First of all, each cartridge that is recycled saves almost 3 pounds of natural resources associated with the production of a new cartridge.

Second, each inkjet cartridge that is recycled also saves an average of 3.5 ounces of oil. With the worldwide demand for oil on the rise and supplies shrinking, a little effort can make a significant impact over time.

The third reason you should recycle or reuse your empty inkjet cartridges is to reduce the strain on local landfills. An inkjet cartridge does not biodegrade in a landfill, as other waste will over time. Once a cartridge is discarded, it will be there for several hundred years.

It is estimated that over 300 million printer cartridges are disposed of in landfills annually. That creates 75,000 tons of waste each year, which is equal in weight to more than 30,500 African Elephants!

The forth reason is that recycled and remanufactured inkjet cartridges save money. Recycling your empty cartridges provides empty cores to cartridge remanufacturing companies that, in turn, professionally refill and sell to users at a discounted price. Consumers will see the same reliability, performance and quality as using an original brand OEM cartridge but at a lower cost.

Finally, recycling ink cartridges is fast and easy. Many companies that sell remanufactured cartridges either at the retail level or online also have a recycling program.
References :
http://www.asapinkjets.com/article-recycle-empty-inkjet-cartridges.html