How to dispose of used ion exchange resin is determined first and foremost by state and local government agencies. Regulations do vary from state to state. To satisfy local regulations it is recommended that you or your environmental manager call your regular waste removal company and ask them what to do.
Generally, used ion exchange resins are dumped in landfill (or tailings dams) in the exhausted form, typically in the Na, K, Ca or Mg form for the cation resin, and Cl, CO3 or SO4 for the anion. The resin in this state is non hazardous and will eventually break down into the soil.
Municipal or City Treated water contains little or no contaminants that are harmful to drink; therefore, it is unlikely that used resin with this feedwater has any contaminants on it to prevent it from being land filled as ordinary trash. Therefore exhausted resins with these feedwaters and domestic softening resins can be safely disposed of in general waste.
Well water and untreated surface water supplies may contain contaminants that can remain on the resin after regeneration. These contaminants are usually metals and are found on the cation resin. They may include but are not limited to lead, copper, and arsenic. For more specific information about contaminants you should refer to the epa site. The disposal of resins in the H or OH form where there is a risk of acid or alkali leaching, or where the resins have been used for non-traditional water purification uses, and may be contaminated with heavy metals or radioactive anions or cations, then the nature of the contaminant determines the safe disposal method :-
Acid or alkali – treat with alkali or acid to render the resin into the exhausted form, while generating a neutral elutant. Dispose of the exhausted resin in the normal way.
Heavy metals – concentrate the heavy metals through regeneration, then treat the resin as for acid or alkali. The concentrated heavy metals will be subject to specific regulations.
Radioactive contamination – check with the federal regulations, but these would be stored in an approved facility until the radiation flux meets the regulated maximum, then they may be disposed of according to the appropriate regulations.
Most likely the waste removal company will ask for an MSDS on the ion exchange resin you want to throw away.