1. Water Purification and Treatment

2. Natural Water Purification
1. Evaporation
2. Bacterial Action
3. Filtration

3. Purifying Water through the Hydrologic Cycle

4. Purifying Water through the Hydrologic Cycle
1. The sun provides energy for water to evaporate this resembles the process of distillation
Evaporation leaves behind minerals, heavy metals, and other dissolved substances.

5. Purifying Water through the Hydrologic Cycle
Water vapor condenses and falls as precipitation  raindrops and snowflakes are nature’s purest form of water containing only dissolved atmospheric gases
However, human activities release a number of gases into the air making today’s rain less pure than it used to be

6. Purifying Water through the Hydrologic Cycle
2. Bacterial Action
When raindrops strike the soil, they collect impurities
But, as the water seeps through the ground the bacteria in the soil feed on those impurities and repurify the water

7. Purifying Water through the Hydrologic Cycle
3. Filtration
As water seeps further into the ground, it passes through gravel, sand, and rock
This allows bacteria and suspended matter to be filtered out

8. Municipal Water Purification
Major Steps
1. Screening
2. Prechlorination
3. Flocculation
4. Settling
5. Sand Filtration
6. Post chlorination
7. Optional Further Treatment
Read article on pages and define these terms
Ended here with period 8

9. Chlorination of Water
Read article on page 90 and outline the 3 methods of chlorination.
What is a potential problem with water chlorination?

10. Chlorination and THM’s
Ways to eliminate THM health risk
1. Pass water through activated charcoal filter.
Can get rid of THM’s but expensive to install and operate.
2. Use ozone or UV light instead of chlorination
Won’t protect the water from contaminants once it has left treatment plant

11. Hard Water
Hard Water is water containing an excess of dissolved calcium (Ca2+) ions, magnesium (Mg2+) ions, or iron (III) (Fe3+) ions
As water flows through limestone, chalk, and other rocks, these ions seep into the water

12. US Groundwater Hardness
Is Your Water Hard or Soft?

13. How do we soften water??? Water Softening Lab 3 ways
1. Sand Filtration
2. Treatment With Calgon
3. Treatment with an Ion-Exchange Resin