Scale-up of bioaugmentation for aerobic metabolic trichloroethene degradation in flow-through systems

Chloroethenes are ubiquitous groundwater contaminants. The aerobic metabolic degradation of TCE leads to the complete oxidative dechlorination of the contaminant without stable intermediates. This study investigates the robustness of the aerobic metabolic TCE degradation and demonstrates the scalability, suitability, as well as the resilience of bioaugmentation with an aerobic metabolic TCE degrading culture. Bioaugmentation with the bacterial culture on a carrier material, similar to a permeable reactive barrier, resulted in faster process establishment in comparison to the injection of a bacterial culture, kept in mineral medium, into the silica sand columns. The established microbiota achieved degradation rates of up to 5 mg TCE /L/d in the columns (volume 10 L) and 6.75 mg TCE /L/d over the complete width of the larger scale box (volume 400 L), with the latter being limited by the available TCE quantity. Additionally, a lateral expansion rate of the TCE degradation of 0.95 cm/day was determined in the box experiment. Taxonomic and functional marker analysis showed similar ratios between bacterial and functional gene biomarkers to previous studies. Short periods with a lack of oxygen (28 days) and slightly alkaline conditions (pH > 8, ∼50 days) halted the TCE degradation but did not impair the long-term performance of the bioaugmented cultures, highlighting its resilience for field applications. These results help bridge the gap between laboratory research and field application of aerobic TCE bioremediation.