As far as we could tell, separating of recyclables from trash is still not done by residents, but remains the job of "cartoneros", who nightly go through trash on the streets in search primarily of cardboard and paper. Plastic bottles take up too much space in the large bags they pull around, so generally go uncollected. The one change we noticed is that the trash put out for pickup is now placed in plastic dumpsters--several per block--which the cartoneros then pick through. They used to tear open plastic bags of trash left on the curb, which made a mess.
Each cartonero may have a different kind of rig to haul recyclables around, but the collective operation is much more organized than it appears.
Princeton's version of this takes the form of guys in old pickup trucks occasionally cruising residential streets in search of scrap. I can put metal objects out on the curb of busy Harrison Street and have them gone within an hour. We also have "gentleman scavengers"--residents who certainly could afford to buy what they need, but snatch up useful items left out for the trash, whether for the sport of it or an aversion to seeing good merchandise hauled off to the landfill.
Milk is irradiated, which means that it need not be refrigerated until opened. On this FDA webpage, I didn't find milk listed as approved for irradiation in the U.S.
Argentine homes are often heated not by forced air but by gas heaters in each room. The advantage is that only rooms being used need be heated, and one can get closer or farther from the heat according to one's preference.
One big change in Buenos Aires is the bike share program. Two-way bike lanes have been installed on one side of many streets, making it much easier for bicyclists to get around in this mostly flat city. In a moment of irony one evening, I was in the midst of a celebratory thought about the increase in bike use when I was struck by a bicyclist. We were a bit traumatized but unhurt. I think she was running a red light, but I could have been more observant. Bikes add one more thing to watch out for on the busy city streets.
Here's a bread-delivery vehicle.
I'm always checking out how small a tree other cities plant. With disease taking a toll on Princeton's street trees, and the devastating Emerald ash borer likely to soon begin claiming Princeton's most common tree, the ash, we may need to stretch dollars by planting smaller replacement trees than in the past.
Along Buenos Aires' central avenue, Nueve de Julio, with its obelisk and one side of a building devoted to the image of Eva Peron, grass is losing out to perennials (always a good sign). The central median, formerly verdant with trees like the Palo borracho (borracho means drunken, in reference to the trunk's bottle shape) have been cleared to make way for dedicated lanes for buses.
A similar post on sustainability in Mexico City can be found here.