Alternative Cyanide Destruction Methods
Engineers and managers in the Aerospace and Surface Finishing/Refinishing industries know firsthand the difficulty of balancing cost-effective solutions with long term results. The current manufacturing process for electroplating and metal surface finishing relies heavily upon the use of cyanide. Cyanide is typically employed to plate complex metals and is more tolerant to certain impurities than other substances.
One of the drawbacks to using cyanide in a manufacturing capacity, however, is its extreme toxicity. Cyanide is easily absorbed by animals and humans through direct contact, vapor, or dust. For this reason, stringent regulations require that plants properly treat any contaminated water that could contain free cyanide, weak acid dissociables, and strong acid dissociables. It is very important these compounds are removed from wastewater before wastewater enters Publicly Owned Treatment Facilities (POTFs) that may not have the ability to eliminate remaining traces.
The most common solution to the cyanide problem is alkaline chlorination (bleach). Alkaline chlorination is an inexpensive and highly effective method for treatment. This method is ideal for most organizations as it actually destroys the cyanide.
While using bleach is the most cost effective method, it is not as environmentally friendly as other available technologies. The EPA has become concerned with the current method’s protentional for health and safety issues, and is now encouraging manufacturers to consider other options. There are several very sustainable alternatives that are already being used successfully.
In Europe for example, regulatory pressure has already pushed many leading companies to implement alternative methods of destruction such as the most common alternatives, ozone oxidation and UV oxidation. Ozone oxidation is beneficial because it adds few, if any, secondary products to the wastewater. UV oxidation exposes hydrogen peroxide. This creates hydroxyl radicals that quickly oxidize the cyanide.
In addition to these two methods, there are several other techniques that are less harmful to the environment. Three of the most common eco-friendly options are hydrogen peroxide, potassium permanganate and thermal destruction. These methods have a smaller environmental impact than bleach, but they do not completely destroy the cyanide. Instead, they produce cyanates which may or may not be acceptable to POTW’s levels. Cyanates are less hazardous but require additional treatment to be removed. Because of their cost, these methods are typically used for lower volumes of wastewater.
Using copper as a catalyst, the hydrogen peroxide chemical process produces cyanates and is effective at creating low cyanide and metal levels that may be suitable for discharge. Because of the high cost of hydrogen peroxide, this approach is generally used for lower volume batches. Potassium permanganate can quickly remove most heavy metals when combined with additional treatment processes.
Thermal destruction is one of the simplest methods of remediation because manufacturers can simply employ a heated pressure chamber to destroy the chemicals. There are several removal techniques that can dispose of remaining waste.
The mission of the MacDermid Envio Corporation is to take the worry out of wastewater. We are the experts you can rely on to help build a unique wastewater plan that meets all regulations and is flexible enough to support unexpected growth and development.If you are interested in learning more about the best cyanide destruction method for your business, contact us today!
Written by a MacDermid Envio Solutions Subject Matter Expert