Abstract |
Water Resource Recovery Facilities (WRRFs) with anaerobic digestion have been harnessing biogas for heat and power since at least the 1920’s. A few are approaching 'energy neutrality' and some are becoming 'energy positive' through a combination of energy efficiency measures and the addition of outside organic wastes. Enhancing biogas production by adding fats, oil and grease (FOG) to digesters has become a familiar practice. Less widespread is the addition of other types of food waste, ranging from municipally collected food scraps to the byproducts of food processing facilities and agricultural production. Co-digesting with food waste, however, is becoming more common. As energy prices rise and as tighter regulations increase the cost of compliance, WRRFs across the country are tapping excess capacity while tempering rates. This report presents the co-digestion practices, performance, and the experiences of six such WRRFs. The report describes the types of food waste co-digested and the strategiesâ€â€specifically, the tools, timing, and partnershipsâ€â€employed to manage the material. Additionally, the report describes how the facilities manage wastewater solids, providing information about power production, biosolids use, and program costs. |