Except in California, alkaline batteries such as AA, AAA, D and 9-volt, can be placed in household trash. Most of other types, including button-style watch batteries, lithium ion batteries, nickel-cadmium batteries and sealed lead-acid batteries, must be taken to household hazardous waste facilities for disposal. Auto parts stores often accept worn-out auto batteries from customers who purchase a new one.
Many batteries contain heavy metals such as lead, cadmium, nickel and mercury, which can pollute the environment. In landfills, heavy metals from batteries can leach into soil, surface water and groundwater. According to the website Environment, Health and Safety Online, dry cell batteries contribute nearly 90 percent of the total mercury and half of the cadmium found in the municipal solid waste stream. A typical car battery contains 18 pounds of lead and a pound of sulfuric acid. Mercury was removed from alkaline-style batteries in 1996, making them safe to place in household trash and community landfills. Alkaline batteries still contain common metals such as zinc, manganese and steel, but those materials are not considered risky to human health or the environment. Many U.S. retailers, including Alltel, Best Buy, Cingular Wireless, Home Depot, Wal-Mart, Radio Shack and Sears, accept rechargeable batteries for disposal or recycling.