In August 2010, an electroplating facility in California specializing in aircraft components was issued specialty permit levels for the reduction of cadmium in discharge wastewater. The current permit of 250 ppb was reduced to 70 ppb and the allowed cadmium levels are expected to move lower over the next few years.
Cadmium has many industrial uses including 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 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.
Evoqua was contacted to evaluate potential treatment alternatives and evaluated both ion exchange and specially 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 Evoqua's Roseville, MN facility and the specialty 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.
A full scale pilot system was installed at the facility to achieve the treatment goals from the plating process.
Evoqua's specialty media effectively reduced the wastewater cadmium level current permit requirements and allowed the customer to avoid penalties for non-compliance.
Treatment using the Evoqua specialty media provided cadmium removal to below the desired permit levels without the need for additional pH adjustment, thereby saving the customer the cost for additional chemical preparation and also, eliminated concerns associated with chlorine damage to the media.