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Silver Recovery

Traditional photographic/film processing is a multi-step process that turns a latent image on film media into a permanent image. The chemistry behind this process involved "fixing" silver to the film media to create the image and washing away the "unfixed" silver. EH&S is interested in silver not only for its precious metal value but because it also happens to be listed as an environmental pollutant by EPA due to its toxicity to aquatic wildlife. To avoid discharging silver in the environment, EH&S outfits all image/photo processing equipment utilizing "wet chemistry" methods (e.g., fixer and developer) with equipment to recover silver halide from the wastewater effluent. Since waste generated in the processing of images/photos contains silver, all waste from these activities is collected and/or filtered in accordance with environmental regulations to avoid entering the environment in wastewater (e.g., equipment effluent) or as a solid waste (e.g., scrap film media) by-product of image/photo developing activities. 

Solventrecycling
 

EH&S services darkroom users in both Arts and Sciences at the Morningside campus and the medical and research community at the Medical Center campus in twenty-eight darkroom locations.   Silver recovery equipment is inspected by EH&S at least once every calendar quarter and silver recovery equipment that has reached its end of useful life is exchanged.  EH&S sends the exhausted silver recovery equipment for refining so the silver can be reclaimed and put back into commerce.  Historically, EH&S collected nearly 100 T/Oz of silver annually.  In recent years, a shift to digital media has decreased the number of darkrooms using wet chemistry and thus decreasing the amount of silver recovered. Below is a graph of recovered silver from our recycling efforts at the Morningside and Medical Center campuses.

 
 
Recycled Silver Recovery Chart 2009

How do I set my darkroom up with silver recovery equipment?

If you are interested in setting up a new dark room and need information on the kind of silver recovery unit that will best suit your process please contact EH&S… envsafety@columbia.edu

Last but not least…

Please help us protect the environment through the proper utilization of silver recovery equipment in the processing of films that use wet chemistry.  Help us to ensure that all spent fixer is properly managed to minimize environmental contamination caused by the release of silver.  Feel free to contact us if you have any questions or concerns regarding the proper management of darkroom chemicals.

Additional Silver Recovery Information and Resources:

For more information on reuse, recycling, or environmental issues, please visit: http://www.ehs.columbia.edu or http://www.columbia.edu/cu/environment/index.html
http://www.epa.gov/epaoswer/hazwaste/id/infocus/photofin.pdf
http://www.kodak.com/eknec/PageQuerier.jhtml?pq-path=4191/4197/4233&pq-locale=en_US
If you have additional ideas for reuse or recycling, please send your suggestions to: envsafety@columbia.edu and environment@columbia.edu