Application of Anaerobic Digestion Model No. 1 for modeling anaerobic digestion of vegetable crop residues: Fractionation of crystalline cellulose

Crystalline cellulose is fully resistant during anaerobic digestion (AD), which brings uncertainty to the use of mathematical models to simulate the dynamic AD process of lignocellulosic waste. In present study, a modified mathematical model, with crystalline cellulose as the primary consideration, was established based on Anaerobic Digestion Model No.1 to simulate the anaerobic bioconversion of vegetable crop residues (VCR) under mesophilic condition. In this model, VCR was divided into inert fraction (contained lignin and crystalline cellulose), as well as biodegradation parts of slowly hydrolysis fraction (SHF, contained hemicellulose and amorphous cellulose), and readily hydrolysis fraction (RHF, contained other organic components in the VCR). Data from a series of batch experiments have been used for the calibration and verification of this model. As a result, the calibrated model was found to match reasonably well the methane production data of three different VCRs, which implies that it was feasible to fractioned VCR into three fractions (SHF, RHF and inert part), and the operation that classified crystalline cellulose into the inert part, while regarded amorphous cellulose as SHF was appropriate. In order to be suitable for simulating the AD process of more other types of lignocellulosic waste, the model needs further modification and inspection. (C) 2020 Elsevier Ltd. All rights reserved.