The ash can be used as an ingredient for concrete.
…or what if we just bury the stuff deeper ? Under the mantle somewhere. Wouldn’t that effectively recycle the mass?
And what do we do with the exhaust? You can’t put filters or scrubbers on rocket engines…
Incinerator Ash is often considered a “hazardous waste” because of heavy metals, such as lead. The ash must be tested often to see whether or not it’s safe to go to a normal (lined) landfill. If it tests hazardous, then it’s treated as a hazardous waste, which is VERY expensive to dispose of.
Here’s a link to the EPA’s website on municipal waste disposal.
Also, the State of Florida, which operates several municipal waste incinerators, has noticed an increase of hazardous lead in soil near the incinerators.
Check out this article on thermal depolymerization: http://www.discover.com/may_03/gthere.html?article=featoil.html
It is a process to break down the molecular bonds of material to convert it into oil, useful gasses, and minerals.