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. 2023 May 20;874:162451. doi: 10.1016/j.scitotenv.2023.162451. Epub 2023 Feb 28.
Constructed wetlands (CWs) are considered a widely used cost-effective technology for pollutant removal. However, greenhouse gas emissions are a non-negligible problem in CWs. In this study, four laboratory-scale CWs were established to evaluate the effects of gravel (CW), hematite (CW), biochar (CW), and hematite + biochar (CW) as substrates on pollutants removal, greenhouse gas emissions, and associated microbial characteristics. The results showed that the biochar-amended CWs (CW and CW) enhanced the removal efficiency of pollutants, with 92.53 % and 93.66 % of COD and 65.73 % and 64.41 % of TN removal, respectively. Both single and combined inputs of biochar and hematite significantly reduced CH and NO fluxes, with the lowest average of CH flux obtained in CW (5.99 ± 0.78 mg CH m h) and the least NO flux in CW (287.57 ± 44.84 μg NO m h). The substantial reduction of global warming potentials (GWP) was obtained in the applications of CW (80.25 %) and CW (79.5 %) in biochar-amended CWs. The presence of biochar and hematite mitigated CH and NO emissions by modifying microbial communities with higher ratios of pmoA/mcrA and nosZ genes abundances, as well as increasing the abundance of denitrifying bacteria (Dechloromona, Thauera and Azospira). This study demonstrated that biochar and the combined use of biochar and hematite could be the potential candidates as functional substrates for the efficient removal of pollutants and simultaneously reducing GWP emissions in the constructed wetlands.
人工湿地（CWs）被认为是一种广泛使用的具有成本效益的污染物去除技术。然而，温室气体排放是 CWs 中一个不可忽视的问题。本研究建立了四个实验室规模的 CWs，以评估砾石（CW）、赤铁矿（CW）、生物炭（CW）和赤铁矿+生物炭（CW）作为基质对污染物去除、温室气体排放和相关微生物特性的影响。结果表明，生物炭改良的 CWs（CW 和 CW）提高了污染物的去除效率，COD 的去除率分别为 92.53%和 93.66%，TN 的去除率分别为 65.73%和 64.41%。生物炭和赤铁矿的单独和联合输入均显著降低了 CH 和 NO 通量，CW 中获得的 CH 通量平均最低（5.99±0.78mg CH m h），CW 中获得的 NO 通量最低（287.57±44.84μg NO m h）。在生物炭改良的 CWs 中，CW（80.25%）和 CW（79.5%）的应用获得了较大的全球变暖潜势（GWP）降低。生物炭和赤铁矿的存在通过改变微生物群落，增加反硝化细菌（Dechloromona、Thauera 和 Azospira）的丰度，从而提高 pmoA/mcrA 和 nosZ 基因丰度的比值，减轻了 CH 和 NO 的排放。本研究表明，生物炭和生物炭与赤铁矿的联合使用可能是作为功能基质的潜在候选物，可有效去除污染物，同时减少人工湿地中的 GWP 排放。
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