The anaerobic digester at the Center for Sustainable Development (CSD) was completed in 2012 in a continuing effort towards environmental stewardship and waste management. The two-stage anaerobic digester converts human waste into energy and fertilizer. Furthermore, it provides a safe, natural means for wastewater treatment on campus. Wastewater treatment is a big concern for CSD; the conventional methods of handling sanitary waste in The Bahamas are either spreading it in a field, using chemicals, or deep well injections. Our anaerobic digester gives us a safe, environmentally responsible way to manage our septic waste stream.
Anaerobic digestion is a biological process in which naturally present microorganisms break down organic matter in the absence of oxygen. The end products of this system are a renewable energy source, biogas, and a nutrient-rich, organic fertilizer. The anaerobic digester at CSD can process 500 gallons of human waste per week. Other organic waste products such as glycerol, a waste product from processing biodiesel, are also used in the digester. Glycerol has an exceptionally high biogas yield potential, and compliments human waste as a feedstock.
After being offline for a time during which an additional pre-pasteurization stage for the system was installed, the anaerobic digester is back online and repurposing waste products into higher-value resources! CSD looks to the anaerobic digester as another component of our larger Waste-to-Energy initiative, in which many systems will utilize products and by-products of multiple processes. Future research on anaerobic digestion will be in the areas of increasing biogas production, minimizing hydraulic retention times, and finding the most effective means of utilizing this energy source.