Three billion dry-cell batteries are sold each year in the United States, and they appear in everything from toys to flashlights to smoke detectors. Some of these batteries are abundant in materials that are toxic to the environment and living tissue. Wet-cell batteries used in automotive units such as automobiles, boats and lawnmowers are even more dangerous. Recycling these batteries is an instrumental part of sanitation and conservation.
Types
Dry-cell nonrechargeable batteries are common disposable household batteries such as zinc carbon, zinc chloride and alkaline manganese batteries. These also include button cells, such as silver oxide, zinc air, lithium and mercuric oxide batteries used in calculators and wristwatches. Dry-cell rechargeable batteries include nickel cadmium, the safer alternative nickel metal hydride and lithium ion, used in laptops and cell phones. Wet-cell batteries include lead acid batteries used in vehicles.
Toxicity
The constituent parts of many batteries are laced with toxic materials and heavy metals that may be dangerous if deposited in a landfill. According to the Los Angeles County Department of Public Works, enough exposure to the cadmium in nickel cadmium batteries can cause blood and reproductive damage. And although most batteries no longer contain toxic mercury, button-cell batteries such as silver oxide batteries still do. Another toxic battery is the lead acid type, which is filled with lead and sulfuric acid.
Recycling Rate
The environmental organization Waste Watch states that the average person uses 21 batteries a year, yet only about 2 percent of consumer disposable batteries and 5 percent of rechargeable batteries are recycled. Lead acid batteries, however, are so toxic that they are recycled at a rate of 97 percent in the United States, which is the highest rate of any consumer product.
Collection
The Mercury-Containing and Rechargeable Battery Management Act, passed in 1996, formally legislated the proper collection of rechargeable batteries such as nickel cadmium and lithium ion. Two years earlier, the rechargeable battery industry had established the Rechargeable Battery Recycling Corp. with the intent to provide collection locations for used rechargeable batteries. Other types of batteries can often be taken by a professional, then sold or recycled by a household hazardous waste program sponsored by a state or county.
Recycling Methods
The method of recycling depends on the battery type. Lead acid batteries are separated into constituent parts, while the metals are processed through heat treatment and recovered in a furnace. Other batteries that undergo some form of thermal-metallurgical processes to recover metal include nickel cadmium, lithium ion, alkaline manganese and zinc carbon. Nickel metal hydride, on the other hand, is separated with a vacuum chamber to prevent hydrogen from escaping. The mercury in button-cell batteries is vaporized and reintroduced into the material cycle as a solid.
Material Reuse
Some batteries contain metals such as zinc and steel; steel can be reprocessed into rebar. The acid in lead acid batteries is neutralized and sent to a wastewater treatment plant to be cleaned for human consumption or is converted into sodium sulfate for laundry detergent. Polypropylene plastic is made into new battery cases.
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