Reducing contamination in green waste

In 12 months, Nillumbik Shire Council has dramatically reduced the percentage of contaminated household green waste bins.

In April 2014, Nillumbik began sending its kerbside garden and food waste to a composting facility after almost five years of it going to landfill.

At the start, contamination levels were so high that most of the kerbside green waste couldn’t be composted.

In June 2014, a shire-wide inspection revealed that 12 percent of green waste bins contained incorrect items.

Now, through a communications and engagement program, multiple bin inspection methods and collaboration across many council units, the state government Metropolitan Waste and Resource Recovery Group (MWRRG) and the composting contractor, just 4.45 percent of green bins are contaminated – a 63 percent improvement – and all of the green waste is recycled into compost for farms, parks, local schools and community gardens.

Nillumbik’s bin collection model was launched in 2003 and is specifically designed to divert food waste from landfill.

Between 2009 and 2014, Nillumbik’s green waste had to go back to landfill due to the closure of its processing facility.

The green waste service accepts food scraps – fruit, vegetables, dairy, bread, pasta, rice, meat, small bones, tea bags and coffee grounds – as well as garden materials, with weekly collection of a 120-litre bin.

Every household has a green waste bin (it is not an optional service like most municipalities) combined with a 240-litre recycling bin and 120-litre garbage bin, which are collected fortnightly.

Because the service is designed around food scraps going in the green waste bin, not the garbage bin, Nillumbik’s main contamination issues are food packaging, plastic bags and, with smaller garbage bin capacity, a smaller number of residents using the green waste bin for household garbage.

In partnership with MWRRG and 10 other councils, a communications and engagement program called The Back to Earth Initiative aims to address these issues.

This ongoing campaign teaches residents the ‘dos and don’ts’, encourages correct bin use, demonstrates why it is important and explains how the composting process works.

Nillumbik has featured ‘Back to Earth’ educational pieces in council newsletters, advertisements in the local newspaper, community newsletters, its website homepage, social media and temporary roadside signage.

The council also encourages residents to take a ‘Back to Earth’ pledge to use their bins correctly and display a sticker on their green waste bin.

Nillumbik participated in the ‘Back to Earth’ spring 2014 campaign, which gave preschools, schools and community groups the chance to vote for and win $5000 towards a nominated gardening project.

The team is also working with community gardens, schools and preschools to use recycled compost in local spaces.

Recent evaluation of the ‘Back to Earth’ communications strategy by MWRRG found that one third of surveyed Nillumbik residents recall seeing information about green waste collection and processing in the past 12 months, compared to 18 percent across other participating councils.

An important message to get across in Nillumbik was that green waste no longer goes to landfill.

The survey found that 92 percent of Nillumbik residents are very confident or somewhat confident that green waste is recycled, compared to 83 percent across other participating councils.
Eighty-five percent of those surveyed in Nillumbik said they understand very or fairly well the environmental benefits of recycling green waste.

Along with the communications campaign, Nillumbik embarked on an intensive bin inspection program.

Initially, the in-house team of waste drivers identified locations with particularly high contamination and council used an external contractor to visually inspect these bins.

Following significant improvement in those locations, Nillumbik decided to roll out inspections shire-wide.

Nillumbik will continue to inspect bins and collaborate with MWRRG and other councils to ensure long-term behaviour change.

The waste team has already had lots of discussion with other councils across Australia looking to introduce food waste into their green waste service.