Abstract
Anaerobic digestion of lignocellulosic biomass, particularly Phragmites australis (common reed), presents prospects for sustainable biogas production. However, its rigid structure and high lignocellulose content obstruct microbial accessibility and the effectiveness of methanogenesis. The review offers a comparative analysis of recent strategies to enhance methane yield and process stability through iron-based nanomaterials, trace metal additions, enzymatic pre-treatments, and co-substrates. Iron-based nanomaterials reduce process inhibition and improve redox balance by facilitating direct interspecies electron transfer. Supplementation with trace metals such as nickel, cobalt, and selenium enhance methanogenic pathways, thereby promoting microbial enzymatic activity. The optimization of additive requirements, taking into account substrate characteristics, microbial community dynamics, and operational conditions, offers a solid framework for designing and adapting additive strategies to specific AD systems. Enzymatic pre-treatment improves hydrolysis by transforming complex lignocellulosic structures into readily fermentable sugars, thereby accelerating biogas production. Compared to other alternatives, the expenses associated with enzymes and the difficulties in process optimization complicate the large-scale implementation. However, improvements vary widely among studies due to differences in enzyme type, dosage, substrate composition, and operational conditions, leading to the need for standardized evaluation methods. Co-digestion with nitrogen-rich substrates improves the carbon-to-nitrogen ratio, thereby minimizing ammonia inhibition and promoting stable microbial activity. This paper addresses current challenges with feedstock recalcitrance, process inhibition, and biogas quality while also emphasizing the additives’ synergistic benefits in maximizing anaerobic digestion performance and offering perspectives for future research and practical implementation of enhanced anaerobic digestion systems.