Omar Aweis Ali, 
Ritesh Pattnaik, 
Abdifatah Ahmed Ali Afyare, 
Sidnei Eduardo Lima‑Junior, 
Abdullahi Mohamud Adam & 
Richard José Rojas Espinoza 

Abstract

Growing demand for energy and materials, together with the environmental impacts of continued fossil fuel use, has increased interest in more sustainable ways of using natural resources; however, its large-scale valorization remains constrained by structural recalcitrance, pretreatment-related costs, inhibitor formation, and integration challenges across multi-product biorefinery systems. This review provides a structured narrative synthesis guided by the SANRA framework. Literature was retrieved from Scopus, Web of Science, ScienceDirect, SpringerLink, and Google Scholar. From an initial pool of 200 records, duplicates and irrelevant studies were removed, resulting in 134 peer-reviewed publications (1989–2026) that were critically analyzed and included in the final synthesis. The collected evidence demonstrates that pretreatment performance is inherently feedstock- and objective-dependent: steam explosion and alkaline systems remain among the most scalable routes for improving carbohydrate accessibility, while ionic liquids and deep eutectic solvents provide high fractionation efficiency under comparatively mild conditions but are limited by solvent recovery and techno-economic uncertainty. Across downstream platforms, anaerobic digestion offers operational resilience for heterogeneous residues but remains hydrolysis-limited without effective deconstruction, whereas sugar-platform routes for bioethanol and related products become viable primarily when inhibitor severity and enzyme demand are economically controlled. Importantly, integrated and lignin-first biorefinery concepts expand the product portfolio by enabling concurrent valorization of carbohydrate and lignin fractions, thereby improving carbon efficiency and strengthening economic potential.

Overall, this review provides a comparative, system-level perspective that links pretreatment outcomes to conversion performance and process penalties, supporting more defensible technology selection for lignocellulosic biorefineries and highlighting the need for standardized benchmarking metrics, scalable recycling schemes, and integration strategies to accelerate deployment at an industrial scale.