The Remediation Technology Summit

February 26-28, 2019

Colorado Convention Center
Denver, CO

NatalieCapiroNatalie L. Capiro
Research Assistant Professor, Deparment of Civil and Environmental Engineering
Tufts University

Dr. Natalie Cápiro is a Research Assistant Professor in the Department of Civil and Environmental Engineering at Tufts University. Prior to coming to Tufts, Dr. Cápiro completed her postdoctoral studies at the Georgia Institute of Technology, M.S. and Ph.D. in Civil and Environmental Engineering at Rice University, and B.S. in Biological and Environmental Engineering at Cornell University. She was a recipient of the National Science Foundation (NSF) Distinguished Science and Engineering Fellowship from the Alliances for Graduate Education and the Professoriate program during her graduate studies. Dr. Cápiro’s research interests include applied environmental biotechnology, fate and transport of traditional and emerging contaminants in natural systems, development of innovative in situ remediation technologies, characterization of pathogenic bacteria and water quality in developing countries, and nanotechnology-biological interactions in the environment. Her work is supported by funding from the National Science Foundation and the Strategic Environmental Research and Development Program (SERDP), including a study that won the 2012 SERDP Environmental Restoration Project of the Year.

PLATFORM PRESENTER – Biological Treatment: Strength in Small Packages

Benefits and Constraints of Low-Temperature Thermal Treatment for Enhanced Microbial Reductive Dechlorination

Parallel 1-D column (15 cm l × 2.5 cm ID; pore volume (PV) = 30 mL) experiments were completed to determine the impacts of low-temperature heating on the growth and dechlorination activity of organohalide-respiring bacteria under continuous flow conditions. Initially, Column A was cooled to 15 °C to represent in situ groundwater temperatures, while column B was heated to 35 °C to represent low-temperature thermal treatment conditions. Tetrachloroethene (PCE; 283±33 µM) and lactate (5 mM) were introduced continuously at a pore water velocity of 15 cm/day to each of two columns packed with Federal Fine Ottawa sand (30 – 140 mesh) and bioaugmented with the PCE-to-ethene dechlorinating KB-1 ® consortium. Column temperatures were adjusted in four phases to assess: I) dechlorinating bacteria performance at ambient versus elevated groundwater temperature; II) dechlorinating bacteria performance in a system raised from ambient to elevated groundwater temperature; III) the maximum temperature permissive of Dehalococcoides mccartyi (Dhc) dechlorination activity; and IV) the maximum temperature permissive of any microbial reductive dechlorination activity. During Phase I, the Column A effluent contained 94±14 µM cis-1,2-dichloroethene (cis-DCE), 43±7 µM vinyl chloride (VC), and 19±2 µM ethene. In contrast, Column B demonstrated more Dhc activity during the same period, with no detectable cis-DCE, 156±20 µM VC, and 45±6 µM ethene in the effluent. During Phase II, an increase in the temperature of Column A from 15 to 35 °C (+2 °C/PV) triggered complete cis-DCE dechlorination to VC within 20 PV. Ethene concentrations initially remained relatively stable following the temperature increase, suggesting a lag in the activity of the Dhc strains responsible for the final VC-to-ethene dechlorination step. After 60 PVs of heating, ethene formation rapidly increased and coincided with an increase of up to three orders-of-magnitude in abundance of Dhc VC reductive dehalogenase (RDase) genes. During Phase III, the temperature of Column B was gradually raised to 43 °C, after which VC became undetectable in the effluent and the ethene decreased by more than an order of magnitude, suggesting that Dhc activity was reduced or eliminated at this temperature. During phase IV, Column B was gradually increased to 74 °C, at which point low concentrations of PCE (< 5 µM) were detectable in the effluent, indicating that higher temperature also impacted PCE-to-cis-DCE dechlorinating bacteria.