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From:(Warren J. Weaver)
Hi, Bonnie. I have a answer to your question. It means changing
treatment system technology however. I work with a company that makes
membrane filter based treatment systems. They have experience with
systems for flexographic washwater. By separating the particles and
large molecules from the small molecules (such as water) in a membrane
filter, the ink solids (pigment and resins) and some of the
co-solvents, anti-foaming agents, adhesion enhancers and other
additives are concentrated for reuse (we call it a recycle system, not
a treatment system). In the flexo newspaper industry, this has become
standard technology. The key is to reuse these ink components in the
black ink where the various colors, when mixed become very dark and
are "hidden" (they use a lot of black ink in the newspaper industry).
If your client does not use much black ink, you've still concentrated
valuable components (some ink pigments cost more than $6 per pound).
Perhaps your client's ink manufacturer would be interested in it. Or,
perhaps, there is another flexographic printer in the area that does
use a lot of black water based ink-the Louisville Courier does, the
Akron Beacon-Journal does, the Pittsburgh Post does among others.
I would be happy to talk to your client and put them in touch with the
recycle system's manufacturer. Call me or have your client call me.
At 4:44 PM 7/15/97 -0700, Bonnie Pray wrote:
>We are working with a plastics printing company that has flexographic
>printing operations. They use all water-based inks. Press cleanups are
>conducted with a water/soap solution. The spent wash water is sent to a
>wastewater treatment system where it is coagulated using aluminum
>chloride solution. Lime solution is also added to the wastewater to
>adjust pH. The wastewater then goes through a plate and frame filter
>press where solids are removed. My assumption is that most of the solids
>consist of ink pigments. Currently, these solids are landfilled.
>Does anyone have suggestions to reduce or eliminate this waste stream?
> Can the ink pigments be recovered? FYI - we are already addressing
>their product scheduling practices to reduce the number of press
>changeovers, this should reduce the amount of wastewater to some extent.
>Thanks for any input.
>Bonnie L. Pray