Co-Hydrothermal liquefaction of sawdust and cow manure for the production of bio-crude oil

Abstract

In Bangladesh, transportation plays a significant role in escalating oil consumption. Moreover, the significant growth of cow manure (CM) and sawdust (SD) throughout the last few years has led to a critical challenge in waste management. To address these issues, this study investigated the current advancements in the utilization of SD and CM as valuable resources for bio-crude oil production through the process of hydrothermal liquefaction (HTL), specifically co-hydrothermal liquefaction (co-HTL). In the co-HTL process, SD and CM feed were mixed at various CM:SD ratios of 1:0, 1:1, 1:3, 1:4, and 0:1 with water. Several process parameters, including temperature, pressure, residence time, and dry feed content, were varied to find the optimum condition. Furthermore, the comparison between the single-feed HTL process and the mixed-feed co-HTL process was also studied. The higher heating value (HHV), lower heating value (LHV), dynamic viscosity, pour point, and density of bio-crude oil were measured in order to compare the fuel properties with conventional fuels like diesel and petrol. In our study, the highest HHV (33.36 MJ/kg) and yield (56.64 wt.%) of bio-crude oil were achieved at 320 °C and 200 bar with a CM:SD mixed feed ratio of 1:3. The energy yield of bio-crude oil was also higher (94.95%) at the same condition. The synergistic interactions between the co-processed feedstocks fostered bio-crude oil production, which evidenced that co-HTL is more promising than HTL in producing bio-crude oil with enhanced energy content.