Ch. 22 Water Pollution

1

• Ch. 22 Water Pollution

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Oil Spills

• Sources offshore wells, tankers, pipelines and
  storage tanks

• Effects death of organisms, loss of animal
  insulation and buoyancy, smothering

• Significant economic impacts

• Mechanical cleanup methods skimmers and blotters

• Chemical cleanup methods coagulants and
  dispersing agents

3
Solutions Preventing and Reducing Surface Water
Pollution
Nonpoint Sources
Point Sources

• Reduce runoff

• Clean Water Act

• Buffer zone vegetation

• Water Quality Act

• Reduce soil erosion

4
Steps in Water Purification

• Water comes from the stream
• Settling pond - Al2(SO4)3 - ALUM added, pulls
  clay particles downward
• Filtration - passing it through porous material
  (sand)
• Adsorption - use of Carbon to remove organic
  pollutants
• Biological oxidation - use of bacteria microbes
  - oxygen helps the organisms grow eliminate
  colloidal particles
• Disinfection - addition of Chlorine, Ozone, or UV
  to eliminate harmful pathogens
• Voluntary fluoride treatment storage in water
  tower for drinking water

5
Technological Approach Septic Systems

• Require suitable soils and maintenance

Fig. 19.14, p. 494
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Technological Approach Sewage Treatment

• Mechanical and biological treatment

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Waste Water Treatment

• Primary
• mechanical
• Secondary
• biological

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Steps in Wastewater Treatment

• Wastewater - sanitary sewer pipes
• Pre-treatment - bar screen removes debris
• Primary
• 1. settling tank- (removes grit)
• 2 clarifier- (lets sludge settle while oil
  removed by skimmer)

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Primary Treatment - Clarifier
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Primary Treatment (Oil Skimmer)
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Steps in Wastewater Treatment

• Secondary
• 1 aeration tank
• colloids organics removed by hungry bacteria
  -aeration increases bacterial growth
• activated sludge
• 2 clarifier-
• lets activated sludge settle
• some reused in aeration tank
• rest goes to anaerobic digester
• 3 disinfection- by Chlorine, Ozone, or sunlight
  in Wetland

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Secondary Treatment - Biological Oxidation
(Aeration Tank)
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Technological Approach Advanced Sewage Treatment

• Removes specific pollutants

Fig. 19.16, p. 495
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Wastewater Treatment Tertiary

• Removal of chemicals (P, N, etc) - not required!
• Anaerobic digester
• sludge from primary/secondary treatment
• breaks down waste further
• disposed in a landfill/treated/used as
  fertilizer
• Water returned to the stream

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After Anaerobic Digestion of Sludge Activated
Sludge - Uses
Biogas produced during anaerobic digestion -
used as fuel Co-composting combined
post-consumer waste paper w/treated sludge
decomposed by bacteria - use as fertilizer
animal crops only Pasteurization drying
sludge in ovens kill pathogens pellets -
sold as fertilizer
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Technological Approach Using Wetlands to Treat
Sewage
Fig. 19.17, p. 497
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Wetland Functions

• Disperses volume of flow
• moderates flow of water - less storm damage
• Recharge groundwater from surface water
• Removes sediment
• Removes excess organic nutrients - microbial
  decomposition
• Increased availability - limiting nutrients
• Creates ecosystem -habitat for animals

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Emergent Wetlands
dominated by perennial plants cattails, sedges
cordgrass which are rooted in bottom
sediments emerge above the surface of the water
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Federal LAWS Protecting Wetlands
Rivers Harbors Act of 1899 - establishes a
program to regulate activities affecting
navigation in US waters
Duck Stamp Act of 1934 - allocates funds for the
acquisition of land for migratory birds
Clean Water Act (Section 404) - establishes a
program to regulate the discharge of dredged and
fill material into water of the US
Food Securities Act of 1985 - establishes rules
for farmers concerning use of wetlands prior or
since 1985 for farming.
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N. A. Wetlands Conservation Act - provides for
voluntary action to create wetlands under a grant
program
Coastal Wetlands Planning, Protection,
Restoration Act - to grant funds to coastal
states to carry out coastal wetlands conservation
projects.
There are a number of regulations that give
various agencies such as the EPA, the Army Corps
of Engineers, and the US Department of
Agriculture the power to oversee and implement
regulations provided for by these Acts.
Having several government agencies oversee
different parts of these regulations creates
friction and leaves gaps in the implementation of
these regulations.
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Wetland Mitigation
If a construction project allows the destruction
of a wetland (allowable by a permit from the Army
Corps of Engineers) then another area of equal or
larger size, has to be created as a new wetland.
The lands are usually sold by private owners to
corporations, that act as mitigators, for the
purpose of restoring what was once a wetland or
to create a new wetland.
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Drinking Water Quality

• Bottled water

• Safe Drinking Water Act

• Maximum contaminant levels

Fig. 19.10, p. 488