Transcript Water Pollution - Leuzinger High School

WATER POLLUTION
PART 2
CULTURAL EUTROPHICATION
• Process by which human activity increases the
amount of nutrients entering surface waters
• Nitrates (NO3-) – water soluble, poison water supply, reduce
effectiveness of hemoglobin, contribute to acid rain, may
be related to decline of amphibians
• Phosphates (PO43-) – not water soluble, up 75% from
preindustrial levels
• Lead to algae blooms
STEPS OF AN ALGAL BLOOM
1. Increased algae due to increased nitrate and/or
phosphate concentrations  decreased light
penetration  deeper plants die off  less oxygen
released into the water
2. Increased material for decomposers  decrease
in oxygen concentrations
3. Lower oxygen concentrations  aquatic
organisms die off  water contamination
4. Decaying fish, algae, and other organisms add
toxins to the water.
ALGAL BLOOMS
ALGAL BLOOMS
HOW TO CONTROL FOR
EUTROPHICATION
• Plant vegetation along streambeds
• Slows erosion
• Absorbs some nutrients
• Control application and timing of fertilizer
run off
• Control run off from feed lots
• Use biological controls
• Denitrifying bacteria
GROUND WATER POLLUTION
• 50% of the people in the US depend on
groundwater for their water supplies
• Some countries 95%
• EPA estimates 4.5 trillion liters of water seep into
ground water supplies each day
• 34 billion liters per year of the most dangerous liquid
wastes are injected into the ground below the
water table
• Water in aquifers remain there about 1,400 years
• Cleaning up contaminated ground water is almost
impossible and very expensive – could cost $1 trillion
per year
MAINTAINING WATER QUALITY
AND WATER PURIFICATION
DRINKING WATER TREATMENT
METHODS
• Adsorption – contaminants stick to surface of granular or
powders activated charcoal
• Disinfection – chlorine, chloramines, chlorine dioxide,
ozone, and UV radiation
• Filtration – removes clay, slits, natural organic matter,
and precipitants form the treatment process
• Flocculation-Sedimentation – process that combines
small particles into larger particles and then settle out of
the water as sediment, uses alum, iron salts or synthetic
organic polymers
• Ion Exchange – removes inorganic constituents, can
removes arsenic, chromium, excess fluoride, nitrates,
radium, and uranium
WATER TREATMENT REMEDIATION
TECHNOLOGIES
• Adsorption/absorption – solutes concentrate at the
surface of a sorbent (absorbing surface), thereby
reducing contamination
• Aeration – bubbling air through water increases rates
of oxidation
• Air stripping – VOCs are separated from groundwater
by exposing water to air (VOCs evaporate due to their
high vapor pressure)
• Bioreactors – groundwater is acted upon by
microorganisms
• Constructed Wetland – uses natural geochemical and
biological process that parallel natural wetlands (living
machines)
WATER TREATMENT REMEDIATION
TECHNOLOGIES
• Deep-well injection – uses injection wells to place
treated or untreated liquid wastes into geological
formations that do not pose a potential risk to
groundwater
• Enhanced bioremediation – the natural rate of
bioremediation is enhanced by adding oxygen and
nutrients into groundwater
• Fluid-vapor extraction – a vacuum system is applied to
low-permeable soil to remove liquids and gases
• Granulated activated carbon (GAC) – ground water is
pumped through a series of columns containing
activated carbon
WATER TREATMENT REMEDIATION
TECHNOLOGIES
• Hot water or steam flushing – steam or hot water is
forced into an aquifer to vaporize volatile
contaminants and is then treated through fluid-vapor
extraction
• In-well air stripping – air is injected into wells, the air
picks up various contaminants (VOCs) the vapors are
then drawn off by vapor extraction
• Ion exchange – involves exchanging one ion for
another
• Phytoremediation – uses plants to remove
contamination
• UV oxidation – uses UV light, ozone, or hydrogen
peroxide to destroy microbiological contaminants
SEWAGE TREATMENT/
SEPTIC SYSTEMS
INCORPORATES PHYSICAL, CHEMICAL, AND BIOLOGICAL
PROCESSES TO REMOVE CONTAMINANTS
SEPTIC SYSTEMS
• Have tank and drain field
• Steps:
1. Waste water enters the tank
2. solids settle out
3. Anaerobic digestion using bacteria treats settled solids,
reducing their volume
4. Excess liquid leaves the tank and moves through a pipe
with holes to a leach field where water percolates into
the soil
• Some pollutants (ex. Nitrogen) do not decompose and
can contaminate ground water
• About 25% of Americans rely on septic systems
SEPTIC SYSTEM
SEWAGE TREATMENT
• Primary Treatment – Separation of Solids Physical
• Reduces oils, grease, fats, sands, grit, and coarse
solids
• Uses sand catchers, screens, and sedimentation
• Secondary Treatment – Breakdown by
bacteria - biological
• Degrade the biological content from food waste,
human waste, soaps, and detergents
• Uses filters, activated sludge, oxidizing beds,
trickle filter beds, secondary sedimentation
SEWAGE TREATMENT
• Tertiary Treatment – Disinfection – chemical
• Treats water before discharge to the environment
• Uses sand filtration, lagooning, constructed wetlands,
nutrient removal via biological or chemical precipitation,
denitrification and phosphorus removal using bacteria,
microfiltration, disinfection with UV light, chlorine, or ozone
• Quaternary Treatment – Ultrapure water
• Treats water for groundwater recharge and industrial use
• Uses membrane filtration, reverse osmosis
SEWAGE TREATMENT
RELEVANT LAWS
• Clean Water Act (1972):
• Established basic structure for regulating discharge of
pollutants into US waters
• Gave EPA authority to implement pollution control
programs
• Continued requirements to set standards for all
contaminants of surface water
• Made it unlawful to discharge into navigable waters without
a permit
• Funded construction of sewage treatment plants
RELEVANT LAWS
• Safe Drinking Water Act (1974): established
standards for safe drinking water in the US
• Ocean Dumping Ban Act (1988): made it unlawful
to dump, or transport for dumping, sewage, sludge,
or industrial wastes into the ocean
• Oil Spill Prevention and Liability Act (1990):
strengthened EPAs ability to prevent and respond to
catastrophic oil spills