Treatment of electroplating waste

A. Anusha:

Some good books available on the treatment of electroplating waste include: "Operation and Maintenance of Surface Finishing Wastewater Treatment Systems" ⇦[this on eBay, Amazon, or AbeBooks affil links] and "Water and Waste Control for the Plating Shop" ⇦[this on eBay, Amazon, AbeBooks affil links]. For a much briefer treatment of the subject, there is coverage in the Metal Finishing Guidebook, the "Products Finishing" Directory, and the Electroplating Engineering Handbook [on AbeBooks or eBay or Amazon affil links] .

I'm glad that you actually had a chance to see a plating shop--that's vitally important--but I think you still need to do some studying. I believe that the sodium bisulphite was used to reduce the hexavalent chromium in the waste stream to trivalent, in preparation for precipitation.

A. Gluconate is a wonderful chelator of many metals. That is why it's used in many alkaline tanks. EDTA is a stronger chelator, so that is no help to your problem.

To the best of my knowledge, most anything that you add to bust the gluconate will cause you other problems, with a net negative cost effect.

Keep the gluconate-bearing rinses/dumps away from the copper-bearing rinses/dumps is probably the most cost effective, even though it requires a second treatment line, or at least separate storage tank and the trouble of shutting down the other treatment to do the copper treatment. This could be cost effective by easier treatment of the other rinses.

A. Hi. I think James is right that keeping the copper and the gluconate separated is the best strategy if possible. However, if not possible, one potential treatment strategy is bringing the pH of the waste low, then adding an iron salt to try to get the gluconate to mostly tie up iron rather than copper, then raising the pH with lime. This strategy is sometimes called "chelate breaking" in the wastewater treatment industry.

Regards,

A. If at all possible, visit a plating shop, Kemal, so you have a real feel for what you will be expounding on.

I've recommended 5 books, and I don't know what information you need for your chemical engineering diploma project that wasn't found in them. But you can search the USA's EPA sites starting at www.epa.gov for hundreds of duplicative reports on the subject. Best of luck.

A. Hi Victor. Ion exchange or electrolytic recovery are two possible methods, although I'm not quite sure if that's what you're asking. Certainly with the right potential applied you could electroplate one out of the solution almost exclusively, leaving the other in solution. This is done for electrowinning or electropurification. Good luck.

 Hi Tejpal. Yes, although any of those five would be a good subject for a thesis (or a report if you are a younger student), best might be to combine the first & second because a discussion of how you can do something together with why you would want to do it could make for an interesting topic. Good luck.

Regards,

Usually available on eBay;

sometimes on
AbeBooks or Amazon

(affil links)
free pdf is currently available from academia.edu

A. Hi Dawid. We've listed a number of books which your university library should be able to obtain, and Metal Finishing Information Services could do a lit search of published articles for you if the project can afford it (surfacequery.com), while scholar.google.com and books.google.com should find some on-line stuff. Meanwhile, though, you can download the Metal Finishing Guidebook which has several good chapters on the subject.

Because technical libraries have whole shelves if not whole aisles on the subject, you obviously must very quickly choose a more narrow thesis for development: waste reduction in one limited area, applicability of RO towards ..., applicability of DI towards ..., recovery of metal values from ... plating sludges, etc. Good luck.

Regards,

A. Hi David. The Metal Finishing Guidebook, already suggested, is available to you instantly on line and for free. It has a chapter titled "Wastewater Treatment" with a subheading 'Conventional Method of Wastewater Treatment'.
That chapter is immediately followed by a "Waste Minimization and Recovery Technologies" chapter with subheadings including 'Evaporation', 'Reverse Osmosis', 'Ion Exchange' 'Electrodialysis', and others. If you will take yes for an answer and quickly skim those 2 chapters you'll have outstanding insight into your whole project. Good luck.

Regards,

Dawid

Try nmfrc.org for some wastewater treatments.

A. Hi Steve. If you can find someone to buy those solutions for $1 each, so they are not waste products that would be best.

There might be a different permit process or effluent standards for closing down a plating shop in BC than for running one; I don't know. But if I were you I would keep very careful logs of exactly what happened to the contents of each tank.

Conventional 'chemical destruct' (including alkaline chlorination of cyanide) should work. Do not mix anything with anything first though; treat each tank separately. If you don't know how to do it, or what is legal and what isn't, you can probably retain a cleanup specialist to haul the contents away or do the treatment on site. Good luck.

Regards,