Transforming biorefinery designs with ‘Plug-In Processes of Lignin’ to enable economic waste valorization

Abstract

Biological lignin valorization has emerged as a major solution for sustainable and cost-effective biorefineries. However, current biorefineries yield lignin with inadequate fractionation for bioconversion, yet substantial changes of these biorefinery designs to focus on lignin could jeopardize carbohydrate efficiency and increase capital costs. We resolve the dilemma by designing ‘plug-in processes of lignin’ with the integration of leading pretreatment technologies. Substantial improvement of lignin bioconversion and synergistic enhancement of carbohydrate processing are achieved by solubilizing lignin via lowering molecular weight and increasing hydrophilic groups, addressing the dilemma of lignin- or carbohydrate-first scenarios. The plug-in processes of lignin could enable minimum polyhydroxyalkanoate selling price at as low as $6.18/kg. The results highlight the potential to achieve commercial production of polyhydroxyalkanoates as a co-product of cellulosic ethanol. Here, we show that the plug-in processes of lignin could transform biorefinery design toward sustainability by promoting carbon efficiency and optimizing the total capital cost.

Recent Biotechnology Advances in Bio-Conversion of Lignin to Lipids by Bacterial Cultures

“…Moreover, this pellet form of microorganism has the potential for lipid production, suggesting a new strategy for the development of the biofuel industry. Liu et al (2021) designed the “Plug-In Processes of Lignin” based on advanced pretreatment techniques to achieve a synergy of lignin biochemical conversion and carbohydrate production by reducing molecular weight and enhancing hydrophilic radicals to achieve profitable and sustainable biorefinery.…”

Bringing Material Concepts into Conventional Biorefineries: Considerations of Sources, Preparations, and Applications of Lignin Nanomaterials

“…For instance, the production of bioethanol is generally carried out by a sequence of techniques including pretreatment, enzymatic hydrolysis, and fermentation, where the residues are rich in lignin that can be further utilized. 73,74 Furthermore, the enzymatic hydrolysis lignin (EHL) retains many active groups that can be used for producing lignin nanomaterials. 74,75 With the increasing demand of bioethanol from renewable biomass, the production of EHL is believed to increase, and its valorization is also meant to gain more interests.…”

“…At present, only a few studies have focused on the utilization of lignin from such sources. 64,73,146 Finding suitable solvents that can achieve good delignification during biomass pretreatment, and the preparation of lignin nanomaterials via subsequent antisolvent methods is encouraged. Using the lignin-rich solid residues obtained from biological treatment for lignin nanomaterial production by antisolvent methods will require an extra hydrothermal treatment to achieve the dissolution of lignin into organic solvents prior to their conversion to nanomaterials.…”

“…In conventional biological biorefineries such as enzymatic hydrolysis and anaerobic digestion (AD), lignin is also widely distributed in the solid residues. For instance, the production of bioethanol is generally carried out by a sequence of techniques including pretreatment, enzymatic hydrolysis, and fermentation, where the residues are rich in lignin that can be further utilized. , Furthermore, the enzymatic hydrolysis lignin (EHL) retains many active groups that can be used for producing lignin nanomaterials. , With the increasing demand of bioethanol from renewable biomass, the production of EHL is believed to increase, and its valorization is also meant to gain more interests. Anaerobic digestion (AD) that uses various lignocellulosic biomass such as grasses and agricultural residues for biogas production is considered as another key source of lignin.…”

Microbial Valorization of Lignin to Bioplastic by Genome-Reduced Pseudomonas putida

“…Large amounts of lignin are being generated from the biorefinery and the paper and pulp industry; however, lignin remains an underutilized solid residue or is only burnt for heat and power generation. Currently, it is of great interest to realize the potential value of lignin since lignin valorization not only produces valuable commodities but also contributes to a low-carbon economy ( Abu-Omar et al, 2021 ; Liu et al, 2021 ).…”