Energy security can be defined as assured access to reliable energy supplies and the ability to protect and deliver energy to accomplish an objective or mission. For military installations within the United States Department of Defense (DoD), electrical energy is essential for almost every mission. DoD has developed strategies in an effort to move towards energy security over the last decade. DoD and its departments (e.g., Department of the Army) continue to publish refined guidance. Most recent, the Department of the Army published a directive that calls for 14 days of energy and water independence to sustain critical missions. Beyond DoD directives, each military installation needs to abide by local government regulations. For example, the U.S. Military Academy at West Point, which exists in New York, is considered a large food scrap generator and is required to divert food waste from landfills by January 2022. To meet these mandates and move DoD military installations to a circular economy, the anaerobic co-digestion of multiple waste streams such as food scraps and wastewater sludge is a possible solution. Anaerobic co-digestion of organic wastes is known to enhance methane production and move facilities towards becoming net energy producers; however, no co-digestion facilities currently exist on DoD installations. This study presents the modeled results of co-digestion of food wastes from major generators on West Point coupled with wastewater sludge produced from a 2.1 million gallon per day wastewater treatment facility. Results suggest that anaerobic co-digestion would enhance methane production relative to digestion of wastewater sludge alone, but methane yield is still too low to create sufficient electrical and heat energy to power more than anaerobic digesters themselves and several additional wastewater treatment processes. Identified challenges include intermittent food generation and low wastewater flowrates. Barriers include administrative hurdles, capital costs, and contractual hurdles with private contractors. Results from this study suggest that anaerobic co-digestion can be a path forward for military installations but numerous technological and non-technological issues need to be addressed. Further, maximizing the use of organic wastes produced will likely be required to generate the amount of methane and electrical energy required for energy autarky at DoD wastewater treatment facilities.

Co-digestion of food waste and wastewater sludge for enhanced methane production and energy security on military installations

ACS Fall 2020 Virtual Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.