I have to wonder how all that waste got there in the first place. Think about how much material could have gone into constructing the Death Star and then just consider how much it would cost to send that material into space. How could you afford to throw all this stuff away if it can be recycled? Surely the galaxy far far away has a need to conserve materials for the war effort against the rebel scum?
Obviously Grand Moff Tarkin is not concerned about the environment... After all, he did blow up an entire planet.
But waste is not confined to the Imperials. While most large organisations are making a conscious effort to reduce waste for both environmental and profitability motives, the message does not get through to everyone. Ever go to a meeting and get handed an agenda only to see that same agenda displayed on a projector screen throughout the meeting? What about having someone hand you an email they printed out with some comments on it? It still happens...
I'm not saying that paper no longer has a place. The current hype surrounding e-books may have you thinking that books are going the way of the scroll. We were reliably informed that offices were going paperless too... Making the best use of information regardless of the format is the goal. That means not printing material that is born digital unless you really need to and not digitising print material unless you can clearly gain something from the effort.
Fortunately the waste disposal has a door (why?) and our heroes are about to make their way out. Meanwhile Obi Wan has a business meeting with Darth Vader.