For removal of Cr(VI)- and Cr(total)-pollutions in ground waters and industrial process waters a new filter material was developed. For this purpose the TZW developed, tested and compared adapted analytical methods for chromate analysis.
Chromium is mainly emitted into ground waters in the form of Cr(VI)-compounds by natural processes of oxygen-driven oxidation from chromium(III) containing minerals and anthropogenic contaminations. In this process Cr(VI)-compounds are typically very good soluble and sorb poorly on soil particles. These properties make Cr(VI) compounds highly mobile and able to reach groundwater under appropriate conditions (especially in the aerobic RedOx environment). Studies from the WHO and the USA show that the contamination of natural ground waters is a worldwide problem. According to the German drinking water ordinance the maximum allowed limit of total chromium amount is 50 µg/L.
In this joint project, a new filter material and process for the selective removal of Cr(VI) compounds and total chromium from groundwater and industrial wastewater was developed.
The TZW participated with its already established trace analysis for chromium and chromate (IC-ICP-MS) and established new chromate analysis methods based on IC with direct UV detection (limit of determination <1 µg/L Cr(VI)) or photometry after derivatization with 1,5-Diphenylcarbazide (DPC). For higher contaminated process waters (>20 µg/L) an online-capable photometric rapid analysis method based on derivatization with DPC was developed. For this purpose the dosing system LSPone, which contains a piston burette with multiple valve, was coupled to a LED-Photometer.
The applicability of the developed chromate methods could be confirmed by project-internal comparative investigations with more than 20 different water matrices and the successful participation in a chromate round robin test organized by the AQS-BW.
Publications:
F. Junginger, O. Happel, Poster für Wassertagung 2019: Methodenvergleich zur Cr(VI)-Analytik in Wasserproben
F. Junginger, O. Happel, L. Massa (2019): Methodenvergleich zur Cr(VI)-Analytik in Wasserproben, Vom Wasser 117(4), 130-133