Chapter 16
Environmental Engineering and the Technology of Clean Air

Introduction

Content

Objectives

Quiz

Links

Graphs

glossary

Corrections

Updates

Amendments

Introduction

Many of the environmental challenges that society is confronted with have been addressed by devising technical solutions. Providing society with water, air, and soil, combating pollution and taking care of waste are such challenges. Environmental engineering is the field where the knowledge, theory and skills in these matters are developed and practiced. As the requirements on industry and many other activities regarding good environmental performance is sharpened the role of environmental engineers is increasing.

Technical systems monitor and track pollutants. In the case of monitoring air pollution this has today reached a high degree of sophistication. Automated systems are used for constant monitoring of air in cities especially along heavily trafficked roads. The systems may advise people to choose the best routes to travel, and when people with asthma should avoid being outdoors. Air quality and weather data are used together in computer systems to calculate the dispersion of pollutants. They are also used to track sources of pollution, such as factories, that today all are operating under specified permits for what may be emitted. The systems are also used to simulate how air quality would be influenced by proposed roads or industries and thus serve as a background for urban planning and investments. Also pollution of water is surveyed automatically by technical systems to track quality changes and dispersion of pollutants, e.g. in the case of polluted ground water.

Technology also has a major role in removal of pollutants from emissions and other exhausts. Both gaseous emissions and waste water is treated by so-called end-of-pipe techniques. In some cases an efficient treatment of exhausts is possible. For example, acidifying sulphur oxides can be removed efficiently from flue gases, and car exhausts can be cleaned to 90% in post-treatment in so-called catalytic converters placed after the motor. But some other pollutants are difficult to remove, such as many chlorinated hydrocarbons, or even impossible. Thus carbon dioxide from combustion is normally not removed at all although it is considered harmful due to its influences on climate.

The provision of air, water, and soil as resources is also a technical task. Water is sometimes treated extensively to be suitable for drinking. Also, air for ventilation is normally treated, e.g. filtered to remove particles.

It is clear that technical solutions as those mentioned have their limitations, and new approaches are today making environmental engineering a much broader discipline than it was previously. It is better, and often even necessary, to avoid pollutants rather than removing them. This "source reduction" or "waste minimization" approach requires that the engineer examines the process itself and redesigns it. This may be more difficult than the traditional end-of-pipe approach but better. Economically it is obviously better to produce products rather than waste or pollution. The new role of the environmental engineer asks for good use of resources, no pollution in the processes and that waste or by-products are used in new production. This is the "cleaner production" approach. As this way of working is spreading in industry, its better technology, economy, and environmental results are recognized.

In this chapter the basic tasks of the environmental engineer will be discussed, and management of air described in more detail. In the following chapters water issues and management of solid waste and contaminated soil are discussed.