Comparative Study on Quality of Fuel Pellets from Switchgrass Treated with Different White-Rot Fungi

Abstract

Fungal pretreatment of switchgrass using Phanerochaete chrysosporium (PC), Trametes versicolor 52J (TV52J), and the Trametes versicolor mutant strain (m4D) under solid-state fermentation was conducted to improve its pellet quality. For all three fungal strains, the fermentation temperature had a significant effect (p < 0.05) on pellet unit density and tensile strength. The p-values of the quadratic models for all the response variables showed highly significant regression models (p < 0.01) except for dimensional stability. In addition, 3.1-fold and 2.8-fold increase in pellet tensile strength were obtained from P. chrysosporium- and T. versicolor 52J-treated materials, respectively. Microstructural examination showed that fungal pretreatment reduced pores in the pellets and enhanced pellet particle bonding. Among the fungal strains, PC had the shortest optimum fermentation time (21 d) and most positive impact on the pellet tensile strength and hydrophobicity. Therefore, switchgrass pretreatment using PC has the potential for resolving the challenges of switchgrass pellet transportation and storage and reducing the overall pelletization cost. However, a detailed comparative technoeconomic analysis would be required to make definitive cost comparisons.

Modeling the microbial pretreatment of camelina straw and switchgrass by Trametes versicolor and Phanerochaete chrysosporium via solid-state fermentation process: A growth kinetic sub-model in the context of biomass-based biorefineries

“…Pretreatment is a crucial step in both biofuel pellets and bioethanol production to enhance the binding mechanisms or enzyme substrate accessibility (Bhatia et al, 2020 ; Robak and Balcerek, 2020 ). Pretreatment employing white-rot fungi, which produce the high-redox-potential ligninolytic peroxidases (lignin peroxidase–LiP, manganese peroxidase–MnP, versatile peroxidases–VP) and low-redox-potential laccase was observed to improve the physical-mechanical properties of the pelletized materials as well as enhance their enzymatic digestibility for bioethanol production (Gao et al, 2017 ; Kalinoski et al, 2017 ; Onu Olughu et al, 2021 ). Compared to other conventional pretreatment methods, biological pretreatment possesses several advantages including 1) an environmentally-friendly process, 2) moderate operating conditions, 3) higher productivity, 4) potential for value-added by-products, 5) fewer fermentation-inhibiting compounds, 6) few side reactions, 7) lower energy consumption, 8) lower requirements for reactor resistance to pressure and corrosion (Chen et al, 2010 ; Wan and Li, 2012 ; Agrawal et al, 2015 ; Su et al, 2018 ; Sharma et al, 2019 ) ( Supplementary Table 1 ).…”