Citation:

Su, C., D. Wang, AND C. Park. Groundwater Remediation Using Environmental Nanotechnology. To be Presented at 6th International Water Industry Conference, NA, Daegu, SOUTH KOREA, September 21 - 23, 2020.

Impact/Purpose:

The purpose of this invited presentation is to showcase the recent research conducted in Groundwater Characterization and Remediation Division on applications of environmental nanotechnology to contaminant treatment and groundwater remediation. The results could be used for treating a variety of contaminants and for cleaning up contaminated groundwater at other sites.

Description:

Recently engineered nanomaterials (ENMs) have been increasingly used to remove contaminants from surface water but also to remediate soil and groundwater contaminated with organic/inorganic pollutants via advanced oxidation and chemical reduction, sorption, complexation, and (co)precipitation. ENMs are efficient for decontamination due to the large specific surface area, high surface reactivity (e.g., catalytic activity), and increased multifunctionality (e.g., nanohybrids). Our studies have shown that among the four NMs (Ag0, NZVI, RGO, and RGO-Ag0/Fe3O4) examined, RGO- Ag0/Fe3O4 showed the highest removal efficiency in the activation of peroxydisulfite (PDS) or H2O2 for phenol removal at all pH 4, 7, and 10. This is due to the synergistic interplay between higher adsorption of phenol and greater catalytic oxidation in activation of PDS than H2O2. Degradation of other contaminants such as pharmaceuticals and endocrine disrupting compounds (EDCs) was also efficient by the RGO-Ag0/Fe3O4 and PDS system. In a field study, we injected Emulsified zerovalent iron (EZVI) into subsurface to treat groundwater contaminated by tetrachloroethene (PCE) at a Superfund site in South Carolina, USA. The field demonstration consisted of two side-by-side treatment areas to evaluate the performance of EZVI to remediate a shallow (58%) and a significant increase in the mass flux of ethene (628%). There were significant reductions in total chlorinated volatile organic compound mass (78%); an estimated reduction of 23% in the sorbed and dissolved phases and 95% reduction in the PCE DNAPL mass. Significant increases in dissolved sulfide, volatile fatty acids, and total organic carbon were also observed along with dissolved sulfate and pH decreasing in many wells. The effective remediation seems to have been accomplished by a combination of abiotic dechlorination by nanoiron and biological reductive dechlorination stimulated by the oil in the emulsion.

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