Transcript Groundwater Pollution

Water Pollution
G. Tyler Miller’s
Living in the Environment
12th Edition
Chapter 19
Dr. Richard Clements
Chattanooga State Technical Community College
Key Concepts
 Types, sources, and effects of water pollutants
 Major pollution problems of surface water
 Major pollution problems of groundwater
 Reduction and prevention of water pollution
 Drinking water quality
Types and Sources of Water
Pollution
Point sources
Refer to Tables 19-1 and
19-2 p. 477 and 478
Nonpoint sources
Biological oxygen
demand
Water quality
Water
Quality
Do (ppm) at 20˚C
Good
8-9
Slightly
polluted
6.7-8
Moderately
polluted
Heavily
polluted
Gravely
polluted
4.5-6.7
Below 4.5
Below 4
Fig. 19.2, p. 478
Pollution of Streams
 Oxygen sag curve  Factors influencing recovery
Types of
organisms
Clean Zone
Normal clean water organisms
(Trout, perch, bass,
mayfly, stonefly)
8 ppm
Decomposition Septic Zone
Zone
Trash fish
(carp, gar,
Leeches)
Fish absent, fungi,
Sludge worms,
bacteria
(anaerobic)
Recovery Zone
Trash fish
(carp, gar,
Leeches)
Clean Zone
Normal clean water organisms
(Trout, perch, bass,
mayfly, stonefly)
8 ppm
Concentration
Dissolved oxygen
Oxygen sag
Biological oxygen
demand
2 ppm
Direction of flow
Point of waste or
heat discharge
Time of distance downstream
Fig. 19.3, p. 479
Pollution of Lakes
 Eutrophication
 Slow
turnover
Thermal
stratification
Discharge of untreated
municipal sewage
(nitrates and phosphates)
Nitrogen compounds
produced by cars
and factories
Discharge of
detergents
( phosphates)
Discharge of treated
municipal sewage
(primary and secondary
treatment:
nitrates and phosphates)
Natural runoff
(nitrates and
phosphates
Manure runoff
From feedlots
(nitrates and
Phosphates,
ammonia)
Runoff from streets,
lawns, and construction
Lake ecosystem lots (nitrates and
nutrient overload
phosphates)
and breakdown of
chemical cycling
Runoff and erosion
Dissolving of
(from from cultivation,
nitrogen oxides
mining, construction,
(from internal combustion
and poor land use)
engines and furnaces)
Fig. 19.5, p. 482
Case Study: The Great Lakes
CANADA
Nipigon Bay
Thunder Bay
Jackfish Bay
Silver Bay
St. Mary’s R.
St. Lawrence R.
Spanish R.
St. Louis R.
MICHIGAN
Penetary Bay
Sturgeon Bay
WISCONSIN
MICHIGAN
MINNESOTA
IOWA
ILLINOIS
Saginaw
Niagara Falls NEW
Saginaw R.Bay Grand R.
System
Niagara R.
St. Clair R. Thames R.
Buffalo R.
Detroit R.
Rouge R.
Ashtabula R.
Raisin R.
Cuyahoga
R. PENNSYLVANIA
Maumee R.
Rocky R.
Black R.
INDIANA
YORK
OHIO
Great Lakes drainage basin
Most polluted areas, according to the Great Lakes Water Quality Board
“Hot spots” of toxic concentrations in water and sediments
Eutrophic areas
Fig. 19.7, p. 484
Groundwater Pollution: Sources
 Low flow rates
 Few
bacteria
 Cold temperatures
Waste lagoon,
pond, or basin
Hazardous
waste
injection
well
Buried gasoline
and solvent
tanks
Mining
site
Water
pumping
well
Pumping
well
Road
salt
Sewer
Landfill
Cesspoll,
septic
tank
Leakage
from faulty
casing
Unconfined freshwater aquifer
Groundwater
Confined freshwater aquifer
Groundwater flow
Fig. 19.9, p. 487
Confined aquifer
Discharge
Groundwater Pollution Prevention
Monitoring aquifers
Leak detection systems
Strictly regulating hazardous waste
disposal
Storing hazardous materials above
ground
Ocean Pollution
Industry
Nitrogen oxides from autos
and smokestacks; toxic
chemicals, and heavy
metals in effluents flow
into bays and estuaries.
Cities
Toxic metals and
oil from streets and
parking lots pollute
waters; sewage
adds nitrogen and
phosphorus.
Urban sprawl
Bacteria and
viruses from sewers
and septic tanks
contaminate shellfish
beds and close
beaches; runoff
of fertilization from
lawns adds nitrogen
and phosphorus.
Closed
beach
Construction sites
Sediments are washed into waterways,
choking fish and plants, clouding
waters, and blocking sunlight.
Farms
Run off of pesticides, manure, and
fertilizers adds toxins and excess
nitrogen and phosphorus.
Red tides
Excess nitrogen causes explosive
growth of toxic microscopic algae,
poisoning fish and marine mammals.
Closed
shellfish beds
Oxygen-depleted
zone
Toxic sediments
Chemicals and toxic metals
contaminate shellfish beds,
kill spawning fish, and
accumulate in the tissues
of bottom feeders.
Healthy zone
Clear, oxygen-rich waters
promote growth of plankton
and sea grasses, and support fish.
Oxygen-depleted zone
Sedimentation and algae
overgrowth reduce sunlight,
kill beneficial sea grasses,
use up oxygen, and degrade habitat.
Fig. 19.11, p. 489
Case Study: Chesapeake Bay
 Largest US
estuary
Cooperstown
NEW YORK
PENNSYLVANIA
Harrisburg
 Relatively shallow
MARYLAND
Baltimore
WEST
VIRGINIA
 Slow “flushing”
action to Atlantic
Washington
ATLANTIC
OCEAN
NEW
JERSEY
DELAWARE
Richmond
VIRGINIA
Drainage
basin
Norfolk Chesapeake Bay
No oxygen
 Major problems with dissolved O2
Low concentrations
of oxygen
Fig. 19.13, p. 490
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
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
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
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.
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