2. Water: What are some ways to obtain safe drinking water? Mercer University School of Engineering Professional Practices, Dr. Davis J. Walsh

3. What’s wrong with our water today? Some contaminants of our water today: Lead Radon Nitrates Parasites Traditionally, chlorine has been used to eliminate these contaminants Problems with chlorine: It reacts with decaying organic matter This causes cancer causing chemical byproducts

4. One way the Army is providing water to its soldiers New technology being tested by the Army Turns exhaust in Humvees to drinking water Five part system: 1. Catalytic converter-device in all modern vehicles that oxidizes the toxic organic compounds not combusted by the engine The army has enlarged its surface area so it takes longer for the fumes to pass through it This makes it cleanse the fumes more 2. Heat exchanger Refrigerates fumes and causes them to condense 3. Treatment tanks Bed of six activated-carbon and ion-exchange filters the liquid goes through

5. Exhaust to drinking water 4. Water-Quality Sensor Checks cleanliness of the water 5. Storage Tank Chlorine is added to purify water Held in a 5 gallon tank on rear Water comes through a spigot Water goes through air conditioning unit to chill and remove chlorine taste

6. Two ways to purify water: UV and desalination UV light Currently 3000 to 5000 systems Useful in wastewater Few official regulations exist for performance-related criteria for UV units for drinking water

7. UV light continued How it works: Proteins, phenols and humic material that contaminate water absorb the rays and die Destroys all bacteria and viruses Made of multiple standard high-quality UV lamps, sealed within quartz tubes or sleeves Photo courtesy of Islandnet.com

8. Two methods of desalination: reverse osmosis and electro dialysis Reverse Osmosis-membrane process for desalting water Uses hydrostatic pressure to drive water through a semi permeable membrane, which means only selected things can go through the membranehydrostatic pressure Pure water comes out at near atmospheric pressure Waste is at original pressure The figure below illustrates how this system works

9. Desalination techniques continued: Electro dialysis Electric energy is used to transfer ionized salts from feed water through membranes, leaving behind purified product water Salts are ionic, so cation and anion-selective membranes are placed, alternately between two electrodes This means the salt particles have a charge and they are attracted to the electrodes so they can be removed Three elements: 1. Supply of pressurized water 2. Membrane stack 3. DC power supply A rectifier converts alternating current to direct current Used on membrane stack Energizes ions and causes them to move through selective membranes

10. How can UV light and desalination be useful? UV light It is an environmentally safe, nonchemical, physical process that produces no toxic side effects The equipment is easy to operate and maintain There can be no overdosing No residue left Very quick; only a few seconds while chlorine takes ¼ to ½ and hour Desalination Uses no chemicals Enables salt water to be harvested for fresh drinking water Also no overdosing or residue left

11. References http://www.islandnet.com/~tiger/Tiger/UV/UV_pics/Trojan/diagram.jpg Keats, J. (2006, January 16). Converting tailpipes into water fountains. Popular Science. Retrieved March 16, 2008, from http://www.popsci.com/scitech/article/2006-01/converting-tailpipes- water-fountains Masschelein, W. J. (2002). Ultraviolet light in water and wastewater sanitation. Boca Raton: CRL Press LLC. Montgomery, J. M. (1985). Water treatment principles and design. Canada: John Wiley & Sons, Inc. 225-235. Spellman, F. R. (1999). Choosing disinfection alternatives for water/wastewater treatment. Lancaster, PA: Technomic Publishing Company, Inc. 108-113. Worshop, R. L. (1994, February 11). Water quality: should safety standards for drinking water be tougher in the US? CQ Researcher, 4, (6).