Water Pollution
Water Pollution
Water Pollution
Water Pollution
Outline
• Types and Effects of Water
Pollution
– Point vs. Non-Point Sources
• Water Quality Today
– Surface Water
– Groundwater
– Ocean Water
• Water Pollution Control
– Source Reduction
– Municipal Sewage Treatment
• Water Legislation
– Clean Water Act (1972)
Water Pollution
• Any physical, biological, or
chemical change in water
quality that adversely
affects living organisms or
makes water unsuitable for
desired uses can be Pollution originating from a single,
considered pollution. identifiable source, such as a discharge
– Point Sources - discharge pipe from a factory or sewage plant, is
pollution from specific called point-source pollution.
locations
• Factories, power plants, drain
pipes
– Non-Point Sources - scattered
or diffuse, having no specific
location of discharge
• Agricultural fields, feedlots
Atrazine is a herbicide, applied in the spring to kill
• Infectious Agents
– Main source of waterborne pathogens is improperly treated
human waste
• Animal waste from feedlots and fields is also important source of
pathogens.
– At least 2.5 billion people in less developed countries lack adequate
sanitation, and about half of these lack access to clean drinking water.
Infectious Agents
• In developed
countries, sewage
treatment plants and
pollution-control
devices have greatly
reduced pathogens.
– Coliform bacteria -
intestinal bacteria;
used to detect water
contamination
– Drinking water
generally disinfected
via chlorination
Oxygen-Demanding
Wastes
• Water with an oxygen content >
6 ppm will support desirable
aquatic life.
– Water with < 2 ppm oxygen will
support mainly detritivores and
decomposers.
cyanobacteria
Oxygen-Demanding Wastes
• Biochemical Oxygen
Demand - amount of
dissolved oxygen consumed
by aquatic microorganisms.
Used as a test for organic
waste contamination.
• Dissolved Oxygen Content -
measure of dissolved oxygen
in the water
• Effects of oxygen-demanding
wastes on rivers depend on
volume, flow, and
temperature of river water.
– Oxygen Sag - oxygen levels
decline downstream from a
pollution source as
decomposers metabolize
waste materials
Oxygen Sag
Plant Nutrients and
Cultural
Eutrophication
• Oligotrophic - bodies of water
that have clear water and low
biological productivity
• Eutrophic - bodies of water that
are rich in organisms and
organic material Oligotrophic
– Eutrophication - process of
increasing nutrient levels and
biological productivity
• Cultural Eutrophication -
increase in biological
productivity and ecosystem
succession caused by human
activities
– Algal blooms often result.
Decomposing algae rob
water of oxygen.
Eutrophic
The effects of possibly agricultural runoff in the Danube can be seen in this SeaWiFS
image as the river empties into the Black Sea at the bottom of this image.
• Until about 70 years ago, most rural areas in the U.S. depended on
outhouses, which contaminated drinking water supplies.
• Wetlands
– Effluent flows through
wetlands where it is filtered
and cleaned by aquatic
plants and microscopic
organisms.
Water Remediation
• Containment methods confine liquid wastes in place, or cap surface
with impermeable layer to divert water away from a site that is
causing pollution.
• Extraction techniques are used to pump out polluted water for
treatment.
– Oxidation, reduction, neutralization, or precipitation of contaminants
• Living organisms can also be used to break down pollution (called
bioremediation).
Ecological Engineering
• Ocean Arks International designs vessels that combine living
organisms with containment. In a machine, water flows through a
series of containers, each with a distinctive biological community.
Waste from one vessel becomes the food for the next vessel.