Removal of Gaseous Trichloroethylene and Tetrachloroethylene by an Activated Carbon Biofilter

Kim, Jong O

Environmental Engineering Research 1997;2(1): 9-19.

Jong O Kim^†

Department of Civil Engineering, University of Missouri-Rolla, Rolla, MO 65401, USA

Corresponding Author: Jong O Kim ,

Received: August 14, 1996; Accepted: December 14, 1996.

ABSTRACT

Gaseous trichloroethylene (TCE) and tetrachloroethylene (PCE) are emitted in the treatment of contaminated groundwaters with air stripping and/or the remediation of contaminated soils using vapor extraction techniques. This study investigated the application of biofiltration using cometabolic process to remediate gaseous TCE and PCE that are highly recalcitrant to biodegradation. The investigation was conducted using two specially built stainless steel columns, one for TCE and the other for PCE, packed with granular activated carbon (GAC) coated with phenol-oxidizing microorganisms at gas loading rates of 56-260 mL/m²-min. Two activated carbon biofilters were fed with phenol at a specific concentration along with a nutrient solution to optimize the various catalyzed biochemical reactions. The removal efficiency of gaseous TCE was 100% at a gas loading rate of 56 mL/m²-min and average inlet concentration of 85 ppm. For gaseous PCE, 100% removal efficiency was obtained at gas loading rates of 56-202 mL/m²-min and average concentrations of 47-84 ppm. It was found that phenol fed to the biofilters was completely utilized by the phenol-oxidizing microorganisms, as an indirect indicator of the microorganisms growth in the biofilters, throughout the period of the biofilter operation. Transformation yields of gaseous TCE and PCE were about 8-48 g of TCE/g of phenol and 6-25 g of PCE/g of phenol, depending on different residence times. It was found that adsorption by GAC and absorption by the influent nutrient solution were a minor or negligible mechanism for TCE and PCE removal in the activated carbon biofilters.

Keywords: Biofilter | Cometabolism | Trichloroethylene (TCE) | Tetrachloroethylene (PCE) | Phenol-oxidizing microorganisms