Movement of Pollutants from the Source

A pollutant is defined as "a substance that occurs in the environment, at least in part as a result of human activities, and has a deleterious effect on the environment." The term pollutant is a broad term that refers to a wide range of compounds, from a superabundance of nutrients giving rise to enrichment of ecosystems to toxic compounds that may be carcinogenic, mutagenic, or teratogenic. Pollutants can be divided into two major groups, namely, those that affect the physical environment and those that are directly toxic to organisms, including human beings. The movement of pollutants and toxic compounds through the environment is called pollution (Fig. 1-1) and is very similar to the movement of energy and nutrients within the ecosystem or, on a larger scale, through the biosphere.

Figure 1-1: Movement of pollutants. VOC, volatile organic compound.

Rapid industrialization in the twentieth century had led to the generation of vast amounts of gas, liquid, and solid waste that were introduced into the environment without much thought by the manufacturers of that waste. This has affected the ecosystem and has caused health problems for the inhabitants residing near the factories. As people became more aware of the toxic effects of this waste, as they saw the destruction of the ecosystem due to the indiscriminate discharge of the pollutants, and as federal and local laws imposed more stringent discharge norms, efforts were made to treat these wastes so as to make them innocuous before...