Single use Alkaline and Carbon-Zinc Batteries (AAA, AA, C, D, 6V, 9V) are wasteful, but not hazardous. Dispose with trash. If your trash goes to Covanta SEMASS, the metal is recovered. All non-alkaline batteries contain hazardous and/or valuable materials. Since it takes about 50 times more energy to make a battery than you get out of it, it is better to use Rechargeable Batteries.