New Media Reduces Cadmium From Electroplating Wastewater Discharge

Cadmium has many industrial uses and is predominantly used in rechargeable batteries, in yellow and red pigments and is widely used in the aircraft industry electroplating applications due to the excellent resistance to corrosion for cadmium plated steel components. Environmental discharge limits for cadmium continue to decrease for industrial facilities across the United States and it is listed as one of the six substances banned by the European Union's Restriction on Hazardous Substances (RoHS) Directive removing it from electrical and electronic equipment. Although Cadmium has many industrial applications it is also linked to many health concerns and regulated by state and federal authorities in the United States due to negative health impacts.

In August 2010, an electroplating facility in California specializing in aircraft components was issued new permit levels for the reduction of cadmium in discharge wastewater. The current permit of 250ppb was reduced to 70ppb and the allowed cadmium levels are expected to move lower over the next few years. The process wastewater from the system was high in pH and also potentially contained chlorine from a prior cyanide destruction process upstream of the process. Siemens was contacted to evaluate potential treatment alternatives and evaluated both ion exchange and newly developed adsorptive media that specifically targets regulated metals such as cadmium in complex wastewaters. Column studies of water sampled from the site were tested at Siemens‘ Roseville, MN facility and the new media was selected as the best technology to achieve the treatment goal. The process wastewater could be treated without pH adjustment and concerns of free chlorine damaging the media. The media's performance reduced cadmium in the lab sample from over 400ppb to less then 1ppb.