ES293 Chapter Notes - Chapter 3: Methemoglobinemia, Methyl Tert-Butyl Ether, Miscarriage
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Chapter 3: water quality and water resources:
Diarrheal deaths, most due to waterborne infectious agents,.
While the widespread use of oral rehyderation thearphy has substantially reduced
the mortality associated with waterborne disease, intensive efforts to provide
improve water and sanitary infrastructure in developing nations have been less
Growing evidence indicates that updating the means of disposal of human wastes
improves human health to a greater extent than purveying clean water supplies.
Sources of water:
Drinking water is obtained primarily from surface water, such as streams, rivers
and lakes or from ground water through artesian or other types of wells.
Other means of obtaining water include collecting rainwater, desalinating
Surface water is in general, more prone to contamination by both microbial
pathogens and chemicals since it directly receives industrial and municipal
wastewater and runoff from the land.
Ground water usually less contaminated than surface water because the soil
through which it proclates serves as a filter.
Uses of water:
Most water is used by toilets, and then cloth washers, showers, faucets, leaks,
other domestic and dishwasher.
Sources of contamination:
Contaminants can enter drinking water by a variety of mechanism.
Many chemicals such as pesticides and fertilizers enter drinking water sources
after being deliberately applied to the land and washing into surface or ground
Can also enter water through moving through the soil
Our methods of treating and distributing drinking water lead to some chemical
being present within our drinking water supplies.
Sources of contaminants that discharge into receiving waters from a pope or other
identifiable device are called point sources.
Point sources include industrial wastes and sewage treatment plants.
Sources of contaminations that cannot be defined by discrete pipes or other
devices are called non-point sources.
Water treatment process:
The developed world reduced the burden of waterborne disease outbreaks by
implementing a process to treat drinking water in the late nineteenth and early 20th
First water is pumped from its sources. The next step involves adding a chemical
Water with chemical contamination may need to undergo additional treatment at
this stage, such as activated charcoal or special ion exchange resins.