title: Combined nano-biotechnology for in-situ remediation of mixed contamination of groundwater by hexavalent chromium and chlorinated solvents.
abstract: The present report describes a 13month pilot remediation study that consists of a combination of Cr(VI) (4.4 to 57mg/l) geofixation and dechlorination of chlorinated ethenes (400 to 6526μg/l), achieved by the sequential use of nanoscale zerovalent iron (nZVI) particles and in situ biotic reduction supported by whey injection. The remediation process was monitored using numerous techniques, including physical-chemical analyses and molecular biology approaches which enabled both the characterization of the mechanisms involved in pollutant transformation and the description of the overall background processes of the treatment. The results revealed that nZVI was efficient toward Cr(VI) by itself and completely removed it from the groundwater (LOQ 0.05mg/l) and the subsequent application of whey resulted in a high removal of chlorinated ethenes (97 to 99%). The persistence of the reducing conditions, even after the depletion of the organic substrates, indicated a complementarity between nZVI and the whey phases in the combined technology as the subsequent application of whey phase partially assisted the microbial regeneration of the spent nZVI by promoting its reduction into Fe(II), which further supported remediation conditions at the site. Illumina sequencing and the detection of functional vcrA and bvcA genes documented a development in the reducing microbes (iron-reducing, sulfate-reducing and chlororespiring bacteria) that benefited under the conditions of the site and that was probably responsible for the high dechlorination and/or Cr(VI) reduction. The results of this study demonstrate the feasibility and high efficiency of the combined nano-biotechnological approach of nZVI and whey application in-situ for the removal of Cr(VI) and chlorinated ethenes from the groundwater of the contaminated site.
authors: ENACON s.r.o., Krčská 16, CZ-140 00 Prague 4, Czech Republic; Technical University of Liberec, Studentská 2, CZ-461 17 Liberec, Czech Republic.
authors: Jan
authors: J
authors: Němeček
authors: ENACON s.r.o., Krčská 16, CZ-140 00 Prague 4, Czech Republic.
authors: Petr
authors: P
authors: Pokorný
authors: DEKONTA a.s., Volutová 2523, CZ-158 00 Prague 5, Czech Republic; Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801, Prague 2, Czech Republic.
authors: Ondřej
authors: O
authors: Lhotský
authors: DEKONTA a.s., Volutová 2523, CZ-158 00 Prague 5, Czech Republic.
authors: Vladislav
authors: V
authors: Knytl
authors: DEKONTA a.s., Volutová 2523, CZ-158 00 Prague 5, Czech Republic.
authors: Petra
authors: P
authors: Najmanová
authors: Technical University of Liberec, Studentská 2, CZ-461 17 Liberec, Czech Republic.
authors: Jana
authors: J
authors: Steinová
authors: Technical University of Liberec, Studentská 2, CZ-461 17 Liberec, Czech Republic.
authors: Miroslav
authors: M
authors: Černík
authors: Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801, Prague 2, Czech Republic; Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Vídeňská 1083, CZ-142 20 Prague 4, Czech Republic.
authors: Alena
authors: A
authors: Filipová
authors: Regional Centre of Advanced Technologies and Materials, Palacký University in Olomouc, 17. listopadu 1192/12, CZ-771 46 Olomouc, Czech Republic.
authors: Jan
authors: J
authors: Filip
authors: Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801, Prague 2, Czech Republic; Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Vídeňská 1083, CZ-142 20 Prague 4, Czech Republic. Electronic address: cajthaml@biomed.cas.cz.
authors: Tomáš
authors: T
authors: Cajthaml
mesh_terms: D001709:Biotechnology / Q000379:methods*; D017606:Chlorine Compounds / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D060587:Groundwater / Q000737:chemistry; D054879:Halogenation; D007501:Iron / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D012997:Solvents / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D017606:Chlorine Compounds; D012997:Solvents; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D007501:Iron
keywords: Bioreduction; Chlorinated solvents; Co-mingled plume; Dechlorination; Hexavalent chromium; Indigenous microorganisms; NZVI; PLFA