AP Environmental Science



Wastewater Treatment –How does waste get treated?

Purpose: To identify primary, secondary, and tertiary treatment methods of wastewater.

Click on website:

Navigate to “Wastewater Treatment—Overview.”

A. Read through the pages and note the progression of stages. Take notes to help you understand each part of the plant.

Preliminary Treatment

( Primary Treatment (Settling)

( Secondary Treatment (Activated sludge)

( Secondary Treatment (Clarifier)

( Tertiary or Advanced Treatment

( Disinfection

( Solids Management

B. After you reach the end of the line, The Final Effluent, take the QUIZ called “Where Does It All Go?” There is a place for your answers at the end of this assignment.

C. Use the diagram on the website to help you answer the questions as you click through the slides.

Ho

1. Follow the water. What color is the path that the water takes?

2. From the pumping station to the grit chamber, this stage is Pre-Treatment. It is a ___ process.

a. Physical

b. Biological

c. Chemical

3. Primary treatment (settling) takes place in the ___________________ chamber.

4. Microbes that clean the water are added in the __________________________.

5. This Secondary stage of treatment is a ___ process.

a. Physical

b. Biological

c. Chemical

6. Tertiary treatment (not shown on diagram) is a stage that not all water treatment plants perform. This could depend on the population size in the area, or how affluent a city is. What does tertiary treatment remove, and why is it important?

7. Two ways that water can be disinfected before release as effluent are:

8. “Solids Management” is shown on the diagram in what color? ______________

9. The solids removed from the water along the way is now called sludge. What two problems does sludge present?

10. Sludge processing involves two steps:

11. In a two-step process, the anaerobic digester converts the sludge to:

12. The solid material from the previous stage is sent for dewatering. How is this final, dewatered stable sludge sample disposed of?

13. Influent means:

Effluent means:

Where does the effluent go?

Take the QUIZ and fill in your answers here:

1. Grit chamber

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2. Bar Racks and Screens

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3. Sludge Disposal

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4. Anaerobic Digester:

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5. UV Disinfection:

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D. Let’s apply what you’ve learned to an actual scenario. Read the story below and identify the steps of water treatment.

Here is the story… Mrs. Brown is a pig farmer in the great Commonwealth of Virginia. She raises many cows and pigs on her farm located in the rolling hills of the Piedmont. She stores her pigs’ waste in a waste lagoon and uses the manure as fertilizer to raise her renowned pumpkins and strange-looking gourds. One day some city kids in town visiting the neighborhood kids thought it would be funny to go exploring; one city kid was balancing on the edge of the lagoon, slipped, and fell in. He was okay but he lost his shoes. A large storm blew in a couple of days later bringing much needed rain. However, there was so much rain that the lagoon overflowed and (in this perfect world) the waste manure flowed overland and ended up running into a sewer system. Mrs. Brown was sad because of the spill and because she lost her source of fertilizer; she now would have to buy commercial fertilizer instead.

Where (in which part of the wastewater treatment plant or other location) would each of the following items i) be treated and ii) be discharged or disposed of?

a) The city-slickers shoes

b) The “chunks” of pig poop

c) The nitrates dissolved in the water

d) The fecal coliforms (the bacteria that naturally live in the wastewater).

e) The antibiotics that were fed to the pigs to fatten them up.

f) Explain to Mrs. Brown why she doesn’t have to buy fertilizer that she could use a product from the treatment plant as a fertilizer.

E. Watch this video and answer questions:

“Constructed Wetlands”

1. Briefly describe the environment.

2. What kind of primary treatment happens before the water reaches the wetland?

3. What happens after the primary treatment?

4. What step in traditional secondary treatment does this replace?

5. What are some ecological and economical incentives to using wetland to treat wastewater?

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