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A study was conducted to determine whether a non-ionic surfactant (Novel II 1412-56) added to the surface of Lima silt loam would enhance the biodegradation of phenanthrene and biphenyl present within the soil. Water containing the surfactant at concentrations of 10 and 100 gg/ml was pumped through the soil. At 10 gg/ml, Novel II 1412-56 markedly enhanced the rate and extent of phenanthrene mineralization and the extent but not the initial rate of biphenyl mineralization. The stimulation was less if the water added to the soil surface contained 100 ~g surfactant/ml. Addition of the surfactant at the two concentrations did not result in leaching of either phenanthrene or biphenyl, but products of the degradation were found in the soil leachate with or without the surfactant. We suggest that surfactants at low concentrations may be useful for in-situ bioremediation of sites contaminated with hydrophobic pollutants without causing movement of the parent compounds to ground-waters.

A study was conducted of the effect of two nonionic surfactants on the biodegradation of phenanthrene and biphenyl sorbed to aquifer material and soil. Alfonic 810–60 and Novel II 1412–56 at 10 and 100 μg/ml enhanced the extent of desorption of phenanthrene and biphenyl from aquifer solids, but concentrations of 1 μg/ml or lower were ineffective. The surfactants at 10 and 100 μg/g of aquifer solids enhanced the mineralization of phenanthrene sorbed to the solids, but the extent of mineralization was low. The addition of N and P to aquifer solids with the surfactants did not stimulate the biodegradation. Inoculation of aquifer solids with phenanthrene‐ or biphenyl‐utilizing microorganisms stimulated the rate and extent of mineralization of the two compounds, and the rate was further increased by either surfactant. The rate and extent of phenanthrene and biphenyl mineralization in soil slurries was increased by either surfactant at 10 or 100 μg/g of soil. We suggest that surfactants at low concentrations may be useful for the bioremediation of sites contaminated with sorbed aromatic hydrocarbons.

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