Top Photo: Courtesy of Mill
The City of Phoenix (AZ) tested a different approach to residential food waste diversion through its Mill x R. City pilot, a model that avoids traditional curbside collection while still delivering high participation and measurable diversion.
Launched in 2025, the program enrolled more than 2,900 households and diverted over 440 tons of food waste, avoiding approximately 957 tons of CO₂ emissions. At the municipal level, installations across two city buildings doubled food scrap recovery compared to prior programs.
Phoenix’s challenge is familiar. The City provides curbside trash, recycling, and yard waste collection across more than 500 square miles, but food scraps collection has remained out of reach due to cost, logistics, and historically low participation. Food waste still represents roughly 14% of the landfill stream.
The Mill x R. City pilot takes a different approach by shifting processing upstream. Instead of relying on weekly set-outs, households use an in-home system that dehydrates food scraps into a dry, shelf-stable material. That material is then collected monthly by R. City, a subscription-based food scrap collection and composting service, and returned to local farms.
“Mill Food Grounds are non-putrescible and shelf stable, allowing for reduced collection frequency and in many cases moving from weekly to monthly collection,” a Mill spokesperson said. “R. City can now utilize the same fleet of vans to service four times the number of customers.”
By reducing the need for frequent pickups and bucket swaps, the model allows haulers to expand service without scaling fleet size. In Phoenix, that translated directly into growth. R. City reported a 5x increase in the rate of residential customer growth after introducing the Mill food recycling bin offering.
The model also changes what arrives at the composting site. Because material is processed and dehydrated at the source, it is more consistent and easier to manage. “Mill Food Grounds arrive consistent, clean, and far easier to handle downstream,” according to Mill and R.City. “Residents are even peeling fruit stickers off before processing.”
That level of engagement shows up in participation data. Households diverted an average of 0.92 pounds of food scraps per day, and 98% of users reported placing all or most of their food scraps into the unit. The system addresses common barriers such as odor, pests, and the friction of daily sorting.
The economic implications are as significant as the operational ones. By shifting processing upstream, the model moves costs out of the most expensive part of the system. “Reducing pickup frequency dramatically increases route efficiency for community compost haulers,” Mill said. “At a city level, this enables implementation with significantly less upfront capital.”
The impact extends beyond logistics. By connecting households, a local hauler, and regional farms, the model creates a tighter loop between food waste generation and agricultural use. R. City offers its subscribers farm boxes of locally-grown produce. In 2025, nearly 2,000 farm boxes were distributed to participants, reinforcing the connection between diversion and local food production.
Still, scaling the model will depend on cost and behavior. Hardware remains a barrier, though Mill is working to lower device costs over time. Beyond that, adoption depends on whether residents change how they manage food scraps in their kitchens.
For Phoenix, the pilot offers a practical alternative. Instead of building out new collection routes, the city is testing whether preprocessing, paired with targeted collection, can deliver higher participation and more efficient operations at scale.
