Thermophilic Anaerobic Digestion Modeling of Lignocellulosic Hot Water Extract Using ADM1

Lignocellulosic biomass is abundant and can become a major feed for anaerobic digestion methane production if its natural recalcitrance is overcome by pretreatment.Bio-degradable organic molecules were extracted by hot water (to produce "hydrolysate") from wood (Norway spruce).A high rate anaerobic sludge bed reactor fed the hydrolysate was modeled by the IWA Anaerobic Digestion Model No.1 (ADM1).Biodegradability kinetics for the hydrolysate material was obtained from batch tests at thermophilic condition, and the hydrolysis kinetic coefficient of carbohydrate ( ℎ_ℎ ) found.Thus obtained ℎ_ℎ = 0.44 d -1 was used to simulate UASB reactor performance at 55°C and comparing results to measured parameters from an experimental reactor at five different organic loading rates.The simulation results correlated well with the experimental results for biogas production rate, biogas composition and chemical oxygen demand.This shows that ADM1 is a powerful tool to predict the behavior of thermophilic anaerobic digestion (AD) of pretreated lignocellulosic feed using standard ADM1 parameters except for hydrolysis kinetics.Hydrolysis was identified as the overall rate limiting step in AD of such feed in UASB.