Title: Impacts of low-temperature thermal treatment on microbial detoxification of tetrachloroethene under continuous flow conditions

Abstract

Coupling in situ thermal treatment (ISTT) with microbial reductive dechlorination (MRD) has the potential to enhance contaminant degradation and reduce cleanup costs compared to conventional standalone remediation technologies. Impacts of low-temperature ISTT on Dehalococcoides mccartyi (Dhc), a relevant species in the anaerobic degradation of cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) to nontoxic ethene, were assessed in sand-packed columns under dynamic flow conditions. Dissolved tetrachloroethene (PCE; 258 ± 46 μM) was introduced to identical columns bioaugmented with the PCE-to-ethene dechlorinating consortium KB-1®. Initial column temperatures represented a typical aquifer (15 °C) or a site undergoing low-temperature ISTT (35 °C), and were subsequently increased to 35 and 74 °C, respectively, to assess temperature impacts on reductive dechlorination activity. In the 15 °C column, PCE was transformed primarily to cis-DCE (159 ± 2 μM), which was further degraded to VC (164 ± 3 μM) and ethene (30 ± 0 μM) within 17 pore volumes (PVs) after the temperature was increased to 35 °C. Regardless of the initial column temperature, ethene constituted >50 mol% of effluent degradation products in both columns after 73–74 PVs at 35 °C, indicating that MRD performance was greatly improved under low-temperature ISTT conditions. Increasing the temperature of the columnmore » initially at 35 °C resulted in continued VC and ethene production until a temperature of approximately 43 °C was reached, at which point Dhc activity substantially decreased. The abundance of the vcrA reductive dehalogenase gene exceeded that of the bvcA gene by 1–2.5 orders of magnitude at 15 °C, but this relationship inversed at temperatures >35 °C, suggesting Dhc strain-specific responses to temperature. These findings demonstrate improved MRD performance with low-temperature thermal treatment and emphasize potential synergistic effects at sites undergoing ISTT.« less

Authors:

Marcet, Tyler F. ^[1]; Cápiro, Natalie L.  ^[1];

• Search DOE PAGES for author "Cápiro, Natalie L."
• Search DOE PAGES for ORCID "0000-0002-8125-1658"

Yang, Yi ^[2]; Löffler, Frank E. ^[3]; Pennell, Kurt D.  ^[4]

• Search DOE PAGES for author "Pennell, Kurt D."
• Search DOE PAGES for ORCID "0000-0002-5788-6397"

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+ Show Author Affiliations

1. Tufts Univ., Medford, MA (United States)
2. Univ. of Tennessee, Knoxville, TN (United States)
3. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
4. Tufts Univ., Medford, MA (United States); Brown Univ., Providence, RI (United States)

Publication Date:

Tue Jul 31 00:00:00 EDT 2018

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1474521

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Water Research

Additional Journal Information:

Journal Volume: 145; Journal Issue: C; Journal ID: ISSN 0043-1354

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING