Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, Chongqing 400715, China.
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing 400715, China.
Sci Total Environ. 2024 Sep 1;941:173740. doi: 10.1016/j.scitotenv.2024.173740. Epub 2024 Jun 3.
Constructed wetlands (CWs) have been used to enhance pollutant removal by filling several types of material as substrates. However, research on substrate filling order remains still limited, particularly regarding the effects of greenhouse gas (GHG) emissions. In this study, six CWs were constructed using zeolite and ferric‑carbon micro-electrolysis (Fe-C) fillers to evaluate the effect of changing the filling order and ratio on pollutant removal, GHGs emissions, and associated microbial structure. The results showed that the order of substrate filling significantly impacted pollutant removal performance on CWs. Specifically, CWs filled with zeolite in the top layer exhibited superior NH-N removal compared to those filled in the lower layer. Moreover, the highest NH-N removal (95.0 % ± 1.9 %) was observed in CWs with a zeolite to Fe-C volume ratio of 8:2 (CW). Moreover, zeolite-filled at the top had lower GHGs emissions, with the lowest CH (0.22 ± 0.10 mg m h) and NO (167.03 ± 61.40 μg m h) fluxes in the CW. In addition, it is worth noting that NO is the major contributor to integrated global warming potential (GWP) in the six CWs, accounting for 81.7 %-90.8 %. The upper layer of CWs filled with zeolite exhibited higher abundances of nirK, nirS and nosZ genes. The order in which the substrate was filled affected the microbial community structure and the upper layer of CWs filled with zeolite had higher relative abundance of nitrifying genera (Nitrobacter, Nitrosomonas) and denitrifying genera (Zoogloea, Denitratisoma). Additionally, NO emission was reduced by approximately 41.2 %-64.4 % when the location of the aeration of the CWs was changed from the bottom to the middle. This study showed that both the order of filling the substrate and the aeration position significantly affected the GHGs emissions from CWs, and that CWs had lower GHGs emissions when zeolites were filled in the upper layer and the aeration position was in the middle.
人工湿地（CWs）已被用于通过填充多种类型的材料作为基质来增强污染物的去除。然而，关于基质填充顺序的研究仍然有限，特别是关于温室气体（GHG）排放的研究。在这项研究中，使用沸石和铁碳微电解（Fe-C）填料构建了六个 CWs，以评估改变填充顺序和比例对污染物去除、GHGs 排放和相关微生物结构的影响。结果表明，基质填充顺序对 CWs 的污染物去除性能有显著影响。具体来说，上层填充沸石的 CWs 表现出比下层填充沸石更好的 NH-N 去除效果。此外，在沸石与 Fe-C 体积比为 8:2（CW）的 CWs 中观察到最高的 NH-N 去除率（95.0%±1.9%）。此外，上层填充沸石的 CWs 的 GHGs 排放量较低，CW 中的 CH（0.22±0.10mg m h）和 NO（167.03±61.40μg m h）通量最低。此外，值得注意的是，NO 是六个 CWs 中综合全球变暖潜势（GWP）的主要贡献者，占 81.7%-90.8%。上层填充沸石的 CWs 中nirK、nirS 和 nosZ 基因的丰度较高。基质填充顺序影响微生物群落结构，上层填充沸石的 CWs 中硝化菌属（Nitrobacter、Nitrosomonas）和反硝化菌属（Zoogloea、Denitratisoma）的相对丰度较高。此外，当 CWs 的曝气位置从底部改为中间时，NO 排放减少了约 41.2%-64.4%。本研究表明，基质填充顺序和曝气位置都会显著影响 CWs 的 GHGs 排放，当沸石填充在上层且曝气位置在中间时，CWs 的 GHGs 排放量较低。
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