1. Water Purification (1-c)
When is water safe (or not safe) to drink?

2. Universal Solvent
Why is water’s ability to dissolve so many substances both good and bad?

3. Where does the water get purified???

4. Natural Purification
As a part of the water cycle, water is continuously purified through numerous processes
Distillation
Crystallization
Sedimentation
Filtration
Aeration

5. Distillation
When water is evaporated, it leaves the dissolved materials behind. This results in water vapor with only traces of impurities.

6. Crystallization
As water freezes most of the salt and other dissolved materials are left behind. This results in relatively pure water in the form of ice.

7. Sedimentation
Solid particles settle to the bottom in slow moving streams and in lakes.

8. Filtration
As water moves through sand, rocks and other permeable substances, material is removed.

9. Aeration
As water moves over rocks and mixes with the air, dissolved materials (like gasses) are released into the air. This also promotes the growth of organisms that eat certain water contaminates.

10. Human methods of water purification
waste water treatment
We use these processes to treat water that goes down your drain and toilets.

11. Provo City Waste-Water Plant

12. Primary Treatment Screens to collect trash
Water slows down; heavy solids settle to the bottom (sedimentation)
Scrappers removed material from the surface of the water
Removes about ⅓ of the solid material

13. Secondary treatment 95-99% of pollutants are removed
Air is mixed with wastewater, along with microorganisms, which eat harmful organic matter.
Sedimentation allows smaller solids and bacteria to settle.
Sand/carbon filter remove remaining solids.
Chlorine is added as a disinfectant.

14. Waste Elimination
The solids are digested by bacteria and then dewatered in a centrifuge.
3 waste products are produced:
The water is eventually dechlorinated and released into a stream, ending up in Utah Lake.
Solids are composted, becoming “biosolids” and are sold as soil enrichment.
Methane gas is used to help power the treatment plant.