Many of the hazardous waste problems that are created is due to lack of sufficient sites for limiting these problems to very small components. It is well established that to large extend many things can be burned creating CO2 and H20 as the main products. In sites that due this they have filters etc on the exhaust to collect Cl, S, N, and heavy metals. The filters, that mainly comprise of carbon, can then be chemical decomposed in the pure or semi-pure forms of the various atoms. This is rarely done since it is very expensive. But still just by liberating the carbon and water from the hazardous parts would make the problem decrease significantly. The heat created in the process can then either be used to create electricity or heat for further decomposition process. The principle here is very well established. The solution is money. Plain and simple. Taxes (high) in landfill sites would force people to you the available techniques.

I can recommend people to look into several of these sites in norther Europe for inspirations.
But again, money talks on this issue.