铁矿石和生物炭添加对潜流人工湿地污水处理效果和温室气体排放及微生物群落的影响

人工湿地中基质的种类和填充方式会影响人工湿地中微生物的多样性及丰度，进而影响污水处理效果.通过在温室内构建空白-人工湿地（CW0）、铁矿石-人工湿地（CW1）、生物炭-人工湿地（CW2）和铁矿石+生物炭-人工湿地（CW3）这4组湿地，研究不同填料人工湿地系统的污水处理效果和温室气体排放及微生物群落结构的差异.结果表明，添加铁矿石或者生物炭能够提高-0.12%～1.7%的COD去除率.添加生物炭能够分别提升22.48%的NH⁺₄-N和6.82%的NO^-₃-N去除率，并分别降低83.91%的CH₄和30.81%的N₂O排放通量.添加铁矿石能够降低1.12%的NH⁺₄-N去除率，提高3.98%的NO^-₃-N去除率，并分别降低33.29%的CH₄和25.2%的N₂O排放通量.添加生物炭或者铁矿石均能够增加放线菌门（Actinobact...

Effects of Hematite and Biochar Addition on Wastewater Treatment Efficiency, Greenhouse Gas Emission, and Microbial Community in Subsurface Flow Constructed Wetland

The type and structure of the substrate in constructed wetland affects the diversity and abundance of microorganisms, thereby influencing the effect of sewage treatment. In this study, four groups of wetlands were constructed in the greenhouse:blank-constructed wetland (CW0), hematite-constructed wetland (CW1), biochar-constructed wetland (CW2), and hematite+biochar-constructed wetland (CW3), to study the differences in sewage treatment effects, greenhouse gas emissions, and microbial community structures of constructed wetland systems under different filler substrates. The results showed that the addition of hematite or biochar increased the COD removal rate of -0.12% to 1.7%. The addition of biochar increased the removal rate of NH₄⁺-N by 22.48% and NO₃^--N by 6.82% and reduced the emission flux of CH₄ by 83.91% and N₂O by 30.81%. The addition of hematite reduced the removal rate of NH₄⁺-N by 1.12%, increased the removal rate of NO₃^--N by 3.98%, and reduced the emission flux of CH₄ by 33.29% and N₂O by 25.2%. Adding biochar or hematite increased the relative abundances of Actinobacteria and Proteobacteria, which was beneficial to the removal of COD. The Ace, Chao, Sobs, and Shannon indexes in the substrate treated with biochar were the largest, and the Simpson index was the smallest. The treatment with hematite was the opposite, indicating that the richness and diversity of microbial communities in the treatment system with biochar was the largest. Adding hematite reduced the richness and diversity of the microbial community in the constructed wetland system. Adding biochar or hematite increased the relative abundances of Dechloromonas, Thaurea, Saccharimonadales, and other denitrifying bacteria, which was beneficial to wetland denitrification. The addition of biochar increased the abundances of nosZ, nirS, and nirK functional genes, which were conducive to the occurrence of denitrification. The addition of biochar increased the abundances of pmoA functional genes, reduced the abundance of mcrA functional genes, and inhibited the production of CH₄. It also increased the abundance of methanotrophic bacteria and promoted the occurrence of the CH₄ oxidation process. Although the addition of hematite increased the abundance of mcrA functional genes, Fe³⁺ competed with methanogens for electron donors and inhibited the production of CH₄.