title: Application of a long-lasting colloidal substrate with pH and hydrogen sulfide control capabilities to remediate TCE-contaminated groundwater.
abstract: A long-lasting emulsified colloidal substrate (LECS) was developed for continuous carbon and nanoscale zero-valent iron (nZVI) release to remediate trichloroethylene (TCE)-contaminated groundwater under reductive dechlorinating conditions. The developed LECS contained nZVI, vegetable oil, surfactants (Simple Green™ and lecithin), molasses, lactate, and minerals. An emulsification study was performed to evaluate the globule droplet size and stability of LECS. The results show that a stable oil-in-water emulsion with uniformly small droplets (0.7 μm) was produced, which could continuously release the primary substrates. The emulsified solution could serve as the dispensing agent, and nZVI particles (with diameter 100-200 nm) were distributed in the emulsion evenly without aggregation. Microcosm results showed that the LECS caused a rapid increase in the total organic carbon concentration (up to 488 mg/L), and reductive dechlorination of TCE was significantly enhanced. Up to 99% of TCE (with initial concentration of 7.4 mg/L) was removed after 130 days of operation. Acidification was prevented by the production of hydroxide ion by the oxidation of nZVI. The formation of iron sulfide reduced the odor from produced hydrogen sulfide. Microbial analyses reveal that dechlorinating bacteria existed in soils, which might contribute to TCE dechlorination.
authors.affiliation: Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan.
authors.forename: Y T
authors.initials: YT
authors.lastname: Sheu
authors.affiliation: Department of Life Sciences, National Central University, Chung-Li, Taiwan.
authors.forename: S C
authors.initials: SC
authors.lastname: Chen
authors.affiliation: Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Chung-Li, Taiwan.
authors.forename: C C
authors.initials: CC
authors.lastname: Chien
authors.affiliation: Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan.
authors.forename: C C
authors.initials: CC
authors.lastname: Chen
authors.affiliation: Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan. Electronic address: jkao@mail.nsysu.edu.tw.
authors.forename: C M
authors.initials: CM
authors.lastname: Kao
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D002244:Carbon / Q000737:chemistry; D003102:Colloids / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D004655:Emulsions; D060587:Groundwater; D006859:Hydrogen / Q000032:analysis; D006862:Hydrogen Sulfide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D007477:Ions; D019344:Lactic Acid / Q000737:chemistry; D008903:Minerals / Q000737:chemistry; D008956:Models, Chemical; D008965:Molasses; D010938:Plant Oils / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: D003102:Colloids; D004655:Emulsions; D006878:Hydroxides; D007477:Ions; D008903:Minerals; D010938:Plant Oils; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; D019344:Lactic Acid; D002244:Carbon; D006859:Hydrogen; D004247:DNA; D006862:Hydrogen Sulfide
keywords: Groundwater contamination; Long-lasting emulsified colloidal substrate (LECS); Nanoscale zero-valent iron (nZVI); Trichloroethylene (TCE)