Fan Yuanyuan, Sun Shanshan, Gu Xushun, Yan Pan, Zhang Yu, Peng Yuanjun, He Shengbing
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China; Shanghai Jiao Tong University Yunnan Dali Research Institute, PR China.
Water Res. 2025 May 1;275:123169. doi: 10.1016/j.watres.2025.123169. Epub 2025 Jan 21.
Iron-based constructed wetlands (ICWs) displayed great potential in deep nitrogen elimination for low-polluted wastewater. However, the unsatisfactory denitrification performance caused by the limited solubility and sluggish activity of iron substrates needs to be improved in an eco-effective manner. To fill this gap, the bioavailability of iron substrates (iron scraps) affected by wetland biomass-derived carbon materials with potential conductivity were explored. Results indicated that the cumulative removal of TN in biochar-added ICW (BC-ICW) and activated carbon-added ICW (AC-ICW) increased by 29.04 % and 22.96 %, respectively. The carbon matrix of AC played the geo-conductor role to facilitate the rapid release of iron ions, as indicated by the higher TN removal efficiency of AC-ICW (45.36 ± 1.45 %) at the early stage, while the reduced conductivity of AC negatively impacted the nitrogen removal. BC-ICW exhibited intensified denitrification potential, with higher TN removal capacity (52.08 ± 3.04 %) and effluent Fe concentration. Electroactive bacteria (EB) (Geobacter, Desulfovibrio, Shewanella, etc.) associated with extracellular electron transfer were enriched in BC-ICW, as well as the expanded niches breadth and improved microbial community diversity. The electron-shuttling effect of BC was mainly attributed to its oxygenated functional groups (quinone/phenolic moieties), which supported the electron transfer from EB to extracellular iron oxides, as evidenced by the increased Fe(III)(hydro)oxides bioavailability. Besides, biochar concurrently up-regulated the gene expression of electron transport chains/mediators and denitrification reductases, suggesting that BC boosted the active iron cycle and iron-mediated autotrophic denitrification in ICWs by accelerating intracellular and extracellular electron transfer. This work explored the electron transfer behavior of biomass-derived carbon materials coupled with ICWs to enhance denitrification, providing insights into the sustainable application of biomass derived carbon-assisted ICWs in tertiary treatment.
铁基人工湿地（ICWs）在深度去除低污染废水中的氮方面显示出巨大潜力。然而，铁基质的溶解度有限和活性迟缓导致的反硝化性能不尽人意，需要以生态有效的方式加以改善。为了填补这一空白，研究了具有潜在导电性的湿地生物质衍生碳材料对铁基质（铁屑）生物可利用性的影响。结果表明，添加生物炭的ICW（BC-ICW）和添加活性炭的ICW（AC-ICW）中TN的累积去除率分别提高了29.04%和22.96%。AC的碳基质起到了地质导体的作用，促进了铁离子的快速释放，如AC-ICW在早期较高的TN去除效率（45.36±1.45%）所示，而AC导电性的降低对氮去除产生了负面影响。BC-ICW表现出增强的反硝化潜力，具有更高的TN去除能力（52.08±3.04%）和出水铁浓度。与细胞外电子转移相关的电活性细菌（EB）（地杆菌属、脱硫弧菌属、希瓦氏菌属等）在BC-ICW中富集，同时生态位宽度扩大，微生物群落多样性提高。BC的电子穿梭效应主要归因于其含氧官能团（醌/酚类部分），这支持了电子从EB转移到细胞外铁氧化物，Fe(III)（氢）氧化物生物可利用性的增加证明了这一点。此外，生物炭同时上调了电子传输链/介质和反硝化还原酶的基因表达，表明BC通过加速细胞内和细胞外电子转移促进了ICWs中活性铁循环和铁介导的自养反硝化。这项工作探索了生物质衍生碳材料与ICWs耦合的电子转移行为以增强反硝化作用，为生物质衍生碳辅助ICWs在三级处理中的可持续应用提供了见解。
