Where it Goes When
I go
A look into London’s waste water challenges
Prepared by:
Danielle Ward
519-661-2500 ext. 2844
dward@london.ca
www.london.ca/teacher
Before you Begin:
The City of London has various resources available to you throughout this lesson
including informational videos and webpages. If you have any questions about the
material before or after the lesson please do not hesitate to contact us. If you have an
idea for another lesson, or have connected this lesson to curriculum we have not,
please let us know. We are always looking for feedback, ideas for improvement and
new lessons.
Resources:
The resources required for this lesson are provided in the resources section, should
more resources be required there is more information on sanitary sewersheds on the
City of London’s website at http://www.london.ca/residents/Water/TeacherResources/Pages/Wastewater.aspx
Please alter this lesson, lesson plan, and resources to fit your student’s needs.
Field Trip Resources:
To help explain the process of how water gets from the lake to the tap, or where waste
goes from the sink or toilet schedule a tour of the Huron and Elgin Area Water Supply
Facilities, or a Tour of the Greenway Pollution Plant.
1. To schedule a tour of the Huron and Elgin Area Water Supply Facility call: 519930-3505 or email watersupply@london.ca (please book field trip 30 days in
advance).
2. To schedule a tour of the Greenway Pollution Plant please call: 519-661-2581 or
email gburrows@london.ca
3. If you would like to book a “what not to put down the drain” lesson. Please
contact Barry Orr please at borr@london.ca or call 519-661-2500 ext. 2844.
Other Field Trips Include:
Vansittart Woods Environmental Education Centre
Grade 8:
1. SPLASH: Students role play different components of the water cycle through an
active game.
London Environmental Education Centre
Grade 8:
1. Water Quality: Students will discuss the importance of water and the movement
of water through the water cycle. They will learn about why the quality of water is
important and what factors affect it. Using different testing methods, including
Lab Quest digital probes, students will test various aspects of water quality.
Upper Thames River Conservation Authority
Fanshawe Outdoor Education Centre
Grade 8:
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1. Managing Water with Dams and Low Impact Design: Fanshawe Dam plays a
vital role in a complex and integrated flood control system. We will tour inside
and outside the dam and learn how the conservation Authority manages water
levels of the Thames River. Near the Watershed Conservation Centre, students
will see firsthand how Low Impact Design for stormwater helps to reduce
flooding.
Feedback:
Finished this lesson?
We would love to hear how it went and any ideas for improvements, activities or
additional lessons! Send us a quick email with your grade and unit that you used this
lesson for with any comments, questions or suggestions.
Thank you for using The Teaching Toolkit and taking the time to help us continue to
develop and improve the resources!
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Curriculum Connections:
Grade 7: Science and Technology
Understanding Structures and Mechanisms: Form and Function
Overall Expectations:
1. Analyze personal, social, economic, and environmental factors that need to be
considered in designing and building structures and devices.
2. Design and construct a variety of structures, and investigate the relationship
between the design and function of these structure and the forces that act on
them
3. Demonstrate an understanding of the relationship between structural forms and
the forces that act on and within them.
Understanding Matter and Energy: Pure Substances and Mixtures
Overall Expectations:
1. Evaluate the social and environmental impacts of the use and disposal of pure
substances and mixtures
2. Investigate the properties and applications of pure substances and mixtures
3. Demonstrate an understanding of the properties of pure substances and
mixtures, and describe these characteristics using the particle theory
Literacy
Media Literacy
Overall Expectations:
1. Demonstrate an understanding of a variety of media texts
2. Identify some media forms and explain how the conventions and techniques
associated with them are used to create meaning
3. Create a variety of media texts for different purposes and audiences, using
appropriate forms, conventions, and techniques
4. Reflect on and identify their strengths as media interpreters and creators, areas
for improvements, and the strategies they found most helpful in understanding
and creating media texts.
Grade 8: Science and Technology
Understanding Structures and Mechanisms: Systems in Action
Overall Expectations:
1. Assess the personal, social, and/or environmental impacts of a system, and
evaluate improvements to a system and/or alternative ways of meeting the same
needs.
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2. Investigate a working system and the ways in which components of the system
contribute to its desired function.
3. Demonstrate an understanding of different types of systems and the factors that
contribute to their safe and efficient operation.
Understanding Matter and Energy: Fluids
Overall Expectations:
1. Analyze how the properties of fluids are used in various technologies and assess
the impact of these technologies on society and the environment
2. Investigate the properties of fluids
3. Demonstrate an understanding of the properties and uses of fluids
Understanding Earth and Space Systems: Water System
Overall Expectations:
1. Assess the impact of human activities and technologies on the sustainability of
resources
2. Investigate factors that affect local water quality
3. Demonstrate an understanding of the characteristics of the earth’s water systems
and the influence of water systems on a specific region
Grade 8: Geography
Global inequalities: Economic Development and Quality of Life
Overall Expectations:
1. Analyze some interrelationships among factors that contribute to global
inequalities, with a focus on inequalities, with a focus on inequalities in quality of
life, and assess various responses to these inequalities.
2. Use the geographic inquiry process to investigate issues related to global
development and quality of life from a geographic perspective
3. Demonstrate an understanding of significant patterns in and factors affecting
economic development and quality of life in different regions of the world.
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Lesson Resources
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Resource 2: Field Trip Worksheet
Greenway Wastewater Treatment Plant
1. How much wastewater does this plant handle each day?
2. How many screens are in the screening room at Greenway?
3. How fast does the vortex system spin ?
4. What landfill does all of the grit go to ?
5. What does the chemical scrubber use to neutralize odors ?
6. How many primary clarifiers does Greenway have ?
7. What happens to the grease and oil once it is collected from the top of the
clarifier?
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Resource 3:
NEWS LOCAL
LONDON SEWERS
Fixing a big, fat mess 70
By Emanuela Campanella, The London Free Press
Monday, August 24, 2015 10:47:49 EDT PM
It can be a big, fat mess, one that causes major grief for London’s sewer system.
When you dump your bacon fat or any content from your frying pan down the drain, it creates giant balls of grease as
it cools, accounting for 40 per cent of the city’s plugged sewers.
But the city has a weapon that can cut fat faster than any Jenny Craig program. It’s called the FOG — fats, oil and
grease — cup.
The city is in its third phase of the pilot program, pleading with residents to store their fat in biodegradable cups to use
it to help power the electricity grid with green energy.
“We get hundreds and hundreds of these balls of grease. That’s why the best choice is for it not to be (in the sewer
system) in the first place,” said Barry Orr, the city’s sewer outreach and control inspector.
It’s easy, Orr says. You take that sizzling bacon fat from your pan, pour it into a cup supplied free of charge by the
city and freeze it. Then you throw it away or drop it off at any of the city’s waste depots.
Fat dropped off at the depots is broken down into methane gas for green energy. One tonne of fat is enough energy
to heat a home for a half-year, Orr said.
The citywide pilot project has been around a couple of years and outreach efforts have expanded.This summer, the
outreach team has gone door-knocking, handing out the green cups in southwest and north London.
Morgan Latvanen, left, and John Gosso operate a suction truck to clean fats from a sewer on St. James
Street Monday. (MORRIS LAMONT, The London Free Press)
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The cup, big enough to hold the grease from five packages of bacon, is making a difference, Orr said.
“A lot of people are aware of fats, oils and grease disposal, whereas before they weren’t,” Orr said. “So we’re seeing
that difference (in the city’s sewers) and at the pumping stations, too.”
The city has distributed 17,000 cups in hopes that some fat won’t make its way through the pipes.
“It really helps with our sewer maintenance and keeping the sewer grease-free. The sewer system is a lot healthier,”
Orr said.
When fat causes problems, the city either has to vacuum it out from the sewers or flush it out.
Before the pilot project, the city sent out trucks to suck out the grease every three months. Now trucks are being sent
out every six months, Orr said.
CUP DISPOSAL
Waste depots where cups can be picked up and dropped off:



3502 Manning Dr.
1450 Oxford St. W.
28 Clarke Rd
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Lesson Notes
Slide 1:
Throughout the lesson there are various words that are highlighted that the students
should write down and define. Explain to the students that the majority of these words
are new and are important to learn before going on the field trip.
Slide 2:
Ask the students if they have ever wondered what happens to the waste that goes down
the drain or even the toilet. Ask they what they wonder about their waste, where it
goes, what happens to it, how is it cleaned, where all the pipes go, etc.
Slide 3:
Explain to the students that there are 6 wastewater treatment plants in London, which is
quite a few. The 6 wastewater treatment plants in London Ontario are
1. Adelaide
2. Greenway (the largest)
3. Pottersburg
4. Vauxhall
5. Oxford
6. Southland
Slide 6:
Ask the students if they know where their waste water goes, ask them if they ever
wondered where the pipes underneath the house went ?
Give each student a copy of resource 1, the Sanitary Sewershed Map. Ask each
student to identify the area in which they live and using the map key identify which plant
their waste water goes to.
Slide 7:
What happens next? Explain to the students that there is a variety of processes
involved in treating their waste water. Explain that all of the wastewater treatment plants
in London treat wastewater similarly. Explain that the image on the right hand side is a
map of how the waste water from households arrives at a wastewater treatment plant
and is than treated.
Slide 8:
Step 1: Wastewater enters the pipes
Explain to the students that when they flush the toilet, do the laundry, brush out teeth,
take a shower, or use the dishwater they create wastewater. Explain that wastewater is
a term that describes any type of water that has been utilized in some capacity, during
which its quality has been impacted negatively.
Explain to the students that the average flow to all treatment plants from everyone’s
houses in London each day is 186,000 cubic meters per day, or 186,000,000 liters a
day. The wastewater in the pipes does not simply drain to one facility. The wastewater
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in the pipes is usually moved to the wastewater treatments plants by gravity or force
mains.
1. Gravity is used as a method as most of the wastewater treatment plants are
located at a lower elevation. Gravity pulls the water toward the treatment centre.
2. The areas that use force mains use 26 pumping stations to pump the sewage
into the treatment centres. These areas are generally at the same elevation or
below the elevation of the wastewater treatment facility
Slide 9:
Step 1: Waste Water Enters the pipes
Once the material goes into the pipes it enters into the city sewers which are either
combined or not combined with stormwater.
1. Combined sewer: A combined sewer is a type of sewer system that collects
sewage and surface runoff in a single pipe system. Combined sewers can
cause serious water pollution problems due to combined sewer overflows,
which are caused by large variations in flow between dry and wet weather.
2. Uncombined sewer: An uncombined sewer system collects sewage and
stormwater/surface runoff in two separate pipe systems. Uncombined sewers
are better in controlling issues revolving around water pollution problems.
During wet weather the stormwater/ runoff is easily piped away from the city
without being contaminated with sewage.
Explain out of all households in London, 5% have a combined sewer system.
Sometimes these homes contribute to increasing the capacity of the wastewater
treatment facilities. When overflow occurs, it generally is due to a large amount of rain
or snowmelt entering into the sanitary sewer. Overflow releases untreated wastewater
(including that from the toilet) into the Thames River if it is above capacity. Use the
picture on the right hand side to help illustrate how overflow happens in wet weather in
both combined and separate sewers.
There are two forms of wastewater that each household contributes, ask the students if
they know what the terms for each type are.
1. Sewage: only comes from the toilet
2. Greywater: comes from all other sources (dishwasher, laundry, sinks)
Slide 10:
Step 2: Wastewater enters the plant through screens
Explain to the students that once the water enters the facility it enters what is called
primary treatment
1. Pre-treatment: per-treatment removes all materials that can be easily collected
from the raw sewage before they damage or clog the pumps and sewage lines of
primary treatment clarifiers. Objects removed during pre-treatment include trash,
tree limbs, leaves, branches, and other objects.
2. Screening: Screening occurs during pre-treatment. Using a bar screen, large
objects such as cans, rags, sticks, plastic packets, etc. The bar screen is most
commonly done with an automated mechanical bar screen that preforms a rakelike motion. The rake action of the mechanical bar screen is paced according to
the amount of water coming through the system. The solids collected in this
process are disposed of in the landfill.
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Explain that the bar screens have 2-19 mm openings to allow the wastewater to move
through the system. These opening sizes are important in preventing large items from
moving through the system , if large items were to enter into the system they could
cause damage to equipment.
Slide 11:
Step 3: Screened Wastewater Enters the Vortex System
Explain to the students that after the wastewater moves through the bar screens it
enters into the vortex system. The vortex system is very important in grit removal
1. Grit removal, is the removal of the heavier small organic solids such as dirt and
stones.
The vortex system spins the waste water creating a vortex where the suspended grit in
the water settles to the bottom centre of the tank.
2. Vortex: a mass of whirling fluid during which larger, heavier, particles are
separated from fluids and settle to the bottom.
The grit that is deposited at the bottom of the vortex system are free of organic
(sewage) material, and suitable for disposal at a sanitary landfill site.
3. Sanitary landfill sites: sites of land where waste is isolated from the environment
until it is safe. It is considered safe once the waste has completely degraded
biologically, chemically, and physically.
The vortex units are enclosed to prevent odor escape and are connected to a chemical
scrubber which prevents odors from escaping.
4. Chemical scrubbers: are air pollution control devices that can be used to remove
some particulars or gases from industrial processes. In wastewater treatment
scrubbers are used to remove odorous emissions such as sulfur and methane.
Slide 12:
Step 3: De-Gritted Wastewater enters the Primary Settling Tank
Explain to the students that after the wastewater exits the vortex system it enters
primary treatment, which includes primary clarifiers.
1. Primary clarifiers: a large settling tank which reduces the content of suspended
solids and pollutants embedded in suspended solids.
In primary clarifiers the process of sedimentation is completed by gravity alone. Often
the process collects larger dirt or organic particles along the bottom and grease and oils
are collected on the surface. Once the solids are settled out on the top and bottom they
are scrapped and skimmed off. The organic solids on the bottom are scrapped off into a
sludge well which pumps the sludge into sludge tanks.
2. Sludge well: a hole located at the bottom center of the clarifier which collects
larger organic particles that are scrapped off the bottom of the tank.
3. Sludge tank: a storage tank which holds organic particles collected in the sludge
well. The sludge tank is eventually emptied and the sludge is either incinerated or
sent to landfill.
The oil and grease along the top of the clarifier are skimmed off using a skimmer arm
and disposed of into a scum outlet. Once in the scum outlet, the grease and oil is stored
and then later retrieved by a fat and oil recycling company.
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4. Skimmer arm: a skimmer arm is similar to a pool skimmer; however it is attached
to a rotating arm which skims the top of the primary clarifier tank to collect grease
and oils.
Slide 13:
Step 3: De-Gritted Wastewater enters the Primary Settling Tank
Explain to the students that the primary clarifier has two pipes that leave it. The first is
the primary sludge pipe which is collected from the sludge well.
1. Sludge: a semi-solid slurry that is produced from sewage during the wastewater
treatment processes, or as a settled suspension obtained from conventional
drinking water treatment.
The other pipe leads to the next step in the wastewater treatment process, known as
the aeration tanks
2. Aeration tanks: a tank where liquid is held in order to increase the amount of air
within it. The high levels of oxygen will increase the speed at which the water is
cleaned.
Slide 14:
Step 4: Clarified Wastewater Enters Aeration Tanks
After the wastewater is clarified it is piped to aeration tanks using an effluent pump
1. Effluent Pump:
In the aeration tanks the wastewater is treated biologically to stabilize any remaining
dissolved or finely suspended impurities.
2. Biological treatment: involves adding a biological component during the treatment
process, in these systems bacteria and other minute organisms are added to
utilize and consume the undesirable contents of waste water in the presence of
air.
Air is added at the bottom of the aerations tanks through dome shaped diffusers, the air
helps the bacteria grow and digest the particles in the wastewater.
3. Diffuser: an aerating device for sewage treatment, it consists of a membrane with
fine pores through which fine bubbles are generated by the supply of air through
blowers.
Slide 15:
Step 5: Aerated Wastewater Enters Final Clarifier
After the wastewater is aerated it enters into the final clarifier as “mixed liquor”
1. Mixed Liquor: A combination of raw or unsettled wastewater and activated sludge
within the aeration tank.
The mixed liquor is left in the tank while suspended solids settle out by gravity as
activated sludge and are removed
2. Activated Sludge: is a mass of microorganisms that are cultivated in the
treatment process to break down organic matter into carbon dioxide, water, and
other inorganic compounds.
After the activated sludge settles out the liquid is than decanted over weirs and sent to
the disinfection process.
3. Decanted: gradually poor liquid from one area to another without disturbing
sediment
4. Weirs: a barrier across water designed to alter its flow characteristics
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Slide 16:
Step 5: Aerated Wastewater Enters Final Clarifier
Explain that some of the activated sludge from the previous step is returned to the
aeration tanks to keep the same amount of bacteria. The remaining sludge that was
collected in the last step is pumped into a flotation unit where the sludge is than mixed
with a polymer and air to thicken up the sludge. The thickened sludge is than stored in
storage tanks.
1. Flotation unit: a treatment process that removes suspended solids by using air to
create a blanket of sludge at the surface of a flotation cell. This is achieved by
dissolving air into the wastewater. The air is than released and forms tiny
bubbles which adhere to the suspended solids, causing the particles to float to
the surface of the water where it is than removed by a skimming mechanism.
2. Polymer: a substance that has a molecular structure consisting chiefly or entirely
of a large number of similar units bonded together.
Slide 17:
Step 6: Wastewater is disinfected
Explain to students that before the treated wastewater is discharged to the river it needs
to be disinfected. Explain to students that this disinfection process only occurs between
April 1st and September 30th
1. Ask the students why they think the wastewater is only treated between April 1 st
to September 30th
All of the wastewater is treated by ultraviolet lights which destroys any remaining
pathogenic bacteria such as E. coli.
1. Ultraviolet lights: an electromagnetic radiation with a wavelength from 400 nm to
100 nm, shorter than that of visible light but longer than X-rays. Ultraviolet is
often harmful to living things as it can damage living tissue, and is why it is often
used in disinfection.
2. Pathogenic bacteria: bacteria that can cause infection the most notable
pathogenic bacteria are strep, staph, tuberculosis, and E. Coli.
The ultraviolet lights are monitored by intensity monitors to ensure the lights are
effective in killing the bacteria.
3. Intensity monitors: an intensity monitor monitors the amount of UV radiation
which is penetrating the water. The more UV rays that are penetrating the water
the higher the rate of disinfection.
Slide 18:
Step 7: Disinfected Waste Water is Discharged to the Thames River
The disinfected water, after being treated is than discharged into the Thames River.
Slide 19:
Ask students where they think all of the sludge that was created goes.
Slide 20:
Step 8: Sludge Disposal and Treatment
Explain that all the sludge generated from each plant is hauled by truck to the
Greenway Pollution Control Centre. The trucked in sludge is than mixed in with the
greenway sludge that are stored in the sludge holding tanks.
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Explain that the sludge than goes through the same process as the previous sludge at
the greenway plant where it is mixed with polymer to thicken it. After the sludge has
been thicken it is all de-watered so that it is drier. The reason the sludge is dewatered is
because it is pumped into a fluid-bed incinerator where it is burned.
1. Dewatering: the removal of water from solid material
2. Fluid bed incinerator: fuel particles (sludge) is suspended in a hot, bubbling
fluidity bed of ash and other particulate materials through which jets of air are
blown to provide the oxygen required for combustion or gasification
The fly ash produced from the burning of the sludge is than sent to landfill or reused by
cement companies.
3. Fly ash: is a byproduct from burning fuels for energy.
Slide 21:
Show the students just how much sludge is produced each day. The Greenway plant
produces the most sludge however is the largest waste water treatment plant.
Slide 22:
There are three main goals for wastewater treatment that are essential in London’s
Wastewater Treatment
1. Remove the majority of carbonaceous and nitrogenous impurities in order to
reduce the oxygen demand of the plant
2. Reduce the phosphorous levels
3. Reduce the amount of suspended solids prior to the plant discharging to the
Thames River.
Slide 23:
Field Trip
Slide 24:
Individual Activity
Ask the students to work on their own and reflect on why it is important that we treat our
waste water. Emphasize the importance of treating the waste water before releasing it.
Ask them to include research on other areas of the world and how they treat their water,
or ask them to research parts of the world that do not treat their water, and what
happens when they do not. After doing research on other methods of wastewater
treatment around the world ask the students to determine any negatives associated with
the treatment system that the City of London currently uses, also highlight any positives
that the plant has.
After completing all of your research and analyzing the process of wastewater treatment
in London, ask the students to write a one page newspaper article highlighting why
wastewater treatment is important, and how ordinary citizens of London can contribute
to a more environmentally friendly and cost effective water treatment process by
watching what they flush down the toilet or dump down the drain. You can use resource
3 as an example.
Slide 25: What did you think?
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Provide the students a minute to talk about what they thought about the lesson and its
resources. Ask them what they would have done and how they would have done it, or if
they found one part of the lesson to be more interesting than other parts. Through
asking students what they think about the lesson the City of London can continue to
make more appropriate and intriguing lessons for school groups.
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