BIOMASS CONVERSION AND BIOREFINERY, vol.14, no.4, pp.5517-5530, 2024 (SCI-Expanded)
The main barriers to the use of biomass as an energy source are high humidity, ash, and oxygen content which can be eliminated by wet torrefaction (WT). In this study, dewatered poultry sludge (DPS), as is complex biomass to dispose of, was subjected to WT by considering the reaction temperature, time, and feed concentration as the independent process parameters. The experiments were designed using response surface methods and carried out in a laboratory-scale batch reactor. The optimum conditions for both maximum solid yield (SY) and calorific value (CV) (85.2, 28.64 MJ/kg) were evaluated for the reaction temperature, time, and feed concentration of 268 degrees C, 47 min, 50 wt%, respectively. According to the results, the feed concentration was the most influential parameter on CV and SY, whereas the reaction time had the lowest effect. In addition to the individual effects, the interactive effects of the process parameters on CV and SY have also been determined with 3D and contour plots, indicating optimum condition. Besides, the proximate analysis revealed that the fixed carbon was increased while the amount of ash and volatile matter in the torrefied DPS (TDPS) decreased under optimum conditions. Through the ultimate analysis, a remarkable reduction in the atomic ratio of oxygen to carbon was reported. This research revealed that the WT method could convert DPS into a solid fuel with desirable properties and provide valuable information on the optimum reaction parameters for producing hydrochar.