Why can't recycling be sorted from trash?

It can, and these facilities are called “dirty Materials Recovery Facility”, where recyclables are sorted from trash, but there are very few facilities that operate this way. The recycling systems are more efficient when a “clean” product of only recyclables is put in. The “dirty MRFs” sort out recyclable items from the trash, but some recyclables are so contaminated by trash that they are no longer recyclable.  As a result, dirty MRFs are not as efficient at sorting as MRFs that only accept recyclables. In order to be the most efficient and cost effective centers, most recycling centers only process recyclable materials. Our campus recycling is sent to a MRF that sorts recyclable materials only.