Improving biodegradability of corn stover pretreated by different organic acids: Investigation on the hydrolysis/acidification and methanogenic performance

Lignocellulosic materials (LM) are abundant bioenergy resources for renewable energy development. Pretreatment using organic acids including acetic acid (HAc) and butyric acid (HBu) was applied to reduce the recalcitrance of LM in methane production by two-phase anaerobic digestion (AD). The structural and compositional changes of solids and aqueous phase were analyzed. It showed that pretreatment with 2 g/L HAc/HBu at 120 degrees C was optimum, under which the net volatile fatty acids (VFAs) production could reach the maximum concentration of 11.5 g/L. The yield of VFAs decreased with the concentration increasing to > 2 g/L due to the feedback inhibition on the microbial metabolism. The species of organic acids also influenced the metabolic pathway of VFAs. The acidogenic metabolites can be transformed in up-flow anaerobic sludge bed (UASB) with organic loading rate (OLR) up to 12 g COD/Ld (COD, chemical oxygen demand). The hydrothermal-organic acid pretreatment (HTOAP) could provide important information for subsequent application.

Automated summary

The study demonstrates that pretreatment of lignocellulosic materials with organic acids can enhance the production of volatile fatty acids (VFAs), but can also inhibit microbial metabolism when the concentration exceeds a certain limit. The type of organic acids affects the metabolic pathway of VFAs, and hydrothermal-organic acid pretreatment can provide crucial information, especially when considering organic loading rates.