Thermal-alkaline pretreatment of different biomass to understand the interplay of composition of biomass, biogas yields, rates and mass balance

Pretreatment of lignocellulosic biomass is essential to overcome its inherent recalcitrance and enhance its conversion to biogas. In this study, six biomass feedstocks from a single group of flowering plants were subjected to thermo-alkaline pretreatment using varying NaOH concentrations at a constant temperature. Substrate loss, biogas production, and the inflection point in the gas production profile were systematically analyzed before and after pretreatment. A mass balance approach was employed to quantify the exposure of underlying components, and an efficiency metric was introduced to evaluate pretreatment effectiveness, defined as the biogas yield per percentage of substrate loss. The results reveal that the optimal NaOH dosage of 0.4 g/g biomass significantly improves methane yields and production rates; however, the response varied with biomass composition. These findings underscore the importance of compositional variability in optimizing pretreatment conditions and provide a framework for enhancing the economic and environmental viability of anaerobic digestion processes.