One topic we think about a lot here at the Island School is how to live as sustainably as possible. Dealing with human waste is an issue that we’ve tried to confront many times in the past, but until now haven’t found a practical solution. There are several reasons as to why the issue of human waste is so problematic. First of all, pumping it out to be driven to a landfill is bad for the environment since it leaches into the ground, which can pollute both fresh groundwater and ocean water. Also, burning it releases greenhouse gases into the atmosphere, which contributes to the widely discussed issue of global warming. Currently we have created a waste water, or, as it is more affectionately known, “Poo-poo” garden on campus to handle our waste. Toilets, sinks, and showers run into this garden, where solids settle out and liquids gravity flow to two beds, providing nutrients that promote plant growth, especially for thirsty plants like bananas. But what about the solids? How can we find a final resting place for our human waste? Can we find a second life or use for it? Does it still have potential to create energy? Enter biodigestion!While the poo-poo garden is great and makes our campus more aesthetically pleasing, it does not fully solve our problem—we need an improvement.

Now, we have discovered a process that could solve our waste dilemma. Biodigestion is an anaerobic process, meaning it occurs in an enclosed setting without oxygen. Naturally occurring bacteria with the biodigestion system break down organic inputs to create a nutrient rich fertilizer that can be used to enhance plant growth and production.  Biodigestion also creates a renewable energy in the form of biogas that be used in many different applications. At Island School, we are putting human waste into the digester along with glycerol, a byproduct of our biodiesel production system. Having a biodigester on campus not only uses resources that we didn’t have a use for before (waste and glycerol), but it also creates a much needed boost for our nutrient weak soil, all while producing another source of energy for our campus. Through developing biodigestion technology, we can simultaneously lower our demand for food imports, increase our production of renewable energy, and effectively deal with several of our waste streams. Biodigestion—a win any way you look at it.

Hannah Twombly