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A Landfill Perspective: Pit half full, or half empty?

Sam Philpott

Published: 2020-06-04

As a child, bin lorries meant it was Friday. A weekly ritual on our drive to school involved tailing the cumbersome machines through the narrow streets of York, watching them decant the waste of household after terraced-household into their gaping maws; a weekly interaction with a great infrastructural marvel which miraculously transported away the waste of each dwelling never to be seen again. How impressive adults were, I mused to myself, to have designed such solutions. 

As I grew up, this rosy awe was tainted by the revelation that detritus did not disappear into oblivion upon entering the bellies of these mechanical beasts, but was later regurgitated into vast pits, to be covered over and forgotten about. What a catastrophe this seemed to my pre-teen self, sitting through lessons on Human Geography. How could society knowingly tolerate such wastefulness?

A decade later, my outlook is more positive. To a conscientious society with arbitrarily advanced recycling capabilities, landfills will come to be increasingly viewed as enormous repositories of the materials necessary for modern life. Virgin aluminium, for example, is notoriously energy-intensive to produce and accounts for nearly 5% of global electricity consumption; aluminium can be found in many landfills in greater concentrations than in the bauxite from which it was originally derived. Add this to the fact that it is infinitely recyclable, and recycling processes result in a 95% energy saving when compared with aluminium production from raw materials, and the concept of material recovery from landfills seems not only desirable but essential.

In amongst the assorted waste there are far more valuable materials packaged into manufactured products, notably into hardware. In 2018, global production of smartphones stood at around 1.5 billion, a figure which, thanks to our acquisitive but fickle societies, is only narrowly above annual disposal rates. Smartphones, like many other modern electrical devices, are known to contain a myriad of materials. To begin with, there’s the glass screen, the aluminium case and lithium-ion battery, but also a number of more exotic elements; yttrium, lanthanum, terbium, neodymium, gadolinium and praseodymium, to name a few. All are extremely rare and becoming increasingly costly to mine due to their vanishing scarcity. The most lucrative part of these devices, however, are their previous metals. One tonne of iPhones (or about 7,700 of them) contains 300 times more gold than a tonne of gold ore and 6.5 times more silver than a tonne of silver ore. Historically, recycling of e-wastes has lagged behind other streams. Currently barely 10% of smartphones are recycled, with the majority being dumped, or exported to locations where it is economical to manually disassemble and recover certain components. One town in southern China, Guiya, holds the title of the largest e-waste sites in the world, a title which brings with it pollution from mercury, arsenic, chromium and lead, causing untold misery to locals. There exists great potential in the further development of digital, automated technologies that can sort and dismantle these products at the efficiency with which they were assembled.

We are beginning to address the challenge of remediating landfills sites. The concept of Enhanced Landfill Mining (ELFM) is already being trialled in Belgium, where the 20-year “Closing the Circle” project is in its fifth year at the Remo landfill site, with the ultimate aim of transforming the site to a 230-hectare nature reserve. This collaboration between Group Machiels and the European Advanced Landfill Mining Consortium estimates that half of the domestic and industrial material can be recovered (in itself quite the economical challenge) with a mobile plasma gasification system being deployed to convert the remaining material to a useful syngas and building material. The project is accompanied by a series of international symposia aimed at stimulating wider societal debate about how Europe is going to deal with its 500,000+ landfill sites over coming decades. What will come of this project, and others like it, remains to be seen, but my naive younger self would certainly agree it constitutes a step in the right direction.