2. Water Facts: 70% of the Earth is covered by water but only 2% is drinkable, fresh water One litre of wastewater pollutes about eight litres of freshwater It’s estimated that there is 12,000 km 3 of freshwater worldwide

3. How is polluted water cleaned? Not easy to reverse the effects of water pollution It can be very expensive too There are 2 common ways to fix pollution…what would they be?? Remove the pollution source Remove the contaminants

4. What are sources of pollution?

5. Removing the source: Depends on the source and the type of pollution Could be from one of 3 source types: Point source The exact place where pollution occurs can be identified non-point source The exact place where pollution occurs cannot be identified but the region can be identified Transboundary source This type of pollution occurs across governmental boundaries Which types of pollution can you identify from the picture on the previous slide?

6. Why not remove the source all of the time? If removing the source of the pollution gets rid of it… why not do it all of the time?? Finding the actual polluter Cost Others?

7. Removing the contaminants: This is the second way to clean up water pollution - Five techniques are used Can be used individually or in combination Most involve pumping the water out, treating the water, and then pumping it back to the source

8. Air Stripping: Uses air to remove contaminants that evaporate easily Polluted water is pumped back into a tank and then sprayed over packing material Water slowly drips through the packing material and a fan blows over the water to help it evaporate Chemicals collected at the top of the tank are treated to prevent further pollution

9. Activated Carbon Filtration: Polluted water is sent through columns of activated carbon Chemicals stick to the surface & pores of the carbon granules and clean water flows through Filters are cleaned or replaced when they are full

10. Bioremediation: Uses naturally occurring microorganisms to digest contaminants Contaminants are converted to water and other gases such as carbon dioxide Often used in wastewater treatment plants in cities and can be used for drinking water too

11. Phytoremediation: Plants & trees are used to remove pollutants The roots of the plant take up the contaminants at the same time as water and nutrients Contaminants are stored in the roots and leaves

12. Chemical Oxidation: Oxidants are used to convert chemicals into less harmful chemicals Wells are drilled into the groundwater source & the oxidants are pumped in Contaminants are removed above ground and are treated and easily disposed of