Aquatic plant biomass like Iris pseudacorus can be used as electron donor to improve denitrification performance in subsurface constructed wetlands. However, the phenomenon that the nitrogen removal rate declined in the terminal stage restricted the utilization of litters. In terms of this problem, this study investigated the performance of the used biomass through alkali treatment on nitrogen removal and analyzed the effect of alkali treatment on the component and structure of biomass and microbial community. The results showed that the alkali-treated biomass could further enhance the nitrogen removal by nearly 15% compared with used ones. The significant damage of cell walls and compact fibers containing cellulose and lignin through alkali treatment mainly resulted in the improvement of carbon release and nitrogen removal. With the addition of alkali-treated biomass, the richness index of microbes was higher compared with other biomass materials. Furthermore, the abundance of denitrification related genera increased and the abundance of genera for nitrification was maintained. Based on these finds, a mode of a more efficient Iris pseudacorus self-consumed subsurface flow constructed wetlands was designed. In this mode, the effluent total nitrogen could be stabilized below 5 mg L⁻¹ for nine months and the weight of litters could be further cut down by 75%. These findings would contribute to efficient utilization of plant biomass for nitrogen removal enhancement and final residue reduction in the wetlands.

水生植物生物量，如Iris pseudacorus可作为电子供体提高地下人工湿地的反硝化性能。但后期脱氮率下降的现象限制了凋落物的利用。针对这一问题，本研究考察了生物质碱处理对脱氮性能的影响，分析了碱处理对生物质和微生物群落组成和结构的影响。结果表明，碱处理的生物质与使用过的生物质相比，氮去除率可进一步提高近15%。碱处理对细胞壁和含有纤维素和木质素的致密纤维的显着破坏主要导致碳释放和脱氮的改善。随着碱处理生物质的加入，微生物的丰富度指数高于其他生物质材料。此外，反硝化相关属的丰度增加，硝化属的丰度保持不变。基于这些发现，一种更高效的模式设计了菖蒲自消耗地下流人工湿地。在这种模式下，出水总氮可以稳定在 5 mg L ^-1以下 9 个月，垃圾重量可以进一步减少 75%。这些发现将有助于有效利用植物生物质以提高湿地中的氮去除率和最终减少残留物。