Recovery of silver from radiographic fixer

This study examined the silver content of 10 brands of dental x-ray film that are commercially available in Japan. Kodak Ektaspeed EP-22 (Eastman Kodak Co., Rochester, N.Y.) was found to have the highest silver content, and SD 100 Gold X-ray Film (San Dental Co., Ltd., Tokyo, Japan) had the lowest content of silver. Electrolysis and ion exchange were used as the methods of silver recovery from films in the general dental office. Ion exchange was more than 99% efficient in silver recovery from the radiographic fixer and resulted in an 80% reduction in biochemical oxygen demand and a 95% reduction in chemical oxygen demand. However, these levels and other environmental pollutants were still above the limits set by the Japanese Pollutant Control law.