Top: Traditional curbside setout (left) and dehydrated food scraps drop-off (right). Photos courtesy City of Castlegar (left) and by Steve Ogle (right)
Nora Goldstein
A March 2024 BioCycle article featured a pilot Pre-Treated Organics Program that started in mid-2023 in Nelson, British Columbia (pop. ~11,000). The purpose of the pilot was to evaluate the effectiveness of household countertop food waste dehydrators versus municipal curbside collection of organics. The alternative was joining the Regional District of Central Kootenay’s (RDCK) proposed curbside organics program that would collect kitchen waste and take it to RDCK’s central composting facility near Salmo. One of the theories going into the pilot was that use of the in-home food scrap dehydrators would reduce GHGs by eliminating truck transport of heavy, wet material, as well as by reducing landfill methane emissions from food waste.
Households in a targeted neighborhood (Fairview), as well as a group of residents throughout Nelson who signed up for the program, received a FoodCycler Eco 5 countertop food waste dehydrator that grinds and dries most food scraps and some food-soiled paper in 5-litre (1.3 gallons) batches. The city purchased the units and provided them at no cost to the households. A total of 1,967 households participated in the pilot — 710 from Fairview and 1,257 from other parts of the city. The pilot ran for 13 months, ending in July 2024.
In October 2024, an evaluation of the pilot project was released by the city. The report, titled “City of Nelson Pre-treated Organics Pilot Project Description & Evaluation,” was prepared by Shannon Ripley, Yarrow Environmental, and John Paul, Transform Compost Systems. It assesses “the social, environmental, and technical aspects of a pretreated organics program in comparison with a more traditional weekly curbside green cart organics collection model.”
Waste Composition Analyses
The RDCK retained a consultant to conduct a multi-sector waste composition study in the summer of 2023. The City of Nelson worked closely with the RDCK to have the study include collection of the residential garbage stream data for the Fairview neighborhood in August 2023, before households began using the FoodCyclers. Figure 1 shows that 52% of the garbage in the Fairview neighborhood consisted of organics, with the majority of the organics being food scraps (41%), with smaller proportions of food-soiled paper (8%) and yard and garden materials (3%).
Results from the August 2023 RDCK Comprehensive Waste Composition Study showed that Nelson’s Fairview neighborhood’s residential curbside garbage had a higher proportion of compostable materials than single-family households sampled in Castlegar and Salmo, jurisdictions also within the RDCK. City of Nelson staff said a possible explanation is that in recent years there has been increasing human-wildlife conflict (and in particular human-bear interactions) occurring in Nelson, which has prompted many Nelson residents to stop backyard composting. This trend was also reflected in community survey results. In a pilot project survey in spring 2024, 20% of pilot project participants indicated that they had stopped backyard composting due to wildlife concerns or issues.
Figure 2 shows the waste composition for Fairview households sampled that had a FoodCycler, while Figure 3 shows the waste composition for Fairview households that did not have a FoodCycler. There was a greater proportion of compostable materials in the garbage of households that did not have the appliance — on average 50% compostable material, while the garbage of households with one had on average 37%. The non-FoodCycler households had a garbage composition similar to that measured across the Fairview neighborhood prior to the implementation of the pilot project. These data indicate that the Pre-treated Organics Pilot Project had reduced the proportion of organics in the garbage stream for those residents who participated.
Pretreated Organics Vs. Curbside Diversion
Ripley and Paul estimate that the pilot project diverted 32 kilograms (70.5 lbs) of food waste per household per year in the Fairview neighborhood. Households with the FoodCyclers can opt to use the dried and ground food scraps as a soil amendment, add them to a backyard composter, or bring them to two drop-off sites established by the City of Nelson for the material, one of which is in the Fairview neighborhood at a Safeway grocery store. During the six-month period from April 1 to September 30, 2024, at the Fairview collection site, 2.2 metric tons (2.4 tons) of pretreated material were collected. During the same time period, 2.8 metric tons (3.1 tons) were collected at the non-Fairview drop-off location (Public Works building). These figures do not take contaminants deposited at the drop-off locations into account. Extrapolated to an annual basis, notes the report, this represents 10 metric tons (11 tons) of pretreated material dropped off by residents per year. Given that on average there is 75% moisture loss when food scraps are processed in the FoodCycler, this quantity of pretreated material collected represents 40 metric tons (44.1 tons) of food scraps that were processed using FoodCyclers.
Figure 4 is a comparison of the estimated quantity of food waste diverted per household per year for the Pre-treated Organics Pilot Project in the Fairview neighborhood and four comparison green cart programs — three in British Columbia (BC) and one in Ontario. The green cart programs chosen as comparisons all focused on collection of food scraps and food-soiled paper (not yard and garden material). The data for green cart programs were provided by municipalities, while the estimate for the quantity of food waste diverted by the Pre-treated Organics Pilot Project in Fairview is based on the change in the proportion of food scraps and food-soiled paper in the garbage stream measured through two waste composition studies, combined with City of Nelson curbside garbage collection tonnage data.
As indicated in Figure 4, green cart programs from neighboring communities have achieved higher rates of organics diversion. The Regional District of Kootenay Boundary, BC diverted 54 kilograms (119 lbs) of food waste/household/year with its green cart program that began in October 2023. The Town of Creston (BC) diverted 84 kilograms (185 lbs) of food waste/household/year through its green cart program that started in 2022. The Regional District of Nanaimo, BC diverted 109 kilograms (240.3 lbs) of food waste/household/year across the first 10 years of its green cart program. The City of Peterborough, Ontario, diverted 222 kilograms (489.4 lbs) of food waste and pet waste per household per year through its green cart program that started in 2023.
“The use of FoodCyclers may be leading to a lower rate of food waste diversion in comparison with green cart programs due to a few potential factors, write Ripley and Paul, including:
- “Effort required: More steps and effort required to manage food waste with the FoodCycler than through a green cart program;
- Limitations for food-soiled paper: Some types of food-soiled paper cannot be processed in the FoodCycler;
- Barriers: Residents are experiencing barriers mentioned by survey respondents (see next paragraph); and
- Limited processing capacity: The FoodCycler can process about 1 kg (2.2 lbs) of food waste at a time, which some households have found limiting.”
The most common barriers cited by pilot project participants who responded to a spring 2024 survey were a jammed bucket or mechanical issues (34%), odor (21%), noise (18%), and unprocessed food waste (16%). Numerous respondents indicated that the weight, size and/or environmental requirements for the FoodCycler were challenging for their household. Despite the barriers, there was “a very high level of satisfaction” among pilot project participants. For example, 87% enjoyed using the FoodCycler in their home. Participants were very likely (77%) or likely (14%) to recommend it to others, and 91% stated they plan to continue to use the appliance in the long-term. A number of participants indicated their strong appreciation for the project, while noting that some aspects of the FoodCycler system may pose barriers to widespread community-wide adoption and use of the appliance as an organics diversion solution.
Composting Dehydrated Food Scraps
Ripley and Paul report that the pretreated material tends to compost very quickly, due in part to its small particle size and the relatively high energy content of the material, given that it is produced primarily from food scraps. “It is best to compost the prereated material with bulking agents that provide porosity, such as wood chips, as the pretreated material contains a lot of energy, and decomposes quickly and easily (resulting in high rates of oxygen consumption from microorganisms),” they note. Dr. Paul acquired samples of pretreated material from the community drop-off bins in Nelson, and conducted a variety of tests and experiments at his research facility in Abbotsford, BC. He confirmed that it composts very quickly, and that when composted, “the compost created from the pre-treated material achieved stability and maturity relatively quickly in comparison with other feedstocks he has composted.”
The pretreated material can pose a challenge when rewet as was experienced by City of Nelson staff at the drop-off bins and by RDCK staff at the composting facility. When rewet “it can become extremely hard, almost like concrete — especially when the rewet material freezes,” says the report. “Given that high humidity conditions can cause pretreated material to mold, RDCK staff identified that proper handling, storage and humidity regulation between pretreated material collection and disposal was important, as well as having staff wear proper respiratory personal protective equipment.”
GHG Emissions Reductions, Wildlife Deterrence, Contamination
Findings on additional factors evaluated include:
GHG Emissions: The implementation of the pilot project in the Fairview neighborhood reduced GHG emissions by 1,633 metric tons, measured over a 30-year time period, states the report: “Transportation emissions are an extremely small portion of emissions. The quantity of GHG emissions avoided through implementation of an organics diversion program is closely correlated with the quantity of organics the program diverts from the landfill. The Fairview FoodCycler pilot resulted in an estimated 1.76 metric tons of GHG emissions reductions/household/year, the RDKB green cart program reduced an estimated 2.11 metric tons GHGs/household/year and the Creston green cart program reduced an estimated 3.31 metric tons GHGs/household/year.”
Wildlife: It was not possible to quantitatively measure the impact of the pilot project on human-wildlife dynamics over the length of the pilot project. WildSafe BC staff are supportive of efforts to reduce the quantity of food waste present in the curbside residential garbage. ‘Both the collection of organics in green carts and the direct use of pretreated material in yards and gardens pose the potential to attract wildlife and cause human-wildlife conflict,” notes the report. “There remain unknowns regarding the level of wildlife attraction the pretreated material poses when present in a backyard composting bin and incorporated directly into garden soil.”
Contamination: Contamination issues experienced with green cart programs were a very minimal challenge in the Pre-treated Organics Pilot Project, given that people are required to process their own food waste using the FoodCycler, and therefore are far less likely to place contaminants like plastic into the unit. The only contamination challenge experienced with the Pre-treated Organics Pilot Project was people placing improper items in the community collection bins for pre-treated organics once the locks were removed in September 2024.
