Environmental Microbiology: Treatment of Water, Wastes, and Polluted Habitats

Delivering fresh water to urban areas and removing human wastes have been practiced at least since Roman times. Ruins of aqueducts used to deliver fresh water long distances can be seen today in many parts of Europe. Ridding cities of human wastes has been more difficult, and the sewers that were used until the mid-nineteenth century were not much more than large, open cesspools.

Long before the discovery of the microbial world, it was recognized that some diseases are associated with water supplies. As early as 330 B.C., Alexander the Great had his armies boil their drinking water, a habit that probably contributed to his huge successes. Certainly, many battles have been lost over the years as a result of waterborne diseases that decimated the combatants. Years before the cholera-causing Vibrio cholerae was identified, it was obvious that cholera epidemics were associated with drinking water. The desire for clean, clear water led to the use of a sand filtration system in London and elsewhere in the early nineteenth century. Late in that century, Robert Koch showed that not only did this kind of filtration yield clear water, it also removed more than 98% of bacteria from the water.

As early as the 1840s, Edwin Chadwick, an English activist, championed a new idea on how wastes could be removed. His idea was to construct a system of narrow, smooth ceramic pipes through which water could be flushed along with solid waste materials. This system would carry the waste materials away from the inhabited part of the city to a distant collection site. There, he hoped to collect the waste materials and turn them into fertilizer to sell to farmers. The system he envisioned required the installation of new water and sewer pipes along with pumps to deliver water under pressure to houses. With the water under pressure and smooth narrow pipes, the system could be kept well flushed.

In 1848, with the threat of a cholera epidemic imminent, the Board of Health in England instituted widespread reforms and began the installation of a sewage system along the lines envisioned by Chadwick. New York City did not establish its Board of Health and a proper sewage disposal system until 1866, again in response to a threatened cholera epidemic. By the end of the nineteenth century, most large European and U.S. cities had established water-sewer systems to deliver safe drinking water and remove and treat waste materials. Cholera in the industrialized nations of Europe and North America virtually disappeared.

—A Glimpse of History

MOST PEOPLE LIVING IN DEVELOPED COUNTRIES take for granted that their tap water is safe to drink, their wastes will reliably disappear into sewers or landfills for proper disposal, and pollutants, substances that are harmful or injurious, will not accumulate in the environment. They seldom consider the role that microbes play in these essential aspects of modern life.

Microorganisms are important in the treatment of water, waste, and polluted environments for two very distinct reasons. We benefit from the fact that microbes are the ultimate recy-clers, playing an essential role in the decomposition of our wastes. At the same time, pathogenic microorganisms and viruses must be eliminated from sewage before it is discharged, and removed from drinking water before it is deemed potable, or safe for human consumption. Recreational waters such as swimming pools, water parks, lakes, rivers, and shorelines are also monitored to ensure they do not contain or accumulate harmful levels of certain pathogens.

Treatment of water, waste, and polluted habitats is a formidable challenge, particularly in densely populated areas. Consider that every day the average American uses about 150 gallons of water, and produces 120 gallons of sewage and 5 pounds of trash. This means that a city with only 1 million inhabitants is faced with the disposal of approximately 44 billion gallons of sewage and a million tons of trash each year!

Nester-Anderson-Roberts: I V. Applied Microbiology I 31. Environmental I I © The McGraw-Hill

Microbiology, A Human Microbiology: Treatment of Companies, 2003 Perspective, Fourth Edition Water, Wastes and

Polluted Habitats

Chapter 31 Environmental Microbiology: Treatment of Water,Wastes, and Polluted Habitats

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