A Printing Pollution Prevention Opportunities Checklist

Prepared by Alison Gemmell
CH2M Hill and
Philip Lo, CSDLA, 12/90.

Solid Waste Management
County Sanitation Districts Of Los Angeles County
1955 Workman Mill Road,
Whittier, CA 90603-4998

Mailing Address:

PO. Box 4998,
Whittier, CA 90607-4998

Charles W Carry
Chief Engineer and General Manager
Telephone (213) 699-7411, (213) 685-5217,
Fax: (213) 695-6139

The keys to pollution prevention in printing are material substitution (nonmetal inks), minimization of changeover, and ink recycling.

 I. Good Operating Practice
 Segregate waste streamsSpent fix baths should be segregated from rinsewaters and developer solutions because silver recovery is more efficient on more the more concentrated spent fix waste stream.
 Control inventoryDo not allow material to exceed shelf life and then have to be discarded as waste. Use materials on a first-in, first-out basis.
Do not get rid of expired products by discharging to wastewater treatment system.
 Adjust replenishmentAdjust chemical replenishment rates and washwater flow rates on photoprocessor to optimize bath life and reduce wastewater quantity.
 Keep lids on solutionsIn storage, keep lids on bulk solutions to prevent oxidation and contamination of these solutions.
 Minimize spillsUse dry method cleanups.
 Return used ink to vendorPurchase ink from distributors that will take back unused or spent ink, so ink will not be discharged to the newer.
 Run similar jobs at onceMinimizes need for cleaning between jobs.
 Use non-dry aerosolSpecial non-drying aerosol materials can be sprayed on ink fountains to keep them from drying out overnight. Fewer ink fountain cleanings required.
 II. Material substitution
 Change to silverless filmSilver does not end up in rinsewaters or spent fix baths when this type of film is used. Examples include vesicular, diazo, and electrostatic films.
 Change to ultraviolet inksWill not dry in ink fountain overnight. Reduces need for fountain cleaning.
 II. Process Modification
 Add ammonium thiosulfateAddition of this chemical to silver contaminated bath extends the useful life of the bath
 Purchase new developing machines that use less rinsewater (e.g., countercurrent rinsing) and/or have squeegees or air bladesTo reduce dragout from chemical baths to rinsewaters.
 Purchase waterless paper and film developing machinesTo reduce the volume of fix waste.
 Add acetic acidAcetic acid added to the fix bath keeps the pH low to maximize soluble complexes, therefore, extend bath life.
 Install electronic ImagingEliminates need for photoprocessing. Expensive.
 Install laser platemakingEliminates need for photoprocessing. Expensive.
 Use flexographic processReplaces metal etch processes for plate processing.
 IV. Material Recovery
 Recover fix bath silverInstall electrowin unit on fix bath of photoprocessor. Extends bath life.
 Install electrowinInstall electrowin unit on first rinse and developer waste streams to recover silver from solution and reduce toxicity of wastewater.
 Metal replacement canisterInstall canister on rinsewaters and on effluent of wastewater electrowin to recover silver from solution and reduce toxicity of wastewater.
 Install rinsewater recyclingReduces wastewater.
 Recycle inksRecycle inks to make black ink instead of discharging to sewer.

(WP, Printer)

Last Updated: January 8, 1996