Here in California, waste management is moving toward single-stream collection. You put all the recyclables in a signle bin, then they are collected and transported to transfer stations or material recovery facilities, where they are separated.
It could be a lot more work to separate already mixed recyclables. Plus, the recyclables could get contaminated on the way. There are the advantages to separate the materials as early as possible. But I know we only have one single recycling bin at home. Where to bring source separated items then?
Grocery stores could be the place.
Grocery stores in Japan has source separated collection box for plastic trays, PET bottles, milk cartons, alminum cans etc.
People usually clean those recycables before bringing in.
Recycling industry is sort of difficult to track (it could be happening in the third country), so I am looking for the information regarding the relationship between "purity" of the feedstock and the quality of secondary materials to demonstrate the benefit of early source separation.
photo source http://www.city.kawasaki.jp/30/30genryo/home/index/honbun/koudou.htm