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THERMALLY ENHANCED IN SITU BIOREMEDIATION OF GROUNDWATER CONTAMINATED WITH CHLORINATED SOLVENTS: A FIELD TEST
Nemecek, J., J. Steinova, T. Pluhar, P. Najmanova, V. Knytl, K. Nesetril, and M. Cernik.
RemTech Europe 2017: European Conference on Remediation Market and Technologies, 20-22 September, Ferrara, Italy. 22 slides, 2017

A thermally enhanced in situ bioremediation technology was tested at a pilot site where the total concentration of chlorinated ethenes (CVOCs) ranged from 249 to 14,539 µg/L. The aquifer at the site is situated in shallow sandy saprolite underlain by irregularly fractured granite. A groundwater circulation system comprising pumping and injection wells was designed using mathematical modeling of heat transfer. Extracted water was heated to 35-45°C with solar and electric heaters and then injected back into the aquifer with the aim of maintaining an aquifer temperature around 20-25°C (the optimal range found in lab tests for reductive dechlorination by the site's indigenous dechlorinating microorganisms). Whey was injected in three batches into the injection well. The test was monitored using hydrochemical and molecular biological tools. Adding substrate and increasing the temperature resulted in a rapid increase in total biomass, sulfate-reducing bacteria, and reductive dechlorinators (especially Dehalococcoides sp. and VC reductase genes vcrA and bvcA), along with a marked increase in CVOC dechlorination. After one month, total CVOC concentration fell by 54-94% in effectively influenced wells. At the same time, chlorine number (average number of chlorine atoms per ethene in the groundwater sample) declined from an initial 1.1-1.6 to 0.1-0.8, indicating the occurrence of significant reductive dechlorination. In a reference well where reductive dechlorination was enhanced with substrate only, the degradation process was much slower. Slides: http://2017.remtechexpo.com/images/2017_presentazioni/PRESENTAZIONI_REMTECHEUROPE_2017/RemTech%20Europe_Nemecek.pdf



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