I think I remember from one of the LHR documentaries that (some) dry waste off aircraft gets incinerated and heat and power for the airport is recovered. I’m sure the “system” at outstations in the developing world, or anywhere to be fair could be more dubious...
I carry my own bamboo/wood cutlery and steel straw around and about to allow me to refuse plastic but onboard admittedly not personally sending a cutlery pack or two to waste is a challenge.
Airlines etc could easily do a lot better I hope they are made to quit disposable plastic before very long.