Three-dimensional biofilm electrode reactors (3D-BERs) represent a novel technology for wastewater denitrification. Formation of mature electroactive biofilm on particle electrodes is crucial to realize successful denitrification in 3D-BERs. However, long start-up time and low electroactivity of the biofilm formed on particle electrodes limit the further application of 3D-BERs in wastewater treatment. In this work, self-assembled hybrid biofilms (SAHB) was cultivated on granular activate carbon particle electrodes of the 3D-BER by assembling nano ɑ-Fe₂O₃ into the biofilm. ɑ-Fe₂O₃ was selected due to its high affinity to bacterial outer-membrane cytochromes, an important mediator for microbial electron transfer. SAHB formed on particle electrodes were characterized and the denitrification performance of 3D-BERs was also investigated. Results indicate that nano ɑ-Fe₂O₃ plays positive roles in the start-up of 3D-BER, which captures more microbes into SAHB and constructs thick biofilm on particle electrodes. Special microorganisms with denitrification function related with genera of Hydrogenophaga and Opitutus are distinctively enriched in SAHB. Nano ɑ-Fe₂O₃ induced SAHB exhibit superior denitrification performance compared to natural biofilm. The average denitrification rate increases from 0.62 mg total nitrogen/L/h for natural biofilm to 1.73 mg total nitrogen/L/h for SAHB, mainly ascribed to accelerated nitrites reduction. Our work provides new technical solution to enhance nitrates removal in 3D-BERs and brings deep insights into application of bio-electrochemical system in wastewater treatment.

三维生物膜电极反应器（3D-BERs）代表了一种废水反硝化的新技术。在粒子电极上形成成熟的电活性生物膜对于成功实现3D-BER中的反硝化至关重要。然而，长启动时间和在颗粒电极上形成的生物膜的低电活性限制了3D-BER在废水处理中的进一步应用。在这项工作中，自组装混合生物膜（SAHB）通过组装纳米ɑ -铁栽培在3D-BER的粒状激活碳粒子电极₂ ö ₃到生物膜。ɑ -铁₂ ö ₃选择它是因为它对细菌外膜细胞色素具有很高的亲和力，而细菌外膜细胞色素是微生物电子转移的重要介体。表征了在颗粒电极上形成的SAHB，并研究了3D-BERs的反硝化性能。结果表明，纳米ɑ -铁₂ ö ₃起着积极的作用在启动3D-BER的，它捕获多种微生物进入SAHB并构造上粒子的电极厚的生物膜。用的属相关脱氮功能的特殊微生物Hydrogenophaga和Opitutus在SAHB的独特丰富。纳米ɑ -铁₂ ö ₃诱导的SAHB与天然生物膜相比，具有出色的反硝化性能。平均反硝化速率从天然生物膜的0.62 mg总氮/ L / h增加到SAHB的1.73 mg总氮/ L / h，主要归因于亚硝酸盐还原速度加快。我们的工作为提高3D-BERs中的硝酸盐去除提供了新的技术解决方案，并为生物电化学系统在废水处理中的应用带来了深刻的见解。