Management of Used Antifreeze

The Problem With Improper Disposal

Antifreeze, which is comprised of ethylene glycol, water, and corrosion inhibitors, is toxic to humans and animals. Used antifreeze may contain metals that can contaminate soil and groundwater.

Hazardous or Non-Hazardous?

Used antifreeze is not regulated as hazardous waste as long as the metal content is not too high and it is not corrosive. (Corrosive means pH less than or equal to 2 or greater than or equal to 12.5).

Antifreeze will be regulated as hazardous waste if the results from the Toxic Characteristics Leaching Procedure (TCLP) indicate metal contents that meet or exceed the following limits:

Metal mg/L (ppm)
Cadmium 1.0
Chromium 5.0
Lead 5.0

To Help Prevent Pollution . . .

Filtration/Centrifugation: Solubles are filtered from used coolant, and the coolant is then heated and centrifuged to remove additional impurities. A corrosion inhibitor is then added.

Ultrafiltration: Used coolant is passed through a 5-micron prefilter and then through an ultrafiltration filter, which removes impurities as small as one half of one micron. A corrosion inhibitor is then added.

Chemical filtration: Includes filtration and chemicals to precipitate certain dissolved solids. Systems may include oxidation to remove dissolved metal oxides and salts or ion-exchange resin beds.

Vacuum distillation: Used coolant is heated to boil off pure ethylene glycol and water. Vapors are then cooled and condensed into liquid. A corrosion inhibitor is then added.

Ion exchange: After the used coolant is filtered several times to remove suspended solids, it passes through ion exchange beds that remove soluble metals and inorganic salts. A corrosion inhibitor is then added

If you are recycling off-site, contact the Office of Waste reduction at (919) 715-6500 for a list of antifreeze recycling companies.

The Wrong Things To Do . . .

Applicable Laws

NC General Statute 130A-309 banned antifreeze from disposal in landfills effective October 1, 1991. Legislation to ban antifreeze from muncipal solid waste incinerators was enacted on July 7, 1993, and became effective July 1, 1994.

For More Information . . .

This Fact Sheet is only an overview and may not contain detailed information suitable to your situation. Should you need further assistance, please call one of these offices:

Hazardous Waste Section, Raleigh: (919) 733-2178
Office of Waste Reduction, Raleigh: (919) 715-6500

For information on equipment for collecting and recycling used antifreeze or suppliers of such equipment or a list of companies that accept antifreeze for recycling, contact the NC Office of Waste Reduction at 919/715-6500 or E-Mail

The North Carolina Office of Waste Reduction provides free, non-regulatory technical assistance and education on methods to eliminate, reduce, or recycle wastes before they become pollutants or require disposal.

OWR-96-02. January 1996.