A Synergistic Platform for Continuous Co-removal of 1,1,1-Trichloroethane, Trichloroethene, and 1,4-Dioxane via Catalytic Dechlorination Followed by Biodegradation

摘要

Groundwater co-contaminated with 1,4-dioxane, 1,1,1-tri- chloroethane (TCA), and trichloroethene (TCE) is among the most urgent environmental concerns of the U.S. Department of Defense (DoD), U.S. Environmental Protection Agency (EPA), and industries related to chlorinated solvents. Inspired by the pressing need to remove all three contaminants at rhany sites, we tested a synergistic platform: catalytic reduction of 1,1,1-TCA and TCE to ethane in a H_2-based membrane palladium-film reactor (H_2-MPfR), followed by aerobic biodegradation of ethane and 1,4-dioxane in an O_2-based membrane biofilm reactor (O_2- MBfR). During 130 days of continuous operation, 1,1,1-TCA and TCE were 95-98% reductively dechlorinated to ethane in the H_2-MPfR, and ethane served as the endogenous primary electron donor for promoting 98.5% aerobic biodegradation of 1,4-dioxane in the O_2-MBfR. In addition, the small concentrations of the chlorinated intermediate from the H_2-MPfR, dichloroethane (DCA) and monochloroethane (MCA), were fully biodegraded through aerobic biodegradation in the O_2-MBfR. The biofilms in the O_2- MBfR were enriched in phylotypes closely related to the genera Pseudonocardia known to biodegrade 1,4-dioxane.