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Recovery of aluminium anodizing sludge [New Zealand] 

February 14, 2007

Hi..
I am just wondering what would be the easiest method to reuse alumium anodize sludge as a flocullant or any other simple procedure that can be used to reuse anodized waste?

Biren Patel
student - New Zealand

Typically there is no "sludge" from the anodizing tanks. Baths are typically decanted on a regular basis to keep the Al content at an acceptable level. Al is not a regulated material, so the decanted solution is normally ph adjusted, and discharged to sewer.

Marc Green anodizer - Boise, ID, USA

If you anodize a fair amount of 2000 or 7000 series aluminum alloy, you very probably will exceed the amount of copper that you are allowed to go to the sanitary sewer with.

James Watts
- FL

Luckily, for me, I deal almost exclusively with 6061, and 5052 alloys for the semiconductor industry. But you are correct, James, without some type of filtering, it's very possible to exceed Cu limits in the bath.

Marc Green anodizer - Boise, ID, USA