School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, China.
Key laboratory of Yellow River Water Environment in Gansu Province, Lanzhou, China.
Int J Phytoremediation. 2022;24(13):1405-1417. doi: 10.1080/15226514.2022.2031866. Epub 2022 May 15.
Sponge iron (SI) is widely used in water treatment. As effluents from wastewater treatment plant (WWTP) require advanced treatment methodology, three forms of constructed wetlands (CWs): wetlands with sponge iron (SI), copper sulfate modified sponge iron (Cu/SI), and sponge iron coupled with solid carbon sources (C/SI), have been investigated in this paper for the removal effects of organic matter and nutrients in WWTP effluents, and the corresponding mechanisms have been analyzed. The results showed the effect of baffled subsurface-flow constructed wetland (BSFCW) with SI dosing to purify the WWTP effluents after the stable operation. The water flow of this BSFCW is the repeated combination of upward flow and downward flow, which can provide a longer treatment pathway and microbial exposure time. The average removal rates of total inorganic nitrogen (TIN) were 27.80%, 30.17%, and 44.83%, and the average removal rates of chemical oxygen demand (COD) were 19.96%, 23.73%, and 18.38%. The average removal rates of total phosphorus (TP) were 85.94%, 82.14%, and 83.95%. Cu/SI improved the dissolution of iron, C/SI improved denitrification, and a winter indoor temperature retention measure was adopted to increase the effectiveness of wetland treatment during the winter months. After comprehensively analyzing X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and two-dimensional numerical simulation diagrams, a plausible conjecture that microbes use electrons from SI for autotrophic denitrification is presented. Moreover, the stress effect of wetlands dosed with SI on plants decreased stepwise along the course since C/SI used on wetlands had less impact on plant stress.
海绵铁（SI）在水处理中得到广泛应用。由于废水处理厂（WWTP）的出水需要先进的处理方法，因此本文研究了三种形式的人工湿地（CW）：带有海绵铁（SI）、硫酸铜改性海绵铁（Cu/SI）和海绵铁与固体碳源结合（C/SI）的湿地，以去除 WWTP 废水中的有机物和营养物质，并分析了相应的机制。结果表明，在稳定运行后，带有 SI 投加的挡板式地下流人工湿地（BSFCW）对 WWTP 出水具有净化效果。该 BSFCW 的水流是上向流和下向流的重复组合，可以提供更长的处理途径和微生物暴露时间。TIN 的平均去除率分别为 27.80%、30.17%和 44.83%，COD 的平均去除率分别为 19.96%、23.73%和 18.38%。TP 的平均去除率分别为 85.94%、82.14%和 83.95%。Cu/SI 提高了铁的溶解率，C/SI 提高了反硝化作用，冬季采用室内温度保持措施，增加了湿地处理在冬季的效果。通过综合分析 X 射线粉末衍射（XRD）、扫描电子显微镜（SEM）和二维数值模拟图，提出了一个合理的假设，即微生物利用 SI 中的电子进行自养反硝化作用。此外，由于湿地中使用的 C/SI 对植物的胁迫影响较小，因此 SI 投加湿地对植物的胁迫影响逐渐降低。
