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from two sources: the monetary value of recovered silver and avoiding fines from the Environmental Protection Agency. image on most types of photographic films. Unlike many other natural resources, silver is not destroyed in the photographic process. Much of this silver can be recovered, refined, and used again. scraps (film and paper). When most films and papers are processed, some of the silver they contain are removed in the fixing bath. With positive types of black-and-white film, as much as 80 percent of the silver that was in the emulsion may be removed during fixing. With color film and paper, close to 100 percent of the silver is removed in the fixer. is processed, most of the silver remains in the emulsion. Most of the silver that remains in film or paper can be recovered. stricter enforcement of existing environmental codes. Silver is one of the heavy metals that is controlled by federal, state, and local legislation. These government agencies monitor the amount of silver that is discharged into the sewer system. Each Navy imaging facility is subject to environmental codes and restrictions of the state and local area. Each state has a similar set of codes that may differ somewhat, so it is important for you to become familiar with them. For example, the maximum silver concentration limit for an imaging facility in Gulfport, Mississippi, may be 5.0 mg/L California, may be 0.05 mg/L (ppm). economic gain. Violations can result in severe fines. Individual violators may also be held personally responsible for such fines. An excessive concentration of silver in the effluent of a photographic processor can cause an imaging facility to be closed until the silver concentration is within acceptable limits. A copy of the the sewer authority or from Navy Public Works. methods that are used commonly in Navy imaging facilities are metallic replacement and electrolytic plating. resembles a 5-gallon bucket with tubes protruding from the cover. The system is inexpensive and well-suited for the small-volume user. is passed through the cartridge, the iron in the steel wool or wire screen replaces the silver ions in the fixer. The silver then drops to the bottom of the cartridge as impure metallic silver sludge. The iron ions in the fixer are drained from the cartridge with the fixer into a drain or holding container (fig. AI-1). percent of the steel wool is dissolved, the cartridge becomes inefficient and silver passes through the system. The cartridge is actually exhausted before the filter is completely dissolved. A metallic-replacement unit is capable of desilvering to a lower level than an electrolytic plating unit; therefore, some imaging the solution through the metallic-replacement cartridge for final treatment. Advanced Photography Course |
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