By Andi Anderson

A University of Illinois Urbana-Champaign study examined the effects of curbside compost collection programs in New South Wales, Australia. The aim was to assess how these programs impacted household waste disposal habits and their potential to reduce methane emissions.

Between 2009 and 2015, 24 local councils in New South Wales implemented curbside collection for food and garden waste intended for composting. Residents received three bins: red for general waste, yellow for recycling, and green for organics. Educational campaigns informed households about acceptable items for each bin, and some councils provided kitchen caddies to aid in sorting.

Researchers analyzed government waste data from 2008 to 2015. They found the programs successfully diverted organic waste from landfills. On average, households composted 4.2 kilograms of waste, representing a 25% reduction in landfill-bound materials.

The study also compared areas allowing both food scraps and garden waste in green bins with those solely accepting garden waste. No significant differences in compost volume were seen, suggesting garden waste constituted most composted materials.

"People were willing to compost yard waste when provided the bins," said Becca Taylor, a study co-author and assistant professor at the University of Illinois. "However, there's potential to improve food waste diversion from landfills, possibly requiring additional efforts beyond just bin provision."

The researchers estimated that diverting a ton of organic waste from landfills to compost could lead to methane emission reductions of 6% to 26%. They acknowledged that specific reductions might vary depending on local composting and landfill technologies.

The study additionally investigated the programs' impact on recycling and overall waste generation. Concerns existed that composting might either encourage increased recycling due to heightened waste consciousness or decrease it due to the added sorting effort. The study did not find significant changes in recycling rates or total waste generation.

"Methane is a potent greenhouse gas with a shorter atmospheric lifespan than carbon dioxide," explained Taylor. "Reducing methane emissions has a more immediate impact on mitigating global warming. Landfills are a major source of human-caused methane emissions, and composting offers a low-cost solution."

The study emphasizes the importance of both recycling and waste reduction. While composting programs effectively reduce methane emissions without increasing waste, minimizing waste generation at the source would lead to even greater emission reductions.

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