1,4-Dioxane Biodegradation Using Bioaugmented Granular Activated Carbon
1,4-Dioxane is a probable human carcinogen that has been emerging in water resources in the US and internationally. Many traditional treatment technologies are ineffective for 1,4-dioxane, while others are costly and energy intensive. Biodegradation is a low cost, environmentally-friendly 1,4-dioxane treatment method. Pseudonocardia dioxanivorans CB1190 (CB1190) and Mycobacterium austroafricanum JOB5 (JOB5), 1,4-dioxane metabolizing and co-metabolizing bacteria, respectively, are primarily studied in planktonic cultures, while most environmental microbes grow as biofilms. This study investigated 1,4-dioxane biodegradation by CB1190- and JOB5-attached commercial sorbents. In abiotic controls, selected sorbents displayed Freundlich isotherm behavior. Norit 1240 and Ambersorb 560 demonstrated high 1,4-dioxane affinity and were used in CB1190- and JOB5-bioaugmented sorbent bioreactors. Abiotic Norit 1240 reactors reduced aqueous concentrations by 85-89%, whereas JOB5 and CB1190 bioreactors reduced concentrations to below 95% and 98%, respectively. Bacterial growth and attachment was visualized using fluorescence microscopy and confirmed by amplification of taxonomic genes by quantitative polymerase chain reaction (qPCR) and an ATP assay. Filtered industrial wastewater and contaminated groundwater samples were tested in bioreactors to ensure effectiveness for nutrient-poor environmental waters. Both CB1190 and JOB5 bioreactors demonstrated greater removal than abiotic sorbent controls. This study suggested bioaugmented sorbents could be an effective and novel 1,4-dioxane treatment technology.