Why is it important to dispose of batteries in a certain way?

According to various government agency websites (National Forest Service, City of Chicago) regular batteries are not considered hazardous waste and can be discarded in the regular trash. That includes alkaline, manganese, and carbon-zinc batteries. The reason alkaline batteries were classified as hazardous was due to the Mercury content. Mercury has been phased out in those batteries, so they are no longer an issue. Rechargeable batteries (Ni-CD) and lithium and button batteries could still be recycled, but places to drop them off might not be available in your area.

Automotive lead acid batteries cannot be sent to landfills.

Other thoughts on the subject:

• Because they polute the soil and don't disintegrate. Use rechargeable batterys to prevent polution.
• Because when the people proses the garbage using big machines to squish the garbage the gas of the battery will leak and so thing horrible will happen.