Full-scale stimulation of reductive dechlorination using the Liner® technique

Following the results of an earlier pilot study, a full-scale remediation project was undertaken at an operational factory in the Dutch town of Zwolle over a 59 week period between August 2002 and September 2003. Contamination from chlorinated aliphatic hydrocarbons (CAHs) in the source zone was treated using a novel gas injection and nebuliser system called LINER. Ethyl lactate was selected as a carbon substrate to stimulate in situ bioremediation. It was atomised and injected at a rate of 500 ml/day over a 3 min duration from 6 no injection wells with a total of 12 no injection filters at 24–25 and 44–45 m depth. The performance of the remediation technique was observed using an array of groundwater monitoring wells. The results are variable with biodegradation to ethene proceeding well at depths of 14–15 and 44–45 m depth. Limitations in biodegradation were attributed to the variations in stratigraphy and limited zone of influence near the injection points.