Reversing Water Pollution

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 km3 of freshwater worldwide

How is polluted water cleaned?Not easy to reverse the effects of water pollution

It can be very expensive tooThere are 2 common ways to fix pollution…what would they be??Remove the pollution sourceRemove the contaminants

What are sources of pollution?

Removing the source:Depends on the source and the type of pollutionCould be from one of 3 source types:

Point sourceThe exact place where pollution occurs can be

identifiednon-point source

The exact place where pollution occurs cannot be identified but the region can be identified

Transboundary sourceThis type of pollution occurs across

governmental boundariesWhich types of pollution can you identify from the

picture on the previous slide?

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

CostOthers?

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

Air Stripping:Uses air to remove contaminants that

evaporate easilyPolluted 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

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

Bioremediation:Uses naturally occurring microorganisms

to digest contaminantsContaminants are converted to

water and other gases such ascarbon dioxide

Often used in wastewater treatment plants in cities and can be used for drinking water too

Phytoremediation:Plants & trees are used to

remove pollutantsThe roots of the plant

take up the contaminants at the same time as water and nutrients

Contaminants are stored in the roots and leaves

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