Powder carbon, known commercially as carbon black, is a powdered form of carbon. It can be found in tires, plastic products and printer ink and ink cartridges. Ranked as one of the "Top 50" industrial chemicals manufactured, carbon black does not break down but it is also non-toxic. This means disposing of the powder locally should not be problematic. You may have loose carbon powder or a substance that contains the carbon black, like an ink cartridge.
Check with the company who sold you the powder carbon about proper disposal of carbon black or carbon powder that has been chemically treated or is water dispersible. Alternately, ask your municipal waste station about disposing of these types of treated powder carbon. If you aren't sure whether the powder carbon has been treated, ask the manufacturer or review the material safety data sheet that came with the powder carbon.
Follow the advice given to properly dispose of treated types of powder carbon. Take care to pick up dust particles created by sweeping up, moving and throwing out the powder carbon.
Take powder carbon that is not chemically treated to your landfill or dispose of it in household garbage. Although not biodegradable, this type of carbon is non-toxic and safe for landfill disposal, per the International Carbon Black Association.
Take care to dispose of loose powder in a sealed container and wear a face mask while putting it in the container so you don't inhale dust.