Laboratory tests of the wastes help to specify in more detail the number, type, and amount of each pollutant present, as well as the relationship to established minimum and maximum exposure safety standards. This is frequently referred to as a TCLP Test. The wastes can come from any number of sources in the average printing and finishing facility. Pressrooms and photographic darkrooms generate many wastes, some of which are classified as hazardous. Some enter the process as chemicals, others as a part of the product used during the process.
Darkrooms generate photographic wastes.
Fixer solution washes the silver off of the film and paper during developing. If the fixer that is discharged from the developing system contains more than five parts per million of silver, that liquid is now a hazardous waste. Better management practices in some areas require the use of silver-halide filtering systems to reduce the silver to a lower concentration. This practice works where there are sewers, but is unacceptable in areas that are still served by septic tanks and cesspools. Photographic film and paper contain leachable silver in the emulsions.