What percentage of CalSTRS’ food waste was diverted to a “biodigester” in 2015?
94 percent of CalSTRS’ food waste was diverted from recycling to a biodigester in 2015.
What is a Biodigester?
According to CalEPA, biogas recovery systems are sometimes known as anaerobic digesters or “biodigesters” because they use a process called anaerobic digestion. During anaerobic digestion, bacteria break down waste in an oxygen-free environment. One of the natural products of anaerobic digestion is biogas, which typically contains between 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and trace amounts of other gases. Applications of anaerobic digestion for biogas capture include wastewater treatment plants, dairies and at organic waste processing facilities.
Biogas can be used to produce electricity using engines or fuel cells, or it can be converted to transportation fuel or “biomethane” (which has the same properties as natural gas).
Learn more about anaerobic digestion at CalEPA .
Learn more about CalSTRS practices in our sustainability report, Fostering a Secure Future.