The Theory of Waste Prevention

Virtually everybody would accept the idea that causing waste is a bad idea. When we waste resources, it costs us money. Even if the resource in question is cheap and plentiful where you live, it won’t always be cheap, if you waste it. The post on ‘Recycling: the Elephant in the Room’ got some attention, so I thought I’d follow up with some of the formal theory behind the views expressed there. Being ‘green’ isn’t just something for ‘tree-huggers’ – it can make good, hard-headed business sense as well.

Government initiatives attempt to address the problem of waste (for example, Directive 2008/98/EC) and they generally set out the principle of a waste prevention hierarchy. I wouldn’t recommend reading the full document unless this is the subject of your thesis or something – it’s very dry – but we can summarise. If you learn nothing else about the Waste Framework Directive, remember the idea that it’s setting out a series of stages at which the harm caused by a product or service can be reduced. It’s illustrated in a variety of ways, often with pyramids, inverted pyramids, cones, bar charts… all with the same basic principle:

The Waste Framework Directive has done nothing to halt the proliferation of visual aids, it seems.

The Waste Framework Directive has done nothing to halt the proliferation of visual aids, it seems.

I’m part of the problem here, having created my own graphic to illustrate the hierarchy…

waste prevention hierarchy

The waste prevention hierarchy

Basically, what we have here is an eight-step model showing opportunities to limit environmental damage. Some authors show it as a five- or six-step model, but I’ve tried to be as detailed as possible. (And if you can think of more stages, please let me know, via the comments…)

1. Prevention of Waste: First off, we have the chance of preventing waste outright. This might mean avoiding over-production, or making a process more reliable, such that its yield improves. It might mean not packaging your product; some things don’t need it. If your customers don’t value something… find out, and stop doing it.


Some products are packaged enough already.

2. Minimisation of Waste:
If you can’t prevent waste, can you minimise it? For example, a retailer might demand that your product is packaged for a number of reasons, or conditions within the supply chain might make it necessary (for more on the eight purposes of packaging, see this post) but can you use less of it? Can you make the box smaller, or use a lighter gauge of cardboard? This tends to reduce wastage.

Original iPod mini packaging

For this ‘mini’ product, Apple used an awfully large box…

3. Reuse of the Product:
For some products there are good reasons not to consider reuse (such as hypodermic syringes, where the health benefit of a disposable outweighs the environmental harm of the single use product)… but elsewhere a product can be of use to other people, or in other roles – if it’s appropriately designed. Consider the Danish success with drinks containers, since Carlsberg introduced the world’s first refillable plastic bottle (in polyethylene napthalate) in 1999; a tremendous improvement in resource efficiency.

4. Reuse of Components: This is another good, common-sense strategy that has been the norm in some industries for decades. When a product as a whole is no longer viable, salvage what parts you can from it, and make them serve again. The talk I did with Dr Joe provides an example of one strategy here; that of remanufacturing.

5. Material Recovery: Good old recycling just makes it into the top five… which isn’t all that great, to be honest. If you’re clever, or if you come from a country with very low labour costs, you can pick materials out of the waste stream, and reuse them. Of course, some materials are more recyclable than others (for example, you can’t melt down a thermosetting polymer for reuse) and some materials are likely to degrade from one use to the next.

Note that material recovery might actually involve an organic process rather than a technical one; composting of vegetable wastes is a valid strategy.

6. Energy Recovery: If recycling isn’t possible for technical or economic reasons, combustion might remain an option. For example, if you have no economically viable way to recover material from a waste stream of mixed plastics, or if you have oil contamination, you might send the whole lot into a power station, and at least get some energy back. This is not without problems, as hazardous dioxins are released if the conditions in the furnace aren’t right… but it’s probably better than leaving end-of-life materials blowing around on the street, or bobbing around on the sea.

Advocates claim that energy recovery is a valuable strategy, and to some extent this is true: weight for weight, burning polystyrene releases twice as much heat as coal… but that doesn’t make it a ‘green’ solution. With an appropriately managed waste stream, that polymer might have been made into something more useful, instead of momentarily feeding our appetite for electricity.

7. Landfill: This is the worst possible outcome shown on most folks’ pollution prevention hierarchies, and with good reason… but it actually encompasses a set of different outcomes. First off, there’s combustion without energy recovery… burning the waste simply to reduce its bulk. That saves space during transportation and/or in the landfill, and may be encouraged for reasons of sterilisation, or to destroy confidential information… but potentially toxic fumes and residues make this a controversial strategy at best.

Then there’s good old landfill – just push the product into a hole in the ground, and hope that contaminants can’t leech out from the waste and into local watercourses. If your product is particularly toxic, it might be sealed up in containers, and stored far below ground.

Star Wars trash compactor scene

Wait… what? They’ve got spaceships, lasers, antigravity, robots and the Force… and the best they can do with their trash is to squeeze it into cubes and dump them?

For some contaminated waste, a ‘land farm’ may be an option: this involves using natural bacterial action to break down a hazardous substance over time. Basically, you plough the substance into the topsoil, turning it over from time to time to aerate the soil, and let the microbes digest the contaminated soil, sediment or sludge,. Not a nice kind of farm… but it is a present-day strategy for dealing with waste.

8. Uncollected waste: Worst of all, but seldom seen on the pollution prevention hierarchy is the idea that waste never actually gets collected. Instead it simply piles up in poor districts, or it gets pushed into a nearby body of water, or it just blows away. I think we need to include this on the hierarchy, because unless we acknowledge that it is happening, we’ll never tackle the problem. In other words, the worst possible outcome is a little worse than most people think.

When a worn-out ship is scrapped, the thousands of tonnes of steel in its hull are worth reclaiming: the vessel is typically run ashore at high tide on a beach in a developing country, and an army of workers cuts it up for scrap. That’s fine for materials with value such as copper, iron and steel… but what happens to the plastics, the waste engine oil, or the asbestos? It isn’t just the low wage costs that cause ship dismantling to happen in developing countries; it’s the lack of oversight. Much of the waste that has no value goes back into the ocean – and it’s our ocean, too.

Hulk of a half-scrapped ship

Long time no sea: this vessel has all but disappeared… but where did the toxic materials go?


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