J.W.C. Wong, Z.Y. Zhao, J. Yang, and S.Y. Wong (PRC)
Biodegradation, microemulsions, PAHs, solubility, andsurfactant
A pilot batch study was performed to investigate the feasibility of using microemulsions to enhance the biodegradation of polycyclic aromatic hydrocarbons (PAHs). Oil in water (O/W) microemulsions composed of Tween-80, 1-pentanol and linseed oil significantly enhanced the apparent solubility of phenanthrene (PHE) up to 110.5 mg L-1 as compared to treatment with Tween 80 alone due to the additional solubilization of PHE in the oil phase of microemulsions, Batch incubation experiment showed that biodegradation of PHE by Bacillus subtilis B-UM in aqueous system was inhibited in the presence of Tween-80 while microemulsion composed of 0.4% Tween-80, 0.1% 1-pentanol and 0.05% linseed oil significantly enhanced its biodegradation up to 46.7% in 18 days. Natural composting of PAH contaminated soil on the other hand could remove 47.6% and 14.6% of PHE and benzo(a)pyrene (B[a]P) respectively while inoculation of B-UM together with the addition of Tween 80 increased the removal of B[a]P to 42.2%. The combined addition of microemulsion and inoculation of B-UM significantly increased the biodegradation of B[a]P and PHE with 63.6% and almost 100%, respectively. The results affirm that microemulsion is more effective than surfactants in facilitating the biodegradation of PAHs under thermophilic composting condition which provides a potential novel approach to remediate soil contaminated with PAHs.
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