Niall Enright argues that it is time to rethink the conventional five-stage waste hierarchy
Notions that some ways of dealing with waste are preferable to others have been around for a long time. In the 1980s, the “Three Rs” – reduce, reuse and recycle – became commonplace. This sets out a hierarchy for dealing with waste – reduction is preferable to reuse, which in turn is better than recycling.
Such ideas gained extra significance when they started to form the basis of regulation. In the US, the Three Rs were introduced into federal waste rules in the 1990s, while in 2008, the EU Waste Framework Directive (2008/98/EC) formalised a five-stage waste hierarchy: prevention, prepare for reuse, recycle, recover (for example, extracting energy from waste) and disposal.
These hierarchies convey the idea that waste is a valuable resource, rather than a burden. Reducing waste in the first instance avoids the cost of raw materials that would have ended up in the waste. For waste that cannot be avoided, you may as well generate some income by recycling it, rather than paying the costs associated with disposal.
This concept of “waste as value” has been remarkably successful and there is now a huge and thriving area of economic activity based on extracting value from a wide range of waste streams.
Moving on
Because the waste hierarchy is such an important part of environment regulation, it is worth revisiting in light of contemporary thinking on sustainability, lifecycle assessment and the circular economy. Three developments come to mind:
- Consideration of the upstream effects of resource use is now as important as the downstream impact of waste arisings and end-of-life disposal. This more holistic approach is generally called resource efficiency, where extraction and issues of scarcity determine the selection of materials, as much as disposal considerations.
- The linear “take-make-waste” model is being rejected in favour of a “cradle-to-cradle” approach. The idea is that materials, once removed from the environment, should be managed in such a way that they circulate permanently in the economy. Ideally, materials are never returned to the natural environment, but if they are, they should serve as a nutrient to improve the environment.
- Broadly speaking, individuals and organisations are more willing to do things on the basis of environmental benefits than because they generate financial value.
When we take these three trends into account, what emerges is an updated version of the hierarchy, called the resource efficiency hierarchy or, more simply, the “Seven Rs” (see below).
At first glance, little seems to have changed. At the top of our hierarchy sits the “prevent” approach, though now in two ways: remove and reduce. By creating a “remove” method, product design and formulation are more clearly signposted as a means of cutting out resource need altogether. Remove is a reminder that the first questions to be asked about whether to use a particular resource should be: Why do we need this resource? What function does it fulfil? Can we design this requirement out? Can we deliver the service this product provides in a different way?
Below reduce there is a new method, to “re-source”. It means that once a resource has been removed or minimised, we should then consider alternative sources or materials with a lower ecological impact. For example, if the resource is electricity, we should start by employing every practical option to reduce its use. Only when those options have been exhausted should we move on to find out if we can source the electricity from an alternate supply, such as a renewable source. Using harvested rainwater water instead of communities’ treated supplies is another example of re-sourcing.
Some organisations behave as if the resource choice is the only method they should use, so they will buy 100% renewable energy and declare the problem solved. But, because they are not affecting demand and because substitute sustainable sources are often more expensive, this approach is often the least cost-effective option.
Also, in a world where renewable supplies do not satisfy total demand, the extra resource that one organisation gets from renewable sources reduces that available to others. Regrettably, this approach persists because it is seen as involving less effort than the alternatives, especially where the resources involved are a small part of the organisation’s total costs.
Return to form
After re-source, we return to the traditional hierarchy. Reuse of materials or goods in the same process is usually better in value and environmental terms than recycling or “down-cycling” – turning waste into new material of a lesser quality – into a different process. Proponents of the circular economy would argue that all products should be designed with reuse in mind. Products should be taken back by their manufacturers, be easy to disassemble and be reincorporated into the next batch of products.
Where recycling is not possible, it may be possible to recover some part of the resource. Examples include converting embedded energy into heat by burning waste or extracting nutrients from the waste by composting. This reduces the need for virgin resources – gas or fertilisers in these cases.
Finally, we can return the waste to the environment. Here, the use of language reflects updated thinking. The old term, disposal, has connotations of discharge, dumping or throwing away, whereas “return” addresses circular-economy thinking – we are borrowing a resource and then carefully returning it to nature. Ideally, the material returned will be a nutrient to enhance natural capital. If the waste is not a nutrient, it should at least be inert. If this is not possible, then it must be contained, treated or diluted to remove its effect on the environment.
Following the sequence
Traditionally, the resource efficiency hierarchy is applied in sequence, so the use of the resource is first minimised, then some material is recycled and the remaining waste returned to the environment. It is becoming increasingly clear, however, that we need to think more in terms of the overall system, rather than just one individual waste stream. For example, the novel, infinitely reusable material used to make the book Cradle to cradle, by Michael Braungart and William McDonough, may require more inputs to produce than conventional paper, but the ability to reuse the material repeatedly leads to much less waste overall. We should not think about the single journey of an isolated waste stream, but the overall flow of many materials over many cycles.
It is sometimes helpful to look at organisational policies around waste to align these with the resource efficiency hierarchy. For example, audits in the US and Europe by French cosmetics firm L’Oréal revealed that it was company policy that any non-product materials that left its sites were categorised as waste.
L’Oréal is to be applauded for using such a strict definition of waste in its reporting to encourage sites to eliminate all forms of waste; however, it had the unintended effect of making it preferable to burn waste onsite in a biomass boiler, as emissions to air are not counted in its waste reports. Prior to adopting this definition, the waste from the shampoo lines was sold in bulk to nearby carwash companies, displacing the need for virgin detergents. This form of recycling is higher up the resource efficiency hierarchy, but L’Oréal’s strict definition of waste unwittingly led to the lower recovery choice being favoured.
Although a bit clumsy, the Seven Rs provide an important reminder that reducing demand is always a better tactic than improving the quality of supply of a resource or, indeed, providing end-of-pipe solutions. The best resource to use is no resource at all. Environmental scientist Amory Lovins coined the term “negawatt” to describe this most valuable resource – a watt of power avoided.
An eighth 'R'
In devising this new hierarchy, an additional “R”, remediate, was considered for inclusion at the bottom of the inverted triangle. This reflects the harmful return of waste to the environment and the obligation to put that right.
However, it was rejected because it could imply that dumping, followed by remediation at a later date, was a legitimate waste management method.
Niall Enright is interested in hearing practitioners’ views on whether remediate should be part of the new resource hierarchy – send your comments to [email protected].
