Sludge concentration, shear rate and nanoparticle size determine silver nanoparticle removal during wastewater treatment
Sludge concentration, shear rate and nanoparticle size determine silver nanoparticle removal during wastewater treatment
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DOI：
10.1039/c7en00734e
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发表时间：
2017-11
期刊：
影响因子：
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通讯作者：
G. Cornelis;A. M. Forsberg-Grivogiannis;N. P. Skold;S. Rauch;J. Perez-Holmberg
中科院分区：
文献类型：
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作者：
G. Cornelis;A. M. Forsberg-Grivogiannis;N. P. Skold;S. Rauch;J. Perez-Holmberg
废水处理(WWT)在去除污水中的纳米颗粒(NPs)方面通常是有效的，但其去除速率的变化尚未得到解释。采用标称粒径为20或80 nm的纳米银颗粒和柠檬酸盐或聚乙二醇包覆的银纳米颗粒，在动态批量附着和沉淀研究中，改变了WWT参数，如活性污泥(AS)浓度、剪切速率和离子强度。拟合的附着和脱离速率常数及其在稳态下的分配比随WWT工艺参数的变化而变化，但最显著的是随NP尺寸的变化，也发现NP尺寸对沉降速率的影响最大。NP包衣分子具有有限的影响或没有影响。对由银和其他材料组成的纳米颗粒的文献分布比率(附着/分离浓度)的荟萃分析表明，NP(聚集体)大小是唯一重要的参数。然而，虽然银纳米颗粒与砷的分配比随着砷浓度的线性增加而增加，但氮磷废水浓度的最终影响被沉降速率的降低所部分抵消。因此，结果证实WWT工艺在去除废水中的NPs方面是有效的，但相对较小(<；20 nm)的非聚集NPs比相对较大的NPs更有可能通过出水进入水中隔间，后者几乎完全离开WWT工厂，使土壤、焚烧厂或垃圾填埋场中的氮磷化合物。
Wastewater treatment (WWT) is generally efficient in removing nanoparticles (NPs) from sewage effluent, but the variety in removal rates has not yet been explained. WWT parameters such as the activated sludge (AS) concentration, shear rate and ionic strength were varied in kinetic batch attachment and sedimentation studies using silver NPs having nominal 20 or 80 nm sizes and citrate or PEG coatings. The fitted attachment and detachment rate constants and the resulting distribution ratios at steady state varied with WWT process parameters, but most notably with the NP size, which was also found to influence the settling rates most. The NP coating molecules had a limited or no effect. A meta-analysis of literature distribution ratios (attached/detached concentration) of NPs composed of Ag and other materials showed the NP (aggregate) size as the only significant parameter. However, while the distribution ratio of silver NPs to AS increased linearly with AS concentration, the final effect of NP effluent concentrations is partly offset by decreased sedimentation rates. The results thus confirm that a WWT process is efficient in removing NPs from wastewater, but relatively small (<20 nm) non-aggregated NPs are somewhat more likely to exit a WWT process via the effluent into aquatic compartments compared to relatively larger NPs, which nearly entirely leave the WWT plants with the AS towards soils, incineration plants or landfills.