Pollution Prevention in the Photofinishing Industry: Capturing the Moment
Photographic processing wastes vary with the type and amount of film being processed. By identifying the type of waste and implementing pollution prevention techniques, photofinishing processors can eliminate high disposal costs and improve the health and safety of individuals.
Materials of environmental concern found in photofinishing effluents include cadmium, chromium, ferrocyanide, lead, and silver. Reduction of these wastes involves good housekeeping practices, process modification, recovery, and reuse. Before modification of an existing process, it is important to know the state regulatory requirements and comply with the wastewater discharge limitations.
Reduction of waste can include simple changes in the techniques used in day-to-day maintenance and operations. Some suggestions include:
– Store materials properly.
– Minimize spills and leaks.
– Use the “first-in, first-out” practice to reduce the possibility of expired shelf life.
– Stop water flow when film processing is halted.
– Keep updated on new products that may be less toxic and produce less waste.
– Accurately add and monitor chemical replenishment of process baths.
– Pay careful attention to storage specifications of photosensitive film and paper.
– Empty containers to prevent the container from being classified as a hazardous waste. No more than 1 inch of residue should remain on the bottom of the container.
Depending on the photofinishing system, changes can be made in the processing by redesigning the system or substituting materials.
– Squeegee film between baths to remove residual solutions and prevent cross-contamination. Adjust squeegees on a regular basis. “Squeegees typically reduce chemical carry-over by 50%” (Waste Reduction Guidebook for the Photofinishing Industry).
– Use floating lids on bleach and developer container to reduce the contamination, oxidation, and evaporation of chemicals.
– Redesign tanks to convert an existing wash system to a counter-current washing system. By using water from a previous rinse to first wash the film, wastewater is reduced. At the final rinse stage, fresh water is used.
– Use water demand zone valves to control water entering the system.
– Substitute less environmentally harmful iron- complexes or ferric EDTA bleach for ferrocyanide bleaches when possible.
– Substitute less toxic metals, such as bismuth, to function as the image carrier in the film. Bismuth has been successful in black and white graphic arts and x-ray film.
– If you are using a system cleaner that contains dichromate compound, investigate switching to a cleaner without the compound.
Recovery and Reuse
Photofinishing wastes can be recovered before entering local sewer systems. In the case of silver, various methods exist to collect silver from the used solution and refine the metal off-site. Bleach and bleach-fix can be regenerated to reduce the volume of waste produced in the process.
– Silver can be recovered from processing solutions, rinse water, and scraps of film negatives, printing and transfer paper. Recovery processes, such as metallic replacement, chemical precipitation, electrolytic recovery, or ion exchange can recapture the silver before being discharged into the sanitary sewer system. Operation and maintenance of the on-site recovery system is crucial. The following sections describe various silver recovery methods and maintenance operations.
Metallic Replacement with Chemical Recovery Cartridges (CRCs) – CRCs are canisters containing iron filings. When the soluble silver found in fixer, bleach-fixer, C-41 bleach, and washless stabilizer come into contact with the filings, the iron dissolves and the silver settles out of the solution. To improve silver recovery, two CRCs should be placed in series and in conjunction with other silver recovery practices. It is important to fill the CRCs with water before using to extend the life of the cartridges. In addition, maintain a flow of 1-3 gallons/hour and adjust the pH of incoming water between 5.5 and 6.5 for efficient silver recovery.
Installing clear tubing between canisters allows operators to see if the system is removing the silver from the solution. Also, a “sample valve” can be installed between canisters. Samples collected can be tested with silver test paper on a regular basis. If high silver levels are detected in the first canister, remove the first canister, rotate the second canister into its position, and replace a new canister in the second canister’s location.
Keeping a maintenance log will allow the processor to develop a “changeover” schedule for the CRCs.
Chemical Precipitation – Chemicals can be added to the used solution to settle out the silver. The sludge remaining can be collected and refined off-site.
Electrolytic Recovery – Electrolytic recovery is a common silver recovery method. A current passes between two electrodes that are suspended in the used fix solution to attract the silver to collect on the cathode. For efficient silver recovery, keep the pH levels between 7.5 and 8.
Other methods exist for silver recovery, including ion exchange, reverse osmosis, evaporation, and low flow prewash, but are not widely used due to problems in applying these techniques to photofinishing solutions.
– Bleach and bleach-fix can be renewed by the use of replenishers and regenerators.
C-41 bleach contains silver which can be recaptured through a CRC recovery system, but not in an electrolytic unit.
Ferricyanide bleach can be regenerated by ozone oxidation, electrolysis, use of persulfate salts, or use of liquid bromine.
Bleach-fix regeneration can result in 90% reduction in the volume of waste produced.
– Developer can be purchased with less than 1% hydroquinone to eliminate a hazardous waste produced in some systems. Also, low replenishment developers can be used for both film and paper to substantially reduce replenishment rates.
– Drain photographic solution filters and ask your silver waste hauler to take them for refining.
– Steel film magazines and plastic film containers can be donated to schools and non- profit agencies.
– Single-use cameras can be recycled at a laboratory where processors send the cameras back to the supplier.
The following materials provided information for this tip sheet:
A Guide for Photo Processors. Washington State Department of Ecology, Environmental Management in Pollution Prevention, WA, 1994.
Waste Reduction Guide: Photo Finishing Business. Alaska Health Project Waste Reduction Assistance Program (WRAP). Alaska Health Project: Anchorage, AK, 1991.
Waste Reduction Guidebook for the Photofinishing Industry. Oregon DEQ, W..R.S. Bellevue, WA, undated.
Waste Reduction in Photographic Processing, Virginia Waste Reduction Assistance Program: Richmond, VA, 1991.