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| Abstraction |
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| Water is pumped from the River
and flows through a series of screens to remove
debris such as sticks, leaves and other large
items. |
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| Pre-Ozonation |
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| The water
is mixed with ozone to remove algae, pesticides
and herbicides. It also kills 99% of bacteria.
The dead algae forms a film on the top of
the water which is removed before the water
flows to the next process. Any unabsorbed
ozone is destroyed. For more information on
ozone and how it is made please click
here. |
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| Pulsator
Clarifiers |
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| The next stage of treatment,
"pulsator clarifiers" remove the suspended
solids (ie small particles) from the water.
The water flows into a large chamber. As it
circulates upwards, the small particles in
the water join together and sink, forming
a sludge blanket at the bottom. The water
carries on to the next stage of treatment
(while the sludge blanket is taken away to
be dried into sludge "cake" and used as fertiliser
by local farmers). |
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| Intermediate
Ozonation Tanks |
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| The water
undergoes further ozone treatment to break
down pesticides and act as a disinfectant.
For more information on ozone and how it is
made please click
here. |
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| Final
Stage Filtration |
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| After intermediate
ozonation the water passes through a Filter
Bed. At the bottom of the filter bed is a
layer of G.A.C (Granular Activated Carbon).
This G.A.C traps the remaining solids and
organic matter that may still be in the water.
With river water treatment, the G.A.C has
to be cleaned every 24 - 72 hours. This is
done by backwashing the G.A.C with clean water.
For more information on G.A.C filtration,
please click
here. |
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| Disinfection |
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| A low concentration
of chlorine is added and remains in contact
with the water for at least one hour. |
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