Liu Zhaoying, Li Jiayu, Zhang Jiaqi, Fang Yuanping, Li Haiyan
Beijing Energy Conservation & Sustainable Urban and Rural Development Provincial and Ministry Co-construction Collaboration Innovation Center, Beijing University of Civil Engineering and Architecture, Beijing, 100044, China; Beijing Engineering Research Center of Sustainable Urban Sewage System Construction and Risk Control, Beijing University of Civil Engineering and Architecture, Beijing, 100044, China.
Beijing Energy Conservation & Sustainable Urban and Rural Development Provincial and Ministry Co-construction Collaboration Innovation Center, Beijing University of Civil Engineering and Architecture, Beijing, 100044, China; Beijing Engineering Research Center of Sustainable Urban Sewage System Construction and Risk Control, Beijing University of Civil Engineering and Architecture, Beijing, 100044, China.
J Environ Manage. 2025 Sep;392:126646. doi: 10.1016/j.jenvman.2025.126646. Epub 2025 Jul 23.
Insufficient availability of electron donors is challenging for nitrate removal in bioretention systems when treating carbon-limited stormwater runoff. This study constructed two ternary electron-donor systems incorporating solid carbon source, pyrite, and iron-scrap to enhance mixotrophic denitrification, and investigated the impacts of natural carbon source (woodchip) and synthetic carbon source (polycaprolactone) on denitrification performance and by-product generation. Results showed that both systems exhibited stable and efficient nitrate removal (85.76 ± 11.00 % and 89.67 ± 5.75 %) under 120 days of variable stormwater conditions, attributing to the synergy of multi-electron donors. Compared with the polycaprolactone-packed system, the woodchip-packed system showed substantial reductions in ammonia nitrogen, dissolved organic carbon, and sulfate production, indicating better comprehensive pollutant control. Woodchips avoided excessive corrosion and passivation of iron-scrap by maintaining low dissolved organic carbon conditions and preventing high OH production, and promoted the reduction of iron oxides through redox-active groups. Meanwhile, woodchips prevented the inhibition of autotrophic denitrification and released volatile fatty acids, stimulating pyrite bio-oxidation and sulfate reduction. The generated abundant free soluble iron and polysulfides immobilized each other and further enhanced autotrophic denitrification. The microbial community and PICRUSt2-based predicted functional analysis revealed that the woodchip-packed system enriched the heterotrophic denitrifiers, sulfur-oxidizing, sulfate-reducing, iron-oxidizing, and iron-reducing bacteria, along with the genes related to carbon, nitrogen, sulfur, iron metabolism, and electron transfer. The findings of this study demonstrated that coupling woodchips with pyrite and iron-scrap strengthened substrate cooperation and microbial synergy, offering a sustainable solution for efficient nitrate removal from stormwater runoff.
在处理碳受限的雨水径流时，电子供体可用性不足对生物滞留系统中的硝酸盐去除构成挑战。本研究构建了两个包含固体碳源、黄铁矿和铁屑的三元电子供体系统，以增强混合营养反硝化作用，并研究了天然碳源（木屑）和合成碳源（聚己内酯）对反硝化性能和副产物生成的影响。结果表明，在120天的可变雨水条件下，两个系统均表现出稳定且高效的硝酸盐去除效果（分别为85.76 ± 11.00%和89.67 ± 5.75%），这归因于多电子供体的协同作用。与聚己内酯填充系统相比，木屑填充系统在氨氮、溶解有机碳和硫酸盐生成方面有显著降低，表明其对污染物的综合控制效果更好。木屑通过维持低溶解有机碳条件和防止高氢氧根生成，避免了铁屑的过度腐蚀和钝化，并通过氧化还原活性基团促进了铁氧化物的还原。同时，木屑防止了自养反硝化的抑制并释放挥发性脂肪酸，刺激了黄铁矿的生物氧化和硫酸盐还原。生成的大量游离可溶性铁和多硫化物相互固定，进一步增强了自养反硝化作用。微生物群落和基于PICRUSt2的预测功能分析表明，木屑填充系统富集了异养反硝化菌、硫氧化菌、硫酸盐还原菌、铁氧化菌和铁还原菌，以及与碳、氮、硫、铁代谢和电子转移相关的基因。本研究结果表明，将木屑与黄铁矿和铁屑耦合可加强底物协同作用和微生物协同，为从雨水径流中高效去除硝酸盐提供了一种可持续的解决方案。
