Materials Included In Kit

Additional Materials Required

Prelab Preparation

The metal pieces, wood pieces, string pieces, and paper strips need to be prepared before the lab. The aluminum strips should be cut into ½" x ½" pieces. The wood splints should be cut every ½". The string pieces should be cut approximately 2" in length. Obtain a normal sheet of paper and cut ½" x ½" pieces. Have students bring in small pieces of dry food to place into their landfill. Pieces of cereal, chips or crackers work well.

Safety Precautions

Wear appropriate eye protection and follow all normal laboratory rules. Be sure that students wash hands after handling soil and sample materials. All work areas should be disinfected thoroughly before leaving the lab. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. All items may be thrown away in the trash according to Flinn Suggested Disposal Method #26a.

Teacher Tips

• Enough materials are provided in this kit for 30 students working in pairs. The initial procedure will require one class period. Observations should be taken over at least a six- to eight-week time period.

• Biodegradation is a slow process and may take more time than six to eight weeks. If time permits, have students record observations for an extended period of time.
• As an extension to this activity, have students bring in items from home to see if they are biodegradable.
• Decomposition rate may also be tested. Students may wish to experiment with variables (e.g., temperature, moisture) to determine decomposition rates.

Further Extensions

Alignment with AP^® Environmental Science Topics and Scoring Components

Topic: Land and Water Use. Other Land Use (Urban land development; transportation infrastructure; public and federal lands; land conservation options; sustainable land-use strategies).

Scoring Component: 5-Land Use, Other Land Use.

Sample Data

Answers to Questions

1. Describe what happened to the materials in the organic soil. What materials were biodegradable in the organic soil?
   

   Answers will vary. The materials in the organic soil broke down easier than the sandy or the sanitary landfills. The cornstarch peanut, paper, foodstuff, cotton string and the wood (somewhat), were biodegradable.
   

2. Describe what happened to the materials in the sand. Were any materials biodegradable in the sand?
   

   Answers will vary. The materials did not degrade as rapidly in the sand. The cornstarch peanut, paper, and foodstuff biodegraded somewhat in the sand.
   

3. Did any of the materials degrade in the sanitary landfill? Why or why not?
   

   None of the materials degraded rapidly in the sanitary landfill. The sanitary landfill was totally isolated from the organic soil.
   

4. What material degraded the most rapidly?
   

   Answers may vary.
   

5. Given your results, what soil type would you use to cover waste in a landfill?
   

   Soil rich in organic material should be used to break down materials the most rapidly.
   

6. What are the advantages and disadvantages of both sanitary and open-air landfills?
   

   Answers will vary. Sanitary landfills help cut down the smell of trash, but the materials do not break down easily. Many trash items break down in open-air landfills, but they are unsightly and the smell can be overwhelming.
   

7. What steps can you take to reduce the amount of trash being placed into landfills?
   

   Answers will vary. Pick up litter, recycle, make compost heaps, etc.

Introduction

As more and more people populate the planet, the amount of trash we create dramatically increases. How should this trash be disposed of? Should all garbage be treated in the same manner? In this activity, simulated landfills will be set up and the effectiveness of each will be tested using various test items.

Concepts

• Decomposition

• Landfills
• Biodegradable products

Background

Each year, Americans generate nearly 210 million tons of trash. That equates to an average of four pounds of trash per person per day! Where exactly does all of this garbage go and what happens to all of this trash?

Some of the trash is recycled or incinerated, however, the majority of the trash is placed into landfills. A landfill is a structure that is built on top of or into the ground that helps isolate trash. There are two basic types of landfills: open-air landfills and sanitary landfills. Open-air landfills, more commonly known as dumps, are nothing more than an open hole in the ground where trash is placed and sometimes covered with a layer of soil. Most of the waste in open-air dumps is left in piles that are open to rain, wind and scavenging animals. Open-air dumps are the most predominant method of waste disposal worldwide. However, in the United States, most open-air landfills have been eliminated and replaced by sanitary landfills.

Sanitary landfills utilize clay or plastic liners to separate and isolate trash from the surrounding environment. Most sanitary landfills cover their trash with compacted soil daily. This helps cut down on the overall smell of the trash, the amount of litter and amount of pests. When a section of a sanitary landfill is completely full, a plastic cap or liner is placed on the landfill. This liner is then covered with another thick layer of soil. Although sanitary landfills have solved some of the problems associated with open-air landfills, many materials in sanitary landfills are not biodegradable. Non-biodegradable objects, such as most plastics and synthetic materials, do not decay. Biodegradable materials such as food wastes and paper also do not decompose rapidly. Once the trash in sanitary landfills is covered with compacted soil and capped with a plastic liner, very little water and oxygen are present. Both oxygen and water are required for most organisms that aid in decomposition.

The most common decomposers in nature are bacteria, molds, fungi and yeast. Decomposers release enzymes that digest and break down materials into simpler compounds. The decomposers absorb the digested materials and recycle the material back in to the environment in useful forms. Certain decomposers, known as anaerobic decomposers, thrive in environments that are void of oxygen. The small amount of decomposition that does occur in sanitary landfills is anaerobic. The major byproduct of anaerobic decomposition is landfill gas. Landfill gas is basically a 50:50 mixture of methane and carbon dioxide gas. This is a very flammable and explosive gas that must be removed from landfills. To accomplish this, a series of pipes are embedded in sanitary landfills that collect the gas. The gas is lead through the pipes to the surface on the landfill where the gas is usually burned.

The ability of an item to decompose depends on factors such as the chemical make-up of the material and the type of environment the material is placed in. In this activity, various items will be placed into three simulated landfill situations. The items will then be observed over an extended time period to see if any decomposition occurs.

Materials

Safety Precautions

Wear appropriate eye protection and follow all normal laboratory rules. Be sure to wash hands after handling soil and sample materials. All work areas should be disinfected thoroughly before leaving the lab.

Procedure

1. Obtain two landfill containers. Using a marker, write your group’s initials on the bottom of each container.
2. Place organic soil into one of the landfill containers. Fill the container three-quarters of the way full with the organic soil.
3. Place the sand into the other landfill container. Fill the container three-quarters of the way full with the sand.
4. Place one of each of the objects into a plastic bag.
5. Place the bag 1" below the soil in the corner of the organic soil landfill container. This will represent sanitary landfill conditions.
6. Label a marker stick “Sanitary” and place the marker near this bag of items.
7. Place one each of the objects into the organic soil container. Place the objects roughly 1" under the surface of the soil. Label a marker stick for each item and place the marker near the object in the soil.
8. This landfill will represent an organic open-air landfill.
9. Place one each of the items into the sandy soil container. Label a marker stick for each item and place the marker near the object in the soil. Place the objects roughly 1" under the surface of the sand.
10. This landfill will represent a sandy soil open-air landfill.
11. Place water into both of the landfill containers until the soils are moist but not thoroughly soaked.
12. Add water to the trays every few days as needed to maintain moist soil.
13. Dig up and observe the appearance of the materials in each type of landfill situation once a week over the next six or eight weeks. Record the observations using the following symbols in Data Table 1 of the Landfill Decomposition Worksheet. Place the items back in the soil after observations have been recorded.

– No degradation
+ Beginning stages of degradation
+++ Large amount of degradation

14. Answer the questions in the Landfill Decomposition Worksheet after the experiment has been completed.

Student Worksheet PDF

10476_Student1.pdf