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Water Purification and Treatment. Natural Water Purification. 1. Evaporation 2. Bacterial Action 3. Filtration. Purifying Water through the H ydrologic Cycle. Purifying Water through the Hydrologic Cycle.
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Natural Water Purification • 1. Evaporation • 2. Bacterial Action • 3. Filtration
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.
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
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 repurifythe water
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
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 88-89 and define these terms
Chlorination of Water • Read article on page 90 and outline the 3 methods of chlorination. • What is a potential problem with water chlorination?
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
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
US Groundwater Hardness Is Your Water Hard or Soft?
How do we soften water??? • Water Softening Lab • 3 ways • 1. Sand Filtration • 2. Treatment With Calgon • http://www.youtube.com/watch?v=ZjNRXfRXnoc • 3. Treatment with an Ion-Exchange Resin • http://www.youtube.com/watch?v=vCg-I5U9X3w