Photographic Silver Recoveryby Sabrina Ehlert
Developing any type of photographic film--35mm, X-ray, etc.--leaves deposits of silver in the fixer during processing. If poured down a drain and into the water system, the silver can become toxic to the wildlife and environment. Photographers and photo developing technicians must discard of used fixer in environmentally safe ways. One way is to recover the silver deposited in the chemicals during processing.
Silver Uses in Photography
In 1727, J.H. Schultze observed a mixture of silver nitrate and chalk react to light; the mixture darkened when exposed to the light. In 1824, the first semi-permanent images were obtained by French physicist, Nicéphore Niepce, on glass coated with silver salts in bitumen. Since then, different forms and types of silver have been used in photographic emulsions. Its sensitivity and reactivity to light makes it ideal for capturing images.
During the development process, the film, or photographic paper, is immersed in a series of chemical solutions. The chemical solutions react with the silver and create the images on the film. During the fixing process, unprocessed silver is removed from the film, halting the developing of the image, and fixing it permanently to the film. The silver that is removed from the film bonds with the fixing chemicals and needs to be removed before the chemicals can be disposed. Places such as photo development labs, hospitals with X-ray machines, photography schools and photographers with darkrooms generate large quantities of used fixer for silver recovery.
How Silver is Recovered
To recover silver, the used fixer is pumped through a cartridge system that extracts the silver from the chemical. There are two types of film-developing systems: tray (or hand) developing, and machine developing. The two types of developing systems have different methods for silver recovery. In the tray system, the fixer is pumped into a bucked with a cartridge system. In machine development, the fixer can be pumped through two or even three cartridge systems to filter out the silver. The silver collected during the recovery process can be recycled and used in jewelry, electronic components, medical supplies and other silver items.
Value of Silver Recovery
Silver is a naturally occurring element that is found in ore, often with other elements. Silver is a valuable material that has been used for currency, jewelry and for electronic and medical purposes. However, since 1951, world silver consumption has exceeded the amount that is extracted from ore. Recycled silver can be reused in products, materials and components that are made from silver. Photo development labs, X-ray labs and any photo development that uses and filters large amounts of fixer can sell the recovered silver for small profits.
Recovering photographic silver from used fixer not only produces silver that can be recycled and reused, it also protects the environment. Unfiltered fixer that is poured down the drain enters the waste water system. During the purification process, where the water is filtered and impurities removed, the silver is extracted and, along with other waste removed from the water, placed into a landfill. The silver deposits can then be absorbed into the ground and go into fresh water, potentially harming plant and wildlife.
- Integrated Publishing - Photography - Silver Recovery
- Harvard University - University Operations Services - Environmental Health & Safety - Silver Recovery Systems for Darkrooms and Photo-Processors
- Environment Information from Kodak - The Fate and Effects of Silver in the Environment
- CDC Toxprofiles - Production, Import, Use and Disposal
- Ecology and Natural Resources Collection - Andren, Andrews W.; Bober, Thomas W. (ed.)/The 6th International Conference Proceedings; Transport, Fate and Effects of Silver in the Environment
- silver sugar bowl with silver spoon image by Alex White from Fotolia.com