1. Water Pollution
Part 2

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

3. Steps of an Algal bloom
Increased algae due to increased nitrate and/or phosphate concentrations  decreased light penetration  deeper plants die off  less oxygen released into the water
Increased material for decomposers  decrease in oxygen concentrations
Lower oxygen concentrations  aquatic organisms die off  water contamination
Decaying fish, algae, and other organisms add toxins to the water.

4. Algal Blooms

5. Algal Blooms

6. 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

7. 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

8. Maintaining Water Quality and Water Purification

9. 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

10. 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)

11. 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

12. 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

13. Sewage Treatment/ Septic Systems
Incorporates physical, chemical, and biological processes to remove contaminants

14. Septic Systems Have tank and drain field Steps:
Waste water enters the tank
solids settle out
Anaerobic digestion using bacteria treats settled solids, reducing their volume
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

15. Septic System

16. 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

17. 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

18. Sewage Treatment

19. 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

20. 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