| Abstrakt: |
A field demonstration of acetate mediated biologically active zone enhancement (BAZE) for in situ reductive transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in groundwater was conducted at the former Nebraska Ordnance Plant (NOP). The primary objectives of the field demonstration were to assess the potential of the BAZE process to remediate the RDX-contaminated groundwater, and to quantify the capital and operation/maintenance costs associated with the use of the BAZE process for in situ treatment of RDX contamination in groundwater. The study also delineated the effects of the BAZE process on subsurface biomass, and water quality parameters (metals mobilization, total organic compound, etc.). The results of this 20-month field study demonstrated that acetate is an excellent source of carbon capable of creating reduced conditions conducive for reductive transformation of RDX in groundwater. Over the period of demonstration, the background RDX concentration of about 256 μg/L was reduced to below the U.S. EPA’s health advisory level of 2 μg/L. Besides significant reduction in RDX background concentrations, other chemical (low Eh and nitrate denitrification) and biological (biomass buildup and enrichment) changes in the subsurface validated the development of a biologically active zone after the amendment addition. A total of 2,250 kg runway deicer (∼1,493 kg acetate) was injected into the subsurface over the period of the demonstration, which translates to a stoichiometric consumption of approximately 161 g acetate/g RDX. Approximately 36,200 m3 of groundwater (∼9.27 kg RDX) were treated during the course of study at a unit cost of about $18.85/m3 groundwater treated ($73.70/g RDX destroyed). [ABSTRACT FROM AUTHOR] |
