On Recycling (in San Francisco)

A geek’s peek into the blue bin

As a kid, I vividly recall roaming the woods near my house and stumbling by accident upon giant trash piles, forcing me to face a truth that seemed simply absurd at the time: refuse simply accumulates. Reflecting back, I think I must have had an implicit mental model that the things we consumed were part of a mysterious cycle of reuse — though the word ‘recycling’ hadn’t yet entered the French vocabulary back in the 80’s (the first recycling mandates date back to 1992). Growing up, I developed a strange fascination with trash. My father worked at a paper production plant that chiefly used recycled paper as source material, and I later worked briefly at a German recycling facility that doubled as a bottle production plant. (Working on quality control for German beer production seems glamorous, until you realize it’s mostly about keeping rodent parts out of the final product…)

Until China decided to essentially close off its imports of material to be recycled under its National Sword policy, I likewise never gave a second thought to the fate of the stuff I put in my blue bin in my current home of San Francisco. The idea that recycling in the Bay Area largely gets sent overseas feels as absurd to grown-up me as the absence of recycling felt to my younger self.

The arcane rules that govern residential recycling also puzzle me: yes, there are guides everywhere telling you how to recycle, but I feel that roughly half the time I approach my recycling bin I have a situation that doesn’t quite fit the neat, easy pattern that’s described in the cheery online videos our local garbage collection company produces. Combine that with the fact that the rules seem to widely differ between neighboring cities in the Bay Area alone, and it became clear that I really didn’t get what was up with trash.

So I did what my inner geek nagged me to do for years: I went to visit one of our local recycling centers. And the story I discovered turns out to be an interesting tangle of economics, technology, and regulation.

Yes, China stopped accepting low-grade recycling, but thanks to a seemingly fortuitous upgrade of our local facility, the flow of material hasn’t been entirely cut. The narrative about the economics of sending trash to China has always been, at a very high level, that China sends lots of goods to the US, and that those ships which would otherwise return empty can be filled cheaply on their return journey, making the economics of sending recycling overseas extremely attractive. Where this narrative breaks down somewhat is that, when China no longer takes the material, it is sent to other southeast asian countries, which presumably don’t have the same shipping imbalance with the US. So really, the crux of the economic equation appears to be more a lack of a domestic market for these base recycling materials, which of course could itself be a consequence of the cheap China markets. Thus the question is whether a local market may now develop as a result of the change in economics. The tone in the press is definitely pessimistic, but it’s always hard to bet against market incentives.

The most valuable commodity in recycling (in San Francisco) appears to be aluminum. This was on display at the facility I visited, with a dedicated, labor-intensive line dedicated to separating aluminum. From an environmental standpoint, recycling aluminum, given its ‘infinite’ reusability and high upfront carbon footprint (due to its energy intensive production process), makes a lot of sense. Should you clean your aluminum foil before tossing it in the recycling? No: scraping food off of it is enough, the recycling process is still high-enough temperature that organics are not a factor. Should you compress your aluminum into a ball? Yes! Open foil may not be caught by the sorters that rely on Eddy currents to separate them from ferrous metals. Should foil be separated from other material it may be attached to? Yep, the plant doesn’t have a way to do it for you. If you’re wondering if there is a chance that a can tossed into a non-recycling bin will ever make it to a recycling center, the answer is a resounding no: there is absolutely no attempt being made at extracting valuable material from what makes it into the black bin.

The next most valuable material is cardboard. Cardboard will not be cut or shredded at the recycling center, so one issue is large Amazon boxes that haven’t been cut up may jam the machinery. The other issue is cardboard that has touched food: it’s entirely useless and is considered a pollutant. This means that pizza boxes and any to-go boxes actually belong in the compost, which I didn’t expect.

Compost is actually something of relatively high value, in that there is essentially infinite demand from the farms and vineyards around the Bay for it. The processing being done to ‘clean’ compost of non-compostable material appears to be surprisingly crude, however, and rely a lot on your keeping your green bin free of non-compostable material. In particular, there is no way to differentiate compostable plates, cups and utensils from plastic ones, which makes separating them post-facto a bigger challenge now that compostable utensils are becoming popular.

Interestingly, paper has very low value in contrast to cardboard, due to its lower fiber strength making it less amenable to recycling. This seems to be very dependent on the geography, as paper recycling was essentially what put food on my table as a kid.

Another marked difference with my European expectations is glass: glass recycling here is of very low value, because it has to be transported long distances and is comparatively heavy. This is an interesting conundrum since glass needs a lot of energy to be recycled, and isn’t a pollutant like plastics, which means it would be tempting to call glass recycling, at least in the Bay Area, a waste of everyone’s time.

The most interesting conundrum however is plastics. Don’t let the presence (or absence) of a ♲ symbol mislead you: it apparently has little bearing on whether something can or can not be thrown into the blue bin. There are roughly two kinds of plastics to consider: hard (they bounce if you drop them) or soft (like plastic bags). Hard plastics are always fine to recycle. Soft plastics are interesting because until relatively recently we were told not to toss them into the recycling. There was a big announcement not long ago that it was now ok to put them in the bin, with a catch that was lost on most people: all soft plastics have to be bundled together into a basketball-sized bundle. The kicker is that, as far as I can tell, that rule exists so that the sorters at the plant can catch them easily, and throw them out of the recycling line. That’s right: your recycled plastics bags don’t appear to be recyclable after all. Soft plastics are the scourge of the recycling plant, polluting the other class of materials, and more importantly, jamming the equipment. In fact, a large fraction of the plant’s processing appears to be devoted to keeping soft plastics out. Why accept them in the first place? That decision appears to be a mandate that has more to do with political wishful thinking than the existence of a plausible recycling strategy for this class of materials.

One aspect which intrigues me, and which I don’t know how to quantify, is the impact of the side economy that’s developed in the Bay Area around picking up recycling from public trash cans and residential curbside bins. On the surface, it looks like it may put additional stress on the system, since much of the material resold to recyclers is stuff that they would otherwise acquire for free. Factoring in the fact that residents don’t particularly like finding people foraging through their garbage when they walk out of their house, one can reasonably question the societal benefit of the practice, unless it materially improves the diversion rates. On the other hand, it appears to support a lot of people who have determined it was their best option at making a living, and who may not even have many other options — including working in the recycling plant it turns out, as one has to live in a specific SF neighborhood to even be eligible to work there per union rules.

Another question I’ve always asked myself is: what is the ‘half-life’ of recycled material? How many cycles can a given consumer product go through before it is no longer reusable? Irrespective of economic and social benefit, if the half-life of a specific type of material is short, calling what we do recycling is a misnomer and should really be considered more of a ‘life extension’ program for consumables.

I wonder whether we could, as a society, decide on more specific packaging rules and incentives that would enhance our ability to reduce trash with little effort. My local farm eggs recently started coming with a glossy cardboard lid instead of the traditional carton, which likely means one needs to separate them now before recycling. I still remember the day my favorite brownie bites suddenly came individually wrapped instead of in one large recyclable container. I no longer buy those. Is it time to treat trash as the externality it is and reflect that in the cost of production? It’s not an easy proposition since the ‘value’ of trash seems to be so tied to geography, but it’s an interesting question to be asking nonetheless.

I am a Principal Scientist at Google, working on Machine Learning and Robotics.

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