DCWASA's Certifiable GHG Inventory and Projected GHG Reductions from Cambi/Anaerobic Digestion Upgrades

DC WASA provides water distribution and wastewater collection and treatment services to the greater Washington, DC metropolitan area serving a population of approximately 2.1 million people. Wastewater is treated at the 370-million-gallon-per-day (mgd) Blue Plains Advanced Wastewater Treatment Plant (AWTP). DC WASA will soon replace the aging lime stabilization sludge-treatment process at the AWTP with Class-A anaerobic digestion using Cambi™ thermal hydrolysis. This upgrade will produce electricity and process heat from a renewable fuel (digester gas) while reducing the mass of produced biosolids by 50 to 60 percent.This paper will document DC WASA's GHG inventories for 2007 and 2008 and show how the proposed digestion upgrades will reduce the utility's overall inventory by an estimated 28 to 39 percent or 46,816 to 73,340 MT of CO2e per year.