Environmental Engineering Reference
In-Depth Information
up into thousands of tiny straws less than three-hundredths the thickness
of a human hair, which help separate out bacteria. This is followed by
reverse osmosis, a process where intense pressure is used to force the
water molecules through a sheet of plastic. Dissolved salts cannot pass
through the membrane. Biological processes may also be used to remove
contaminants. Microorganisms consume the organic matter as food.
After the bugs do their work, chlorine, ultraviolet light, hydrogen per-
oxide, and radiation may used to kill the organisms before the water is
released from the purifi cation plant into streams and the ocean. The
entire process ensures that not even the tiniest bacterium, virus, chemical,
or hormone can survive. According to California's Department of Health
Services, water from such a modern plant is purer than expensive moun-
tain spring water but is piped into streams and the ocean because current
state regulations do not permit the water to be fed directly into homes.
Instead of being fed into streams after leaving the purifi cation plant,
the water may be injected underground to replenish depleted ground-
water supplies that supply drinking water to millions of humans above
ground. Underground injection adds another step, and perhaps an unnec-
essary one, to the decontamination process. A new half-billion-dollar
purifi cation plant in Orange County, California, processes 70 million
gallons of sewage per day that is pumped underground but will eventu-
ally stream out of faucets in people's homes.
Only about a dozen water agencies in the United States recycle treated
sewage to replenish drinking water supplies, but none steers the water
directly into household taps. The concept of toilet-to-tap drinking water
is hard for many people to swallow. Many Americans have a psychologi-
cal barrier to imbibing water that at one stage had fecal matter fl oating
in it. But with education, and as water shortages become more severe,
their fecophobia will be overcome.
Israeli scientists have developed a system that instantly purifi es con-
taminated water, removing organic, biological, and chemical contami-
nants. 28 The technology has been miniaturized to fi t into the top of a
cork that can be plugged into virtually any size bottle, container, or tap.
One cork can purify 250 gallons of water before being replaced, and,
according to the developers, it costs no more than a large coffee and
pastry at an upscale coffee shop. The device is ideal for hikers, soldiers
in the fi eld, or victims of disasters and can prevent the deaths of the 1.6
million children under the age of fi ve who die each year in the undevel-
oped world from drinking untreated water. Impure water is the major
killer of people in the Third World.
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