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Reductive precipitation and removal of Cr(VI) from groundwaters by pipe flocculation-microfiltration
Publikationstyp
Journal Article
Publikationsdatum
2018-05
Sprache
English
TORE-URI
Enthalten in
Volume
25
Issue
13
Start Page
12256
End Page
12262
Citation
Environmental science and pollution research international 13 (25): 12256-12262 (2018-05)
Publisher DOI
Scopus ID
Chromium (Cr(VI)) is a very toxic and carcinogenic element, which is widely present in groundwaters, mainly due to geogenic conditions. The limit of Cr(VI) in drinking water is expected to be reduced to 10 μg/L in both the USA and the European Union. Recent literature findings indicated that the most efficient process in reducing Cr(VI) levels to below 10 μg/L proved to be Cr(VI) reduction by Fe(II), by applying a molar ratio Fe(II)/Cr(VI) of around 9. In the present work, we investigated the reduction of Cr(VI) by Fe(II) in pipe flocculation reactors followed by filtration of insoluble products by microfiltration. The proposed technology involves re-circulation of a part of the sludge in the pipe reactors, in order to improve kinetics and efficiency of the process. The obtained results showed that with a Fe(II) dose of around 1 mg/L, Cr(VI) was reduced to below 10 μg/L, by even an initial concentration as high as 300 μg/L of Cr(VI), corresponding to a molar ratio Fe(II)/Cr(VI) of around 3, thus reducing the overall quantity of reductive reagents and of the produced sludge. This ratio was also confirmed by the XPS analysis, which also showed that Cr(VI) was reduced to Cr(III) and then precipitated either as Cr(OH)3 or associated with the produced iron oxides.
Schlagworte
Coagulation
Hexavalent chromium
Microfiltration
Pipe flocculation
Chromium
Ferrous Compounds
Filtration
Flocculation
Groundwater
Kinetics
Water Pollutants, Chemical
Water Purification
Water Supply
Chemical Precipitation