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.