Abstract
Using surfactant to enhance the biodegradation efficiencies of PAHs in soil is an interesting subject in soil bioremediation. Normally, microorganisms can degrade few rings PAHs in laboratory. But the biodegradation efficiency decreases in the natural environment. Soil environment is a very complex matrix which includes organic matter, heavy metals and bacteria. PAHs that have high hydrophobicity can partition into soil organic matter (SOM) more easily. However, microorganisms can only use soluble compounds as carbon and energy source. So, the biodegradation of PAHs decreases in soil environment due to that PAHs can partition into the SOM in soil. Surfactant can enhance the apparent water solubility of PAHs, especially when the concentration of surfactant exceeds critical micellar concentration (CMC). This property may enhance the bioavailability of PAHs in soil, but the type and concentration of surfactant may also inhibit the activity of microorganisms. This study is focused on the solubilization effect and the influence of surfactants on biodegradation of PAHs. The target compounds in this study were naphthalene, phenanthreneand pyrene. In the solubilization effect experiment, nonionic surfactantshave greater effect on the solubilization of higher hodrophobiccompounds. Anionic surfactant has the inverse effect. Brij 30 has greatersolubilization effect than Triton X-100, Tween 80, SDS and Brij 35. In the biological system, the biodegradation rate of pyrene in Brij 30 higher than in Triton X-100, but need a longer time to complete thereaction. Brij 30 can enhance the mineralization of pyrene in soil, but themicelle of Brij 30 also have higher efficiency than monomer to enhance the biodegradation of pyrene in soil.