What must be done to x-ray fixer prior to disposal?

Removing silver from x-ray fixer before disposal is important because x-ray fixer contains silver, which can be harmful to the environment. Silver is classified as a heavy metal and can cause toxicity to aquatic life and ecosystems if released untreated. By removing silver, the fixer can be disposed of in a manner that is less harmful to the environment. This process typically involves using silver recovery systems that capture and extract silver from the fixer, allowing for safer disposal or recycling of both the fixer and the recovered silver.

Other options do not address the environmental concerns associated with the silver content in x-ray fixer. For example, adding water could dilute the solution but would not eliminate the harmful silver, while diluting with bleach could create hazardous reactions and would still not address the silver issue. Cooling down the substance does not relate to the necessary steps for safe disposal and would not affect the environmental impact of the heavy metals present in the fixer.