Combined abiotic and biotic in-situ reduction of hexavalent chromium in groundwater using nZVI and whey: A remedial pilot test.
The paper describes a pilot remediation test combining two Cr(VI) geofixation methods - chemical reduction by nanoscale zero-valent iron (nZVI) and subsequent biotic reduction supported by whey. Combination of the methods exploited the advantages of both - a rapid decrease in Cr(VI) concentrations by nZVI, which prevented further spreading of the contamination and facilitated subsequent use of the cheaper biological method. Successive application of whey as an organic substrate to promote biotic reduction of Cr(VI) after application of nZVI resulted in a further and long-term decrease in the Cr(VI) contents in the groundwater. The effect of biotic reduction was observed even in a monitoring well located at a distance of 22 m from the substrate injection wells after 10 months. The results indicated a reciprocal effect of both the phases - nZVI oxidized to Fe(III) during the abiotic phase was microbially reduced back to Fe(II) and acted as a reducing agent for Cr(VI) even when the microbial density was already low due to the consumed substrate. Community analysis with pyrosequencing of the 16S rRNA genes further confirmed partial recycling of nZVI in the form of Fe(II), where the results showed that the Cr(VI) reducing process was mediated mainly by iron-reducing and sulfate-reducing bacteria.
ENACON s.r.o., Na holém vrchu 708/3, Prague CZ-14300, Czech Republic; Technical University of Liberec, Studentská 2, CZ-46117 Liberec, Czech Republic.
Jan
J
Němeček
ENACON s.r.o., Na holém vrchu 708/3, Prague CZ-14300, Czech Republic.
Petr
P
Pokorný
Technical University of Liberec, Studentská 2, CZ-46117 Liberec, Czech Republic.
Lenka
L
Lacinová
Technical University of Liberec, Studentská 2, CZ-46117 Liberec, Czech Republic.
Miroslav
M
Černík
Technical University of Liberec, Studentská 2, CZ-46117 Liberec, Czech Republic.
Zuzana
Z
Masopustová
DEKONTA a.s., Volutová 2523, Prague CZ-158 00, Czech Republic; Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801, Prague 2, Czech Republic.
Ondřej
O
Lhotský
Institute of Microbiology AS CR, v.v.i., Vídeňská 1083, CZ-14220, Prague 4, Czech Republic; Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801, Prague 2, Czech Republic.
Alena
A
Filipová
Institute of Microbiology AS CR, v.v.i., Vídeňská 1083, CZ-14220, Prague 4, Czech Republic; Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801, Prague 2, Czech Republic. Electronic address: cajthaml@biomed.cas.cz.
Tomáš
T
Cajthaml
D002857:Chromium / Q000737:chemistry*; D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry*; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000032:analysis; D010865:Pilot Projects; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics; D019163:Reducing Agents / Q000737:chemistry*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D000067796:Whey / Q000737:chemistry*
D005290:Ferric Compounds; D010743:Phospholipids; D012336:RNA, Ribosomal, 16S; D019163:Reducing Agents; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion
Geofixation; Hexavalent chromium; Microbial community; PLFA; nZVI