For those who actually clicked on a mod idea regarding trash, here you go:
A mod where you have to pay attention to what you do with the things you use and eat. When you eat any food item you will be returned a set amount of "scraps" that you have to deal with, this mod will make it so you can't burn things in fire, lava, or use a cactus, etc. to get rid of things. You have a choice that represents real life, recycle or landfill. When you drop these "scraps" on the ground they don't just float like tiny items until you pick them up, they would turn into a small blob of garbage (for this I think just changing the snow fraction block texture and using that would work). You could either turn these scraps into compost and then bonemeal (or something else) which would require patience and the use of special equipment to do so, feed it to animals and get manure (more fertilizer), or make a landfill, which could have negative effects like having mobs spawn from piles of this trash or something.
Functionality-wise this mod would have to:
Change the way this special item works, no despawning, turning into a block of garbage when dropped, not being destroyed by fire or other things, perhaps turned into a black blob of unusable garbage.
Add things to help recycle these scraps like a compost pile (not like the one in the new update that instantly turns food into fertilizer, I'm talking a more realistic one) or a shredder to turn it into food for animals.
I have played minecraft for about 10 years now and it has had a substantial impact on my life, and hearing as how it has become an educational tool for some schools I think a mod like this would be interesting. Making students realize that you can't incinerate all your garbage and that it actually has a use to you, as well as having people be unconsciously aware of their own relationship with the environment.
If anyone seems to like this idea at all I'll go into depth of how exactly this mod could work, I've got a few ideas with my basic knowledge of modding. So lemme know.