Trash bins in China come in pairs now. One is for recyclables and the other for stuff that can't be recycled. That's a good step forward, compared to what it used to be -- one trash bin for all.

Beijing airport. Photo by Nina Ying Sun

But does the public know what is recyclable and what isn't? Not really. In Shanghai, I saw people throw things in without looking at what is what, and I also watched bottle collectors dig out PET bottles from both bins.

I thought I knew more about recycling and plastic than the average person. But when I had a plastic bag to dump, I couldn't decide which bin.

The Japanese system, in comparison, is much more user-friendly. A park in suburban Tokyo. Photo by Chen Lin

In the photo, from left to right, the first three bins with pink signs are for trash that can be incinerated; the next three in the middle with blue signs are for PET bottles; the next two ones with orange signs are for metal cans; and the one on the very right is for all other types of trash.

But don't always expect a fleet of nine trash bins in Japan. This sign in downtown Tokyo actually asks people to take their trash home. And there were no trash bins on that street. Tokyo downtown. Photo by Chen Lin

What's more impressive than the system itself is how well people abide by the rules and keep the world's second most densely populated country clean and efficient.