1. Drinking Water Treatment

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

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: After aeration, the water treatment process can be divided into 4 main steps: Coagulation & Flocculation Coagulation & Flocculation Sedimentation Sedimentation Filtration Filtration Disinfection Disinfection Now, let’s look at each step more in- depth!

4. Aeration This is considered to be the very 1 st step in the treatment process. This is considered to be the very 1 st step in the treatment process. Aeration refers to the addition of air to the water. Aeration refers to the addition of air to the water. This allows gases trapped in the water to escape & adds oxygen 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. 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. 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. 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. 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. Water must remain in the tank for a long period to allow the floc to settle out. Then, the clear water moves to filtration. 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. 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. 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 Go to http://www.epa.gov/OGWDW/kids/teachers_ 9-12.html http://www.epa.gov/OGWDW/kids/teachers_ 9-12.html http://www.epa.gov/OGWDW/kids/teachers_ 9-12.html Click on “Interactive Water Filtration Instructions” Click on “Interactive Water Filtration Instructions” When prompted, click on the bottom of the screen to start When prompted, click on the bottom of the screen to start Then, click on 3 “How to Complete the Lesson” and watch the animation. 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. As you watch, please write down each step in the treatment process.

11. SDWA (continued) Maximum Contaminant Level Goal (MCLG) Maximum Contaminant Level Goal (MCLG) A level for substances found in drinking water set by the EPA and based on health effects A level for substances found in drinking water set by the EPA and based on health effects Maximum Contaminant Level (MCL) Maximum Contaminant Level (MCL) Legal limit (max) of a pollutant that’s allowed in drinking water Legal limit (max) of a pollutant that’s allowed in drinking water Often MCLG & MCL are same 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. 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. Requires water suppliers to test water for regulated substances. If they exceed legal limits, they must make adjustments. If they exceed legal limits, they must make adjustments.