How Municipal Water Travels In A City
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Transcript of How Municipal Water Travels In A City
Municipal Water and Wastewater treatment
Magic!!!
Magic!!!
Magic?
Not really
I come from a RIVER in your state
Magic? I come from a LAKE or a RESERVOIR close to your city
I come from deep UNDER THE GROUND. In the river bed and other places,
there are borewells through which I come out during the
summer months
I come from the SEA….but what follows is not my story, because I go through a different
path before I reach you.
A big pipe sucked us in
Along the way, there was a mesh
We could go through but 3 friends of
ours (pebble, stick and leaf) couldn’t make it.
A pipe sucked us in
Along the way, there was a mesh.
We could go through but 3 friends of
ours (pebble, stick and leaf) couldn’t make it.
A pump pushed us a long distance until we reached this big factory like place
called ‘Water treatment plant’
There were boards all around which said
‘Restricted Area’. I wonder why. Do you know?
Flocculation
From a dark gloomy pipe where we were really rushed, we reached a BIG tank.
When we were resting, something called Aluminium Sulphate (let’s call him ALUM ) and some of
his friends joined us.
Flocculation
Alum and his friends are very sticky and my pals ‘Dirt’ from the river, who managed to pass the mesh earlier on, got really attracted to them.
Flocculation
Alum and friends, along with ‘Dirt’ stuck together. We called them ‘FLOC’
Flocculation
Alum and friends, along with ‘Dirt’ stuck together. We called them ‘FLOC’
Flocculation
We were then stirred and churned around and
the ‘FLOC’ started getting bigger with more dirt
sticking around.
We also saw many more ‘flocs’ forming
We were then pushed into another tank. Ah! Rest at last. This was called the sedimentation tank. Hey! the flocs are sinking.
The big ones are going down first. Our friend ‘Dirt’ has gone down too with his ‘floc’
We were in this tank for about 2 hours and by then all the flocs had sunk down below and formed a gooey mass called ‘sludge’
Sedimentation
Rapid sand filtrationWe then passed quickly through another tank with a layer of sand and gravel
Little flocs and some dirt that did not get into flocs, got trapped in the sand
Chlorination
A small amount of chlorine was then added to our tank, which killed pathogenic bacteria, protozoa, viruses, helminths and other micro organisms.
http://www.cpcb.nic.in/oldwebsite/New%20Item/status-WTP-In-India/Chapter1%20.rtf will give you some more information on municipal water treatment systems in India
Photo by C C Krause; Source: http://www.flickr.com/photos/charleskrause/3185090628/
We then travelled a large distance
through pipes
Photo by John Brian Silverio; Source: http://www.flickr.com/photos/psilver/2280385292
to large tanks within your city
And from there to overhead tanks near your school
Photo by BockBilbo; source: http://www.flickr.com/photos/bockbilbo/247405160/
We got to your school this morning and here we come…….. Out of your tap
Waste water treatment
Once you wash your hands with us or flush us down the toilet, we go down through the drains of your school, and through bigger drains under your city and reach a waste water treatment plant.
Our story doesn’t end here
This is what we look like when we reach the wastewater treatment plant
We’re full of poop, soap, oil, grease, soil, garbage, chemicals….all kinds of stuff
Photo by flippy rice; Source: http://www.flickr.com/photos/flippy/110659044/
Sedimentation • All the solid stuff is separated out
• We then go to sedimentation tanks where the sludge settles down and oil and grease float on top. • Both these are removed
Photo by Benjamin Pender; Source: http://www.flickr.com/photos/benpender/2432095138/
Trickling Filter• We trickle on to a bed of rocks and gravel on which a
layer of microbes are present.
• Bacteria, protozoa and fungi on this bed eat up the organic matter in the sewage
Photo by Naturenet; Source: http://www.flickr.com/photos/naturenet/199836849/
AerationAir is pumped through us in aeration tanks
We may go through another round of the trickling filter
Sometimes we go through a tertiary treatment system where chemicals are added to purify us
Then we rejoin a stream
A recap – water treatment
Primary Filters (to remove large matter)
Flocculation tank
Sedimentation tank
Rapid / slow sand filtrationChlorination
Water from rivers / lakes
To tanks in the city
A recap – waste water treatment
Grit Filters (to remove large
matter)
Sedimentation tank
Trickling filter
AerationSecondary filters
Wastewater from city
To streamTertiary
treatment