Treatability Study for Biologically Active Zone Enhancement (BAZE) for In Situ RDX Degradation in Groundwater

摘要

The work reported here is the first phase of a 4-year field demonstration project under DoD's Environmental Security Technology Certification Program (ESTCP). The purpose of this treatability study was to determine the suitability of two formerly used Federal ordnance facilities (Nebraska Ordnance Plant and Cornhusker Army Ammunition Plant) for pilot-scale demonstration/validation of in situ bioremediation of hexahydro-l,3,5-trinitro- l,3,5-triazine (RDX) contaminated groundwater. A series of column studies were conducted using site-specific soil and groundwater to determine the feasibility of using the biologically active zone enhancement (BAZE) process with indigenous microbial population to remediate RDX-contaminated groundwater. This treatability study examined the use of four amendments (acetate, ethanol, soluble starch, and acetate plus ammonium) as electron donors. All the amendments studied were able to achieve the necessary reducing conditions for remediating RDX inlet concentration of 100 ppb to less than 1 ppb. The addition of some amendments resulted in increased toxicity based on Microtox analysis. Ethanol addition itself did not result in increased toxicity, but biological activity in this system did induce high toxicity. The addition of soluble starch resulted in increased toxicity that was partially removed by biological activity in the columns. The addition of ammonium as a nitrogen source did not significantly increase the removal rate of RDX. Based on these observations, acetate was chosen to be used in the field evaluation.