Bio-beads With Immobilized Anaerobic Bacteria, Zero-valent Iron,and Active Carbon For The Removal Of Trichloroethane From Groundwater

Chlorinated hydrocarbons are the most common organic pollutants in groundwater systems worldwide. In this study, we developed bio-beads with immobilized anaerobic bacteria, zero-valent iron (ZVI), and activated carbon (AC) powder and evaluated their efficacy in removing1,1,1-trichloroethane (TCA) from groundwater. Bio-beads were produced by polyvinyl alcohol (PVA), alginate, and AC powder. We found that the concentration of AC powder used significantly affected the mechanical properties of immobilized bio-beads and that1.0%(w/v) was the optimal concentration. The bio-beads effectively degraded TCA (160mg/L) in the anaerobic medium, and could be reused up to6times. The TCA degradation rate of bio-beads was1.5and2.3times greater, respectively, than ZVI or anaerobic sludge alone. Measuring FeS produced by microbial reactions indicated that TCA removal occurred via FeS-catalyzed dechlorination. Analysis of clonal libraries derived from bio-beads demonstrated that the dominant species in the community were Betaproteobacteria and Gammaproteobacteria, which may contribute to the long-term stability of ZVI reactivity during TCA dechlorination. This study shows that the combined use of immobilized anaerobic bacteria, ZVI and AC in bio-beads is effective and practical for TCA dechlorination and suggests they may be applicable towards developing a groundwater treatment system for the removal of TCA.