Alum for water treatment

[brianle]

We have a water precipitator to treat river water that will be used for equipment cooling, not for boiler water or drinking water. Some of the cooling water is returned to the river without further treatment. We use "purified" alum as a coagulant. Is there a such thing as "un-purified" alum that would be less expensive? If so, are there environmental concerns?

Thanks,

Brian

 

[bimr]

Are you refering to NSF-potable grade? If it costs more money, it probably is not worth the cost. There are no environmental issues as long as you are not using a waste product.

 

[kenvlach]

Do you have any aluminum anodizers around?
If so, what they do with spent sulfuric acid anodizing solution [some purify, most neutralize into alum & dump].
Also, ask what alloys they mostly anodize [2024 & 7075 have Cu, Cr, Zn, etc.; 5000- & most 6000-series are better].
May get for free but need to test for Cu, Cr & Zn.

 

[brianle]

Thanks for your responses. The alum is "Certified to NSF/ANSI 60". If I want to order "unpurified" alum, what would I call it? I'll check if there are any local aluminum anodizers.

 

[bimr]

Suggest that you talk to a supplier like general chemical:

http://www.genchemcorp.com/products/alumliq.shtml

http://www.genchemcorp.com/products/coag_enhanced.shtml

Alum was formerly supplied without NSF certification. Ask them if there is a cost difference with/without NSF certification.