Co-contaminant effects on 1, 4-dioxane biodegradation in packed soil column flow-through systems. (December 2018) - Zhao, Linduo
Abstract: Biodegradation of 1, 4-dioxane was examined in packed quartz and soil column flow-through systems. The inhibitory effects of co-contaminants, specifically trichloroethene (TCE), 1, 1-dichloroethene (1, 1-DCE), and copper (Cu 2+ ) ions, were investigated in the columns either with or without bioaugmentation with a 1, 4-dioxane degrading bacterium Pseudonocardia dioxanivorans CB1190. Results indicate that CB1190 cells readily grew and colonized in the columns, leading to significant degradation of 1, 4-dioxane under oxic conditions. Degradation of 1, 4-dioxane was also observed in the native soil (without bioaugmentation), which had been previously subjected to enhanced reductive dechlorination treatment for co-contaminants TCE and 1, 1-DCE. Bioaugmentation of the soil with CB1190 resulted in nearly complete degradation at influent concentrations of 3–10 mg L −1 1, 4-dioxane and a residence reaction time of 40–80 h, but the presence of co-contaminants, 1, 1-DCE and Cu 2+ ions (up to 10 mg L −1 ), partially inhibited 1, 4-dioxane degradation in the untreated and bioaugmented soil columns. However, the inhibitory effects were much less severe in the column flow-through systems than those previously observed in planktonic cultures, which showed near complete inhibition at the same co-contaminant concentrations. These observations demonstrate a low susceptibility of soil microbes to the toxicity of 1, 1-DCE and Cu 2+ in packed soil flow-through systems, and thus have important implications for predicting biodegradation potential and developing sustainable, cost-effective technologies for in situ remediation of 1, 4-dioxane contaminated soils and groundwater. Graphical abstract: Image 1 Highlights: Biodegradation of 1, 4-dioxane was examined in packed column flow-through systems. Degradation of 1, 4-dioxane is inhibited by co-contaminants 1, 1-DCE and Cu2+. Inhibitory effects of co-contaminants are much less severe in the column than in planktonic systems. Bioaugmentation with Pseudonocardia dioxanivorans CB1190 is effective in degrading 1, 4-dioxane in the soil column.