Entfernung von Cr(VI) aus Grundwasser durch chemische Reduktion, Koagulation und Membranfiltration

Project Title
Chromium removal through iron reductive precipitation in drinking water treatment
Principal Investigator
Funding Organization
Project Abstract
Chromium is commonly used in a broad range of industrial applications, such as leather tanning, production of steel and other alloys and textile processing. Depending on production conditions chromium can often be found in soil and groundwater. Apart from contamination, chromium can be naturally washed into groundwater by erosion of ophiolithic and metamorphic rocks. In aqueous solutions hexavalent (Cr(VI)) and trivalent chromium (Cr(III)) are the predominant redox species. While Cr(III) at low concentrations is essential for metabolic processes, Cr(VI) is highly toxic due to its carcinogenic and mutagenic properties. This fact has triggered an ongoing discussion of existing standards in different countries. As a consequence it is expected that the European commission will reduce the acceptable limits of Cr(VI) in drinking water (currently 50 μg/L of total chromium) to much lower values (<10 μg/L of Cr(VI)).

As Cr(VI) does not precipitate readily, chemical reduction followed by precipitation is a widely used technique for Cr(VI) removal. The resulting Cr(III) has low solubility in water and can either be precipitated as Cr(III) hydroxide or adsorbed on iron hydroxides and subsequently being removed from water through filtration. However, in this treatment process the role of natural organic matter has rarely been investigated and is not sufficiently understood. As a result the removal of Cr(VI) from natural organic containing ground water is a delicate task, especially if low concentration of total chromium are targeted.


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