Composting
Residential Source Separated Organics Collection Strategies
Best management practices using certified compostable liner bags.
Dave Douglas, President – VisionQuest Environmental Strategies Corporation
For many municipal jurisdictions across Canada and the U.S. seeking to maximize the diversion of residential solid waste from landfill, food residue offers the next level of “low hanging fruit” in the spectrum of residential waste, offering an incremental diversion through source separation organics (SSO). When designed and implemented correctly, the incremental diversion may top 20 percent of residential solid waste. However, if implemented poorly the negative reaction could jeopardize realized achievements and actually result in overall lower diversion across the board, simply by turning participants off entirely.
Quite simply, the issue associated with consumer acceptance and participation in the diversion of food organics boils down to the three Cs—cost, convenience and cleanliness. Failure to address all three of these issues will impact the overall success or failure of your program. Of the three Cs, cleanliness—addressing the “ick” factor—is easily the most important (see Figure 1).
As the saying goes “The second mouse gets the cheese”, there is a direct relevance here too. While SSO (food) diversion programs are certainly not new to the industry as such programs have been in place across Canada since the very early 1990s, program parameters have evolved greatly over the years in an effort to address the three Cs. First generation programs that struggled to maximize food residue capture rates have learned from the early days and those jurisdictions that have waited to launch pilot or full scale programs now have extensive resources to draw from to design and implement highly successful programs.
The Early Days
One aspect of SSO (food) program evolution relates to the recognition of the inherent relationship between bins and liner bags. In the early days, the debate often centered on “bins” or “bags” as the mechanism of transfer from the household to the curb. Discussions now focus on “bins” and “bags” with the understanding that both items offer their own inherent positive aspects to a well designed program. While bins offer pest proofing, liner bags address the “ick” factor associated with drips and odours.
During the early days of program design, single use plastic bags offered participants the convenience, ease of use and cost-effective option for residents to line bins. However, challenges faced at centralized compost facilities associated with the extraction of food from the bags and ultimate separation of polyethylene film from the organic feedstock and ultimate compost.
In response, municipal SSO program administrators began looking at the use of kraft paper liner bags as an alternative to traditional plastic liner bags. However, although these products provided improved operating by breaking down along with the organic feedstock, the first “C”—cost—became a factor in maximizing residential participation.
Current Standards
Over the past decade, technological advances have been made towards the development of compostable bag technology that facilitate product integrity while the bag must remain a bag, but also fragment and mineralize in a manner conducive to centralized composting facility timelines.
While many experts in the waste industry may attest to the early days of the advancement of the biodegradable and/or compostable bag technology as very turbulent, the industry has evolved and matured with the establishment of a certification process under the Biodegradable Products Institute (BPI) in the U.S. and the Bureau De Normalization Du Quebec (BNQ) in Canada. Now, products certified as compostable by either BPI and/or BNQ must identify the logo of conformity on product packaging and each individual compostable bag to ensure that they are easily identified upon collection.
In order for products to be deemed to comply with to BPI/BNQ certification standards compostable bags must meet the American Society for Testing and Materials Standard Specifications for Compostable Plastics (ASTM D6400). To comply, products must:
- biodegrade to carbon dioxide at a rate comparable to yard trimmings, food scraps and other compostable material
- disintegrate into small enough particles so no remnants remain that could clog screening equipment
- safely biodegrade leaving no visible or toxic residues so that the compost is able to support plant growth
The advent and availability of certified compostable liner bags as a lower cost alternative to kraft paper bags served to address the cost issue, resulting in an increase in residential participation and SSO (food) feedstock capture in programs where such products are allowed to be used.
In 2010, a comparison analysis of SSO (food) capture rates between a number of Ontario municipal SSO (food) programs was undertaken to assess incremental differences between programs accepting only kraft paper liners to those accepting certified compostable bags. Chart 1 offers a comparison in food capture rates per household per year. The Ontario, Canada based programs identified in brown (ie. Waterloo Region, Kingston) do not presently allow for the use of certified compostable bags, while those in green (Peel Region, Simcoe County, Dufferin County, Durham Region and Halton Region) do allow for use.
Program Launches
Within Canada, more than 4.3 million households are now able to use certified compostable liner bags for SSO (food). Although such programs have been slower to launch across the U.S., there are numerous states (i.e. California, Oregon, Washington, Minnesota) that have been implementing such programs, including large cities such as San Francisco, Seattle and soon Portland). Numerous other pilot projects are planned or underway.
Municipal promotional education and communication strategies developed to support local SSO (food) programs offer a key role in identifying and promoting the use of acceptable certified compostable products. Typically, rather than endorsement of any one (or more) approved brand name certified compostable products, key messages simply advise residents to look for the logo(s). Messaging typically is included in the program launch package for distribution door-to-door or on the municipality’s Web site. Additionally, pre-launch notification to local retailers of applicable products also serves to ensure that compostable bags are made available through local retail channels.
Ultimately, successful source separated organics diversion programs will be achieved when the wide range of residential needs are addressed. Restrictive programs that fail to provide participants with the flexibility to choose how they would prefer to deal with food scraps in their home or at the curb will also so often fail to fulfil the program goals. Subsequently, failure to include certified compostable liner bags into these programs will also challenge the ability of such programs to maximize their diversion potential. As they say “There is a horse for every course”.
Dave Douglas is President of VisionQuest Environmental Strategies Corp. (Aurora, ON), providing strategic and innovative insight and professional support towards environmental sustainability with a key focus on providing public & private sector clients with direction towards the design and implementation of municipal solid waste management diversion strategies (including SSO food/yard and recyclable materials). Additionally, VQ provides corporations with guidance towards meeting corporate stewardship obligations and extended producer responsibility requirement obligations across North America (state and provincial level). For more information, call (416) 570-4379 or e-mail [email protected].
For more information about the U.S. Biodegradable Products Institute, visit www.BPIworld.org. For more information about the Canadian Bureau De Normalization Du Quebec, visit www.bnq.qc.ca.
Figure 1
Addressing the “Ick” Factor.
Chart 1
Comparison of food capture rates in Ontario source separated organics (SSO) food collection programs between those that allow certified compostable bags for use to those that presently do not.
Images courtesy of BPI and CCC-BNQ.