Modification of the anaerobic digestion model No.1 (ADM1) for lignocellulosic biomass

Abstract

The lignocellulosic biomass will be the resource for an alternative energy in the
future. To evaluate the dynamical products from anaerobic digestion process such as sugars,
VFA and gas product, the ADM1 model can be modified to apply for lignocellulosic biomass
digestion. The selected lignocellulosic biomasses as Napier grass, empty palm fruit bunch and
acacia leave which had different cellulose and lignin content was selected to research in this
part. This difference between based and modified model was additional term as cellulose. The
results depicted that the term of fiber and solubilization of biomass controlled anaerobic
digestion process. The simulation results indicated that the modification model based on
ADM1 model was able to describe the anaerobic digestion process from lignocellulosic
biomass. The calibrated variable in the model was that the hard digestible content as
cellulose (Xfi) was additional term in dynamic state variable in DAE system. The estimated
value of cellulose hydrolysis rate constant (khyd,ce) was 0.01 d-1. The hydrolysis rate
constant of easy digestible carbohydrates (khyd,ch), proteins (khyd,pr) and lipids (khyd,li)
was calibrated to 0.03 d-1. The disintegration rate of lignocellulosic biomass (kdis) was
calibrated to 0.025 d-1. The different by-products from various lignocellulosic biomass was
the composition in substrate, which is validated as stoichiometric parameter
(fcomposition,xc) in hydrolysis step in based model. The benefit of this work is to reduce the
time and cost consuming in evaluating sugar, VFA and gas product from lignocellulosic
biomass digestion.