Comparative study of nano zerovalent iron, micro zerovalent iron and emulsified nano zerovalent iron for the remediation of TCE and Cr(VI) contaminated groundwater

Abstract

Groundwater pollution by volatile organic contaminants (VOC) and heavy metals is a serious environmental problem and the application of zero valent iron (ZVI) is one of the more promising solutions. The purpose of this research is to assess the efficiency of Nano zerovalent iron (nZVI) as compared to Emulsified nano zerovalent Iron (EZVI) and micro zerovalent iron (MZVI) for the remediation of trichloroethylene (TCE) and Cr(VI) contaminated groundwater. Test results revealed that nZVI achieved satisfactory reduction of TCE compared to EZVI within the experimental time frame. It also appears that for some of the nZVI treatments, the reduction of TCE was biologically mediated; i.e., minimal or no TCE reduction was observed for the sterilized duplicates or in the control samples with no nZVI. The treatability results for low Cr(VI) concentrations (< 1 mg/L) indicated that all the reductants performed satisfactorily. However, only partial reduction was observed for some of the corresponding sterilized samples, which may indicate that part of the reduction could be biologically mediated. For high Cr(VI) concentrations (8.5 mg/L), only nZVI performed satisfactorily and it seems that the reduction was not biologically mediated. EZVI achieved a borderline performance, whereas MZVI achieved poor performance.