Phenanthrene mineralization in soil in the presence of nonionic surfactants

This research addresses the effect of surfactant addition on the microbial degradation of slightly soluble organic compounds in soil. Biodegradation of phenanthrene, coated on sand with a low f(oc), was studied in the presence of nonionic surfactants. Phenanthrene coated sand was designed to simulate soil contaminated with excess phenanthrene which remains after evaporation of the lighter hydrocarbon solvents. A mixed culture acclimated to phenanthrene was used as the inoculum. Four nonionic surfactants were used in this study: Triton X-114, Brij 35, Tween 40 and Corexit 0600. Continuous flow columns were employed to simulate groundwater flow through aquifers. The addition of Corexit 0600 and Tween 40 surfactants enhanced the biodegradation rate of phenanthrene while there was no enhancement by the other two surfactants. No appreciable lag period for mineralization was observed in these experiments. Additional tests are required to assess surfactant bacteria interactions to determine why certain surfactants perform better than others.