Using Algae for Phytoremediation (Part 3/3)

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Objective

Students will test algae's ability to remove pollutants from waste water to better understand phytoremediation.

Big Idea

Algae are amazing living things especially when it comes to clean-up.

What Students Will Learn in this Lesson

1 minutes

Today students are going to compare the data they collected over the past two days with a peer-reviewed study.  They are going to determine where the data they collected is similar and where it is different from the peer-reviewed study. This is the final day of a three day lab.  Find day one here and day two at this linkHere is an overview of what students will learn today.  

Hook

3 minutes

Show students the following video to demonstrate a practical application of phytoremediation. 

Have students ask the 5Ws (who, what, where, when, why) and 1 H (how) after watching the video.  Then using their notes, students should complete a current events summary.

A Scientific Study: How Chlorella Remediates Water

20 minutes

Explain to students that they will be looking at an explanation summary and data overview of the peer-reviewed study, "Phytoremediation of Partially Treated Wastewater by Chlorella vulgaris."

Using the same lab groups that were assigned for day one and two of this lab, students should read through the student handout  and answer the questions throughout the handout.  

 

Comparing Our Data with the Data of Others

20 minutes

Using the provided handout, students will compare the data they collected with the a 2012 study, "Phytoremediation of Partially Treated Wastewater by Chlorella vulgaris."  This study looked at the ability of a pure strain of algae to remove pollutants from waste water. 

First have student read the abstract of the paper and highlight the following: 

  • Highlight the organism studied in green.
  • Highlight the test performed to determine the effectively of the removal of the pollutants in yellow.
  • Highlight the results of tests in pink.
  • Highlight the conclusion of the study in blue. 

Next have students take a closer look at the organism, equipment, and tests performed in this experiment in the Materials and Methods section and:

  • Highlight the similarities of this experiment with the experiment that you did in class in green.
  • Highlight the differences of this experiment with the experiment that did in class in pink.
  • Give each paragraph a heading that describes the main point of the paragraph.

Have students look at the results and explanation of the results.

  • Remind them to notice the underlined sentence in this section.  Write a prediction to explain why both control and experimental groups saw a decrease in nitrogen and phosphorus over the two week period.
  • Students should also  Graph the data from table III.  Fit a curve to the data points for each test. Have them also analyze the data using the statistics tool.  
  • Students should print off a copy of the graph and place it in their lab notebook.

 

(Note:  Here are some samples of some typical student work (Total Nitrogen GraphCOD graph, and Total Phosphorus graph). Here are several examples of excellent student work (Total Phosphorus graphCOD graphTotal Nitrogen graph). All criteria were met in this graphic analysis. A line of best fit was determined. Descriptive statistics were calculated. A summary of the graph's trends were included. In the examples of typical student work only line of best fit was determined. This student was familiar with line of best fit because we have determined it in a previous class. The other two tasks were unfamiliar and so they chose not to attempt them. The next day I remind this student how what tools to use to finish the tasks.)    

Next, have students look at the VSS graph and write a trend that explains what happened to the VSS over the course of the 14 day study

Finally, students should write a conclusion of the study based on what they have read. 

 

 

Putting It All Together: Have the Algae Reached Its Limit (Part 2)?

5 minutes

Have students compare the shape of Removal of Pollutants with Time graph from the 2012 Chlorella study to the graph they made from the data they collected from yesterday.  Ask them to list the similarities and differences.  

Remind them in the Chlorella study that the algae removed the maximum amount of pollutants that it could (hence the shape of the graph).  If the graph that the students made does not mirror the Chlorella study graph, then the algal mat could remove more of the copper from the simulated wastewater.  

Have students extrapolate their graph and make a prediction concerning how long they think it would take the algal mat to reach the maximum amount of removal of pollutants.  Have them record their prediction in their lab notebook and explain their thinking.  

Finally, explain to students that by making these types of models, scientists can determine the amount of time wastewater can remain in a holding tank before it should be moved to maximize the removal of pollutants.