This is an alternative to the those incinerators that are being installed for processing collected rubbish but questionable net merit. A city pyrolyser would yeild tar and char for sequestering carbon as well as removing pollutants from the environmnt.

The feedstock is noxious and wet and will need preprocessing to make it suitable.

The main output will be char. Not very nice char and probably not suitable for Terra Preta but in huge quantity and with the same capacity to absorb organic chemicals (particilarly forever chemicals) and available .

So why not use it for decontamination?

I have suggested sewage as part of the feedstock. It would only contribute a small fraction of the input, but is full of nasty stuff which would get decomposed or locked into the char.