The problem with food waste
You might think that food waste in a landfill simply breaks down naturally – but this is not the case. In a landfill, the food waste is buried by other rubbish and crushed, which limits its exposure to sunlight, oxygen, and helpful microorganisms.
As it breaks down anaerobically (without oxygen), it releases more methane than it would if it decomposed naturally, like in a compost bin. Methane is a powerful greenhouse gas and has roughly 30 times the impact of carbon dioxide on climate change.
Through our zero waste strategy – He anamata pare kore mō Pōneke, A zero waste future for Wellington we’ve set a goal to reduce the amount of waste going to the Southern Landfill by half by 2030. Our strategy identifies food / green waste collection as having the largest potential for diversion of waste from landfill.
About the Para Kai trial
The trial ran from September 2020 to March 2022 on the Miramar Peninsula. 500 households trialled a weekly kerbside food waste collection service, while another 450 households were composting their food waste in either a compost bin, worm farm, or bokashi system.
The Miramar Peninsula was chosen for the trial because it has a diverse range of established communities which are representative of Wellington’s demographics, socioeconomics, and topography in a relatively small, easy to define area.
Predator Free Wellington have almost entirely eradicated rats, mustelids, and possums from the area. Since rodents can be a problem associated with compost bins, any increase in pest numbers in the trial area could be closely monitored.
What we learned
Information was gathered over a 12-month period through a rubbish audit of participating households before the trial began, and again during the trial to provide a comparison.
We also conducted two surveys to understand participant’s perceptions of the success of the trial and a willingness to pay for a food waste collection service in the future. The second of these was finalised in March 2022.
Kerbside collections
- Approximately 33,000 kg of food scraps collected and diverted from landfill.
- Average reduction in food waste going to landfill of 38.8% per household.
Home composting
- Approximately 13,000kg of food scraps diverted from landfill.
- Average reduction in food waste going to landfill of 16.4% per household.
Key findings
- The trial and survey indicate that organic kerbside collection is the most effective method for diverting food waste from landfill. The home composting systems were also popular among most participants and reduced the amount of food waste going to landfill.
- The survey indicated that participants thought the trial was a good idea. Respondents agreed that waste related issues are important and environmental purpose and goals were the key motivation to take part.
- At least four in five respondents across both trial groups indicated they would continue to use the system if the trial continued.
- Key concerns about all the bin types were around smell, attracting rodents, animals, bugs, the volume of food to process, and what to do if something goes wrong. Some in the home composting trial felt they may have selected the wrong type of bin for their household.
More about what we learned
Para Kai – lessons learned from the survey responses (262KB PDF)
Infrastructure Committee paper – Para Kai including Audit Results (9.65MB PDF)
Survey results:
Para Kai Trial - Phase One Survey - Topline Report (Final) (1.06MB PDF)
Para Kai Trial - Phase Two Survey - Report (Final) April 2022 (1.10MB PDF)
Next steps
The trial findings have informed our next steps in tackling food waste disposal issues.
In the 2024-34 Long-term Plan, the Council committed funding to progress changes to our kerbside collection, including the introducing of an organic waste collection.
Contact us
If you have a question about the Para Kai trial please email us at waste.education@wcc.govt.nz.