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Zinc waste water

As part of our soldering process we generate about 1 gallon of zinc-contaminated wastewater (~800mg/L)per week. Is there a way of filtering/precipitating the zinc out to significantly reduce the concentration and avoid it from being classified as hazardous waste?

Maruta Yallop
Sheet metal production - Alberta, Canada
February 4, 2008

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The first step is to determine if there are categorical regulations for your industry. There probably are, and they probably dictate the effluent limitations and how the wastewater discharge program is regulated. For example, in most places in the USA, you would get a discharge permit through the local POTW and you would do most of your reporting through them.

Once you know what you legally must do and can do, it's a reasonably easy matter of lab work to determine how to remove the zinc from the water and discharge the water to a sewer (if applicable). This should leave you a far smaller quantity of hazardous waste.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 6, 2008

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I'm not sure of the Regulations in Canada, but in the US, while zinc is regulated in industrial effluents, sludges that contain only zinc and iron can be delisted so that they do not have to be managed or treated as a hazardous waste.

If this is the case in Canada, also, then you could, with proper regulatory approvals,batch treat this waste, discharge the clarified water and send the sludge to any industrial landfill.

Lyle Kirman
consultant - Cleveland Heights, Ohio
February 12, 2008