With proper filtering, the problem here is that in a typical refinery, you do not filter the kind of compounds released by these new plastic handling processes.

With proper filtering, the problem here is that in a typical refinery, you do not filter the kind of compounds released by these new plastic handling processes. You filter out mercaptan, H2S, CO2 using post processing gas treatment like amine cycles. This is because you have a very clear process line, which has not changed in the past 100 years or so. You basically separate from the raw oil what is already good from what needs more processing. What needs more processing is simply "cut in small pieces and possibly recombined" to get more out of your feed. The new processes try to "keep" more good molecules from the "plastic feed", this leaves more room for loss of good molecules for the chemical use downstream but bad for the environment if not filtered out. Burning everything to make electricity/heat is what you have everywhere in Europe (at least) and this cuts "everything in small pieces" and as such you can use normal gas treatment down the line. The gas treatment is expensive but effective. Update: I am surprised the EPA is so lax, the US is way stricter than the EU for normal emissions from refining.