Printech Archive, October, 1998: Cu in flexo water from greens, blues

Cu in flexo water from greens, blues

rhartwig@printing.org
Thu, 22 Oct 1998 10:28:06 EDT

The following questions and answers occured from the PNEAC website and GATF.
We thought it would benefit everyone to post on the listserve.

This Ask PNEAC question was from:
wayne-olson@meyers.com

What is the most cost effective way of dealing with copper in the waste
water stream? Source is Flexographic inks Green and blue. Thanks in advance.

Wayne Olson, Meyers

The following response to the question from Wayne Olsen is provided by Fred
Shapiro:

Copper free blues and greens can be made but at great expense. Limited
pigment resources which are not based on copper oxides.

Given that you will always have copper in the blues and greens, there is one
way of minimizing the amount that goes into the water waste. The waste would
come from discarded inks and wash-up water at the end of a job(or shift.) To
minimize, follow good clean-up procedures:
a. At end of run, use limited amount of water on rollers to clean off surface
ink, allowing the wash water to empty into ink trays. Keep water to minimum
in order to add a small amount to the ink in the ink fountain.

b. Empty all inks from trays or chambers(doctor blades) into can or jug for
reuse. Even if diluted slightly with the roller clean-up water, the ink can
be brought up to press viscosity and color by adding fresh ink at a later
time.

c. Wipe ink trays with wipers/rags to remove all solids. The wipers should be
placed in your laundry can or collected as hazardous waste if required.

d. Use fresh water to clean rollers; add a detergent or aqueous cleaning agent
if necessary to get the ink solids out of the anilox roller cells. Use anilox
brush to get into cells.

e. Never put raw inks, even if no longer usable, into the waste water or sewer
system.

If a procedure such as this is followed, the wash-up water will contain a bare
minimum of ink solids, hence very little copper. A test of the process water
waste should determine how much copper is in the solution and whether it is
below the acceptable limit for your sewer system. Submitting the test results
can develop acceptance by the POTW for discharge into the sewers.

Trying to use a water treatment system for the amount of copper present in
your flexo ink wash-ups may not be cost effective. However, there is a system
provided by Dynatec Systems which might provide the level of service needed in
this situation at a reasonable cost. The number for Dyntec Systems is (609)
387-0330.

 

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