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Compost Bioreactor Design

A brown dirt or ground compost patch with a spiral of black tubing on top. In the middle of the spiral the tube rases up into the air.
Learning Goals

Learning Goals:

  1. Students will research the science of composting and proper maintenance methods to build their own bioreactor.
  2. Students will research the proper composition of compost for maximum heat production.
  3. Students will transfer the thermal energy in compost to a container of water heat water by placing a vessel in the middle of the active compost/bioreactor.
Materials List

Handouts

  • Student lab notebooks

Classroom Supplies

  • 5-10 Gallon containers/buckets
  • Probe thermometer (1 per group)
  • Graph paper
  • Beakers (250mL – 1L)
  • Outdoor space that won’t be disturbed
  • Disposable gloves
  • Compost materials (grass clippings, horse/cow/sheep manure, food leftovers from the cafeteria, chicken manure, dry leaves/straw/shredded paper/sawdust
  • Garbage bags or large bioreactor to store/use excess compost materials

Important Links

Next Generation Science Standards

Next Generation Science Standards

  • MS-PS3-3. Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer.
  • MS-PS3-4. Plan an investigation to determine the relationships among the energy transferred, the type of matter, the mass, and the change in the average kinetic energy of the particles as measured by the temperature of the sample.
  • MS-PS3-5. Construct, use, and present arguments to support the claim that when the kinetic energy of an object changes, energy is transferred to or from the object.
  • HS-PS3-3. Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.

Lesson 2 of 3 / Time: 2-3 periods spaced over 1 month

Solar energy is available when the sun shines but energy can be supplemented at night by the release of energy during the composting of organic waste. In this activity we will experiment with the feasibility of harnessing thermal energy to heat water with a bioreactor. Students will experiment with using compost buckets as bioreactors, first experimenting to increase temperature yield of the compost and then using that generated thermal energy to heat water. This lesson is a prep lesson towards the ultimate goal of designing a system that uses compost and a heat exchanger to keep water from freezing over during the winter. To increase temperature yield, students will examine the effects of different types of “fuel,” or organic waste, for their bioreactor.

 

Bioreactor Water Heating

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