Day 5 – Water Purification

1. Day 5 – Water Purification • Water purification is important for providing clean, drinkable water for communities. • There are many different things to consider when purifying water.

2. Distillation • Distillation relies on the idea that when you boil water you leave behind any dissolved solids. This removes inorganic pollutants. • It does NOT work for things like gasoline or pesticides, which also boil with the water.

3. Filtration • You can filter water with something like sand or charcoal, which removes many fine particles including organics. • This is similar to the way the ground filters water going into wells.

4. Disinfection • Bacteria and viruses are small. So small they can make it through filters. • The easiest way to disinfect water is to boil it for ten minutes. • Iodide tablets (KI) will also kill all bacteria, and 99.3% of viruses.

5. Precipitation • You can use precipitation to remove metal ions that you know are in your water. • The issue with this is that you need to replace any ion with another one. • This can be solved by using ions we consume every day like sodium or potassium carbonate. • You just need to filter out the precipitate once you make it.

6. pH • The pH of water is important to animals and plants. • Normal water has a pH of 7 (neutral). • Acids have a lower pH (0-6) and can be corrosive to metals and many other substances. • Bases have a higher pH (8-14) and are called alkaline or caustic.

7. pH • Adding an acid to a base (or vice versa) results in neutralization. • The H+ from the acid reacts with the OH- from the base to make water. • We can use indicators or pH paper to determine the pH of water. NaOH + HCl H2O + NaCl