Assessing a Large-Scale Sequential In Situ Chloroethene Bioremediation System Using Compound-Specific Isotope Analysis (CSIA) and Geochemical Modeling

Compound-specific isotopic analysis (CSIA) and geochemical modeling were applied to evaluate the effectiveness of an 800 m-long sequential in situ bioremediation (ISB) system Northern Italy. The was created for clean-up a polluted aquifer affected by chloroethenes. A hydraulically upgradient anaerobic (AN)-biobarrier-stimulated reductive dichlorination (RD) higher chloroethenes (PCE, TCE) downgradient aerobic (AE)-biobarrier-stimulated oxidation (OX) lower (DCE, VC) proposed. Carbon CSIA concentration data collected PCE, TCE, cis-DCE VC interpreted using reactive transport model that able simulate fractionation. suggested combination critical efficiency ISBs remediation It found ISB could reduce TCE concentrations >99% >84% along flow path. First-order RD degradation rate constants (kRD) increased 30 times (from kRD = 0.2–0.3 y−1 up 6.5 y−1) AN barrier. For VC, AE barrier had fundamental role enhance OX. OX (kOX) ranged between kOX 0.7–155 1.7–12.6 VC.