PLEASE don't just throw it in the trash. That's like throwing away batteries. Everybody does it, but it's an environmental nightmare...
Alkalines/Heavy Duty/General Purpose are okay to put in the trash. Only downside is that they take up space in the land fill. There's really nothing harmful in them.
Ni-CAD, NIMH, Lithium Ion/Polymer, Silver Oxide, Sealed Lead Acid and regular lead acid batteries are a big no no in the trash. They are very harmful to ground water etc.
There are VERY few companies that recycling Alkaline batteries. The reason? No money in it and they're not harmful. Nickel based cells can be broken down. Silver Oxide batteries contain silver which can be scrapped. 80% of your new car batter is made of recycled materials, a good majority of it being lead and the plastic casing.
If you're talking your alkalines to a local retailer to be recycling, the dirty truth is they're probably recycling you're nicd/nimh/li-ion etc batteries in your bag, but their alkalines are getting tossed. Most retailers are not paying for the recycling. Recycling companies generally provide recycling boxes and shipping free of charge to retailers because they'll make money from recycling. But like I said before, there's no money in alkalines. I've been in the battery business for a few years now and there is quite a low number of the general public that knows what goes on for recycling, both in batteries, materials, and lighting/fluorescents.
