One of the interesting notes in the article is that they apparently use a lot of oyster shells. I would assume the shells are typically a waste product in other (likely food) industry processes. That's pretty darn green. Besides, we have a lot of limestone, veritable rock-oceans of it.

That's part of why it's incredibly difficult to talk about waste on industrial scales. One plant's garbage is frequently another's input. Waste is expensive, so plants will always try to reduce it to the bare minimums, and if possible make money off it, in the case of certainl classes of recyclables.