Printech Archive
Re: Rinse water for photographic plates and scrap paper generation rates

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From: Jeff Adrian (
Date: Wed Apr 14 1999 - 16:27:43 CDT

                      Re: Rinse water for photographic plates an 4/14/99
Mr. Sharma:

It seems to me that there are two issues that need addressing with regard to photo processing of "plates (film?): 1) the issue of fixer container silver, and 2) the issue of washwater usages and discharges containing any residual fixer (carryover), and t
hus containing small amounts of silver.

To the first question, know that there are excellent commercial systems available for the recovery of silver from fixer by the electrolytic method followed by two in-series mettalic exchange cannisters. The very best of the electrolytic systems have the
ability to constantly monitor their performance and adjust amperage for maximum efficiency. Such a system (with excange cannisters) should reduce silver to less than 2 ppm.

To the second question: Consider utilizing commercial available devices called Water Mizers (one brand name). These units constantly recycle washwater from film processors and extract any carryover silver via a cannister on the unit. Two benefits will re
sult: drastically reduced total water usage, and easily discharged waste water without carryover silver. It should be noted that a small amount of fresh water will be constantly introduced to the Water Mizer system during use.

The net result for our company was that when it came time to renew our wastewater permit with the local treatment facility, the wastewater authority determined that we were no longer required to be permitted as our total wastewater discharge had been so
drastically reduced! This saves the company thousands of dollars in testing fees and permit fees.

Hope this is useful.

Jeffrey R. Adrian
The John Roberts Company
Sharma, Aarti wrote:
>We are working with a printing company outside the US that does Offset
>lithography and are having trouble finding some specific environmental / P2
>performance information that the company is interested in - would someone on
>this listserver be able to shed some light on the following?
>1. How much rinse water do the "best" US plants typically use for rinsing
>fixing solution or "hypo" off from photographic plates? Is this water
>pretreated prior to discharge?
>Background: When this company rinses "fixing" solution from their plates
>(it's also called sodium thiosulfate, or "hypo"), they use approximately 6.2
>gallons of water per plate. (106,000 gallons/year for approximately 17,000
>plates). The rinse water with the "hypo" goes down a drain, and directly
>into a canal leading to the river. >
>2. What are "average" and "best" numbers for scrap paper produced in a
>comparable offset litho plant. >
>Background: This company produces 275 tons per year of printed sheet
>products, and 275 tons per year of books, magazines, booklets, catalogs, and
>posters. I have printing press models and ages, if this will help. >
>Thank you very much for your help!
>Aarti Sharma >RTI

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