New Catalytic Process Treats Cyanide In Industrial Waste

Chemists at the University of Amsterdam have discovered a new process for removing cyanide from industrial wastewater.

The new process “has been shown to reduce CN– concentrations by 90 percent within minutes from wastewater simulating that’s produced at steel mills. Higher destruction efficiencies — up to 99.9 percent — can be achieved,” Chemical Engineering reported, citing the researchers.

The backdrop: “The typical sources of cyanide contamination are industrial waste from plating and mining industries, burning coal and plastics, and effluent from publicly owned treatment works. In wastewater, the EPA specifies cyanide discharge limits by industry and size of the facility (<38,000 or >38,000 liters per day),” according to a paper published by Thermo Scientific.

The new process aims to simplify cyanide control, relying on a simple metallic salt as a catalyst. The composition and price of the salt “are such that it can easily be applied to a large-scale process without any economic penalty,” said Gadi Rothenberg, one of the researchers. “The catalyst can be used in either small-scale batch reactors or large-scale packed-bed continuous reactors,” the report said.

So far, the process has been tested at steel mills and in the precious-metals sector, the report said.

With precious metals, “the process volumes are smaller, but the CN– concentrations are much higher (up to 10,000 times higher). In a collaboration with Germany’s oldest gold and silver refining company, Heimerle + Meule GmbH, tests on industrial samples have demonstrated a similar 99.9 percent CN–removal efficiency within minutes,” the report said, citing Rotenberg.

Heimerle + Meule is considering how it can use the process at its wastewater treatment plants.

The U.S. EPA says the best technologies for cyanide control are oxidation by chlorine, ion exchange and reverse osmosis. The agency “established a maximum contaminant level (MCL) of 0.2 mg/L and a maximum contaminant level goal (MCLG) of 0.2 mg/L as free cyanide.”

For similar stories, visit Water Online’s Contaminant Removal.