Transcript File

WATER POLLUTION
PART I
NINE TYPES OF WATER
POLLUTANTS
• Disease Causing Agents
• Sediment Pollution (suspended solids)
• Inorganic Chemicals and Oxygen-Demanding
Wastes
• Organic Chemicals and Oxygen-Demanding
Wastes
• Water-Soluble Radioactive Isotopes
• Thermal Pollution
• Genetic Pollution (non-native species)
DISEASE CAUSING AGENTS
• Bacteria, viruses, protozoa, parasitic worms.
• Waterborne Diseases – typhoid, cholera, bacterial dysentary, polio,
and infectious hepatitis.
• Cause of Typhoid fever: Salmonella typhi bacteria from food or
water or if sewage contaminated with S. Typhi bacteria gets into the
water you use for drinking or washing food. “Typhoid Mary”
• Cause of Cholera: Feces exposure from poor hygiene and
sanitation of food or water. A person may get cholera by drinking
water or eating food contaminated with the cholera bacterium.
• Common in developing nations. Threat following Katrina in USA!
DISEASE CAUSING AGENTS
• Pfiesteria piscida – “Cell from hell”
• A microscopic organism that can behave as both a plant and animal
cell. Flips from an algae eater into a fish-eating dinoflagellate.
• Lacks suitable prey to keep population in check.
• Releases neurotoxins that kill fish within 10 hours and the
neurotoxins form an aerosol above the water and can harm humans.
• Pfiesteria live in waters from Chesapeake Bay to Florida.
• Scientific research show increased population growth of Pfiesteria
associated with cultural eutrophication from hog farms.
• Joanne Burkholder’s research was not well-received from law
makers and big business. Her research indicates that farmers need
to implement nutrient-loading management plans and that
government needs to implement policy and regulations to limit
Pfiesteria outbreaks to protect human health!
SEDIMENT POLLUTION
• “Sediment Kills Reefs”
• Sediment releases into surface waters due to poor land
management decreases water clarity, increases turbidity, buries
organisms, decreases the availability of light for photosynthesizing
organisms, and brings insoluble toxic pollutants including PCB’s
and DDT.
• 1.3 million pounds of PCB’s in Hudson River from GE Plant. Must
dredge 2.6 million yards! Long residence time in environment.
• DDT banned in the USA for application BUT we are the #1
producers of DDT for sales worldwide! Long residence time in
environment. DDT (50years), DDE (200 years).
INORGANIC CHEMICALS
(water-soluble nutrients)
• Heavy metals such as mercury (Hg) and lead (Pb) from industry,
mines, irrigation runoff, oil drilling, and urban runoff from storm
sewers. (point source and non-point source pollution)
• Lead (Pb) – additives in gasoline (MTBE’s) contaminate the air.
Lead gas banned in the USA (still available in other parts of the
world). It is also present in incinerator ash. This is classified as
“hazardous” waste and must be disposed of in a special landfill. It
leaches into groundwater. Residues can also be found on food
resources located downwind from incinerators. Lead paints –
banned in USA, but can still be found in buildings.
• Greatest risk for Pb poisoning are mid-aged men (high blood
pressure), pregnant woman (miscarriage, premature births and
stillbirths), and young children (mental/physical impairments –
hearing loss, hyperactivity, ADD, low IQ, LD).
INORGANIC CHEMICALS
(water-soluble nutrients)
• Mercury (Hg) – mostly from industrial processes
(wastewater), also from batteries, paints and plastics
burned in incinerators. Burning converts it to methyl
mercury which readily enters food webs.
• Bioaccumulation in muscle of tuna, shark, and swordfish.
• Biomagnification since they are top predators.
• Long residence time in environment – toxic to humans
and causes mental retardation in children and kidney
failure.
BIOACCUMULATION AND
BIOMAGNIFICATION
Biomagnification
• Nitrogen and phosphorous loading (cultural eutrophication causes
and increase in algae (bloom) which causes a decrease in DO
resulting in the death of aquatic organisms. Decomposing aerobic
bacteria continue using DO (increase in BOD) in water until the
conditions become Anoxic!
SEPTIC TANKS
Septic tanks are used in areas where there are no combined sewers.
Septic tanks
(cesspools) must be
emptied each year.
Old tanks can crack
and leak coliform
bacteria into
surrounding soil,
groundwater, and
surface waters.
Figure 9-28
Page 196
Septic tank with
manhole (for cleanout)
Household
wastewater
Non-perforated pipe
Distribution box (optional)
Gravel or
crushed
stone
Drain
field
Vent pipe
Perforated pipe
SEWAGE TREATMENT
• Sewage treatment
means removing
impurities so that the
remaining waste water
can be safely returned
to the surface waters
(river, bay, ocean) and
become part of the
natural water cycle
again.
• sewage treatment
separates solids from
liquids by physical
processes and purifies
the liquid by biological
and chemical processes
PRIMARY TREATMENT
• solids like wood,
paper, rags and
plastic are removed
by screens, washed,
dried and taken
away for safe
disposal at a
licensed waste tip.
Grit and sand, which
would damage
pumps, are also
removed by settling
tanks and disposed
of in a similar way.
PRIMARY TREATMENT
• the remaining solids are separated
from the liquid by passing the sewage
through large settlement tanks, where
most of the solid material sinks to the
bottom. About 70% of solids settle out
at this stage and are referred to as
sludge. The sludge is used on farms
after further treatment called sludge
treatment.
SLUDGE TREATMENT
•
Sludge is an excellent soil conditioner and is used as a fertilizer on
farmland. However, it needs additional treatment to make it suitable. This
treatment is called anaerobic digestion and takes place in large, enclosed
tanks. NYC sludge has too many heavy metals (Hg, Pb, Cd, Cu) and may
not be used as a soil amendment for food resources in NY State.
•
The rate of digestion is increased by heating the sludge to a temperature
where naturally occurring bacteria (microorganisms) respond to these
comfortable conditions and feed on other bacteria. On cooling, the well-fed
bacteria die off, and the sludge is suitable for use on agricultural land.
•
A by-product of the sludge digestion process is methane gas. This can be
burned to produce electricity. The electricity can be used to heat more
sludge or to provide heat and light for the treatment works. Sometimes more
energy is produced than is required. The surplus is sold to local electric
companies.
SECONDARY TREATMENT
• a biological process which relies
on naturally occurring
microorganisms acting to break
down organic material and purify
the liquid.
• In a simple sewage treatment
process, micro-organisms are
encouraged to grow on stones
over which the sewage is trickled.
They feed on the bacteria in the
sewage and purify the water.
These treatment units are called
percolating filters.
SECONDARY TREATMENT
•
The rate of this process
can be increased by
pumping air into tanks of
sewage where the aerobic
digesters float freely and
feed on the bacteria.
These treatment units are
called aeration tanks.
•
Following either form of
secondary treatment, the
waste water is settled in
tanks to separate the
biological sludge from the
purified waste water.
TERTIARY TREATMENT
• Extra treatment is
needed to give the
waste water a final
"polish". This is known
as tertiary treatment.
Various methods may
be used, including sand
filters, reed beds or
grass plots (artificial
treatment wetlands).
Disinfection, using ultra
violet light to kill
bacteria, is another
method, and is being
used at a number of
coastal sewage
treatment plants.
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
(Sludge cake or pellets)
IMPACTS FROM ORGANIC WASTE
8 ppm
8 ppm (mg/L)
WAYS TO REDUCE CULTURAL
EUTROPHICATION
• Advanced waste treatment (sewage and industrial)
• Regulate detergents cleaning products for phosphates.
They have been regulated since the 1970’s on Long
Island!
• Promote soil conservation and preservation of wetlands
to capture and filter pollutants before they enter surface
waters.
• Regulate fertilizer, pesticide, agricultural and livestock
runoff to control Nitrogen, phosphate, and PAH’s.
• Create policies and economic incentives
for doing these things!
ORGANIC CHEMICALS
(Synthetic)
• Pesticides, solvents, industrial chemicals, and plastics, oil, gasoline,
and MTBE’s.
• Many are hydrocarbons (PAH’s) and leach into soil and
groundwater. All of these are toxic to aquatic organisms.
• Standards: benzene (1ppb) (DDT)
•
MTBE (5 ppb)
• As soon as Clean Air Act Ammendments of 1990 went into effect,
childhood asthma increased as well as bronchitis, depression, and
nuerological disorders.
• Senator Marcellino wants to remove the mandate for MTBE’s. New
Hampshire is the only state that has outlawed MTBE’s.
• Problematic due to NAFTA – violates Article 11
• Oil Spills – Exxon Valdez
EXXON VALDEZ OIL SPIILL
•
On March 24, 1989, shortly after midnight, the oil tanker Exxon Valdez struck Bligh
Reef in Prince William Sound, Alaska, spilling more than 11 million gallons of crude
oil. The spill was the largest in U.S. history. Capt. Joe Hazelwood, who later admitted
to having had several alcoholic drinks that day, (From Huntington, Long Island). In
jail NOW!
•
The spill posed threats to the delicate food chain that supports Prince William
Sound's commercial fishing industry. Also in danger were ten million migratory shore
birds and waterfowl, hundreds of sea otters, dozens of other species, such as harbor
porpoises and sea lions, and several varieties of whales.
•
In the aftermath of the Exxon Valdez incident, Congress passed the Oil Pollution Act
of 1990, which required the Coast Guard to strengthen its regulations on oil tank
vessels and oil tank owners and operators. Today, tank hulls provide better protection
against spills resulting from a similar accident, and communications between vessel
captains and vessel traffic centers have improved to make for safer sailing.
OIL SPILLS
• Spills occur at offshore oil drilling rigs during natural disasters
(Katrina) and due to human error. They are called “blowouts”
• Spills occur from tanker accidents.
• Damage to environment from oil spills is dependent on type of oil
(crude oil most toxic due to benzene and toluene), weather
conditions, season, and type of organisms in the area.
• Oils spill cleanup is difficult and EXPENSIVE. It is very difficult to
save animals who have ingested the hydrocarbons into their
digestive tracts, especially aquatic birds who preen to insulate
themselves.