Water Pollution
Chapter 21
Major water pollutants
• Infectious agents
– Bacteria, viruses, protozoa, parasites
Source – human and animal waste
Effect - disease
Major water pollutants
• Oxygen Demanding Wastes
– Organic waste like manure and plant debris
Effect – decomposing bacteria population soars,
leads to lower dissolved oxygen
Major water pollutants
• Inorganic chemicals
– Water soluble acids, metals (Pb, As, Se, Hg),
and salts
Source – surface runoff, industrial effluent,
household cleansers
Effect – degrade drinking water, skin cancer,
damage nervous system, lower crop yield,
corrode structures
Major water pollutants
• Organic chemicals
– Oil, gasoline, plastics, pesticides, solvents,
detergents
Source – industrial effluents, household cleansers,
runoff from agriculture and yards
Effect – nervous system damage, reproductive
disorders, cancer (oil, gas, solvents)
Major water pollutants
• Plant Nutrients
– Nitrate, phosphate, and ammonium ions
Source – sewage, manure, runoff urban and
agricultural
Effect – cultural eutrophication, drinking water
with excess nitrates lowers oxygen carrying
capacity of blood
Major water pollutants
• Sediment
– Soil, silt
Source – land erosion
Effect – cloud water (less photosynthesis), disrupt
food webs, carry pesticides, cover breeding
areas, fill lakes prematurely
Major water pollutants
• Radioactive Materials
– Iodine, radon, uranium, cesium, and thorium
Source – nuclear power plants, mining, nuclear
weapons, natural sources
Effect – genetic mutations, miscarriages, birth
defects
Major water pollutants
• Heat
• Source – water cooling of power plants,
industrial effluent
• Effect – less dissolved oxygen, more
vulnerable to disease, quick change cause
thermal shock
Types of
organisms
Clean Zone
Decomposition
Zone
Septic Zone
Normal clean water organisms
(Trout, perch, bass,
mayfly, stonefly)
Trash fish
(carp, gar,
Leeches)
Fish absent, fungi,
Sludge worms,
bacteria
(anaerobic)
Recovery Zone
Trash fish
(carp, gar,
Leeches)
8 ppm
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
Slide 3
Water
0.000002 ppm
Herring gull
124 ppm
Phytoplankton
0.0025 ppm
Herring gull eggs
124 ppm
Lake trout
4.83 ppm
Zooplankton
0.123 ppm
Rainbow smelt
1.04 ppm
Fig. 19.4, p. 481
Slide 4
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)
Lake ecosystem
nutrient overload
and breakdown of
chemical cycling
Dissolving of
nitrogen oxides
(from internal combustion
engines and furnaces)
Natural runoff
(nitrates and
phosphates
Manure runoff
From feedlots
(nitrates and
Phosphates,
ammonia)
Runoff from streets,
lawns, and construction
lots (nitrates and
phosphates)
Runoff and erosion
(from from cultivation,
mining, construction,
and poor land use)
Fig. 19.5, p. 482
Slide 5
Industrial
pollution
Suffocated
fish
Beaches
closed
Sewage
runoff
Dead algae
Low
dissolved
oxygen
Mercurytainted fish
Decreased fish
population
Fig. 19.8a, p. 485
Slide 8
Suburban
sprawl
Clear
water
PCB’s in
sediment
Lower
water
levels
High
dissolved
oxygen
Thriving fish
population
Fig. 19.8b, p. 485
Slide 9
Waste lagoon,
pond, or basin
Hazardous
waste
injection
well
Mining
site
Water
pumping
well
Pumping
well
Road
salt
Buried gasoline
and solvent
tanks
Sewer
Landfill
Cesspoll,
septic
tank
Leakage
from faulty
casing
Unconfined freshwater aquifer
Groundwater
Confined freshwater aquifer
Groundwater flow
Confined aquifer
Discharge
Fig. 19.9, p. 487
Slide 10
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
Slide 12
Septic tank
Nonperforated
pipe
Manhole (for
cleanout)
Household
wastewater
Perforated
pipe
Distribution
box
(optional)
Drain
field
Vent pipe
Gravel or
crushed
stone
Fig. 19.14, p. 494
Slide 15
Secondary
Primary
Bar screen
Grit
chamber
Settling tank
Aeration tank
Settling tank
Chlorine
disinfection tank
To river, lake,
or ocean
Raw sewage
from sewers
(kills bacteria)
Sludge
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
Slide 16
Effluent from
Secondary
treatment
Alum
flocculation
plus sediments
Activated
carbon
Desalination
(electrodialysis
or reverse osmosis)
98% of
suspended solids
90% of
phosphates
Nitrate
removal
Specialized
compound
removal
(DDT, etc.)
To rivers, lakes,
streams, oceans,
reservoirs, or industries
98% of
dissolved
organics
Most of
dissolved salts
Recycled to land
for irrigation
and fertilization
Fig. 19.16, p. 495
Slide 17
(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.
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.
Fig. 19.17, p. 497
Slide 18