Field Evaluation of In Situ Source Reduction of Trichloroethylene in Groundwater Using Bioenhanced In-Well Vapor Stripping

Abstract

Two technologies in combination, cometabolic bioremediation and in-well vapor stripping, were applied to reduce trichloroethylene (TCE) concentrations in groundwater at a contaminant source area without the need to pump contaminated groundwater to the surface for treatment. The vapor-stripping well reduced source TCE concentrations (as high as 6-9 mg/L) by over 95%. Effluent from the well then flowed to two bioremediation wells, where additional reductions of approximately 60% were achieved. TCE removal was extensively monitored (for research and not regulatory purposes) using an automated system that collected samples about every 45 min at 55 locations over an area of approximately 50 x 60 m2. During 4.5 months of system operation, total TCE mass removal was 8.1 kg, 7.1 kg of which resulted from in-well vapor stripping and 1.0 kg from biotreatment. The system reduced the average TCE concentration of about 3000 microg/L in the source-zone groundwater to about 250 microg/L in water leaving the treatment zone, effecting greater than 92% TCE removal. A 6 month rebound study after system operation ceased found TCE concentrations then increased significantly in the treatment zone due to diffusion from the fractured rock below and perhaps other processes, with mass increases of about 1.5 kg in the lower aquifer and 0.3 kg in the upper aquifer.

Biochar supported nanoscale zerovalent iron composite used as persulfate activator for removing trichloroethylene

“…The objectives of the present work are to (1) synthesize and characterize a novel composite (i.e., nZVI/BC), and to verify whether the biochar networks efficiently prevent particle aggregation and create nZVI on carbon surfaces with uniform morphology and homogeneous distribution; (2) evaluate the activation ability of nZVI/BC for persulfate to remove organic contaminant of Trichloroethylene (TCE) in aqueous solutions. TCE was selected as a representative organic contaminant since it has been widely used as a chlorinated solvent and has the potential effects of carcinogenicity, teratogenicity and mutagenicity on humans (Goltz et al, 2005).…”

Bioremediation of Chlorinated Solvent Plumes

“…However, aerobic cometabolism has proven to be difficult, but not impossible, to implement in situ. Despite considerable research, the fieldscale use of this approach has been rare (Hopkins and McCarty, 1995;Goltz et al, 2005;Semprini, 1997;Kim et al, 2006).…”

Aerobic biodegradation of trichloroethylene and phenol co-contaminants in groundwater by a bacterial community using hydrogen peroxide as the sole oxygen source

“…[4][5][6] Groundwater contaminated with TCE has been treated in situ via co-metabolic biodegradation by injecting phenol or toluene. [7] Furthermore, the TCE co-metabolic pathway involving the Lph gene is well established. Lph catalyses the conversion of phenol to catechol and simultaneously co-metabolizes TCE.…”