When you think of composting, chances are you envision one of a variety of bins or holding systems that are used for composting outdoors. For fastest composting, these bins need to provide adequate moisture, heat retention, and air flow to facilitate aerobic, heat-producing decomposition of organic matter. Composting can also be carried out right in the classroom, in containers ranging in size from soda bottles to garbage cans. Because these units are so much smaller than the outdoor bins, they need to be carefully designed to provide proper conditions for aerobic, heat-producing composting to occur.
Three types of composting vessels, or bioreactors, are described here:
Garbage Can Bioreactors will process enough organic matter to fill a 20-gallon can, producing finished compost within two to three months.
Soda Bottle Bioreactors are designed primarily as tools of research rather than waste management. They are small and inexpensive enough to enable students to design and carry out individualized research projects, comparing variables such as reactor design, moisture content, and nutrient ratios of mixtures to be composted.
High-Tech Bioreactors are also designed for research purposes. They are similar to the less complicated 2-can or soda bottle bioreactors, but they use more sophisticated technology for measuring temperature and regulating air flow.
Worm Bins are another form of indoor composting. Here the decomposition is accomplished by redworms as well as microorganisms, and the temperatures do not get as high as in the bioreactors above. Worm bins are popular in elementary school classrooms, where the students use them for activities ranging from scientific measurement to story writing.
 |
 |
 |
 |
|
Composting |
Engineering |
in Schools |
|