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 Waste Water
Dealing With Waste Water
An enormous problem is dealing with water that has become
polluted. Storm water management ponds filter the runoff from highways,
construction sites, and city
streets.
Photo Courtesy of the U.S.
Fish
& Wildlife Service
These management ponds are often equipped with wetland
plants that assist in cleaning the waste water. This water from runoff
rests allowing for soil and chemicals to settle to the bottom while the
cleaner water moves on through the ecosystem.
Water pollution has been attributed to three main
causes: human population growth, industrialization, and natural resource
development.
The average person uses 150 gallons of water a day
that is drawn from natural resources. Water pollution is any extraneous
matter in water harmful to living beings.
The extraneous matter might include substances such as chemicals, bacteria,
heat, or any other harmful substances to humans and aquatic life.
Where Does Your Water Come From? And Go To?
Water treatment plants pump water from a natural
resource, lakes, rivers, or groundwater. They first must treat the water,
and then pump the treated water into holding tanks and towers before people
can use the cleaned water.
Water treatment plants clean water by letting dirt
settle, filtering, and then adding chemicals such as chlorine to kill
germs. In the case of many cities and towns after the clean water has been
used the waste water from homes and businesses goes into the sewer system.
Underground pipes move sewage from city neighborhoods
back to a sewage treatment plant. Primary treatment is the first part of
treating and cleaning up the waste water. This is where the water is moved
through screens that removes large particles of waste. The heavier waste
particles settle to the bottom and the water moves into the next phase of
treatment.
In the next treatment phase, one half of the
pollutants have been removed. Now the water is aerated, meaning, air is
added and bacterial microorganisms will consume the remaining waste
material.
In the third phase, the water enters another
settling tank where the heavier polluted particles, called sludge, settle
to the bottom. This sludge is then pumped into a larger tank along with the
particles from the first phase. These combined wastes are heated and more
bacteria break down the material reducing its volume, and killing disease
causing organisms. The treated sludge is finally properly disposed of
either in a land fill, or used as fertilizer.
Sometimes waste water is filtered through sand to
eliminate any remaining odors and solids. The final process is where the
waste water is treated with chlorine and is put back into a river, lake, or
the ocean.
In some cases the waste water will go through one
more process called tertiary treatment. This is where the waste water is
treated much like drinking water. The water that goes through the tertiary
process is reused to irrigate parks, golf courses, school yards, and some
food crops.
Waste Water Pollution and Water Contamination
Point source pollution is pollution discharged or
stemming from a single source.
Non-point source pollution is pollution generated from a diffuse source
rather than one specific, identifiable source. Heavy rainfall often
increases non-point pollution by washing sediment and contaminants from
fields and cities into surface water.
Water contamination is different from water
pollution. Water contamination is the dirtying of water resources through
natural processes. Water pollution is the dirtying of water resources,
mostly by human-generated wastes.
Thermal pollution is caused when industries use
water as a coolant. In this industrial use of water the water absorbs heat
and then is returned to a pond, stream, river, or lake before it is cooled.
If this continues for prolonged periods of time the hot water can actually
harm and kill fish, wildlife, and aquatic plants.
A major side effect of thermal pollution is that it
also reduces oxygen in in the water and thus
harms plant and animal life by starving them for air.
It is more difficult for a lake to recover from contamination than a river,
because rivers "overturn" and circulate nutrients and oxygen from
top to bottom and bottom to top.
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