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Drinking Water Treatment

Drinking Water Treatment. Originally passed in 1974 Federal law that ensures the quality of Americans’ drinking water EPA sets standards for drinking water quality MCLG MCL. The Safe Drinking Water Act (SDWA). How do we treat our water in order to make it safe to drink??.

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Drinking Water Treatment

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  1. Drinking Water Treatment

  2. Originally passed in 1974 Federal law that ensures the quality of Americans’ drinking water EPA sets standards for drinking water quality MCLG MCL The Safe Drinking Water Act (SDWA)

  3. How do we treat our water in order to make it safe to drink?? • After aeration, the water treatment process can be divided into 4 main steps: • Coagulation & Flocculation • Sedimentation • Filtration • Disinfection Now, let’s look at each step more in-depth!

  4. Aeration • This is considered to be the very 1st step in the treatment process. • Aeration refers to the addition of air to the water. • This allows gases trapped in the water to escape & adds oxygen to the water.

  5. Coagulation & Flocculation • Coagulation removes dirt and other particles suspended in water. • Alum (aluminum potassium sulfate) and other chemicals are added to water to form tiny sticky particles called "floc" which attract the dirt particles. • The combined weight of the dirt and the alum (floc) become heavy enough to sink to the bottom during sedimentation. http://techalive.mtu.edu/meec/demo/Flocculation.html

  6. Sedimentation • The heavy particles (floc) settle to the bottom. • Water must remain in the tank for a long period to allow the floc to settle out. • Then, the clear water moves to filtration. http://techalive.mtu.edu/meec/demo/Sedimentation.html

  7. Filtration • The water passes through filters, some made of layers of sand, gravel, and charcoal that help remove even smaller particles. http://techalive.mtu.edu/meec/demo/Filtration.html

  8. Disinfection • A small amount of chlorine is added or some other disinfection method is used to kill any bacteria or microorganisims that may be in the water. http://techalive.mtu.edu/meec/demo/Disinfection.html

  9. Overview…

  10. Animation on EPA Website • Go to http://www.epa.gov/OGWDW/kids/teachers_9-12.html • Click on “Interactive Water Filtration Instructions” • When prompted, click on the bottom of the screen to start • Then, click on 3 “How to Complete the Lesson” and watch the animation. • As you watch, please write down each step in the treatment process.

  11. SDWA (continued) • Maximum Contaminant Level Goal (MCLG) • A level for substances found in drinking water set by the EPA and based on health effects • Maximum Contaminant Level (MCL) • Legal limit (max) of a pollutant that’s allowed in drinking water • Often MCLG & MCL are same

  12. SDWA (continued) • The EPA regulates over 80 inorganic (ex: lead, mercury, & fluoride) and organic chemicals (ex: pesticides) found in drinking water. • Requires water suppliers to test water for regulated substances. • If they exceed legal limits, they must make adjustments.

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