Anaerobic digestion of hazelnut (Corylus colurna) husks after alkaline pretreatment and determination of new important points in Logistic model curves.

In this study, anaerobic digestion (AD) of hazelnut (Corylus colurna) husks (HH) was investigated by NaOH pretreatment at 1-6% w/w concentrations. The highest methane yield was 278.45 ± 7.85 mL/g volatile solid (VS), and this was obtained in a 4% NaOH pretreated reactor. In this reactor, the methane yield increased by 162.2% compared to that in the control. The concentrations of volatile fatty acids (VFAs) varied during the digestion process according to the different NaOH pretreatment results. The highest lignosellulosic solubilizations were obtained in a 6% NaOH pretreated reactor. Furthermore, in the second part of kinetic studies, it was defined critical points for cumulative methane yield (CMY) in the Logistic model (LM). These points were the absolute acceleration point (PAA), maximum acceleration point (PAM), inflection point (PI), maximum deceleration point (PDM), and asymptotic deceleration point (PDA). Using these points on the CMY curves, the AD process of HH was mathematically interpreted and explained.