[marshray]

I'm don't think we really know yet what the energy requirements for these processes are.

Ever had something plastic melted (and burned) by the dishwasher? Why not just melt all of it and avoid dumping all the energy in that steaming water down the drain?

[eftpotrm]

Well, you're dumping waste heat either way, and at too low a difference to ambient to be efficient to extract, but while I'm not an expert in the energy usage of 3D printers, I find it very hard to believe that reducing an item to granules and then recreating it from the same granules can be particularly energy efficient from the perspective of information theory.

The other side which I should have considered before is that if the purpose of this is cleaning (as was originally suggested), reducing the item to parts to reassemble without first cleaning it will result in contaminated build components and a lower quality physical product, but with the contamination spread liberally through the item rather than being on the surface where it can be more easily cleaned away.

[marshray]

This is probably far enough away that we can get a little handwavey about little details like contamination.

What if instead of a water heater you had a plastic heater in your house? What if it had some section where the temp was high enough to kill organisms or used other means?

Still it seems like I'd want to give them a quick rinse-off first.

Perhaps everyone's eating utensils will end up some shade of brown. :-P People would likely want some very dark pigments added. Or "junior! we told you not to put Froot Loops in the dishmelter again..."

Or maybe the stuff just gets hauled off for recycling where it can be re-purified efficiently in large scale processes.