Have you ever wondered what happens to the water that goes down drains and toilets?
Hi, I'm Barry. Today I'm going to show you how wastewater is treated.
The journey begins here, in your community.
When it rains, snows or when you wash your car, the water run off is known as storm water.
It goes to these storm drains that you see on neighbourhood streets.
Storm drains connect to streams and creeks, and eventually, enters Lake Ontario. It's
not treated.
But something different happens to the water that we use inside the home.
The water that goes down drains and toilets is what we call wastewater.
Because it's mixed with food, soap, waste and more, wastewater never goes straight to
a river or a lake.
It goes down the drain and then into a series of pipes underground.
In fact, if we lined up all the wastewater pipes in Peel, they would stretch from Mississauga
to Calgary - that's over three thousand two hundred kilometres. That's 37 hours of driving!
And when you flush the toilet or take a shower, it can take a couple days for the wastewater
to get to the wastewater treatment facility.
So let's skip ahead a couple days.
All the wastewater from thousands of homes and buildings in Brampton, Mississauga and
parts of Caledon arrives here. It's collected in six big underground pipes right underneath
me. Each pipe is 6 feet in diameter.
Now let's go see the first step in wastewater treatment.
The wastewater flows through these screens, and look something like this.
These trap all kinds of things that you should never flush down the toilet. Things like rags,
plastics, and dental floss.
Everything the screens trap ends up on these conveyor belts. The conveyors take all this
garbage to big bins in the building next door.
Trust me, this is the worst smelling place here because of the wet garbage.
When the bins are full, trucks take the garbage away to landfill.
Now let's get some air and go see where wastewater goes.
After the screening, wastewater travels into underground grit chambers.
Each chamber is round and spins wastewater, like swirling water in a cup. As it spins,
sand and small rocks are separated, move to the edges of the chambers and removed.
Now that solid particles and garbage have been removed from wastewater, it flows into
a settling tank like this one.
We call it a settling tank because wastewater is given time to settle!
At the top of the tank is where scum floats and is made up of grease, fats and oils
At the bottom of the tank is where sludge sinks and is made up of solid material, mainly
human waste.
Over here we have an empty settling tank. This tank is empty so you can see how deep
it is.
So now that we have sunken sludge and floating scum. What happens next?
See this big thing across the tank? We call it the bridge, but it doesn't stay in one
place like a regular bridge.
As the bridge moves it scrapes the sludge along the bottom and skims the scum along
the top.
It takes 30 minutes for the bridge to move all the way across the tank. Watch, I'll show
you!
time lapse of bridge moving
The scum is pushed to the end, where it's collected. We can't see the sludge underwater,
but you can see the scum collecting here.
This process is a continuous cycle. The bridge will lift, go back to the far end and start
over again.
Now our journey splits into two. First, let's see where the sludge and scum goes. Then we'll
come back and find out where wastewater goes.
The sludge and scum from the settling tanks referred to as biosolids go into these machines
called centrifuges.
A centrifuge spins biosolids super fast, like a dryer, to get rid of excess water.
But getting rid of the biosolids? That�s where things really heat up.
This is a biosolids incinerator, which heats up to over 840 degrees Celsius.
Biosolids enter the incinerator with a consistency that's like cake batter, up to about this
point.
Points to area on incinerator
And the biosolids end up as ash, just like this.
For every 100 tonnes of biosolids, we end up with 10 tonnes of ash.
Let's go see where the ash ends up.
This is a lagoon where ash is stored. It's red because of natural iron minerals.
This is just a little ways from the incinerators over there, so we add water to the ash so
it's easy to pump it here.
And that's how biosolids have turned to ash.
Now let's go back where our journey split in two and find out what happens to the wastewater
from the settling tanks.
With the biosolids removed from wastewater, something interesting happens.
Wastewater flows into these aeration tanks. Aeration is pumping oxygen into the water.
See all those bubbles? That's the oxygen.
Aeration allows good bacteria to eat the sludge that didn't sink and the scum that didn't
float in the settling tanks. This process is what makes wastewater clear.
But it's not quite clean yet.
Here are clarifying tanks.
Remember the good bacteria that ate everything in the water to make it clear? They sink to
the bottom of the tanks and are removed.
The surface water is what we discharge to Lake Ontario. Along the way, we add chlorine
to it as a final disinfectant.
The outfall is an underwater pipe that stretches just over one kilometre out into Lake Ontario.
Along the way, there are 35 holes in the pipe that the treated wastewater is dechlorinated
and discharged into the Lake. We do this to spread and reduce the environmental impact
of treated wastewater.
The entire wastewater treatment process is closely monitored from this control room.
Operators monitor the machinery and make sure that chemical levels are meeting the right
environmental standards at all times.
Lake Ontario is our most important body of water. It's home to a variety of fish and
plants, the source of our drinking water, and as we showed you today, where treated
wastewater and storm water ends up.
And even though wastewater goes through an intense treatment process before it's returned,
it's important that we limit our impact on the environment. We can do this by keeping
harmful chemicals , things like paint, expired medicine and harsh cleaners out of sinks,
drains and toilets.
Let's all do our part to keep Lake Ontario clean and healthy.