Unlocking the potential of conductive materials for advancing the frontiers in anaerobic digestion

• State-of-the-art review on conductive material enhanced anaerobic digestion. • Properties of carbon-based and metal-based conductive materials. • Mechanism of conductive material in improving biogas production. • Microbial dynamics induced by conductive materials in AD. • Research and application scopes for conductive material supplementation. The anaerobic digestion (AD) process is a cornerstone of the bioenergy sector, bridging sustainable waste management with renewable energy production. Global research efforts are focused on enhancing the efficiency, robustness, scalability, and expanding the scope of AD while addressing existing challenges. Key parameters such as substrate characteristics (e.g., solids content and C/N ratio), operational factors (e.g., pH and temperature), and design elements like hydraulic retention time (HRT) and organic loading rate (OLR) are critical for optimizing microbial activity and process performance. The supplementation of conductive materials (CM) has emerged as an innovative approach to improve AD systems. Supplementing AD systems with CM has emerged as a promising strategy to enhance microbial activity, promote direct interspecies electron transfer (DIET), and mitigate toxicity, thereby boosting system efficiency. Current studies are actively exploring the effects of CMs on AD performance and their potential for large-scale applications. This review highlights the significance of these parameters in understanding and optimizing the AD process. It explores the role of different CMs by emphasizing their physicochemical properties. Since microorganisms are central to AD dynamics, a brief discussion of microbiological studies is presented to provide crucial insights into how CM supplementation influences microbial community structure and function. Finally, this review discusses future perspectives in AD research, focusing on advancing fundamental knowledge of the process while translating its potential into real-world applications. By addressing current challenges and leveraging innovations like CM supplementation, AD can be further developed as a sustainable solution for bioenergy generation and waste management.