Synergistic Biological Pretreatment and Bioaugmentation for Enhanced Biogas Production from Lignocellulosic Biomass

Abstract

Lignocellulosic biomass is the most abundant renewable organic resource on Earth and represents a sustainable feedstock for biogas production through anaerobic digestion. However, the complex association of lignin, cellulose, and hemicellulose restricts microbial access, slows hydrolysis, and ultimately constrains methane yields from this resource. While existing reviews assess biological pretreatment and bioaugmentation as discrete interventions, this review evaluates their integration as complementary strategies for overcoming the recalcitrance of lignocellulosic biomass. As mechanistically distinct interventions, biological pretreatment mitigates substrate recalcitrance through selective lignin modification and biomass deconstruction, whereas bioaugmentation strengthens microbial functionality by enriching specialised populations that enhance hydrolytic, fermentative, and methanogenic activity. Integrating these approaches may therefore constitute an environmentally sustainable, energy-efficient, and process-compatible alternative to conventional thermochemical pretreatments. Limited available evidence indicates that when integrated, these strategies can improve lignocellulose digestibility, enhance process stability, and increase biomethane production. However, due to limited studies that explicitly combine biological pretreatment and bioaugmentation within a single experimental framework, claims regarding sustainability, energy efficiency, or economic advantages should be treated cautiously unless supported by direct life-cycle or techno-economic evidence. Key knowledge gaps include the mechanistic basis of their interactions, optimisation of microbial consortia and operating conditions, long term process stability, and scalability under industrially relevant conditions. Future research should prioritise integrated, systems level investigations that link substrate transformation with microbial community dynamics and evaluate techno-economic feasibility at larger scales. Addressing these challenges will be critical for advancing sustainable industrial biogas production from lignocellulosic biomass.