part 2 water pollution. cultural eutrophication process by which human activity increases the amount...
TRANSCRIPT
PA RT 2
WATER POLLUTION
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
I N C O R P O RAT E S P H Y S I C A L , C H E M I C A L , A N D B I O LO G I C A L P R O C E S S E S T O R E M O V E C O N TA M I N A N T S
SEPTIC SYSTEMS
• Have tank and drain field • Steps:
1. Waste water enters the tank2. solids settle out3. Anaerobic digestion using bacteria treats settled
solids, reducing their volume4. 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