Hydrothermal liquefaction conversion of lignocelluloses with enhanced fungal pretreatment

Although it is considered to be an environmental-friendly approach to reduce recalcitrance of lignocellulosic biomass, current fungal pretreatment methods suffer from major weaknesses, including inefficient delignification, loss of cellulose, and the need for long processing time. The addition of Mn to white-rot fungal treatment process could facilitate selective removal of lignin. However, the effect of Mn addition on the thermal decomposition and conversion of fungi-pretreated biomass is not clear. In this study, three types of lignocelluloses (poplar, wheat straw, and corn stover) were pretreated with fungi that was cultured with Mn supplements. Results demonstrated that the Mn addition affected thermogravimetric properties, as well as lignin and hemicellulose contents. The poplar samples showed the highest delignification (50.5 %) and lowest loss of cellulose (1.1 %). The initial degradation temperatures were lowered by 11-36 celcius, measured with thermogravimetric analysis. Additionally, fungi-pretreated feedstocks were converted in a two-stage hydrothermal liquefaction process to produce hydrolyzed sugars and value-added derivatives in a stepwise manner. A 163.6 % more hemicellulose sugars were recovered from poplar with the addition of Mn compared with untreated samples, while 75.2 % of hemicellulose sugar production was achieved in the first stage from fungi-treated corn stover with the Mn addition. Pretreating lignocelluloses with fungi that includes Mn supplements significantly improved sugar production. Thus, the combination of fungal pretreatment with the subsequent thermochemical conversion process offers a promising alternative technical route for lignocellulosic biomass valorization.

Automated summary

The addition of Mn to fungal pretreatment of lignocellulosic biomass improves sugar production, particularly the recovery of hemicellulose sugars.