Enhancing Biogas Production From Wheat Straw Through Titanium Dioxide Assisted Alkaline Pretreatment

Abstract

A huge quantity of lignocellulosic biomass is generated in Pakistan and can be used for sustainable production of biogas by anaerobic digestion (AD). However recalcitrant structure of lignocellulosic biomass is the main impediment to biodegradation. The present study evaluated the effect of sodium hydroxide (NaOH), titanium dioxide nanoparticles (TiO2 NPs) and combined (NaOH+TiO2) pretreatment on lignocellulosic composition, physical structure and biogas production efficiency of wheat straw (WS). The effect of 2% NaOH pretreatment increased lignin removal by 48.7% as compared to control (untreated WS). While 2 g/L TiO2 pretreated WS showed maximum lignin degradation, which was 33 % higher as compared to untreated WS. The highest lignin removal efficiency was achieved from combined (2% NaOH + 2g/L TiO2) pretreatment, which was 79% more in comparison to control. As compared to untreated WS, 2% NaOH pretreatment alone augmented biogas and methane production by 27% and 24% respectively. The effect of 1.5 g/L TiO2 pretreatment alone enhanced biogas and methane production by 4% and 12% respectively. Conversely, the highest biogas and methane production was achieved for combined pretreatment (1% NaOH + 1.5g/L TiO2), which accounted for 73% and 74% increments respectively. SEM and FTIR analysis explicitly exhibited changes in physical and chemical structure of WS after combined pretreatment. Moreover, the modified Gompertz model was used to validate the experimental statistics acquired from anaerobic digestion of WS.