Enhancing faecal sludge derived biocrude quality and productivity using peat biomass through co-hydrothermal liquefaction

Faecal sludge (FS) and drained peatlands have become the hotspots research area in recent years, causing significant environmental pollution and greenhouse gas (GHGs) emissions. Hence, this study explored the co-hydrothermal liquefaction (co-HTL, 300 °C for 60 min) of peat (P) and FS at different ratios (100:0, 25:75, 50:50, 75:25, and 0:100% of P: FS) to produce high-quality biocrude as a “waste to energy” approach. A positive synergistic effect was observed in P and FS co-HTL with higher biocrude yield and enhanced quality than individual HTL. Among the co-HTL ratios, the optimum biocrude yield of 44.58% was observed for the 50-50 ratio (P50FS50) with a conversion rate of 55.8% and energy recovery of 72%. However, the highest HHV was obtained from co-HTL of P75FS25 (35.5 MJ/kg), where biocrude had higher C (70.5%) and H (10.4%) contents with less amount of N (0.01%). The elemental composition of co-HTL indicated that biocrude had potential similarities to petro-crude. FTIR analysis confirmed that biocrude samples had aliphatic hydrocarbons, phenols, and esters, where the oil quality was immature to premature grade oil of kerogen type I (highly oil-prone). GC-FID hydrocarbon fractionation analysis revealed that the optimum lighter fraction crude (35.3%) was produced from co-HTL of the P50FS50 sample. In this context, the findings demonstrated that the co-HTL of P and FS might be an alternative approach for green biocrude oil production.