Skip to content

Public Wastewater Treatment Explained

Learning Experience 4

Big Ideas

All life depends on our ability to treat our waste water effectively.

Cities have an obligation to create the infrastructure to treat waste water for public health to comply with federal regulations.

There is no such place as away. Water cycles around and around in the urban water use system

Summary

Cities like Philadelphia rely on sewers to carry waste to Pollution Contol plants. The process of cleaning wastewater is an important one to keep citizens, plant life and aquatic animals healthy and to adhere to environmental regulations.

Engage

“Wastewater” Sample Observation Ask students to recall the steps they remember from the previous learning activity.

Discuss possible similarities and differences between treating drinking water and treating waste water.

Density
Have a clear water bottle containing water with soil clumps or other debris that will settle after being shaken.

Shake up the water  bottle and allow the water to settle. While waiting for the water to settle, introduce the concept of density.

Present students with two clear plastic cups that are filled with marbles. Add water to one of those cups.

Present students with a clear tub and one can of diet coke and one can of soda.

Guiding Question:

Why does the sugary soda sink while the diet soda floats? 

The 16 teaspoons of sugar in the soda makes the soda denser than water. The artificial sweetener in the diet soda does not add significant mass. Return to the water bottle that was filled with wastewater. What happened?

The material that was denser than water sank to the bottom. The material that was less dense than water floated to the top.

Explore and Explain

Make a Model of Wastewater Treatment

Guiding Questions:

How do we build a model of a wastewater treatment system?

When graphic organizers are complete, return to density and settling.

Guiding Question: 

How do wastewater treatment plants make use of density and settling to help with the treatment process?

This activity is set up to demonstrate primary treatment only. Review vocabulary provided if you are not familiar with the differences of primary, secondary and tertiary treatment.

If you are just using a clear bottle, shake it up with the prepared “medium” as described in the materials section and let it settle for a day. Students will observe what happens. If you can add a drainage hole in the middle of the bottle,  do this now and observe the clarity of the water that escapes

Diagram the wastewater treatment plant process

Design and/or diagram a model of a wastewater treatment plant in order to “clean” a water sample. The diagram and/or model should include all the steps of PWD’s wastewater treatment process:

Explanation of the role of bacteria.
Explanation of the role of density.
Explanation of the role of screening and sorting.
Explanation of how the treatment process emulates natural systems.
A description of what substances are removed and what still remains and the implications of both.

Two videos show students how wastewater is treated with a virtual tour inside the Philadelphia Treatment Center.

Students will diagram the wastewater treatment process annotating the stages with the roles bacteria, density, screening, and sorting play.

Finally, have students consider the types of waste that is going through the system. Have students consider various types of waste such as medicine in the water system. This is an opportunity for them to recall how the water being treated is part of a larger system, with water being sources for uses beyond our water needs.

Elaborate

Watch this VIMEO or take a virtual tour PWD–Wastewater Treatment (Some students may have viewed this video during their research)

STEPS OF THE PROCESS

Students will make a 2D presentation tool like a foldable with a diagram and describe in detail the steps of our local wastewater treatment process.

ACTS AND IMPACTS

What are some things that individuals and communities could do differently to put less stress on the wastewater treatment system?

Extension

WHAT SHOULD BE DONE WITH WHAT’S LEFT?

Research the uses for by-products of wastewater treatment. Create a business plan for a wastewater treatment plant. Include water that can be re-claimed, by-products that can be sold, PSAs that could lead to reduced costs, etc.

Compare and contrast different types of urban wastewater treatment systems. See Materials and Resources for explanations of wastewater treatment systems in different urban areas.

Compare and contrast different types of wastewater treatment systems in different parts of the world. Use: World Bank: Technical Options for Sanitation, Hygiene and Wastewater.

Research the uses for by-products of wastewater treatment. Create a business plan for a wastewater treatment plant. Include water that can be re-claimed, by-products that can be sold, PSAs that could lead to reduced costs, etc.

Design an alternative wastewater processing treatment system. See the article about a Living Machine or research John Todd’s Ecological Design website.

Teacher Support

Essential Question:

What became of Philadelphia’s natural streams and valleys?

Guiding Questions:

Engage

Which marble cup weighs more?
Why does it weigh more?
Why does the sugary soda sink while the diet soda floats?
Could a settling basin be an advantage to a waste water treatment process?
Are some systems more efficient? Are some systems more effective?
How do wastewater treatment plants make use of density and settling to help with the treatment process?

Explore and Explain:

How do we build a model of a wastewater treatment system? What will it teach us?
How do we test it?

Elaborate

What impacts do industries, community buildings, and residences in your neighborhood have on the wastewater treatment system? How do those impacts impact us?

Students will be able to:

Build a model of a wastewater treatment system in order to “clean” a water sample.
Test the design of their wastewater treatment system in order to evaluate the design/effectiveness of their wastewater treatment system compared to each other and compared to the natural process.
Describe the basic steps of our local wastewater treatment process.
Compare their wastewater treatment models to PWD’s wastewater treatment process in order to evaluate the effectiveness of each and to consider how to make a positive difference.

Engage

Secchi Disk

White Bucket (clarity test)

Add 5 of the following ingredients to a bucket of water:

  • Toilet Paper
  • Soap
  • Toothpaste
  • Detergent
  • Plastic bags/trash
  • Iron filings
  • Oil
  • Food Scraps/Coffee Grinds
  • Biodegradable Styrofoam
  • Mouthwash

Explore & Explain 

Wastewater from Engage Activity

Wastewater Model:

  • Dirty water sample with things that will both sink and float (e.g gravel, pebbles, dirt, leaves, oil, feathers)
  • Empty see-through (plastic  ) bottle with cap or lid

 

Optional: “Jeffrey’s model” (Here is a link to a video to help you visualize this model)

1 – GE 2.8-oz Clear Silicone Window and Door Caulk ($3.98)
4 – AMERICAN VALVE 1/2-in PVC Sch 40 Female In-Line Ball Valve with Integral Stops ($2.52 each)
5 – Deer Park 3 QT water bottles ($1.00 each)
1 – 2 ft. of Samar 5/8-in x 1-ft PVC Clear Vinyl Tubing ($.45 a foot)
1 – Exacto knife or small box cutter
Roll of paper towels
Sand
250 mL potting soil
Sugar/Yeast
Oil

For Evaluating Models:

Beakers
Scale (for weighing)

BASIC WORDS

Bacteria noun
Microscopic living organisms, usually one-celled, that can be found everywhere.

Density noun
Degree of consistency measured by the quantity of mass per unit volume

Gravity noun
The force that attracts a body toward the center of the earth, or toward any other physical body having mass

Scum noun
A layer of grease and oil that rises to the surface of the liquid.

Sludge noun
Solids that settle by gravity in the wastewater treatment process made up of organic materials such as food, feces, paper fibers, etc.

ADVANCED TERMS
Dissolution noun
The act or process of dissolving into parts or elements or to disintegrate.

Influent/Effluent noun
Inflow/outflow

Permit noun
An official document authorizing permission to do something.

Design and/or diagram a model of a wastewater treatment plant in order to “clean” a water sample. The diagram and/or model should include all the steps of PWD’s wastewater treatment process:

  • Explanation of the role of bacteria.
  • Explanation of the role of density.
  • Explanation of the role of screening and sorting.
  • Explanation of how the treatment process emulates natural systems.
  • A description of what substances are removed and what still remains and the implications of both.

Test the design of their wastewater treatment system in order to evaluate the design/effectiveness of their wastewater treatment system compared to each other and compared to the natural process.

Make a 2D presentation tool like a foldable with a diagram and describe in detail the steps of our local wastewater treatment process.

Compare their wastewater treatment models to PWD’s wastewater treatment process in order to evaluate the effectiveness of each and to consider how to make a positive difference.

Reflect on what changes we can make to help the process at the wastewater treatment plant improve overall water quality.

Create posters/pamphlets/videos (Public Service Announcements) to raise school wide awareness about wastewater treatment. These PSA’s should include:

  • A description of what goes down the drain and the effects of these substances on the wastewater treatment process.
  • A description of what and when substances are removed in the wastewater treatment process and what still remains and the implications of both.

PA STEELS Standards

Environmental Literacy and Sustainability

3.4.6-8.G Sustainability and Stewardship: Obtain and communicate information to describe how best resource management practices and environmental laws are designed to achieve environmental sustainability.

Related Standards

MS-ETS1.A  Engineering Design – Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.

ELA W.7.4.A  Produce clear and coherent writing in which the development, organization, and style are appropriate to task, purpose, and audience.

EfS C.1  The Dynamics of Systems and Change – See the whole system, its parts, and their place within the system.

EfS C.17  The Dynamics of Systems and Change – Make choices and decisions and take action(s) that maximize the health of the whole system upon which the specific part(s) depend(s).

Student Materials

Back To Top
Skip to content