Haz-Flote{trademark}: Ex-situ decontamination of materials

Abstract

Western Research Institute (WRI), in conjunction with the US Department of Energy (DOE), Morgantown Energy Technology Center, is developing a soil remediation technique called Haz-Flote{trademark}. Initial tests were conducted for petroleum-contaminated materials employing a number of chemical combinations. The most promising chemicals used in this study showed about a 75% reduction in organic carbon content in the coarse fraction. This reduction demonstrates that the treatment can remove some petroleum contaminants from the coarse fraction. Tests were conducted using the fine fraction of the petroleum-contaminated soil. The preliminary results show that the process separates a portion of the hydrocarbons from the very fine soil fraction under less than optimum conditions. After separation, the organic carbon content of the fine size fraction was about 26% lower than that of the feed material. The material collected had a 54% increase in organic carbon content compared to that collected from the feed. Optimization of the equipment and the chemistry of the system should enhance these results significantly. The bulk of the work on the Haz-Flote process has been focused on removing mercury from contaminated soil fines. A sample of mercury-contaminated soil was obtained, and the distribution of mercury within the various size fractions was determined. The {minus}200 mesh (< 75 {micro}m) material contains the majority of the mercury contaminant. For convenience, the sample was sieved through a 70 mesh screen. All of the testing was conducted on the {minus}70 mesh (< 212 {micro}m) fraction. This fraction contained on average 122 mg Hg/kg of dry soil before processing. Mercury concentrations after processing were reduced to as low as 0.95 mg Hg/kg of dry soil. This represents > 99% mercury radiation for the fine fraction. Tests have removed > 99.5% of the mercury from the system.