Trichloroethylene (TCE), a common groundwater contaminant, moves to unsaturated zone because of high density of the compounds. Distribution of TCE in porous media is complicate and it makes pool upper a less permeable layer. Furthermore, since TCE from the pool is slowly released into groundwater, i...
Trichloroethylene (TCE), a common groundwater contaminant, moves to unsaturated zone because of high density of the compounds. Distribution of TCE in porous media is complicate and it makes pool upper a less permeable layer. Furthermore, since TCE from the pool is slowly released into groundwater, it can be persistent source zone.
Physical and chemical remediation processes have been applied to remove the contaminant, but new remediation technology was required to overcome a low efficiency of the traditional treatment processes. Since dehalococcoides spp. that can completely dechlorinate TCE into ethylene (ETH) was isolated, biological remediation of TCE has been noticed. There are two different types (i.e., bioremediation injecting an effective substrate into an aquifer and bioaugmentation) of biological remediation process.
In this work, we focused on bioremediation by injecting formate as a substrate TCE degradation by indigenous microorganism lived in TCE contaminated soil. To keep anaerobic microorganism, field soil sampled anaerobically was packed into a column (6 cm x 30 cm) inside anaerobic glove box.
Transport test was performed to evaluate adsorption of both TCE and formate. In the result, breakthrough curve of formate was similar with that bromide, but TCE showed retardation (Retardation factor=1.3). After transport test, we continuously added formate with media of dehalococcoides spp. into the column to stimulate hydrogen production fermentation and anaerobic dechlorination. After 2 weeks of addition of formate, formate degradation, hydrogen production, and TCE degradation to c-DCE were observed. To confirm whether TCE degradation occurred by biological process, we monitored reductases (pceA, tceA, bvcA, vcrA) and tecA was detected in the column effluent. These results suggest that formate addition stimulate anaerobic microbes being capable of degrading TCE to c-DCE not to vinyl chloride or ETH.
Based on electron balance, we confirmed that the electron donors injected by formate were used for TCE dechlorination (0.97%), acetate production(56%), biomass synthesis (43%). Consequently, anaerobic respirators degrading TCE to ETH might not reside in the TCE contaminated aquifer, so bioaugmentation process may need to be considered as an alternative remediation method.
Trichloroethylene (TCE), a common groundwater contaminant, moves to unsaturated zone because of high density of the compounds. Distribution of TCE in porous media is complicate and it makes pool upper a less permeable layer. Furthermore, since TCE from the pool is slowly released into groundwater, it can be persistent source zone.
Physical and chemical remediation processes have been applied to remove the contaminant, but new remediation technology was required to overcome a low efficiency of the traditional treatment processes. Since dehalococcoides spp. that can completely dechlorinate TCE into ethylene (ETH) was isolated, biological remediation of TCE has been noticed. There are two different types (i.e., bioremediation injecting an effective substrate into an aquifer and bioaugmentation) of biological remediation process.
In this work, we focused on bioremediation by injecting formate as a substrate TCE degradation by indigenous microorganism lived in TCE contaminated soil. To keep anaerobic microorganism, field soil sampled anaerobically was packed into a column (6 cm x 30 cm) inside anaerobic glove box.
Transport test was performed to evaluate adsorption of both TCE and formate. In the result, breakthrough curve of formate was similar with that bromide, but TCE showed retardation (Retardation factor=1.3). After transport test, we continuously added formate with media of dehalococcoides spp. into the column to stimulate hydrogen production fermentation and anaerobic dechlorination. After 2 weeks of addition of formate, formate degradation, hydrogen production, and TCE degradation to c-DCE were observed. To confirm whether TCE degradation occurred by biological process, we monitored reductases (pceA, tceA, bvcA, vcrA) and tecA was detected in the column effluent. These results suggest that formate addition stimulate anaerobic microbes being capable of degrading TCE to c-DCE not to vinyl chloride or ETH.
Based on electron balance, we confirmed that the electron donors injected by formate were used for TCE dechlorination (0.97%), acetate production(56%), biomass synthesis (43%). Consequently, anaerobic respirators degrading TCE to ETH might not reside in the TCE contaminated aquifer, so bioaugmentation process may need to be considered as an alternative remediation method.
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