Integrated nano zero valent iron and biosurfactant aided remediation of PCB-contaminated soil

Zhang, He (2015) Integrated nano zero valent iron and biosurfactant aided remediation of PCB-contaminated soil. Masters thesis, Memorial University of Newfoundland.

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Abstract

Polychlorobiphenyls (PCBs) have been identified as environmental hazards for many years. Due to historical issues, a considerable amount of PCBs were released deep underground in Canada. In this research, a nanoscale zero valent iron (nZVI)-aided dechlorination followed by biosurfactant enhanced soil washing method was developed to remove PCBs from soil. During nZVI-aided dechlorination, the effects of nZVI dosage, initial pH level and temperature were evaluated, respectively. The results showed that the nZVI dosage of 7.5 g nZVI/kg led to the maximum PCB dechlorination rate. Adding more nZVI could cause particle aggregation, and thus, lower the PCB dechlorination rate. A pH level of 5 was selected for PCB dechlorination before soil washing. The results also indicated that the temperature changes could positively influence the dechlorination process. In the soil washing process, results showed that the presence of nano iron particles played a key role in PCB removal. The crude biosurfactant was produced using a bacterial stain isolated from the Atlantic Ocean and was applied for soil washing. The soil washing results indicated that a higher concentration of the biosurfactant solution led to an increased solubilization of PCBs. The overall removal rate of PCBs using the biosurfactant solution with a concentration of 0.5% was 80%. The study has led to a promising technology for PCB-contaminated soil remediation.

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