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Sustainability

Did you wander past the Sidgwick site on 31 October and wonder why there was a team of people in hazmat suits rifling through rubbish? We can explain that…

Most of us think that we know our stuff when it comes to throwing away our waste at home: there are few now who don’t carefully separate their waste and ensure that recycling makes it into the right bin. But do we really practice what we preach in our place of work and study? To launch ‘Spotlight on Waste’ month at the University of Cambridge, a team of fearless Living Lab associates donned hazmat suits and gloves and got down and dirty in our ‘Bin-Busting’ event to find out what we are putting into our bins in University buildings

Faced with six huge ‘general waste’ bins from six different randomly-selected sites around the University, participants split into two teams and raced to sort the contents of each bin into their constituent parts – such as paper towels, plastic bottles, plastic wrapping, glass jars, food and (compostable) Vegware packaging, textiles and electrical waste. A similar event in 2015 discovered that 43% of the total waste placed ‘general waste’ bins should have been recycled or composted, so this study provided a chance to see if any progress had been made!

Some highlights from the results were:

  • Of the 158kg of waste sorted, just over 74% (117kg) was actually meant to be there – it was unrecyclable waste ready to be turned into ‘refuse derived fuel’
  • Meanwhile 15% (25kg) of the waste was incorrectly in the bin, as it should have been put into mixed recycling bins instead! This compared to 42% in the study carried out in 2015, so it seems that some improvement has been made…
  • 10% (16kg) of the waste would have been better off composted. The composting waste collections introduced in 2016 seem to have had an impact, as this figure was 27% in the 2015 study!
  • Under 1% (under 1kg) belonged in a separate waste stream (e.g. pens and electrical waste). While seemingly a small amount, it’s important that these waste streams are kept out of the general waste bins and instead sent to the appropriate separate collection.

While these results seem to be a big improvement on the study carried out in 2015, two of the bins in the study were found to contain a large majority of non-recyclable (but non-hazardous) laboratory waste, skewing the results.

This can be seen in the data displayed in figure 1, the average (mean) proportion of waste types in each of the 6 bins bin. On average, only 52% of the waste in the general waste bins actually belonged there; meaning that 48% should have been placed in mixed recycling, composting, or other waste streams. As was seen in 2015, the variation between the bins from different sites is significant, with anywhere from under 10% to over 80% of waste incorrectly sorted. Clearly this demonstrates significant discrepancies in recycling performance from building to building, and highlights that staff behaviour has a huge bearing on recycling performance.

Average waste breakdown

Figure 1: Average waste breakdown per bin

So what are the most common items that are mistakenly placed in ‘general waste’ bins?

  • As displayed in figure 2, the most common culprit is organic, compostable waste – food, tea, coffee, and Vegware packaging (the compostable packaging used in University cafés) – this makes up 40% of the total ‘misplaced waste’ in these University bins. If your department/building hasn't yet got an external food waste bin, email [facman @ admin.cam.ac.uk] to request one then set up internal collection points and establish who empties them).
  • Paper, letters, cardboard, magazines and leaflets are all recyclable, but make up 28% of the items being disposed of incorrectly into general waste bins.
  • Plastic bottles, containers and wrapping follow close behind, with 26% of the recyclables finding their way into general waste bins.

Misplaced waste

Figure 2: Common misplaced waste

In terms of correctly placed waste, an amazing 90% was made up of just two types of waste: 70% was contaminated but non-hazardous lab waste, while 20% was paper towels. A further 4% came from contaminated packaging. So perhaps we should be re-labelling ‘general waste’ bins as ‘contaminated lab waste, paper towels, and sometimes contaminated packaging’ bins! For full details of what can and can’t be recycled in each bin, you can download bin labels from our website.

The Environment and Energy team would like to thank all of the Bin-Busting volunteers for their hard work on collecting this invaluable data. If you would like to see the data in more detail, or have queries about improving recycling and waste management practices in your building, please contact environment@admin.cam.ac.uk