Innovative Air Pollution Control Technologies For Cleaner Air

Air pollution control technologies are an increasingly important aspect of modern life as cities around the world face growing air quality challenges. Air pollution control techniques aim to reduce or eliminate the emission of harmful substances into the atmosphere, protecting both the environment and human health. While natural phenomena, such as volcanic eruptions and forest fires, contribute to air pollution, only pollution caused by human activities, such as industry and transportation, can be mitigated and controlled. This article will discuss some of the technologies available to address this pressing issue.

Catalytic converters

The first catalytic converter prototypes were designed in France in the 19th century, but it wasn't until the 1950s that the first functional catalytic converter was invented by Eugene Houdry, a French mechanical engineer, to address the smog problem in Los Angeles. Since then, catalytic converters have become standard equipment in most gasoline-powered vehicles, with many jurisdictions making it illegal to remove or disable them.

Despite their success in reducing pollution per vehicle, the increasing number of vehicles on the road has led to an overall decline in air quality. Additionally, catalytic converters have some drawbacks. They can restrict the flow of exhaust, reducing fuel efficiency and vehicle performance, and they require a warm-up period during which the vehicle emits unrestricted pollution. The use of rare and expensive metals like platinum and palladium in their construction also contributes to pollution during the refining process.

However, researchers like Tanya and Elijah Shirman have been working to address these challenges. They drew inspiration from the unique properties of butterfly wings to develop a customizable scaffold for catalysts, allowing control over the composition, size, and placement of catalytic nanoparticles, as well as the shape and pattern of the scaffold. This technology aims to improve the performance and temperature stability of catalytic converters while reducing their cost.

Scrubbers

Wet scrubbers can serve two simultaneous functions: particulate collection and acid gas control. Gas emissions are absorbed in devices columns that attempt to maximize liquid-to-gas contact to achieve maximum absorption of the pollutants into the liquid phase. Venturi scrubbers are the most efficient of the wet collectors, achieving efficiencies of more than 98% for particles larger than 0.5 μm in diameter.

Wet scrubbers offer a contained, efficient solution for eliminating unwanted air contaminants, making them a great option for air pollution control. They can remove organic and inorganic pollutants, including those that cause illness, deplete the ozone, or disrupt ecosystems. For example, a wet scrubber can also remove volatile organic compounds (VOCs) from the air. VOCs are human-made chemicals produced during specific manufacturing processes, especially those used to make paint, pharmaceuticals, and refrigerants.

There are several configurations of wet scrubbers in use. In a spray-tower scrubber, an upward-flowing airstream is washed by water sprayed downward from a series of nozzles. The water is recirculated after it is sufficiently cleaned to prevent clogging of the nozzles. Spray-tower scrubbers can remove 90% of particulates larger than about 8 μm. In orifice scrubbers and wet-impingement scrubbers, the air-and-droplet mixture collides with a solid surface. This collision atomizes the droplets, reducing droplet size and increasing the total surface contact area. These scrubbers have the advantage of lower water-recirculation rates, and they offer removal efficiencies of about 90% for particles larger than 2 μm.

Dry scrubbers are the other main type of scrubber, though they are less common than wet scrubbers.

Sustainable transit

Public Transportation and Active Travel

Public transportation, such as buses, subways, and taxis, offers a cleaner alternative to private vehicles by controlling pollutant emissions and reducing exposure to air pollutants. Many cities are investing in public transport infrastructure and implementing policies to encourage its use. Active travel, such as walking and cycling, is also being promoted by cities through initiatives like dedicated bike lanes and rentable e-bikes and e-scooters. These options provide pollution-free transportation for short distances without burning fossil fuels.

Electric Vehicles (EVs)

The adoption of electric vehicles is increasingly gaining popularity as a sustainable transport option. Electric cars, autonomous vehicles, and electric public transport fleets can significantly reduce air pollution, especially in urban areas. Governments are offering incentives for EV purchases and investments in electric transport infrastructure.

Green Cities and Low-Carbon Development

The concept of "green cities" and "low-carbon development" involves implementing environmentally friendly technologies and concepts for public transport. This includes the systematic inclusion of non-motorized transport (NMT) infrastructure in urban road investments. By combining climate change mitigation, improved road safety, and increased accessibility to essential services, cities can reduce traffic congestion and enhance urban air quality.

Fuel-Efficient Vehicles and Alternative Power Sources

Technological improvements in fuel-efficient vehicles and alternative power sources are crucial to combat the growing demand for transport. While these advancements have not kept pace with the rapid expansion of the global vehicle fleet, innovations like catalytic converters in gasoline and diesel-powered vehicles help transform dangerous air pollutants into less harmful ones.

International Cooperation and Agreements

International agreements, such as the Paris Agreement, set global targets for reducing greenhouse gas emissions from the transport sector. Through cooperation, countries can address transport-related pollution on a larger scale. Additionally, international agreements facilitate the sharing of knowledge and best practices, accelerating the transition to a cleaner, more sustainable transport system.

In conclusion, sustainable transit involves a combination of public and active transportation, the adoption of electric vehicles, the development of green cities, improvements in fuel efficiency, and international collaboration. By implementing these measures, we can significantly improve urban air quality and reduce the impact of transport on the environment and human health.

Multi-pollutant monitoring

One key advantage of multi-pollutant monitoring is its ability to reduce costs and time burdens associated with ambient pollution monitoring. By addressing multiple pollutants simultaneously, regulatory bodies can ensure compliance with emission limits for different pollutants more efficiently. This integrated approach can also lead to significant health, environmental, and economic benefits, especially when dealing with industrial facilities that emit a wide range of pollutants.

Technologies such as air quality monitors and analytics dashboards play a vital role in multi-pollutant monitoring. These tools help workplace leaders and building managers assess and improve indoor air quality. For example, Kaiterra's Sensedge and Sensedge Mini are indoor air quality monitors used in iconic buildings like the Empire State Building and the Burj Khalifa.

To further enhance multi-pollutant monitoring, portable, lower-cost air pollution sensors can be utilised. These sensors provide high-time resolution data in near real-time, improving the estimation of spatial and temporal variability of air pollutants. They support ambient modelling, exposure assessments, and health effects studies. However, it is essential to thoroughly evaluate the performance specifications of these sensors to ensure they meet designated monitoring objectives and data quality standards.

In addition to technological advancements, multi-pollutant monitoring also involves understanding the complex mixture of pollutants and atmospheric transport mechanisms. Real-time and time-integrated sampling devices are employed to measure air quality at multiple distances and heights from major roadways, providing continuous assessments of near-road air pollutant concentrations. This information is crucial for developing effective air pollution control strategies and policies.

Electrostatic precipitators

The first electrostatic precipitator was invented by Frederick Gardner Cottrell, a professor of chemistry at the University of California, Berkeley, in 1907. Cottrell's device charged particles and then collected them through electrostatic attraction. He first applied this device to the collection of sulphuric acid mist and lead oxide fumes emitted from various acid-making and smelting activities.

The most basic precipitator design consists of a row of thin vertical wires and a stack of large flat vertical metal plates. The plates are spaced from less than 1.3 cm (0.5 inch) to about 17.8 cm (7 inches) apart, depending on the application. Dry electrostatic precipitators operate above the dew point of the gas stream to remove impurities from smoke and dust. Wet electrostatic precipitators, in contrast, operate with saturated airstreams that have 100 percent relative humidity. Wet precipitators are commonly used to remove liquid droplets, including oil, resin, tar, and sulfuric acid mist, from gas streams in industrial settings.

Frequently asked questions