Modeling and Analysis of Convective Drying Kinetics of Household Biodegradable Waste Using Semi-Empirical Thin Layer Models

Abstract

Household organic waste contains high moisture levels that hinder its efficient utilization and increase disposal costs. This study examines the convective hot-air drying characteristics of domestic organic waste at air temperatures of 70, 90, 100, 120, and 140 °C. The starting moisture content of the fresh waste was 68–75% wet basis (w.b.), and we determined its physicochemical properties using established analytical procedures. Eight established thin-layer drying models, including Newton, Henderson–Pabis, Page, Logarithmic, Midilli–Kucuk, Verma, Wang–Singh, and Two-Term, were implemented in the MATLAB environment to describe the experimental moisture ratio profiles. Model adequacy was assessed using a combination of statistical indicators, namely the coefficient of determination (R^2 ),root mean square error (RMSE), reduced chi-square (χ^2 ), Akaike information criterion (AIC), and Bayesian information criterion (BIC). Among the evaluated models, the Midilli–Kucuk model provided the closest agreement with the experimental data, achieving an R^2of 0.9996, an RMSE of 0.0071, and a χ^2value of 7.21\times 10^(-5). The effective moisture diffusivity increased from 4.70\times 10^(-9)to 2.60\times 10^(-8) m²s⁻¹, while the activation energy was evaluated to be 27.22 kJ mol⁻¹. Energy analysis showed that 100 °C offered the optimal balance among drying time, specific energy utilization, and product quality attributes. The results confirm that the Midilli–Kucuk model is suitable to simulate the drying process of household organic waste and offer a strong basis for the optimization of energy-saving drying systems in the waste valorization process in a circular economy context.