Co-liquefaction of organic solid waste with fecal sludge for producing petroleum-like biocrude for an integrated waste to energy approach

Globally, approximately 600–700 million tonnes/yr. of solid waste (SW) and 250–300 million tonnes/yr. of fecal sludge (FS) are not managed in an environmentally safe manner. Conversion of these two waste streams using this ratio (2–3: 1 of SW: FS) to produce biocrude for fossil fuel substitution would act as an integrated waste to energy approach to address current global crises (GHGs emissions, climate change, and global warming). This study took the opportunity to produce petroleum-like biocrude through co-liquefaction of organic solid waste (OSW) and fecal sludge (FS) and optimized crude production yield and quality by varying feedstock ratios (1:0, 1:3, 1:1, 3:1, and 0:1) and temperature (280–340 °C). A higher synergistic effect was observed at feedstock ratio 3:1 (OSW: FS) and 320 °C with 52% biocrude yield, of which 64% was lighter-fraction (C < 20). The produced light crude contained 60% ester, 14% heterocyclic, and 12% fuel hydrocarbon fractions and exhibited a heating value of 42.7 MJ/kg, suggesting a potential candidate for petro crude (42–49 MJ/kg) substitution. This energetically feasible process (energy recovery 86% and energy consumption ratio 0.36) would provide a revenue of US$ 467.8 per metric ton of waste feedstock, validating the high economic prospects for a cleaner production pathway.