Academy of Eco-Environmental Science, School of Environmental Science and Engineering, Tianjin University, No. 135 Yaguan Road, Jinnan District, Tianjin 300350, China.
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090, China.
Sci Total Environ. 2022 Oct 20;844:157060. doi: 10.1016/j.scitotenv.2022.157060. Epub 2022 Jun 30.
Vivianite widely existed in digested sludge and activated sludge as a potential phosphate resource recovered from wastewater treatment plants (WWTPs). As an important product of extracellular electron transfer (EET) and biological iron reduction, the production of vivianite can be enhanced by conductive materials. Carbon nanotubes (CNTs) with excellent electrical conductivity have been reported to promote electron transfer, which was applied in wastewater treatment to accelerate the degradation of the contaminants. However, the impact of CNTs on vivianite formation was barely reported. In this study, the iron reduction, vivianite recovery, and the biotoxicity of CNTs were investigated in order to determine the influence of CNTs towards the vivianite production. The enhancement of vivianite production after CNTs adding reached up to 17 % by promoting the electron transfer between dissimilative iron-reducing bacteria (DIRB) and Fe(III). However, at the initial stage (0-24 h), Fe(III) reduction efficiency decreased by 81 % after inoculating with sewage sludge, which was attributed to CNTs destroying of the cell membrane (as indicated by SEM, CLSM and AFM analysis). The biotoxicity of CNTs stimulated DIRB to secret extracellular polymeric substances (EPS) and form bio-flocs to resist the physical puncture. After 48 h, the proportion of living DIRB in 1000 mg/L CNTs batch increased to 98 %, which was 79 % higher than 12 h. As a result, the vivianite recovery of raw sewage with 1000 mg/L CNTs increased to 44 ± 1 %, which was 33 % higher than that in the CNT-0.
纤铁矿广泛存在于消化污泥和活性污泥中，是从污水处理厂（WWTP）回收的潜在磷酸盐资源。作为细胞外电子转移（EET）和生物还原铁的重要产物，通过导电材料可以增强纤铁矿的生成。具有优异导电性的碳纳米管（CNT）已被报道可促进电子转移，从而应用于污水处理中以加速污染物的降解。然而，CNT 对纤铁矿形成的影响几乎没有报道。在这项研究中，研究了 CNT 对铁还原、纤铁矿回收和生物毒性的影响，以确定 CNT 对纤铁矿生成的影响。通过促进异化铁还原菌（DIRB）和 Fe(III) 之间的电子转移，添加 CNT 后纤铁矿的产量提高了 17%。然而，在初始阶段（0-24 h），接种污水污泥后 Fe(III) 还原效率降低了 81%，这归因于 CNT 破坏了细胞膜（SEM、CLSM 和 AFM 分析表明）。CNT 的生物毒性刺激 DIRB 分泌细胞外聚合物物质（EPS）并形成生物絮体以抵抗物理穿刺。48 h 后，1000 mg/L CNT 批次中存活的 DIRB 比例增加到 98%，比 12 h 时高 79%。因此，含 1000 mg/L CNT 的原污水中纤铁矿的回收率增加到 44±1%，比 CNT-0 时高 33%。
