Original post from Green Cart Chronicle Summer 2019 Edition –
In January 2019, organics collection was launched in the cafeteria of two Newton schools, Angier Elementary School and Zervas Elementary School. Each lunch period, students sort their waste into three categories of waste: trash, recycling, and organics. Organic material includes food waste, napkins, and other compostable material.
The organic material is hauled from the schools by a vendor to Charlestown, MA. The Charlestown facility turns the food waste into a slurry that is then anaerobically digested at a wastewater treatment facility. Anaerobic digestion is a process through which the organic material mass is reduced, producing methane gas, which is then used to generate energy. Solids remaining after anaerobic digestion are composted. DPW is working with NPS to add organics diversion in up to 12 more schools in the 2019-2020 school year.
ANAEROBIC DIGESTION VS COMPOSTING
Composting is a natural degradation process. The breakdown of organic matter occurs over time from exposure to oxygen, moisture, and naturally occurring bacteria. The result of the process is a humus material called compost.
Anaerobic digestion is a biological process by which microorganisms break down biodegradable material in the absence of oxygen, producing carbon dioxide and methane gas. The process is used for industrial or domestic purposes to reduce waste solids and produce renewable fuel that can be captured and used, offsetting the use of fossil fuels and reducing greenhouse gas emissions. The remaining solids are then composted.