Abstract
The degradation of 2,4 dinitrotoluene (DNT), in sandy soils and clay soils, is shown to be affected by salts in Spizizen nutrient medium, by addition of Pseudomonas organisms recovered from soil contaminated with DNT, and by addition of prairie silt loam to contaminated soils (80:20 ratio). 110 kilogram batches of soil were used per treatment. Addition of Spizizen medium to the aged clay soil, containing plasticized propellant, initially resulted in a marked increase in the DNT that was extracted by methylene chloride. DNT in contaminated sandy soils was rapidly degraded when Pseudomonas and Spizizen medium were added (85% degraded in 20 days). Pseudomonas isolated from DNT contaminated soils have particular utility for the in situ degradation of 2,4 DNT in clay and sandy soils because they metabolize Spizizen medium, thrive in diverse climates, and have been selected for their ability to grow in soils contaminated with DNT. The loam retained water throughout the mixture and precluded clumping of the clay soil. We propose that citrate in Spizizen medium chelates metals in aggregates of humin in aged clay soils, thereby releasing propellant components. The estimated cost of remediation, using this process is $95 per ton of contaminated soil when remediating 10,000 tons or more.