Biodegradation of 1,4-dioxane in planted and unplanted soil: Effect of bioaugmentation with Amycolata sp CB1190

1,4-dioxane is one of the most recalcitrant and toxic contaminants in the s ubsurface. This study investigated the potential to enhance dioxane biodegr adation in both planted and implanted soil. by adding the dioxane-degrading actinomycete, Amycolata sp. CB 1190. Dioxane was not removed within 120 da ys in sterile controls or in viable microcosms not amended with CB 1190, Po plar root extract (40 mg/L as COD) stimulated dioxane degradation in bioaug mented soil, and 100 mg/L dioxane were removed within 45 days. Other co-sub strates that enhanced dioxane degradation by CB1190 include tetrahydrofuran (THF) and 1-butanol. while glucose and soil extract did not affect dioxane degradation. The stimulatory effect of THF was partly due to enhanced enzy me induction. while that of root extract and 1-butanol was attributed to ad ditional growth of CB 1190. In another experiment with dioxane added at 10 mg/kg-soil, reactors planted with hybrid poplar trees removed (by evapotran spiration and biodegradation in the root zone) more dioxane within 26 days than unplanted reactors. regardless of whether CB1190 was added. Neverthele ss, CB1190 enhanced mineralization of [C-14]-dioxane in all experiments, Th is enhancement was more pronounced in unplanted soil because plant uptake r educed the availability of dioxane for microbial degradation. These results suggest that bioaugmented phytoremediation is an attractive alternative to remove dioxane from shallow contaminated sites. (C) 2001 Elsevier Science Ltd. All rights reserved.