard the quality of our air, water, and soil. Their goal is to promote healthier and more sustainable living by enabling us to coexist with the environment in a more efficient and less harmful manner.

Environmental engineers are often overlooked champions who have played a pivotal role in shaping today's world, ensuring access to safe food and water, clean air, disease-free living spaces, and energy-efficient solutions that power nearly every aspect of our lives. With the global population nearing 7 billion and rising, the significance of this field will only continue to grow.

Numerous groundbreaking innovations have already been instrumental in helping humanity thrive. Discover the contributions these earth stewards have made in the past and the advancements they are currently developing for the future.

10: Sewers

For centuries, humans have sought to create living environments free from waste, initially to eliminate unpleasant odors and later to prevent deadly disease outbreaks. Sewer systems have been instrumental in achieving this by efficiently removing waste from populated areas, and their development has been ongoing for millennia.

From 2000 to 4000 B.C.E., civilizations like the Mesopotamian Empire (present-day Iraq), Mohenjo-Daro (modern-day Pakistan), Egypt, Crete, and Scotland's Orkney Islands had established drainage systems, with some even featuring indoor sanitation. By a few centuries B.C.E., the Greeks developed sewer networks that directed rainwater and wastewater to basins used for irrigation and fertilization. The Romans, meanwhile, built underground sewers that emptied into the Tiber River.

Over centuries, experimentation and disease outbreaks highlighted the necessity of keeping sewer systems separate from drinking water sources. This led to innovations like manholes, which allowed for maintenance, and systems designed to be flushed periodically by tidewater or rainwater.

Historically, sewers carried untreated waste directly into rivers, oceans, or other water bodies. Today, modern sewer systems are far more advanced, channeling waste to treatment plants where it undergoes filtration and chemical processes to disinfect and remove harmful substances before being released back into the environment. This evolution is ongoing, with further advancements expected.

9: Aqueducts

Water is essential for survival, which is why many ancient civilizations flourished near natural water sources. However, the Greeks and Romans innovated ways to overcome nature's limitations by developing aqueducts. These structures transported vast quantities of water over distances as long as 60 miles (96.6 kilometers), utilizing gravity to move water downward through carefully engineered channels built at a gradual decline.

Constructed primarily from materials like concrete, cement, brick, and stone, aqueducts often began at springs in elevated regions. Dams and reservoirs were also created to supply them with water from rivers or streams. While the iconic arcades—stone bridges supported by arches—are the most recognizable feature, aqueducts also included low walls, covered trenches, underground tunnels, and pipes to navigate diverse terrains.

The endpoint of an aqueduct was a distribution tank known as a castellum, typically located at a city's highest point. From there, water flowed to smaller tanks, which then supplied fountains, baths, public basins, and occasionally private homes through masonry channels or pipes.

Rome's first aqueduct was built in 312 B.C.E. By the time Emperor Trajan constructed the Aqua Traiana around 109 C.E., the Roman aqueducts were delivering hundreds of millions of gallons of water to the city daily. This infrastructure enabled Roman cities to sustain populations far larger than what natural water sources alone could support.

8: Biofiltration Systems

Biofiltration involves passing air or water through a moist, porous material filled with microorganisms to eliminate odors and pollutants. These contaminants are broken down into simple compounds such as water and carbon dioxide, along with harmless biomass byproducts, as a result of microbial metabolic activity. Biofiltration systems are employed in treating wastewater, industrial emissions, and composting gases, among other uses. While initially used in the 1950s for odor control, they are now widely applied for removing industrial pollutants.

By utilizing specific bacterial strains and controlling moisture, pH, and temperature, biofilters can effectively break down various pollutants. Unlike conventional filters, biofilters eliminate harmful substances rather than just trapping them, though they are only effective against biodegradable contaminants. This method is primarily used to neutralize toxic emissions, such as hydrocarbons from fuels and certain volatile organic compounds (VOCs).

VOCs are produced and emitted during the manufacturing of numerous products containing organic chemicals, including paints, cleaning agents, cosmetics, and fuels. These carbon-based compounds react with oxygen molecules in the atmosphere under sunlight, contributing to the formation of ozone and smog.

7: Bioswales

Bioswales are vegetated areas consisting of grasses, flowers, trees, or other plants designed to absorb stormwater runoff. They help break down or remove pollutants before the water enters nearby water bodies or sewer systems untreated. These green strips can form channels to direct and filter water or be placed as biofiltration strips to catch runoff from paved surfaces. Some bioswales also incorporate additional features like under-drains and infiltration trenches to enhance water filtration and flow management.

Bioswales effectively remove pollutants such as heavy metals, oil, grease, and sediment from stormwater. They also cool water that has warmed up on paved surfaces before it reaches natural waterways, where elevated temperatures could harm aquatic life. In urban areas with limited greenery, bioswales can replace traditional storm drains and help prevent sewer overflows during heavy rainfall.

The types of plants used in bioswales vary by region, though they are less suitable for arid climates. In areas where they thrive, bioswales offer significant environmental benefits. They can resemble small landscaped parks, providing a more visually appealing alternative to concrete drainage systems. Additionally, they can serve as habitats for small wildlife like birds and butterflies, making them a beneficial solution for both nature and urban environments.

6: Hybrid Vehicles

Hybrid vehicles were developed much earlier than many realize. During the late 19th and early 20th centuries, they competed with gas-powered, electric, and even steam-powered cars for supremacy. Gasoline vehicles ultimately dominated, but as concerns over fuel efficiency and emissions grew, hybrids made a comeback. Prototypes emerged in the 1970s, though few reached production. The Toyota Prius, launched in Japan in 1997 and in the U.S. in 2001, became the first commercially successful hybrid, paving the way for many others.

Here, we’re discussing hybrid-electric vehicles (HEVs), which combine internal combustion engines with electric motors (or motor generators) to achieve superior fuel efficiency compared to conventional cars.

While hybrids still require gasoline, the electric motor enhances fuel efficiency by allowing the combustion engine to shut off during idle periods through automatic start/stop systems. It also supplements power during acceleration or uphill driving, enabling the use of a smaller, more efficient gas engine. Some hybrids employ regenerative braking, where the motor generates electricity as it slows the car, storing it in a nickel-metal hydride (NiMH) battery for later use. Higher-end models can even operate solely on electric power for short distances, though most will not function without gasoline.

Depending on the make and model, hybrid-electric cars can achieve significantly better fuel economy than their traditional counterparts of similar size.

5: LEED, BREEAM, Green Star and Other Certification Programs

Buildings are increasingly earning green certifications. As awareness grows about the environmental and health impacts of structures, organizations have established voluntary rating systems to evaluate the sustainability and efficiency of buildings, homes, and similar constructions. These include the Building Research Establishment Environmental Assessment Method (BREEAM) and Leadership in Energy and Environmental Design (LEED). BREEAM, launched in 1990 by the BRE Trust, is the leading standard in the U.K. LEED, developed by the U.S. Green Building Council in 1998, is prominent in the U.S. While BREEAM and LEED are the most widely used globally, other systems like Green Star (created by the Green Building Council of Australia in 2003), CASBEE in Japan, and Estidama in Abu Dhabi are gaining traction.

Certification assessments occur during both the design and post-construction phases. Existing buildings and commercial interiors can also be evaluated. These standards are adaptable to different regions and building types, with ratings based on factors such as energy and water efficiency, land use, pollution, waste management, and indoor environmental quality.

The presence of these certification programs promotes eco-friendly construction and operational practices, which is crucial given that buildings account for over 20 percent of greenhouse gas emissions in some regions [source: HVN Plus]. Green buildings can reduce energy, water, and operational costs while enhancing the health of occupants. Additionally, high ratings may qualify buildings for tax incentives, increase property values, and boost rental income.

4: Ecosan Systems

Ecological sanitation (ecosan) systems encompass a variety of eco-friendly toilet designs that typically use minimal or no water, effectively isolating waste to prevent odors and disease. Often, the waste can be composted and repurposed as fertilizer or fuel. Certain models, like urine diversion systems, separate urine and feces immediately. Others use materials such as sawdust, lye, or sand to neutralize odors, absorb moisture, and aid decomposition for safe disposal or composting. These systems are particularly suitable for areas with limited water access, as they don't rely on plumbing or sewer connections.

The EcoSan brand, launched in 2000, features a self-contained toilet. When the lid is lifted, waste travels through a coiled conveyor over approximately 25 days. During this period, liquid waste evaporates and vents, while solid waste undergoes biological breakdown. The remaining dry, odorless material, reduced to 5-10% of its original mass, is collected in a receptacle for removal and reuse.

Unicef India describes an ecosan toilet resembling a large outhouse with a concrete bunker beneath each unit. The floor-level toilets have distinct openings for liquids (diverted to external pots) and solids, along with a water basin for cleansing. Users can drop lime, sawdust, ash, or similar materials into a designated hole after depositing solid waste to aid decomposition, reduce moisture, and control odor.

Various ecosan toilet designs and products exist, differing in cost, features, and level of complexity.

3: Ultraviolet Germicidal Irradiation

Ultraviolet germicidal irradiation (UVGI) eliminates harmful microorganisms like viruses and bacteria from water, air, and surfaces. While sunlight naturally achieves this to a degree, concentrated UV light is more effective. Although UV light can harm human skin and eyes, it also neutralizes or destroys certain microbes.

UVGI systems utilize focused UV light, specifically shortwave ultraviolet-B and ultraviolet-C radiation within the germicidal range of 200 to 320 nanometers, often produced by low-pressure mercury lamps. This light disrupts the cells or DNA of microorganisms, either killing them or preventing replication. UV light in the 320 to 400 nanometer range lacks germicidal effectiveness.

UVGI technology is integrated into ventilation ducts, HVAC systems, and air purification units. It is also applied to entire rooms, ideally when unoccupied or when occupants wear protective gear. Certain systems release UV light near ceilings to sanitize the air above people, often paired with vertical airflow systems. HEPA filters or similar filtration methods can complement UVGI by removing contaminants that UV light cannot eliminate.

Extensive research on UVGI was conducted from the 1930s to the 1970s in hospitals and schools. Despite its proven effectiveness, UVGI fell out of favor due to advancements in immunization, antibiotics, and concerns about UV radiation safety.

The rise of antibiotic-resistant bacteria, including drug-resistant tuberculosis, and fears of bioterrorism have revived interest in UVGI. While it is widely accepted for water purification, its applications for air and surface disinfection are growing. In 2003, the CDC approved its use in hospitals alongside air cleaning systems to combat TB spread.

2: Agroforestry

Agroforestry involves the integrated management of trees, shrubs, crops, and livestock to create more efficient, sustainable land use. When implemented correctly, it enhances product diversity, boosts agricultural output, improves soil and water quality, and reduces erosion, pollution, and vulnerability to extreme weather. Additionally, it supports wildlife habitats, safeguards watersheds, and improves carbon emission management. These benefits can lead to increased farmer income and a healthier environment.

Different agroforestry techniques can be applied based on land and resource availability. Alley cropping, for instance, involves planting crops between rows of trees such as oak, ash, or nut trees, allowing for dual harvests of crops and nuts. Forest farming uses tree canopies to provide optimal shade for shade-loving crops like ferns, mushrooms, and ginseng, which can be harvested before the trees. Riparian forest buffers, consisting of trees, shrubs, and grasses, are planted along waterways to prevent pollution and erosion. Windbreaks, another method, use strategically placed trees and shrubs to protect crops and livestock from wind damage and erosion while enhancing bee pollination and managing snow distribution. Silvopasture integrates trees with livestock grazing, offering shelter and forage. These methods create a symbiotic relationship between crops, animals, and trees, enabling farmers to focus on harvesting available resources.

In some regions, government policies hinder agroforestry practices due to fragmented oversight among agencies. However, agroforestry is gaining recognition as a sustainable farming approach. In the U.S., the 1990 Farm Bill established the USDA National Agroforestry Center to promote these practices.

1: High-altitude Wind Energy from Kites

While windmills are the traditional image of wind energy, few consider kites as a viable option. Makani Power, a San Francisco-based startup established in 2006, has been developing kite-like wind turbines tethered to generate power at high altitudes, where winds are stronger and more consistent than at ground level. Interestingly, Makani translates to 'wind' in Hawaiian.

The tethers can extend up to 2,000 feet (609.6 meters) above the ground, serving both as suspension and power transmission systems. The kites, approximately 100 feet long and constructed from carbon fiber, feature four propellers and are equipped with sensors and GPS units on their wings. These components relay data to optimize flight patterns. Instead of hovering, the kites fly in loops and are lightweight enough to stay aloft in winds under 15 miles per hour (MPH).

These turbines are reported to produce up to twice the power of conventional ground-level wind turbines, potentially at half the cost. Their expenses are comparable to coal-based energy, and they require less space than many other power generation methods.

Although still a few years from commercial release, the kites are expected to be deployed along coastlines or anchored to buoys in the ocean. Makani Power has secured funding from Google and the Advanced Research Projects Agency for the Department of Energy (ARPA-E) and is set to be acquired by Google X, the lab behind innovations like Google Glass and autonomous vehicles.