The Bioavailability Of Hydrophobic Organic Pollutants(HOCs) Under The Action Of Surfactants

The removal of hydrophobic organic contaminants in soil and groundwater system of has always been a difficult problem in environmental remediation. The bioavailability of hydrophobic organic pollutants(HOCs) has also been one of the hot topics in the field. Due to the superior properties, the application of surfactant become more and more important in environmental remediation. The surfactant can increase the bioavailability of the pollutants, but the specific action mode is still not clear. In this experiment, the hexadecane was chosen as the original contaminant and the different forms of hexadecane treated by different surfactants were obtained. The P.aeruginosa 9027 was cultured by the different hexadecane, the degradation of hexadecane and cell growth were observed in order to explore bioavailability of the different forms hexadecane.Two common surfactants were chosen for the study: the anionic surfactant SDBS and nonionic surfactant Triton X-100. For the hexadecane treated by SDBS, the bioavailability of pseudo-solubilized hexadecane is reduced; when hexadecane with a quantity significantly higher than the pseudo-solubility was used as the carbon source in presence of SDBS, the degradation was also delayed in a certain degree. For the hexadecane treated by Triton X-100, the bioavailability of pseudo-solubilized hexadecane is also reduced, but when hexadecane with a quantity significantly higher than the pseudo-solubility was used as the carbon source in presence of Triton X-100,the bioavailability of hexadecane has a certain degree of improvement. This result is mainly due to the formation of surfactant and hexadecane aggregation, it's hard to destroy the aggregation, the cell could not contact the hexadecane directly caused the decrease of bioavailability. Meanwhile, the Triton X-100 can be degraded by P.aeruginosa ATCC 9027 strain in a degree, but the SDBS can't. Triton X-100 degraded as the preferential carbon source can promote the growth of the strain, it can promote the degradation of hexadecane. Based on the above conclusions, the possibledegradation mechanism was given. And the SEM images were got to verify the accuracy of hypothesis, it gets a very good consistency which proved the correctness of the degradation mechanism. The above conclusion shows that the simple solubilization of contaminants is meaningless in improve the bioavailability of contaminants; the bioavailability depends on the complex system of surfactant,pollutants and water. The emulsion, dispersing, biodegradable of surfactant may have a great impact on the bioavailability of pollutants.