Konferensartikel

Explosives; such as TNT; 2;4-DNT; RDX and HMX; and heavy metals; such as lead (Pb); are often found on old military sites. The simultaneous presence of both organic and inorganic pollutants; so called mixed contaminants; causes great problems for the remediation process since the different contaminants possess diverse chemical properties. This survey aims to find new approaches to the remediation of mixed contaminants; whereby the desorption patterns of both organic and inorganic contaminants are studied simultaneously. Simulated soil washing and bench-scale bioremediation are the central constituents of the project. Soil washing is a technique where size separation; thereby minimizing the amount of soil needing further treatment; and mechanical washing; sometimes with the addition of specific washing solutions; are combined to fractionate and wash soil-particle surfaces. Bioremediation; utilizing microorganisms to degrade organic contaminants in the soil; is a technology which is both cost-efficient and easy to use. Two different soils; containing high levels of explosives and lead; were collected at the open destruction area at Bofors Test Center (BTC). Following primary classification; the soils were washed in a simulated soil-washing process. To enhance the washing; pH-adjustment was used. Additionally; the effect of three different bioremediation technologies was evaluated in bench-scale surveys.

While both an increase and a decrease in pH had an effect on the explosives;. there was a larger effect from a pH-increase. During the pH 12 washing; OH- ions were consumed; indicated through a decrease in solution pH; at the same time as the solution was colored red; which may imply the degradation of TNT.

Results from the bioremediation study indicate that this technique can be applicable on explosives-contaminated soil. The concentration of explosives decreased in all three studied applications of bioremediation. Further on; the microorganisms seemed to affect the binding of lead to the soils.

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