2026-05-25T03:13:53Zhttps://keep.lib.asu.edu/oai/request

oai:keep.lib.asu.edu:node-1570222024-12-20T18:25:12Zoai_pmh:alloai_pmh:repo_items

157022 https://hdl.handle.net/2286/R.I.51797 http://rightsstatements.org/vocab/InC/1.0/ 2018 xi, 64 pages : illustrations (some color) Masters Thesis Academic theses Text eng Luo, Yihao Rittmann, Bruce E. Krajmalnik-Brown, Rosa Zhou, Chen Arizona State University Partial requirement for: M.S., Arizona State University, 2018 Includes bibliographical references (pages 60-64) Field of study: Civil, environmental and sustainable engineering Widespread use of chlorinated solvents for commercial and industrial purposes makes co-occurring contamination by 1,1,1-trichloroethane (TCA), trichloroethene (TCE), and 1,4-dioxane (1,4-D) a serious problem for groundwater. TCE and TCA often are treated by reductive dechlorination, while 1,4-D resists reductive treatment. Aerobic bacteria are able to oxidize 1,4-D, but the biological oxidation of 1,4-D could be inhibited TCA, TCE, and their reductive transformation products. To overcome the challenges from co-occurring contamination, I propose a two-stage synergistic system. First, anaerobic reduction of the chlorinated hydrocarbons takes place in a H2-based hollow-fiber “X-film” (biofilm or catalyst-coated film) reactor (MXfR), where “X-film” can be a “bio-film” (MBfR) or an abiotic “palladium-film” (MPfR). Then, aerobic removal of 1,4-D and other organic compounds takes place in an O2-based MBfR. For the reductive part, I tested reductive bio-dechlorination of TCA and TCE simultaneously in an MBfR. I found that the community of anaerobic bacteria can rapidly reduce TCE to cis-dichloroethene (cis-DCE), but further reductions of cis-DCE to vinyl chloride (VC) and VC to ethene were inhibited by TCA. Also, it took months to grow a strong biofilm that could reduce TCA and TCE. Another problem with reductive dechlorination in the MBfR is that mono-chloroethane (MCA) was not reduced to ethane. In contrast, a film of palladium nano-particles (PdNPs), i.e., an MPfR, could the simultaneous reductions of TCA and TCE to mainly ethane, with only small amounts of intermediates: 1,1-dichloroethane (DCA) (~3% of total influent TCA and TCE) and MCA (~1%) in continuous operation. For aerobic oxidation, I enriched an ethanotrophic culture that could oxidize 1,4-D with ethane as the primary electron donor. An O2-based MBfR, inoculated with the enriched ethanotrophic culture, achieved over 99% 1,4-D removal with ethane as the primary electron donor in continuous operation. Finally, I evaluated two-stage treatment with a H2-based MPfR followed by an O2-MBfR. The two-stage system gave complete removal of TCA, TCE, and 1,4-D in continuous operation. Environmental engineering 1,1,1-TCA 1,4-dioxane Biodegradation Catalytic reduction Groundwater TCE Dechlorination Groundwater--Purification. Water--Purification--Organic compounds removal. Synergistic reductive dechlorination of 1,1,1-trichloroethane and trichloroethene and aerobic degradation of 1,4-dioxane