Support for Regional Community Anaerobic Digestion for Organic Waste Diversion

As the global population is increasing, the generation of various waste materials (fats, oils and grease, fruit waste etc.) is increasing, which when landfilled, takes up valuable landfill space. Anaerobic digestion techniques have been developed that potentially convert these waste materials into energy and fertilizer, thus reducing landfill demand. It has been hypothesized that addition of high strength organic waste to conventional wastewater sludge can enhance the generation of onsite biogas at wastewater treatment plants, to meet the energy requirements of the plant partially or fully.
To determine the anaerobic biodegradability of fats, oils and grease and fruit waste residuals, lab scale ultimate digestibility tests were conducted for a period of 63 days under mesophilic conditions. High strength organic wastes, thickened waste activated sludge and inoculum were mixed at 9 different ratios, and the mixtures were incubated in 500 mL serum bottles. After 63 days, the highest methane yield of 280 mL/gVS and 243 mL/gVS were obtained with mixtures containing 10% FOG with 10% red apples and 10% FOG only respectively whereas the methane yield of inoculum was only 8 mL/gVS. Preliminary cost analyses were conducted using the laboratory derived data