Composting at UC


Recycling food scraps and organic waste into compost significantly reduces the volume of waste sent to landfill, making it an important waste minimisation tool. Compost can then be used by gardeners to improve soil fertility and structure. Food and organic waste generated at UC is taken to Living Earth. You can put all food scraps and organic material in the green wheelie organics bins and small bench top containers in staff kitchens. This includes:

  • Fruit and peels
  • Tea bags
  • Sandwiches
  • Cakes
  • Meat
  • Coffee grounds (and filters)
  • Flowers
  • Any other plant material
  • All food waste (both raw and cooked)
  • No Plastic
  • No coffee stirrers
  • No chopsticks
  • No cardboard or paper

Organic waste disposal costs are much cheaper than landfill costs, so putting food scraps and organic waste into the green organics bins are an important way to manage UC's waste disposal costs. Unfortunately regular waste audits have found that a lot of organic waste is being disposed of through the red landfill bins by the UC community. Between 12-30% of the contents of landfill bins can comprise of organics. Community education programmes are required to address this issue on an ongoing basis.

Composting single-use takeaway cups

The UC Sustainability Office is running a unique trial which explores the feasibility of composting single-use coffee cups. This will determine if a new pathway to divert waste from landfill will be effective.

Bins with blue hoods have been placed a strategic points around campus (mostly close to cafes) for the UC community to put their single-use takeaway cups in. The cups collected through these bins are sorted at UC to make sure there is no contamination in them. Then they are taken out to a HotRot facility north of Christchurch where they are put through a high temperature mechanical composting system with other compostable waste products and turned into compost.

Please remember, these are for empty cups only and not for any other items (e.g. pie wrappers, bottles or any other contaminant). It is extremely important that only takeaway cups are placed in these bins. This helps to keep the sorting process before we send them away to be very fast and efficient. Please help us keep this project going by telling your colleague and friends about it and not to contaminate the bins!

Coffee Cups

What difference will this trial make? We estimate that the UC cmmunity produces more than five tonnes of waste from coffee cups alone every year. That’s five tonnes we can keep out of Kate Valley Landfill!

If the cups are being composted, why can’t I put organic waste in the blue bins? At this stage in our trial, the contents of the blue bins are all being sorted by hand. This is so we can ensure quality control and provide accurate reporting. Sometimes the material sits around for a while before being handled, and it is not pleasant or safe to deal with rotting food.

Why can’t we just put them in the green bins? Coffee cups must not go in the green organics bins. The contents of green bins go to a composting plant that cannot process takeaway cups (even if they say they are ‘compostable’). Coffee cups in the blue hooded bins are sent to a different composting facility that is able to compost them. In addition, because of our contractual arrangements with our current waste services provider, it is not economically efficient to do this. We are working together to find a solution that will work for everyone.

What about composting them on-site? We have been exploring options to do this for a number of years, including worm farming. We need to get a back end system in place first that works, we need more physical space than is currently available and we may require some capital (which will not be available for some years).

What are the future plans for this project? We are setting up a system to help us deal with a much bigger waste issue than many people realise, in order to create the possibility of treating more of our waste as an environmental resource rather than a contaminant. We want to phase out certain kinds of packaging from campus (like plastic plates, sushi containers, plastic cups etc), but first we need to make it possible for compostable options to actually be composted. In time, we hope that compostable plates, cutlery and other food containers will all be able to be composted using the blue bins.

Compostable or biodegradable plates and cutlery

UC's caterers have sourced a range of compostable/biodegradable cups, plates and cutlery to serve with their food. These are usually made out of some kind of cardboard. Unfortunately these products CANNOT be recycled through the yellow/recycling, green/organics or grey/paper bins. The main reasons for this are

  1. the recycler that processes the contents of co-mingle recycling (yellow bins) treats this as contamination.
  2. Canterbury’s local composting system is a cold, slow composting system. All the products provided by the caterers require a hot composting system. This is partly due to the fact that food-grade biodegradable plates and cups are often treated with a ‘wet strength coating’ on them, which alters the way they are decomposed or recycled. (This applies especially to single-use takeaway cups).
  3. Cardboard soiled by food cannot be recycled with other paper (grey bins).

UC needs to minimise contamination of yellow/recycling, green/organics and grey/paper bins by compostable by UC’s caterers as much as possible The options for disposing these compostable/bioware products are to put them in.

  • RED (landfill) bins
  • BLUE bins. These bins divert compostable products out to a hot composting system north of Christchurch.

If you are running an event which uses compostable products, they can be collected separately and taken to the blue bin closest to you – they are located outside many campus cafes. We are realistic that this may not be practicable for many, so we appreciate any efforts you may be able to make in this respect.

Location of blue bins

  • Outside Reboot, Erskine – (north entrance)
  • James Hight/Puaka – (by fountain/ponds)
  • James Hight/Puaka/C block lawn – western corner
  • James Hight/Puaka – outside the Berg
  • James Hight/Puaka/C block lawn – eastern corner
  • Undercroft by Café 1894
  • Outside Café 101
  • By Hardhard Café
  • Outside Business and Law
  • Collective Café (Dovedale)