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Your Environment. Your Health.

Final Progress Reports: University of Arizona: Biosurfactant-Enhanced in Situ Metal Remediation

Superfund Research Program

Biosurfactant-Enhanced in Situ Metal Remediation

Project Leader: Raina M. Maier
Grant Number: P42ES004940
Funding Period: 1995-2010

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Final Progress Reports

Year:   2004  1999 

During the fifth year of this project, researchers completed bench-scale experimental work that demonstrates the feasibility of using biosurfactants for metal removal. Results are available for two surfactants that differ in their metal removal abilities; rhamnolipid produced by Pseudomonas aeruginosa and cyclodextrin, a starch degradation product. Focus then shifted to the study of metal-contaminated field soils. The first step in this process was to identify and obtain samples from field sites. Project investigators have identified and collected field samples from 7 different sites including: Broken Hill (mining operation) San Manuel, AZ; Camp Navajo (army depot) Bellemont, AZ; Silver Valley (mining operation) Silver Valley, ID; Klondyke (former mining operation) Klondyke, AZ; Raytheon (military defense contractor) Tucson, AZ; Asarco (mining operation) WA; and a plating company in Vancouver, WA. The types of metals present include: arsenic, barium, beryllium, cadmium, chromium, lead, nickel and zinc. Researchers have characterized these soils with respect to soil properties and metal contamination. Project investigators found that metal bioavailability differs greatly in these soils depending on the type of soil and type and history of metal contamination. The researchers have therefore focused initial biosurfactant treatment efforts on two of the soils with differing properties, Camp Navajo and Silver Valley. Initial results from biosurfactant treatment of these soils are promising, indicating that both biosurfactants are effective at metal removal, but the effectiveness of these two agents differs with respect to the soil tested. These results make it clear that no single metal complexation agent will work in all situations, rather, an array of agents is needed to meet the differing needs of each contaminated site.

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