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The Waste Hierarchy

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The waste hierarchy underpins what most of us know about waste processing, but there is more to it than you might think.

A Brief History Of The Waste Hierarchy

The waste hierarchy was initially introduced in 1975 in the European Union’s Waste Framework Directive (1975). At the time, the waste hierarchy was not what we know it as today, it was essentially just a list. This changed in 1979 when Ad Lansink, a Dutch politician, suggested it should be arranged in a ladder format with the most desirable option sitting at the top, and the least desirable at the bottom. This became known as Lansink’s Ladder. The Dutch adopted this format into policy in 1993.

The European Commission suggested a three-step hierarchy to be implemented in The Waste Framework Directive but received strong criticism. Their suggestion bundled prevention and reuse into the top tier, recycling, and recovery into the middle tier, and left disposal on its own at the bottom. This suggested that recovery was equally as good as recycling when in reality it isn’t. In 2008, the EU revised The Waste Framework Directive, in which they described a five-step waste hierarchy, the same one we use today:

• Reduce
• Reuse
• Recycle
• Recovery
• Landfill

The Waste Hierarchy

So what is the waste hierarchy? You know the catchy phrase: reduce, reuse, recycle? That’s the top half of the hierarchy. In addition to these three steps, we also have recovery and landfill. In short, the hierarchy set out the five steps that must be considered by companies, top to bottom when managing their waste. Applying the waste hierarch to waste is a legal obligation, not something that is optional.

The Waste Hirearchy

Reduce

The most important step in the hierarchy, and probably one of the most difficult. Reduction is the most desirable approach to managing waste. Humanity continues to extract Earth’s natural resources at unsustainable rates, often wasting most of them. Currently, we are extracting around 100 billion tonnes of stuff from the Earth each year with only 30% of that making stuff that we keep permanently^[1]. Reducing waste means reducing consumption, maximising resource utilisation, and designing products with their end of life in mind. In doing so, less needs to be taken from the Earth and less needs to be thrown away.

Reducing the waste we produce doesn’t just reduce waste; it also reduces energy usage, resource usage, labor, and greenhouse gas emissions. It’s not hard to see why reduction was popped at the top of the waste hierarchy.

Reuse

Most environmental folks accept that we can’t just stop mining, making, and wasting things. Resue is the next best thing. Reuse targets that 30% permanence figure and tries to increase it. Taking items that are no longer needed and reusing them for the same, or a new, purpose prevents them from going to waste. This can be as simple as using a two-litre plastic bottle as a funnel for filling your bird feeders. Or sanding down an old coffee table and giving it a lick of paint (lead-free I hope). By reusing these items we extend their useable life, preventing them from going to waste and spreading their initial environmental impacts over a longer time period (E.g., embodied carbon). It’s worth noting at this point that repairing a broken item can be considered reused because otherwise it would be wasted.

Whilst not strictly reused, I bought a refurbished camera a few years ago, and I love it!

Design and manufacturing are other areas that impact reuse. I’m not going to ask you to reuse a kitchen roll or every shampoo bottle you have. Nor am I going to ask you to reuse your garden furniture that has rusted to pieces. We can’t reuse these products, it’s not practical. This is because these products just are not designed to be reused.

This is an opportunity for manufacturers to design their products with reuse, and repair, in mind. Building garden furniture out of steel isn’t a great idea because it rusts over time. Maybe aluminium might be a better option as it doesn’t rust? Not designing electricals to be fixed when they break makes reuse more expensive, hence why a new screen on an iPhone can cost up to £250.00! We really need to fix this, we have a #righttorepair! Finally, shampoo bottles don’t serve much use once empty, so the manufacturer should consider this too, which leads us to the topic of recycling…

Recycling

Workers at a waste transfer station I visited in 2017 pick through the mixed waste, separating it into bays for recycling.

Definitely the most common and known tier in the waste hierarchy. Everyone knows about recycling, right? Recycling is similar to reuse in the sense that we don’t throw the product away, however it differs in the fact that recycling tends to involve the destruction of the original product. When we recycle something, let’s say an old metal and plastic table, we break it down to its constituent materials. In this case that would be metal and plastic. We then take the metal and plastic and process them so that they can be used to make something new. For example, the metal can be melted down into raw metal which can then be sold on the metals market. The plastic can be shredded, melted and pelletised, and sold on the injection moulding market.

The key to this process lies in two facts: Firstly, we are not throwing the materials away. This means that we don’t have to find somewhere to put them which could potentially damage the environment. Secondly, we can displace the use of virgin materials. If we use 100 gigatonnes (billions of tonnes) of stuff each year but recycle, for example, 35% of that, then we only need to dig up 65 gigatonnes of stuff the next year (assuming no growth in consumption). We called this process ‘closing the loop’. I’ve got a post regarding the circular economy model coming soon (Edit: it’s here!)

To summarise the above, recycling is one of the key approaches to waste management. It serves to provide for society whilst minimising impacts on the Earth. As with Reuse, manufacturers need to think about the recycling of their products when they design them in order to maximise recyclability.

Recovery

The most controversial R. Recovery, on the face of it, is an incredibly attractive opportunity. When we ‘recover’ waste, we essentially accept that it has been lost from ‘circularity’ and we try to recover what we can. Now, nine times out of ten, this is in the form of energy from waste (EFR).

There are a few types of energy from waste such as Sold Recovered Fuel (SRF) and Syngas from gasification (and pyrolysis). These each deserve their own post, but in short, SRF is burned just like coal and Syngas is a fuel gas product created by heating waste at high temperatures in the absence of oxygen which then produces Syngas.

With SRF, What happens is simple, we clean the waste and remove anything we think we can recycle. We then shred the waste up, dry it and bale it up. These bales are not too dissimilar in appearance to the bales of straw you see in farmers’ fields, however inside they are 100% waste. Specially adapted Power stations then buy these bales and burn them in place of traditional fuels such as coal and natural gas. The resulting heat is then used to generate electricity in the same way traditionally fueled power stations do. Sounds great right? Well not quite. This form of waste processing releases plenty of carbon dioxide into the atmosphere along with other forms of pollution such as dioxins. While not as bad as coal per unit of energy, it’s still not sustainable.

Landfill

Thousands of birds live around this inland landfill site seeking out food at every delivery of waste and every move of the bulldozers

There isn’t too much to say about landfills other than they are incredibly harmful to the environment and ultimately unsustainable. Granted, while landfills are way more complicated than you’d think, with restrictions and special technologies in place to minimise the harm they cause, they are still really bad.

Landfills produce greenhouse gases which make their way into the atmosphere. The main gasses we see are carbon dioxide and methane. Many landfills capture the methane and burn it onsite to power the facility, but this still results in the locked-up carbon from the waste, making it into gaseous carbon in the atmosphere. In addition to this, landfills produce a liquid chemical called landfill leachate. This results from water passing through the waste and collecting compounds on the way. The resulting liquid is often full of nasties, something we don’t want finding its way into water courses. Many landfills capture this liquid but as you can imagine, a bit does leak out. Finally, landfills are big holes in the ground that smell, attract pests, allow waste to blow around and ultimately look horrible. We simply can’t keep using them.

A side note regarding a type of landfill called an inert landfill. These are holes in the ground, usually as a result of quarrying, that need filling in to allow landscape restoration to take place. Oftentimes, inert waste fills this gap, allowing restoration to begin. They are not anywhere near as bad as normal landfills as the waste we put in them is normally just clean rocks, soil, and other unreactive wastes. The latter deserves a post in its own right but in short, plasterboard in a landfill releases hydrogen sulfide, a nasty gas. That’s why plasterboard cannot go into a normal landfill.

In Summary

The waste hierarchy is a great framework for waste management. It provides an easy process for understanding what we should do with our waste. That said, it’s not perfect and doesn’t really provide much in the way of how to use it. The hierarchy doesn’t have much consideration for hazardous waste, which often causes the most environmental harm. For example, how do you go about reusing or recycling industrial process chemicals? Can I just landfill them if nobody will recycle them? What the framework does is provides a legal incentive for companies to think about their waste, even if the implementation isn’t always the best.

Waste management is a vast topic and there are so many interesting things to dive into. This has been a bit of a ramble, emptying some of what is in my brain about the waste hierarchy onto a screen. I’m sure I’ll revisit this for an update in the future, but for now, that’s all I’ve got!

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Created by Niall Bell (niall@niallbell.com)