In chapter 2 (Optical), right at the start, go through the reception to see a vending machine. Get any drink from it and drop the can in the bin next to it. This will get you the Please recycle achievement.
Get a second can from the same vending machine, and then go into the reception room you just came through. In the dark corner (if you're coming from the vending machine room, it's at the back right) is a dark blue recycling box right next to another trash can. Put the second drinks can in the recycling bin for the Environment saved achievement. Now pick up the can, and take it with you through a couple of corridors until you reach a T-junction in a red-carpeted, white-walled room. Take the right turn and you'll see a large, 'rounded' bin with a lid and a hole in the side. Put the can inside THIS rounded bin for this achievement. It'll spit it back out at you.