Examine every change that has been made upstream, and any changes in suppliers or supplier’s formulations.  We have found chelated cyanides as a component in the metal cleaning solutions: they were being carried through to the waste water. We have also confirmed cyanide false positives tests that just did not make sense. The way we worked around it was to spike the sample with a known cyanide solution and then test again.  Do you get more cyanide than the known spike.  Just repeat testing of the same sample will lead to the same results.   “How would you distroy cyanides?”  This was a question that one of the EPA managers asked me because he didn’t know. When I indicated that I would start with hydrogen peroxide to break the Carbon Nitrogen bond he thought it was the same reaction as with chlorine - big difference.  Cyanide can also be destroyed by many other methods.  Remember to keep the solution alkaline so that it remains in solution.  It is the cyanide complexes that are more difficult to break than the simple salts.

Published December 13, 2018 21:36 by Waymon Hofheins