Transcript Clean Water Act

Ch. 22 Water Pollution
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
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
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
Technological Approach: Septic
Systems
Require suitable soils and maintenance
Septic tank
Manhole (for
cleanout)
Nonperforated
pipe
Household
wastewater
Perforated
pipe
Distribution
box
(optional)
Drain
field
Vent pipe
Gravel or
crushed
stone
Fig. 19.14, p. 494
Technological Approach: Sewage
Treatment
Mechanical and biological treatment
Secondary
Primary
Bar screen
Grit
chamber
Settling tank
Aeration tank
Settling tank
Chlorine
disinfection tank
To river, lake,
or ocean
Raw sewage
from sewers
Sludge
(kills bacteria)
Activated sludge
Air pump
Sludge digester
Sludge drying bed
Disposed of in landfill or
ocean or applied to cropland,
pasture, or rangeland
Fig. 19.15, p. 494
Waste Water Treatment
• Primary
– mechanical
• Secondary
– biological
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)
Primary Treatment - Clarifier
Primary Treatment (Oil Skimmer)
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
Secondary Treatment - Biological Oxidation
(Aeration Tank)
Technological Approach: Advanced
Sewage Treatment
Removes specific pollutants
Effluent from
Secondary
treatment
Alum
flocculation
plus sediments
Desalination
Activated (electrodialysis
Nitrate
carbon or reverse osmosis) removal
98% of
suspended solids
90% of
phosphates
To rivers, lakes,
streams, oceans,
reservoirs, or industries
98% of
dissolved
organics
Recycled to land
for irrigation
and fertilization
Specialized
compound
removal
(DDT, etc.)
Most of
dissolved salts
Fig. 19.16, p. 495
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
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
Technological Approach: Using
Wetlands to Treat Sewage
(1) Raw sewage drains by
gravity into the first pool
and flows through a long
perforated PVC pipe into
a bed of limestone gravel.
(3) Wastewater flows through
another perforated pipe
into a second pool, where
the same process is repeated.
Fig. 19.17, p. 497
Sewage
Treated
water
Wetland type
plants
First concrete pool
Wetland type
plants
45 centimeter
layer of limestone
gravel coated with
decomposing bacteria
(2) Microbes in the limestone gravel
break down the sewage into
chemicals, that can be absorbed
by the plant roots, and the gravel
absorbs phosphorus.
Second concrete pool
(4) Treated water flowing from the
second pool is nearly free of
bacteria and plant nutrients.
Treated water can be recycled
for irrigation and flushing toilets.
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
Emergent Wetlands
dominated by perennial plants
cattails, sedges & cordgrass – which
are rooted in bottom sediments
“emerge” above the surface of the water
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.
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.
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.
Drinking Water Quality
 Bottled water
 Safe Drinking
Water Act
Contaminated Probability
10 to 20 percent
Greater than 20 percent
Not tested
 Maximum contaminant levels
Fig. 19.10, p. 488