The Dangerous Waste Regulations identify chemicals and specific waste streams as dangerous wastes. If you have a waste on the list, it’s a dangerous waste.
F waste codes are the most common waste codes. They include spent solvents, like those that are dirty from cleaning or dissolving something. "F" codes also include several process wastes, like the wastes generated from cyanide-based electroplating.
"K" waste codes are from specific industries or sources. You won’t have a "K" code unless you use a process described in the "K" list. Some examples are wastewater sludges from treatment processes or distillation bottoms. Industries on the "K" list include pulp and paper mills, wood preservation, iron and steel production, and a few others.
P and U codes
Waste codes that begin with "P" or "U" are for discarded chemical products—unused, commercial products that become waste and contain only one active ingredient. "P" and "U" codes aren’t that common and mainly come from labs or medical facilities.
Acutely hazardous "P" listed chemicals are more toxic than "U" codes and are more stringently regulated.
"U" listed chemicals are less stringently regulated.