Analysis of biochemical arithmetic models to predict the calorific value of the easily degradable fraction of landfilled MSW

Due to the increasing global energy demand and the current heavy reliance on non-renewable energy sources, the utilization of biomass as an energy source presents an intriguing alternative. Substantial quantities of biomass are annually discarded in landfills. The objective of this study was to analyse the applicability of arithmetic mathematical models for estimating the Higher Heating Value (HHV) of the easily degradable fraction of recovered 8-year-old Municipal Solid Waste (8-year-old ED) through the landfill mining technique, and different biomass samples from the Literature. The applied models were formulated based on biochemical components (Carbohydrates, Lipids, Proteins, Lignin, Cellulose, Hemicellulose, and Extractives), with some incorporating elemental (Carbon, C) and physical (Ash) components. To assess the models’ applicability, real HHV values were compared with the theoretical values provided by the models. In general, the application of the biochemical models overestimated the real HHV values. Only models 10 and 13, incorporating the variables C and Holocellulose (with Cellulose predominantly considered), demonstrated suitability in predicting the HHV of the 8-year-old ED, suggesting that these parameters may offer better prediction of HHV values for 8-year-old ED compared to other biochemical parameters. Furthermore, the application of these models indicated a closer resemblance of landfilled easily degradable fraction to lignocellulosic waste rather than fresh MSW, attributed to food waste degradation and the accumulation of Lignin and Cellulose within landfills. Using Lignin as the sole explanatory variable was found inadequate for calculating HHV of 8-year-old ED, yet proved suitable for calculating HHV of various biomass types from literature data. Thus, models 1, 5, 9, and 14 (based solely on the Lignin variable) proved adequate for these samples. Additionally, the application of Hemicellulose, akin to various biomass types, was deemed unsuitable for calculating HHV of either fresh or landfilled wastes.