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Ask the Expert Question-and-Answer Archive (Wastewater Treatment)

by Mike McGinness, EcoShield Environmental Systems, Inc.
October, 2006

Wastewater Ventilation

Q. Can I combine my ventilation ducts for copper cyanide and HCl cleaning and send them to the same scrubber? I know that chlorination can occur and result in precipitates, but all the literature suggests that the reaction only occurs at high pH. The HCl should lower the pH of the scrubber water such that precipitate won't occur. Am I correct?

A. No, I would strongly advise against combining them as the two will react to make the extremely toxic, volatile, poisonous HCN gas, Hydrogen Cyanide! Even worse the pH of the scrubber solution could be affected by the HCl gas, reducing the pH of the scrubber solution over time which could make the scrubber solution a source of HCN gas! It might also produce Cyanogen Chloride, another poisonous gas. Glad you asked first!


Mike McGinness

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