I would say the most strategic challenge, right now, is the sorting of aluminum coming from streams such as automotive or consumer packaging.
You either avoid using multiple materials, including aluminum, when designing packages—in order to enable tracking the aluminum and bringing it out of the stream—or have the challenge of sorting the various materials downstream and being able to disassemble the materials from one another. A good example is the Tetra Pak container, which has layers of different materials. It's a very complex type of container to deal with when you want to recycle the materials optimally.
It can be in the design, which is smart to do. You can do it upstream. You address the issue when you design the container, package or object. If you don't do that, you have to accept the challenge of dealing with it downstream at the end, when it's very complex. It has been used, so there are contamination problems and stuff like that. You have to choose your challenge.