Weng Zhongshuai, Ma Haiyuan, Ma Jingchen, Kong Zheng, Shao Zhiyu, Yuan Yunsong, Xu Yanhong, Ni Qichang, Chai Hongxiang
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), College of Environment and Ecology, Chongqing University, Chongqing 400045, China.
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), College of Environment and Ecology, Chongqing University, Chongqing 400045, China; Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, Brisbane, QLD 4072, Australia.
Chemosphere. 2022 Nov;306:135534. doi: 10.1016/j.chemosphere.2022.135534. Epub 2022 Jun 27.
Solid biomass waste amendment and substrates modification in bioretention systems have been increasingly used to achieve effective dissolved nutrients pollution control in stormwater runoff. However, the risk of excess chemical oxygen demand (COD) leaching from organic carbon sources is often overlooked on most occasions. Pyrite is an efficient electron donor for autotrophic denitrification, but little is known about the efficacy of autotrophic-heterotrophic synergistic effect between additional carbon source and pyrite in bioretention. Here, four bioretention columns (i.e., corncob column (C), pyrite column (P), the corncob-pyrite layered column (L-CP), and the corncob-pyrite mixed column (M-CP)) were designed and filled with soil, quartz sand, and modified media to reveal the synergistic effects. The results showed that the corncob-pyrite layered bioretention could maintain low COD effluent concentration with high stability and efficiency in treating dissolved nutrients. When the influent nitrogen and phosphorus concentrations were 8.46 mg/L and 0.94 mg/L, the average removal rates of ammonia nitrogen, total inorganic nitrogen, and phosphate were 83.6%, 70.52%, and 76.35%, respectively. The scouring experiment showed that placing the corncob in the mulch layer was beneficial to the sustained release of dissolved organic carbon (DOC). Erosion pits were found in the SEM images of used pyrite, indicating that autotrophic denitrifying bacteria in the bioretention could react with pyrite as an electron donor. The relative abundance of Thiobacillus in the submerged zone of the corncob-pyrite layered bioretention reached 38.39%, indicating that the carbon source in the mulch layer increased the relative abundance of Thiobacillus. Coexisting heterotrophic and autotrophic denitrification in this bioretention created a more abundant microbial community structure in the submerged zone. Overall, the corncob-pyrite layered bioretention is highly promising for stormwater runoff treatment, with effective pollution removal and minimal COD emission.
在生物滞留系统中，固体生物质废弃物改良和基质改性已越来越多地用于实现对雨水径流中溶解性营养物污染的有效控制。然而，在大多数情况下，有机碳源中化学需氧量（COD）过量淋溶的风险常常被忽视。黄铁矿是自养反硝化的有效电子供体，但关于生物滞留中额外碳源与黄铁矿之间自养-异养协同效应的功效却知之甚少。在此，设计了四个生物滞留柱（即玉米芯柱（C）、黄铁矿柱（P）、玉米芯-黄铁矿分层柱（L-CP）和玉米芯-黄铁矿混合柱（M-CP）），并填充土壤、石英砂和改性介质以揭示协同效应。结果表明，玉米芯-黄铁矿分层生物滞留能够在处理溶解性营养物时保持较低的COD出水浓度，具有高稳定性和高效性。当进水氮磷浓度分别为8.46mg/L和0.94mg/L时，氨氮、总无机氮和磷酸盐的平均去除率分别为83.6%、70.52%和76.35%。冲刷实验表明，将玉米芯置于覆盖层有利于溶解性有机碳（DOC）的持续释放。在使用过的黄铁矿的扫描电子显微镜图像中发现了侵蚀坑，表明生物滞留中的自养反硝化细菌可以与黄铁矿作为电子供体发生反应。玉米芯-黄铁矿分层生物滞留淹没区硫杆菌的相对丰度达到38.39%，表明覆盖层中的碳源增加了硫杆菌的相对丰度。这种生物滞留中异养和自养反硝化共存，在淹没区创造了更丰富的微生物群落结构。总体而言，玉米芯-黄铁矿分层生物滞留对于雨水径流处理极具前景，具有有效的污染去除和最小的COD排放。
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