Suspended biofilm carriers mediating direct interspecies electron transfer (DIET)-based syntrophic metabolism is a promising strategy to enhance anaerobic digestion and methane production by associating the advantages of conductive suspended biofilm carriers and anaerobic integrated floating fixed-film and activated sludge (An-IFFAS) process. However, the current knowledge of DIET using conductive suspended biofilm carrier is still limited. In this study, novel electron mediator suspended biofilm carriers had been prepared by introducing a series of graphite powders (3 wt%, 5 wt% and 7 wt%) into high-density polyethylene (HDPE), and applied in An-IFFAS reactors. Results showed that An-IFFAS reactors filled with graphite-modified carriers could enhance the degradation of organic matters and the production of methane significantly in comparison with the control reactor filled with conventional HDPE carriers at organic loading rates (OLRs) of 5.9–23.7 kg COD/m³/d. Microbial analysis proved that 7 wt% graphite-modified carrier improved approximately 4.2% abundance of Geobacter and 7.3% abundance of electrotrophic methanogens (Methanothrix) that exchange electron via DIET comparing with that of HDPE carriers, respectively. These findings demonstrated that electron mediator suspended biofilm carrier was able to potentially proceed DIET and enhance the efficiency of anaerobic digestion and recover CH₄-related energy.

悬浮生物膜载体介导基于种间直接电子转移（DIET）的共营养代谢是一种有前途的策略，可通过结合导电悬浮生物膜载体和厌氧集成漂浮固定膜和活性污泥（An-IFFAS）的优势来增强厌氧消化和甲烷生成处理。但是，目前对使用导电悬浮生物膜载体的DIET的了解仍然有限。在这项研究中，通过将一系列石墨粉（3 wt％，5 wt％和7 wt％）引入高密度聚乙烯（HDPE）中，制备了新型电子介体悬浮生物膜载体，并将其应用于An-IFFAS反应器中。³ /天 微生物分析证明，与HDPE载体相比，7wt％的石墨改性载体分别提高了约4.2％的地细菌丰度和7.3％的通过DIET交换电子的电营养型产甲烷菌（Methanothrix）的丰度。这些发现表明，电子介体悬浮的生物膜载体能够潜在地进行DIET并提高厌氧消化的效率并回收CH ₄相关的能量。