Earlier quoted context omitted.
Is incineration of plastic really better for the environment than a landfill? And would the ash not go to a landfill of sorts?
A modern plant turns plastic into CO_2, electricity, and, often, residential heat. So, yes, that's preferable. Among the sheer ugliness and wastefulness of landfills, burning at high temperature avoids the toxic intermediates plastics give off when degrading in nature, which landfills struggle to contain. Ash is, by definition, inert. It is the remaining mass that does not chemically react even under extreme heat. It…
You're correct that sufficient incineration temperatures ensure the complete destruction of organic intermediaries, such as dioxins.