Tian Liping, Ou Yang, Yan Baixing, Zhu Hui, Liu Huiping, Cheng Lei, Jiao Peng
Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Fundam Res. 2022 Nov 2;3(6):890-897. doi: 10.1016/j.fmre.2022.10.012. eCollection 2023 Nov.
Sanjiang Plain is intensively used for rice production, and ditch drainage diffuse pollution prevention is crucial. Groundwater, rich in Fe ions, is the main source of irrigation water in this region. In this study, pyrite and zero-valent iron (ZVI) (sponge iron and iron scraps) were used as substrates to identify the synergistic influence of exogenous Fe addition and solid iron substrates on pollutant removal in constructed wetlands. Based on the results, iron substrates hardly improved the ammonia removal, mainly because of the physical structure and oxidation activity. At a hydraulic retention time longer than 8 h, the pollution removal efficiency in the zero-valent iron (ZVI) substrate treatment increased significantly, and the removal of nitrate (NO -N) and total phosphorus (TP) in the iron scrap substrate treatment reached about 60% and 70%, respectively. The high-throughput sequencing results showed a significant increase in the abundance of microorganisms involved in denitrification and phosphate accumulation in biofilms on ZVI substrates. The highest diversities of such microorganisms in biofilms on iron scraps were found for denitrifying bacteria (), nitrate-reducing Fe (II)-oxidizing bacteria (), and with autotrophic denitrification and phosphate accumulation, with a 43% cumulative abundance. dominated in the iron sponge substrate treatment. The highest relative abundance of was found in the mixed iron substrate (pyrite, sponge iron, and iron scraps) treatment. The addition of ZVI substrate significantly improved the removal of NO -N and TP and reduced the hydraulic retention time through the continuous release of Fe and the promotion of microbial growth. When designing constructed wetlands for treating paddy field drainage, the appropriate addition of iron scrap substrates is recommended to enhance the pollutant removal efficiency and shock load resistance of CWs.
三江平原被密集用于水稻生产，沟渠排水的面源污染防治至关重要。富含铁离子的地下水是该地区灌溉用水的主要来源。本研究以黄铁矿和零价铁（ZVI）（海绵铁和铁屑）为基质，探讨外源铁添加和固态铁基质对人工湿地污染物去除的协同影响。结果表明，铁基质对氨氮去除的促进作用不明显，主要是由于其物理结构和氧化活性所致。当水力停留时间大于8 h时，零价铁（ZVI）基质处理的污染去除效率显著提高，铁屑基质处理对硝酸盐氮（NO₃-N）和总磷（TP）的去除率分别达到60%和70%左右。高通量测序结果表明，ZVI基质生物膜上反硝化和聚磷相关微生物的丰度显著增加。铁屑生物膜中反硝化细菌、硝酸盐还原型铁（II）氧化细菌等具有自养反硝化和聚磷功能的微生物多样性最高，累积丰度为43%。铁海绵基质处理中 占主导地位。混合铁基质（黄铁矿、海绵铁和铁屑）处理中 的相对丰度最高。ZVI基质通过持续释放铁和促进微生物生长，显著提高了NO₃-N和TP的去除率，缩短了水力停留时间。在设计处理稻田排水的人工湿地时，建议适当添加铁屑基质，以提高人工湿地的污染物去除效率和抗冲击负荷能力。
