Environment Research Institute, Shandong University, Qingdao, 266237, PR China.
College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China.
Environ Res. 2022 Sep;212(Pt C):113453. doi: 10.1016/j.envres.2022.113453. Epub 2022 May 7.
Nitrate and sulfate are crucial factors of eutrophication and black and odorous water in the surface water and thus have raised increasing environmental concerns. Constructed wetlands (CWs) are the last ecological barrier before effluent enters the natural water body. To explore the simultaneous removal of nitrate and sulfate, the CW microcosms of CW-Con (with quartz sand), CW-ZVI (quartz sand and zero-valent iron), CW-Mag (quartz sand and magnetite), CW-ZVI + Mag (quartz sand, ZVI and magnetite) groups were set up under the low (100 mg/L)/high (300 mg/L) chemical oxygen demand (COD) concentration. Under the high COD condition, CW-ZVI group showed the best performance in nitrate (97.1%) and sulfate (96.9%) removal. Under the low COD concentration, the removal content of nitrate and sulfate in CW-ZVI group was better than CW-Mag group. The reason for this result was that zero-valent iron (ZVI) could be the electron donor for nitrate and sulfate reduction. Meanwhile, ZVI promoted chemical denitrification under high COD concentration according to PCA analysis. In addition, the produced sulfides inhibited the relative abundance of denitrifying bacteria, resulting in the lowest nitrate removal rate in CW-Mag group with sufficient electron donors. This study provided an alternative method to enhance simultaneous sulfate and nitrate removal in CWs.
硝酸盐和硫酸盐是地表水富营养化和黑臭的关键因素,因此引起了越来越多的环境关注。人工湿地(CWs)是污水进入自然水体前的最后一道生态屏障。为了探索同时去除硝酸盐和硫酸盐,在低(100mg/L)/高(300mg/L)化学需氧量(COD)浓度下,建立了 CW-Con(石英砂)、CW-ZVI(石英砂和零价铁)、CW-Mag(石英砂和磁铁矿)、CW-ZVI+Mag(石英砂、ZVI 和磁铁矿)组的 CW 微宇宙。在高 COD 条件下,CW-ZVI 组在硝酸盐(97.1%)和硫酸盐(96.9%)去除方面表现出最佳性能。在低 COD 浓度下,CW-ZVI 组硝酸盐和硫酸盐的去除含量优于 CW-Mag 组。造成这种结果的原因是零价铁(ZVI)可以作为硝酸盐和硫酸盐还原的电子供体。同时,根据 PCA 分析,ZVI 在高 COD 浓度下促进了化学反硝化。此外,产生的硫化物抑制了反硝化菌的相对丰度,导致 CW-Mag 组在有足够电子供体的情况下硝酸盐去除率最低。本研究为增强 CWs 中同时去除硫酸盐和硝酸盐提供了一种替代方法。