As I understand it, the real issue with "clean coal" is not the soot but rather the CO2. Depending on what this garbage actually is, the CO2 problem isn't really a problem in this case.
The study emphasizes their focus on composting for food products and recycling everything else, so a minimum of waste needs to be incinerated or dumped. Also, Oslo closed their landfill in 2007, and it seems they burn the residual gasses (methane?) for electricity, if not burning all of their old trash. The report focuses on home recycling requirements, but does not mention commercial or industrial waste, which are by far larger generators of waste.
So, it seems likely that the incinerated waste is not "in-system".
That doesn't make it better. We have too much carbon in the atmosphere. We should be growing corn for the sole purpose of pouring it into oil wells and coal shafts.
Dumping corn down mineshafts seems like it would be pissing in the ocean. Maybe instead of pissing in the ocean we should be experimenting with dumping fertilizers and nutrients into the ocean to trigger algae blooms. If that works as the theories say it should, and is seen to have acceptable consequences, that is something that we could actually do at scale (and without further subsidization of corn...).