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Green and sustainable remediation of a TCE contaminated site: A case study in Kaohsiung.

A TCE contaminated site located in Daliao district, Kaohsiung was identified in early 2001. Different remediation strategies were implemented since 2003, including in-situ chemical oxidation (ISCO), hydraulic control and enhanced in-situ bioremediation (EIB). After site investigation and pilot test, ISCO was chosen as major remedy for groundwater remediation during 2003~2005. However, TCE concentration rebounded within half year when stopping KMnO4 injection. Therefore, hydraulic control and EIB were applied in this site since 2009. Two hydraulic control wells were installed on the edge of the site to prevent the downstream TCE contamination and to treat TCE in the meantime. After one year pilot test and monitoring, anaerobic dechlorination was observed on pilot area which indicates the potential of EIB. In this study, 3 substrates─Molasses, Sorbitol (Panasonic) and emulsified oil (SetDSEMO) were applied for different tiers. TCE concentration decreased gradually since the application of hydraulic control and EIB, and TCE was biodegraded to Cis-1,2-DCE, VC and end product─ethene. The latest data indicates the TCE concentration is lower than the groundwater control standard in Sep. 2017. Besides, the pollution volume was reduced from 700 to 0 m3 within 2 years. It shows application of hydraulic control and EIB is a effective remediation method in this TCE contaminated site. To promote green and sustainable remediation, environmental footprint was evaluated in this study. A solar energy equipment as auxiliary power supplier electric energy for hydraulic control system could reduce 3,496 kg CO2 emission during 2014~2017, and it could decrease about 30% electricity. Furthermore, the results of CO2 emission of different remediation strategies indicates that the relative CO2 emission of hydraulic control and EIB is lower than hydraulic control and ISCO. It means the remediation strategy of this site is relatively environmental friendly.
trichloroethene, enhanced in-situ bioremediation, hydraulic control, green and sustainable remediation