Intermittent bed homogenization as a strategy for improving the biodrying process of orange solid waste biomass

Abstract

This study investigates the effects of intermittent air flow rate (Q) and bed homogenization period (BHP) on the biodrying process of orange processing waste. A central composite design (CCD) was used to analyze the effect of these parameters on temperature and water removal. The minimum bed temperature (T_min) during the experiments ranged from 6.8 °C to 17.8 °C, while the mean and maximum temperatures ranged from 11.8 °C to 27.2 °C and 19.9 °C to 44.9 °C, respectively. The final moisture content ranged from 2.59 db to 1.58 db. Besides process achievement of 44.9 °C without external heat, CCD analysis showed that neither Q nor BHP had a significant effect on temperature during the biodrying process. While higher air flow rates improved moisture removal by convective mechanisms, they also increased evaporative cooling, which limited the temperature increase. Bed homogenization increased porosity and prevented preferential pathways but had a negligible effect on water loss and temperature increase. Biomass energy analysis showed that the biomass higher heating value (HHV) was maintained even in experiments where organic matter was consumed to generate heat. This indicates the integrity of the lignocellulosic compounds and preserves the potential of the waste for energy recovery. It was possible to identify challenges in optimizing biodrying processes, especially in systems with native microorganisms, highlighting the importance of detailed characterization of the microbiota. Future research should focus on refining operational parameters to improve water removal and thermal efficiency, thus contributing to sustainable waste management and process intensification.