Printech Archive, February, 1998
Re: Treatment of Wastewater for Reuse; Flexo Printer


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From: Malcolm F. Boyle (boyle@cmcusa.org)
Date: Wed Feb 11 1998 - 07:25:35 CST


Tim Lindsey, Illinois Waste Management and Research Center, is working
with a large (non printing) company to remove microbes from their aqueous
based coolants and cutting fluids. Since they also are susceptible to
bacterial growth. He is using ultrafiltration to remove the microbes. You
may want to contact him to find out how his work is proceeding. Phone:
(217) 333-8955.

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From: Wayne Pferdehirt[SMTP:pferdehi@epd.engr.wisc.edu]

Forwarded from Warren Weaver, of PENNTAP

------- Forwarded Message Follows -------

Wayne-

I agree with Mike Callahan that a UV/ozone generator would be an
alternative for biocide and may be the only alternative if your
clients products are for packaging food or drug industry products. You
can probably find some vendors in the Thomas Register. On the other
hand, I doubt that your client will be able to maintain conditions in
his plant which will negate the need for some means of biological
activity control. The problem is 1) the lapse between generation of
the wastewater and its reuse, 2) the ambient conditions of the
wastewater during processing, storage and reuse (warm, humid
environment), 3) the fact that starch and the organic components of
water based flexo inks are an excellent food source for bacteria, 4)
the fact that none of the starch or flexo ink components (other than
the biocide most flexo ink manufacturers add to their products
specifically for control of biological activity) are highly toxic to
bacteria and 5) the fact that, whether continuous or batch, the
treatment process does not lend itself to complete removal of the
components favorable to bacteria at anytime during their operation.

Given this, bacteria will rapidly reproduce and can, even if you were
to start out with sanitary conditions, reach a colony count high
enough to consume most of the food source (starch, etc.) within about
2 weeks. To avoid this and the detrimental effects of the bacteria on
the client's gluing operation, every square inch of the system would
have to be cleaned weekly or even twice per week with a bleach
solution or other biocide. Because all systems have blind spots, dead
corners and other impediments to complete cleaning (even if totally
enclosed), this is a physical impossibility. Therefore biological
activity will have to be controlled with a formaldehyde based biocide
or, as Mike suggested, a UV/ozone system.


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