Almost two years after a kitchen waste trial concluded, Nelson City Council is looking at its next steps for rolling out the service city-wide.
The year-long kitchen waste collection trial, which was conducted in 2021 at a cost of $120,000, was used to form data on average household kitchen waste and the frequency that residents required collection.
20L bins were given to households for kitchen waste and collected from the kerb once a week, much like recycling bins.
Organic waste takes up space in landfill, but also significantly contributes to the production of greenhouse gases as it decomposes over time.
“Of the 130 households on board we collected 5.5kg of waste per week per household on average,” group infrastructure manager, Alec Louverdis, says.
“This would equate to diverting 3000 tonnes of food waste to landfill per year and prevent the production of 2850 tonnes of methane and approximately 1500 tonnes of carbon dioxide.”
The waste was collected and composted by Community Compost, and founder Ben Bushell hopes council will choose to continue composting the waste in the near future.
Ben says the trial successfully collected the data needed to paint a picture of the infrastructure needed for the region and he and his team set about putting together a proposal for council to save waste across Nelson Tasman.
Following the trial, funding was placed in the Long-Term Plan to roll out the service on the basis that a processing facility of sufficient scale could be found in the Nelson Tasman region.
“Since then, it has become clear that there is currently no facility large enough in our region and until one is established, a collection service cannot be started,” Alec says.
“The next step in the process is a business case that will identify and investigate options for kitchen waste processing, collection infrastructure, and potential methodologies, in order to fully inform best options for rolling out the service.”
Considerations include how kitchen waste is collected, for example - weekly, small bin, or large bin, and how it would be processed. Council will consider composting, worms, and anaerobic digestion.
Ben says this is where his main concern lies. He says composting should be the only consideration.
He says worms take up a significant amount of space and can only digest a portion of food waste but can’t process things like meat, onions, and citrus and also points out that anaerobic digestion is simply creating another form of landfill – one where the gas is harvested.
“We know that there’s enough organic waste produced in our region to sustain all of the farmers and it would increase the value and nutritional value of the produce which would then increase the health of the region.”
He says an option council is considering is that they build a huge processing plant in Murchison for anaerobic digestion.
“Imagine all the fuel just shipping it down here. Composting creates heaps more jobs which is what we want. It’s a no-brainer.”
Ben’s organisation processed food waste using bEartha, an in-vessel composting machine designed and built right here in Nelson. Its primary purpose is to make the hot composting process more automated and efficient.
bEartha does this by continuously monitoring the compost temperature with sensors, and automating the turning of the compost with an electric motor and mixer when the highest optimal temperature is reached.
This re-oxygenates and optimises the conditions for the micro-organisms doing the decomposition.
The machine also captures the methane produced by the composting process using a biofilter, reducing both emissions and odours.
“This can process food that home composts can’t,” Ben says. “bEartha takes care of the heat so we can break it down much faster and protect it from all the pests and smells it’s very contained and safe.”
After the week-long process, the raw compost then gets handed over to the team at Tim’s Gardens who manage it for the next few months.
“Our organisation has the technology, the experience, the will and the business model that will work,” Ben says.
“We believe in our ethics. We believe in taking care of our region’s soil first. We know that we can produce enough quality compost to transition the whole region away from synthetic fertilisers.
“We would be leading the country, we would be securing our food and soil for hundreds of years to come.”
Alec says of the options being considered, each would have a very different cost and take quite different amounts of time to establish.
“Under the New Zealand Waste Strategy 2023 we are required to have a domestic kerbside collection service in place by 2030.
“Costs for a processing facility cannot be determined until the options for processing and collection have been established.”
Ben says he has put forward a proposal that would see 50 bEarthas strategically placed around the region, but says he doesn’t even mind if it’s not Community Compost that gets the contract, he just wants composting to be the choice made.
“Everyone’s looking to council to make the right environmental choice for us.”
