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Activity (Hands-On)Grades 6 - 8

Digest Your Food!

A drawing shows a capped 2-liter bottle (a mini-anaerobic digester) on the left, with a tube connecting to the capped top of an open-bottom container floating in a jar of water (a gas measurement device) on the right.Students build food digesters

In a multi-week experiment, student teams gather biogas data from the mini-anaerobic digesters that they build to break down different types of food waste with microbes. Using plastic soda bottles for the mini-anaerobic digesters and gas measurement devices, they compare methane gas production from decomposing hot dogs, diced vs. whole. They monitor and measure the gas production, then graph and analyze the collected data. Students learn how anaerobic digestion can be used to biorecycle waste (food, poop or yard waste) into valuable resources (nutrients, biogas, energy).

Anaerobic digestion is an integral part of many environmental engineering processes, such as wastewater treatment, and food and agricultural waste management. Engineers design these systems to recycle and minimize the impacts of waste on our environment, as well as produce useful products such as heat, energy and nutrient fertilizers.

After this activity, students should be able to:

  • Explain why breaking up organic waste before adding it to a digester helps microbes break it down faster, much like chewing food helps a stomach digest it faster.
  • Explain why researchers use a blank (or control) within an experimental setup.
  • Explain the relationship between biogas production and microbial activity.
  • Demonstrate how to record, analyze and interpret data.
  • Recognize opportunities in which biorecycling can turn waste management into resource creation.

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