Title

COMBINED ANAEROBIC/AEROBIC BIOSTIMULATION FOR REMEDIATION OF RAIL YARDS CONTAMINATED BY DIESEL ENGINE REPAIR AND MAINTENANCE

Authors

P J. Hirl

Document Type

Journal Article

Publication Date

1998

Subject Area

infrastructure - vehicle, mode - rail

Keywords

Vehicle maintenance, Soils, Soil remediation, Site remediation, Railroad yards, Microbial degradation, Leakage, Laboratory tests, Groundwater, GROUND WATER, Fuel tanks, Fuel spills, Diesel fuels, Diesel engines, Diesel engine maintenance, Decay, Contamination, Contaminants, Chlorinated ethylenes, Chemical spills, Bioremediation, Biodeterioration, Biodegradation, Bacterial degradation

Abstract

Perchloroethylene (PCE) and trichloroethylene (TCE) have been commonly used in the repair and maintenance of diesel engine locomotives. Improper handling, storage, and disposal lead to contamination of rail yard soils and groundwater with chlorinated ethylenes. Benzene, toluene, ethyl-benzene, and xylene (BTEX) are also common contaminants at rail yards because of the leakage of diesel fuel storage tanks and spills of diesel fuel. Co-contamination of groundwater with BTEX and chlorinated ethylenes allows for the application of anaerobic/aerobic bioremediation to achieve mineralization of both types of compounds. Bench scale laboratory experiments were run to select and enrich for an undefined, mixed, microbial consortium able to mediate PCE dechlorination to dichloroethylene (DCE), mineralization of the DCE, and mineralization of aromatic compounds. A periodically operated suspended culture reactor created alternating anaerobic/aerobic environments. When glucose was added to the reactor as the sole electron donor, the mixed culture dechlorinated PCE to cis-1,2-dichloroethylene (cDCE) in 24 hr. When phenol and glucose were added to the reactor, the mixed culture dechlorinated PCE to cDCE, metabolized the influent phenol, and oxidized 90% of the cDCE produced in 24 hr. Because both phenol and toluene can induce the enzymes necessary for mineralization of TCE and DCE, an anaerobic/aerobic bioremediation approach has potential application for remediation of groundwater at rail yards co-contaminated with diesel fuel and chlorinated ethylenes.