Identifying High Strength Wastes Suitable for Co-Digestion at Blue Plains AWTP

Co-digestion of high strength organic waste (HSW) with municipal solids can increase biogas production due to the high biodegradability and energy value characteristic of these wastes. In recent years, technological improvements in converting biogas to energy in anaerobic digesters and a growing interest in energy recovery have attracted an increasing number of Water Recovery Facilities (WRFs) to evaluate the viability of co-digestion. In 2015, the District of Columbia Water and Sewer Authority (DC Water) pursued an evaluation to accept HSW for co-digestion to utilize available digestion process capacity, offset operating costs, and increase bioenergy production from the recently installed Cambi units and mesophilic anaerobic digesters at the Blue Plains Advanced Wastewater Treatment Plant (AWTP). As part of the evaluation, DC Water initiated a market assessment to identify regionally-available HSW from industrial and non-residential dischargers suitable for co-digestion in the anaerobic digestion process at the Blue Plains AWTP. The market assessment, conducted by Material Matters, defined the economically viable radius for hauling HSW, identified specific generators of HSW in the DC Water region, and determined current HSW practices and costs. Ultimately, it was determined that capturing HSW for co-digestion at the Blue Plains AWTP will require reasonable transportation costs and attractive tipping fee structure. Findings of the assessment indicate that food processing waste, grease trap waste, and airport deicing runoff wastewater represent the most promising sources for inclusion in the technical screening and laboratory R&D co-digestion program development.