Chromate is found in the effluent from chromium-plating operations and has been used in cooling tower water chemistry. Chromate is also found in ground water both as a natural contaminant and from man-made sources. While trivalent chromium (Cr3+) is not considered to be harmful, hexavalent chromium (Cr6+) is toxic. The World Health Organization (WHO) and many countries have established a maximum tolerable concentration of 50 µg/L (ppb).
Weak base anion resins have a strong affinity for chromate, making them a good choice to minimize leakage. The common practice today is to dispose of the resin after it is loaded with chromate, so a high-capacity resin is desirable. AMBERLITE™ PWA7 Resin is a unique phenol-formaldehyde weak base anion resin that has demonstrated significantly higher chromate loading capacity compared to other commercially-available ion exchange resins.
Filtration can also be used to remove chromate from drinking water. Ferrous sulfate is used to reduce hexavalent chrome to trivalent chrome. This material is then precipitated, coagulated, and filtered out of the water. DOW™ Ultrafiltration SFD Modules can facilitate low levels of chrome-containing particles in the final drinking water.
These ion exchange and ultrafiltration products may be subject to drinking water application restrictions in some countries. Please check the application status before use and sale. For more information see our regulatory information. (Even when ultrafiltration modules are certified, their use is not recommended for drinking water where dedicated operators are not available.)