College of Science and Engineering, Flinders University, Adelaide, SA, Australia; National Centre for Groundwater Research and Training, SA, 5001, Australia.
College of Science and Engineering, Flinders University, Adelaide, SA, Australia; National Centre for Groundwater Research and Training, SA, 5001, Australia.
Chemosphere. 2020 Jun;248:125929. doi: 10.1016/j.chemosphere.2020.125929. Epub 2020 Jan 18.
This research was conducted to evaluate the effect of co-transport of different-sized microorganisms on graphene oxide nanoparticles (GONPs) transport and retention in saturated pristine and biofilm-conditioned limestone columns. The transport and retention behavior of GONPs was studied in columns in the presence of MS2 -as a nano-sized- and Escherichia coli (E.coli) -as a micro-sized- microorganisms at low and high ionic strength conditions. Results showed no changes in GONPs transport and retention at high ionic strength in the presence of MS2 or E. coli, which was attributed to the effect of high concentration of divalent cation on aggregation of nanoparticles and microorganisms. Furthermore, simultaneous enhanced transport and decreased retention of GONPs in column was observed in the co-presence of microorganisms at low ionic strength. Results revealed that the main mechanism governing increasing GONPs transport in porous media was occupation of reactive surface sites of collectors by microorganisms, which prevented attachment of nanoparticles. The pre-saturation of columns with MS2 and E. coli caused increasing transport of GONPs in the columns, due to the occupation of surface reactive sites. Moreover, conditioning limestone collectors with natural biofilm resulted in the same rates of nanoparticle elution and retention (i.e., in the presence or absence of microorganisms) by straining of GONPs in the inlet end of columns which shows that the biofilm acts as a bio-filter against discharging nanoparticles into the effluents. Finally, from the obtained results, it can be postulated that the presence of microorganisms in a MAR site causes risk of groundwater pollution by toxic nanoparticles.
本研究旨在评估不同大小微生物的共运移对氧化石墨烯纳米颗粒（GONPs）在饱和原状和生物膜条件下的石灰岩柱中传输和保留的影响。在低离子强度和高离子强度条件下，研究了在存在 MS2（纳米级）和大肠杆菌（E. coli）（微级）微生物的情况下，GONPs 在柱中的传输和保留行为。结果表明，在高离子强度下，无论是否存在 MS2 或 E. coli，GONPs 的传输和保留都没有变化，这归因于二价阳离子浓度对纳米颗粒和微生物聚集的影响。此外，在低离子强度下，同时存在微生物时，观察到 GONPs 在柱中的传输增强和保留减少。结果表明，控制 GONPs 在多孔介质中传输增加的主要机制是微生物占据了收集器的反应性表面位点，从而阻止了纳米颗粒的附着。MS2 和 E. coli 对柱的预饱和导致 GONPs 在柱中的传输增加，这是由于表面反应性位点的占据。此外，用天然生物膜对石灰岩收集器进行预处理，导致纳米颗粒洗脱和保留的速率相同（即在存在或不存在微生物的情况下），这是因为 GONPs 在柱入口端被截留，这表明生物膜起到了生物过滤器的作用，防止纳米颗粒排入废水。最后，根据所得结果，可以推断出 MAR 场地中微生物的存在会导致有毒纳米颗粒对地下水造成污染的风险。
