Isn't keeping different types of waste sorted inherently useful in other ways?
And more detail: This is how household plastic is recycled: Collected plastic packaging is first finely sorted in Germany, before moving on to recyclers in the same country or elsewhere in Europe. We differentiate between the recycling of household plastic, which is the plastic you sort at home, and plastic packaging from businesses. - The plastic packaging you sort at home is collected by the municipality or an inter-municipal waste company. They press the plastic together into large bales. - Plastretur transports the plastic to a sorting facility. - At the sorting facility, incorrect sorting and contaminants are removed. This can include paper and metal, or other items that ended up in the wrong collection at your home. - Additionally, the plastic is sorted into different qualities, and non-recyclable packaging is removed. The sorting facilities classify the plastic into several plastic qualities such as PP, LDPE, HDPE, PET before it is transported to a recycling plant. - At the recycling plant, the plastic is washed. This process also removes labels and glue. - Then it is ground and melted into small beads, called pellets. Pellets are a raw material that can be used to make new products from recycled plastic.
This really is the key - if people weren't so scared of incinerators, the "landfill" problem would be basically solved.
Seems like a perfect machine learning/robotics application, but probably not one that will receive funding if it's pitched with the objective of, "look now all of this problematic crap is in one place."
Even so, you think there would be no worthy efficiency gains for pure sorting or materials mining in using machines that can identify known objects effectively, and hands that will go where humans will not?
Some places incinerate their waste for energy. If done well, pollution (except CO2) is minimal, and the outputs are energy and ash. Perhaps some day the ash could be processed to extract useful minerals.
More generally, if you imagine waste to be a clumpy soup of organic goo, assorted interesting elements and minerals, and polymers (which are technically organic goo but are sort of worthy of a different category), perhaps it could be treated as such and processes could be developed to economically extract useful things from it, kind of like how geological processes turn dead cells into oil.
But I see no fundamental reason that, say, old polyester needs to turn into new polyester as opposed to anything else. And keep in mind that, even if burnt to CO2 and ash, there are processes that use energy that turn CO2 into valuable chemical feedstock.