Is there anyone that can offer insight into how to manage a sulfuric acid based, potassium oxidizing salts copper etchant waste? Hello Everyone, I'm not sure what specifically is included in "Potassium oxidizing salts", but this sounds similar to what we call Cobra etch, which is a mixture of sulfuric acid and peroxide. I'm guessing that the end result is the same in that copper etched ends up as copper sulfate. We know that by cooling Cobra etch, the CuSO4 will precipitate, and the resulting supernatant can be recycled back into the process. If cooling doesn't drop out the dissolved copper, perhaps electrowinning could plate it out, but you'll have to evaluate this with some EW units, as some don't like a lot of oxidizers in the feed. You'll have to pilot this with some mfgrs of these units. Also, depending on the cost of the etchant solution, diffusion dialysis might be cost effective. I've focused my response on ways of recycling the solution as opposed to chemically treating it for discharge. Going the treatment route, there's different routes depending on whether the copper is chelated in this sollution or not. Lee Wilmot HADCO Corp [log in to unmask]