Physical Danger
You're around giant machinery. Of course it's dangerous (source).
Specifically, let's start with the recycling trucks. Ever see those? You have all the dangers you associate with giant trucks, and then throw in robotic arms and a compactor container. Yeah, those things are terrifying.
Wait, it gets worse. Assembly lines can be dangerous as well. The stuff being conveyed on them isn't exactly sterile in a recycling plant, so infections are also a worry when dealing with mounds of trash.
Working in the recycling plant can cause motion sickness of an extreme variety. It'll be worse for the people on the line, but if you end up staring at the belts, you may find your experience of movement distorted by the machinery. Your body will be still, but your mind will be zipping down the road. Vomiting on the assembly line isn't uncommon—and you can't recycle barf.
We saved the best for last. The belts include junctions of twisting metal teeth called screens, which sort the materials by weight. And the excess of teeth doesn't produce a pretty smile, but rather a swirling vortex of bone-crushing pressure. So...yeah, advising you to just "be careful" around those would probably understate the dangers a tad. Try to curb your nightmares, too.