Lowering Food-Waste Co-digestion Costs through an Innovative Combination of a Pre-Sorting Technique and a Strategy for Cake Solids Reduction
Bringing new strategies to make co-digestion cost effective to enhance biogas energy production
Projects Updates/The Results
Project successfully demonstrated two complementary approaches to lower the overall cost of co-digestion: a new technology to lower preprocessing cost of food wastes (FW), and a new strategy for the addition of Fats, Oil, Grease (FOG) or FW to lower the mass of cake solids requiring disposal. The technology uses an organic waste separation technique known as an organic extrusion press (OEP/OREX) for selective extrusion of organic materials that has a higher efficiency than conventional techniques. Also, the technology is more economical than typical source separation programs since it requires minimal preprocessing. Results indicated 54% savings compared to source separation and polishing of FW currently practiced. Economic evaluation of a 100 MGD plant indicated $8.9 to $9.3 million worth of energy savings by energy recovery, due to increased gas production.
The project demonstrated two complementary approaches to lower the overall cost of co-digestion: a new technology to lower preprocessing cost of food wastes, and a new strategy to lower the mass of cake solids requiring disposal. The new technology for the preprocessing of food wastes uses an organic waste preprocessing technique known as an organic extrusion press (OEP) for selective extrusion of organic materials and is capable of recovering 95% of organics. The project applies a new strategy in operating co-digestion systems that involves optimizing the organic waste loading in a way that will lower the mass of cake solids requiring disposal relative to the conventional process.
Environmental & Public Health
The technology from this project has the potential to reduce greenhouse gas emissions by 443,345 MTCO2e/year at a modest 10% market penetration. Furthermore, a lower volume of sludge requiring disposal will lower the emissions from trucks used for hauling sludge.
Applying the results of this project to waste water treatment facilities will reduce grid imports and provide a reliable generation source for these facilities and the grid. With the technology advancement supported by this project, the estimated increase in annual energy production at the demonstration facility is approximately 7,400 MWh.