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 removing 1,1,1-trichloroethane (TCA) from groundwater. Bio-beads were produced by polyvinyl alcohol, alginate, and AC powder. We found that the concentration of AC powder used significantly affected the mechanical properties of immobilized bio-beads and that 1.0 % (w/v) was the optimal concentration. The bio-beads effectively degraded TCA (160 mg L−1) in the anaerobic medium and could be reused up to six times. The TCA degradation rate of bio-beads was 1.5 and 2.3 times greater, respectively, than ZVI + AC treatment or microbes + AC treatment. 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.
Bibliographical noteFunding Information:
Acknowledgments This work was supported jointly by funding from the National Natural Science Foundation of China (41003031, 41273109, 51378208), the Program for New Century Excellent Talents in University (NCET-13-0797), the Shanghai Rising-Star Program (12QA1400800), the Specialized Research Fund for the Doctoral Program of Higher Education (20110074130002), the Innovation Program of Shanghai Municipal Education Commission (14ZZ059), the Fundamental Research Funds for the Central Universities (WB1314002, 222201313008), and the Key Science Foundation of Shanghai Environmental Protection Bureau (Huhuanke2012-07). We also would like to thank the anonymous referees for their helpful comments on this paper.
- Anaerobic bacteria
- Zero-valent iron