Printech Archive, April, 1999: Re: Rinse water for photographic plates and scrap paper generation rates

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

gjonesprinting@aol.com
Sat, 17 Apr 1999 16:41:40 EDT

Dear Aarti:

I am a little confused as to the specific type of material and processor that
you have a question about. You mention the use of "hypo" in conjunction with
plate developing. The term "hypo" is used to describe fixer that is used to
remove unexposed silver from film in the development process. The film in
turn is used to image a plate, which is then developed in a separate
processor. However, the printer you are assisting could be using one of the
new direct to plate system that utilizes a silver halide emulsion over the
diazo plate imaging material.

To answer your first question, the amount of water used is highly dependent
upon the size of the unit and the physical amount of film/plate material
processed. In order to appropriately compare water and chemistry use, it
needs to based on the amount of water/chemistry used per area of film/plate
processed. Unfortunately, I do not have data that reflects a comprehensive
survey on the subject, but I do have some data. For film processors, the
reported consumption for fix is 0.3-liter/square meter (0.0068-gal/square
foot), developer is 0.4-liter/square meter (0.009-gal/square foot), and for
washwater it is 20-30 liters/square meter (0.45-0.68-gal/square foot).

Also included in your question is a description of the fate of the wastewater
being released during the processing of the film or plate. In the United
States, a discharge that you are describing would be illegal. While the
material being discharged from the processor is directed eventually to a
river, discharging untreated material such as this to a waterway without
proper treatment is not permitted. The discharge would have to be treated and
a pretreatment permit would have to be obtained. There is a direct discharge
standard that has been developed for film processors. The maximum daily limit
for silver is 0.14 klograms/1,000 cubic meter of material processed (0.03
pound/1,000 square foot) with a daily average of limit of 0.07
kilograms/1,000 cubic meter of material processed (0.015 pounds/1,000 square
foot). The maximum daily limit for cyanide is 0.18 klograms/1,000 cubic meter
of material processed (0.038 pound/1,000 square foot) with a daily average of
limit of 0.06 kilograms/1,000 cubic meter of material processed (0.019
pounds/1,000 square foot). The limit for pH is within the range of 6 to 9.

There should also be a high level of concern with discharging materials to a
ditch as they contaminate the soil and could eventually contaminate the
ground water. In many instances, ground water is used for drinking purposes.
This waste should be not be discharged and collected and sent to a proper
treatment facility.

Your second question pertains to the amount of waste paper generated at a
printing facility and if the amount seems appropriate. This question is also
a little difficult to answer because you have not provided a description of
the type of presses used and how many impressions are involved in printing.
According to some waste ratio studies I have, the average combined, which
includes makeready and running waste for heatset web offset lithographic
printers is 15.8%. For nonheatset web offset lithographic printers the
average combined waste is 13.2% and for sheetfed offset lithographic printers
printing four color work, the average combined waste is 12.6%.

Please let me know if you need additional information.

Gary Jones
GATF

 

PNEAC

Disclaimer/Copyright Info
Email the Webmaster