A review on application of single and composite conductive additives for anaerobic digestion: Advances, challenges and prospects

The supplementation of conductive materials (CMs), including carbon-based CMs and metal-based CMs, is a promising strategy to improve the performance of anaerobic digestion (AD). CMs can assist direct interspecies electron transfer and enhance the activity of microorganisms to accelerate organic matter degradation and methane production. To take full advantage of different CMs and simultaneously avoid their defects for enhancing AD, this review summarizes the effects of single CMs on AD performance and the limitations of their use, discusses the coupled effects of multiple CMs on AD enhancement, and confirms that multiple CMs can improve the complex organic matter degradation, electron transfer efficiency, and CM maintenance. According to the analyses of previous publications, the main challenges in CM application in AD are identified as the poor conductivity, electron capture ability, stability, and bio-affinity of CMs. The direction of future efforts, mainly focusing on optimizing the preparation of and strengthening the reuse of CMs, is proposed. These findings are expected to provide a reference for the development of advanced CMs and their applications in engineering.

Automated summary

Supplementation of conductive materials (CMs) can enhance the performance of anaerobic digestion, but challenges such as poor conductivity, stability, etc., exist. Future efforts should focus on optimizing the preparation and strengthening the reuse of CMs to improve their application in engineering.