Novel microbial biocatalyst composites for bioremediation of multiple chlorinated hydrocarbons in groundwater

Chlorinated hydrocarbons (CHCs) are a class of persistent environmental pollutants which threaten human health. Certain naturally occurring microorganisms can degrade individual CHCs, however, simultaneous biodegradation of multiple CHCs remains a technical challenge for ex situ bioremediation technologies, especially when polychlorinated CHCs are present. Cometabolic biotransformation of both mono- and polychlorinated CHCs by novel biocatalyst composites harnessing single strain microorganism was demonstrated for two sites requiring ex situ bioremediation of groundwater. Batch testing with propane-induced biocatalyst revealed rapid degradation of several CHCs, including 1,2,3-trichloropropane (TCP) to low parts per billion levels. Continuous-flow treatment of synthetic groundwater containing nine CHCs revealed biocatalyst consistently degraded trichloroethene, tetrachloroethene and 1,1,2,2-tetrachloroethane to below the target 50 μg/L concentration, along with equimolar chloride formation (within 10% of theoretical stoichiometric yield). These results highlight the efficacy of a novel biocatalyst process utilizing a single strain of microorganism for aerobic ex situ bioremediation of mono- and polychlorinated CHCs including TCP.