Biogas Recovery from Hyper-Thermophilic Anaerobic Co-Digestion of Thickened Waste Activated Sludge, Organic Fraction of Municipal Solid Waste and Fat, Oil and Grease

The use of organic fraction of municipal solid waste and Fat Oil and Grease (FOG) as co-substrates for thickened waste activated sludge anaerobic digestion has the potential to improve the biodegradation process and significantly enhance biogas production and methane yields. This will not only help convert these potential waste streams from landfills increasing the longevity of existing landfills, but also provide a sustainable waste to energy waste management method. In this study the anaerobic co-digestion of organic fraction of municipal solid waste, with thickened waste activated sludge (50:50, w/w based on total volatile solids) was investigated using anaerobic digestion thermophilic and hyper-thermophilic biochemical methane potential (BMP) assays. The hyper-thermophilic BMP assays outperformed the thermophilic BMP assays by providing faster biogas production rates, higher cumulative biogas productions and methane yields. Additionally, 10, 20 and 30% FOG (based on total volatile solids) were added to the co-digestion mixtures in order to boost the biogas production and methane yield in three hyperthermophilic assays. 30% FOG in the co-digestion mixture enhanced the biogas methane content for sample TWAS:OFMSW:30%FOG(H) to 66.4% compared to 60.1% for the control sample TWAS(T), and accordingly improved the methane yield to be 84.4% higher than the methane yield of the control.