DEMONSTRATION-SCALE EVALUATION OF A NOVEL HIGH-SOLIDS ANAEROBIC-DIGESTION PROCESS FOR CONVERTING ORGANIC WASTES TO FUEL GAS AND COMPOST

Early evaluations of the bioconversion potential for combined wastes s uch as tuna sludge and sorted municipal solid waste (MSW) were conduct ed at laboratory scale and compared conventional low-solids, stirred-t ank anaerobic systems with the novel, high-solids anaerobic digester ( HSAD) design. Enhanced feedstock conversion rates and yields were dete rmined for the HSAD system. In addition, the HSAD system demonstrated superior resiliency to process failure. Utilizing relatively dry feeds tocks, the HSAD system is approximately one-tenth the size of conventi onal low-solids systems. In addition, the HSAD system is capable of or ganic loading rates (OLRs) on the order of 20-25 g volatile solids per liter digester volume per d (gVS/L/d), roughly 4-5 times those of con ventional systems. Current efforts involve developing a demonstration- scale (pilot-scale) HSAD system. A two-ton/d plant has been constructe d in Stanton, CA and is currently in the commissioning/startup phase. The purposes of the project are to verify laboratory-and intermediate- scale process performance; test the performance of large-scale prototy pe mechanical systems; demonstrate the long-term reliability of the pr ocess; and generate the process and economic data required for the des ign, financing, and construction of full-scale commercial systems. Thi s study presents conformational fermentation data obtained at intermed iate-scale and a snapshot of the pilot-scale project.