Enhanced bioremediation of trichloroethene contaminated by a biobarrier system

The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to develop a barrier system, which includes a peat (used as the primary substrates) layer to enhance the aerobic cometabolism of TCE in situ. A laboratory-scale column experiment was conducted to evaluate the feasibility of using this peat biobarrier to remediate aquifers contaminated by TCE. This system was performed using a series of continuous-flow glass columns including a soil column, a peat column, followed by two consecutive soil columns. Activated sludges were inoculated in all three soil columns to provide microbial consortia for TCE cometabolism. Simulated TCE contaminated groundwater with a flow rate of 0.25 L/day was pumped into the system. Effluent samples from each column were analyzed for TCE and its degradation byproducts [cis-dichloroethylene (cis-DCE) and vinyl chloride (VC)]. Average removal efficiency was 96% for TCE over a 60-day operating period. Accumulation of VC was observed due to the depletion of oxygen in the system. Results from this laboratory study reveal that the developed biobarrier treatment scheme would be expected to provide a more cost-effective alternative to remediate chlorinated-solvent contaminated aquifers.