In Situ Bioremediation of Perchlorate in Groundwater

Abstract

Perchlorate has been detectable at milligram/liter concentrations in groundwater for decades, and investigations were originally primarily limited to sites where rocket-fuel development or testing had occurred. Other compounds of concern with low-concentration toxicity have been detected at many sites and have dominated the focus of the remedial industry since the 1970s. Once a revised analytical method was developed in 1997 to detect perchlorate concentrations down to 4 µg/L, its widespread presence was recognized at many sites and led perchlorate to claim center stage attention on a national level by the early 2000s. Although perchlorate's early association with military use persists (headlines often equate perchlorate with “rocket fuel,” regardless of the actual source), perchlorate detection at non-military sites has led to the recognition that other potential sources also require consideration. The ability to definitively distinguish potential sources from one another remains a challenge even today. Initial concerns over perchlorate recalcitrance, however, have since been allayed by the repeated demonstrations of successful remediation using a variety of familiar technologies. In this sense, perchlorate remediation strategies have been an outgrowth from chlorinated solvent–focused remediation technologies that had evolved since the 1970s. The fact that in situ technologies were being deployed aggressively—an approach that took many years for the solvent remediation industry to implement with regulatory approval—even as the extent of perchlorate was still be determined at many sites, is evidence that lessons learned from decades of chlorinated solvent remediation have and will continue to benefit perchlorate remediation speed and efficiency. As the debate over risk to human health from perchlorate exposure via food and water continues, it is apparent that in situ bioremediation of soil and groundwater has been demonstrated to be a powerful tool that remedial engineers and scientists would be wise to seriously consider at any site. In Situ Bioremediation of …