I recently posted an entry for @daltono's #PredictTheFuture Challenge and while working on the entry post I was obviously spending time thinking about the future. Due to the way I set up my entry post I restricted myself to the future of a home setting. Without that self-imposed limit I could have expanded further in my worldbuilding to a larger geographic area. Some of those areas wouldn't change much though. For example, the city landfill.
I can imagine a scenario in which landfills will be mined in the future by tiny robots. Nature already has created its own version of waste reclamation through various insects and worms. Fundamentally there should be no reason why humans couldn't copy that process artificially. If you read the Wikipedia entry for landfill mining you'll see that the process as it currently exists requires a lot of manpower and brute force. It's also rather inefficient and can cost more than the value of what could potentially be recovered.
I can imagine it happening but I am pessimistic about how realistic that scenario would be.
No matter how soon advancements in miniaturized robotics and artificial intelligence occurs I think it will be many more years beyond that before I can hold in my hand a plastic cup whose recycled material came from a plastic container that had been buried for twenty or thirty years before robots dug it up.
When one imagines what is buried in a landfill it can be disgusting. Disgust is a psychological response that has evolved for protecting us from infection through disease avoidant behavior. That's what my $115 college textbook claimed.
When I was taking a psychology class at the local community college I read about the psychology of disgust. I remember that there was a study in which participants watched apple juice being poured into a brand new bedpan and were asked to drink it. Even after seeing the bedpan being taken out of its sealed store bought box and seeing the sealed store bought apple juice bottle being opened most of the study participants still associated apple juice in a bedpan with disgust. It wasn't urine but as far as the participants were concerned it might as well have been.
If humans can't handle pure apple juice in a brand new unused bedpan than how would they respond to a drinking cup made from a recycled plastic toy that had been in close proximity to a dirty diaper since the Clinton administration? It doesn't have to be a drinking cup. Generally anything you can hold in your hand that is made of plastic or metal. You can sterilize and irradiate the plastic refuse as much as you want before you shred and melt it down into pellets but maybe it still wouldn't matter to most people. As my college textbook stated the disgust response is a matter of how you frame it in your mind. Maybe most people wouldn't overthink it like I am.
Right now the inefficient method of landfill mining for substance is mostly for construction material. That can be "out of sight, out of mind" for most so disgust might not be a factor there. When I hold a plastic or metal product made from 100% recycled material; like most people I imagine it originated from someone dropping off their sorted trash at a recycling center. That's the way I frame it in my mind since robots digging around a landfill like ants, breaking down plastic and metal into smaller pieces to be carried into a pile for processing, isn't happening. Would I mentally frame it differently in the future when that level of recycling is possible? Astronauts filter urine to be reused as drinking water. That doesn't mean I do that when a faucet is an available alternative. Neil deGrasse Tyson can joke all he wants about how the water I drink has gone through other people's kidneys at some point in the past. The Coca-Cola company won't advertise it's Dasani water as 100% recycled in those terms.
I'd like to think that I could handle a drinking cup made from landfill material that was sterilized and melted down for reuse. Honestly though it might take some effort on my part to overcome the psychological hurdle. That's not the fault of the company using the recycled landfill plastic to make the drinking cup. It's their problem though because if I have an issue with it then I am not buying the plastic cup. Not only would that company be selling plastic products it would also have to educate the public so their minds don't associate their products with literal trash.
Do you remember everything that was in the garbage bag you hauled out to the apartment building's dumpster on March 11, 2003? The drinking cup in your hand full of water right now was made from processed plastic that was in the dumpster that day and it may or may not have been some plastic from your trash bag. It might have been from your neighbor's trash bag. As far as chemistry goes there is little difference between plastic recycled from a recycling center drop-off or an old landfill recovery.
Will you drink the water?
In the Star Trek franchise replicators use matter-energy conversion to synthesize molecules. Replicators don't simply shuffle around atoms. The in-universe explanation is that the underlying principle is similar to transporter technology. I suspect though that at some subconscious level the writers understand the disgust psychology. Several episodes have explicitly referred to how dirty dishes should be returned to the replicator to be broken down back into subatomic particles. Breaking something down to its subatomic components is as sterilized as something can get before its mass is reused.
I hope I am wrong but I think humans will end up leaving the majority of what is in the landfill for future archeologists or until the Sun uses up the last of its fusion material and expands to engulf the Earth. The robots that could be mining the landfills will probably be sent to mine the Martian and lunar regolith instead.