From: Debra Jacobson(email@example.com)
Date: Wed, 14 Aug 2002 06:39:28
Forwarded from the P2Tech listserv. There has been an interesting discussion about the subject of metals in printing ink.
I would just like to add one caution for listserver members: many states consider copper and nickel to be hazardous metals, whose presence in printing wastes may be subject to regulation. For example, in California, waste solids with copper concentrations above 2500 ppm and nickel concentrations about 2000 are regulated as hazardous wastes. For waste solutions (like ink waste), concentrations of copper above 25 mg/l or nickel above 20 mg/l make the waste hazardous. In the wastewater arena, levels of concern are even lower, often at or below 1 ppm and sometimes on the ppb level (for rare direct discharges to receiving waters). Even though many inks are still solvent-based, it is amazing how these metals can wind up in wastewater discharges from printers at levels that subject the printers to strict regulation by water quality agencies.