The right to use the mark of conformity "COMPOSTABLE" on compostable plastic bags and on compostable products is granted only to those manufacturer/distributors that demonstrate that their product conforms with specific performance attributes and adheres to the parameters for "compostability" as set out in the BNQ documents, Compostable Plastic Bags - Certification Program
(BNQ 9011-911/2007) and Compostable Products – Certification Program (CAN/BNQ 0017-988).
It is important to be aware that "compostable" and "biodegradable" are not equivalent. Similarly, "disintegration" cannot be used interchangeably with either of these terms.
The definitions established for the purpose of the program are as follows:
Biodegradation: degradation caused by biological activity especially caused by enzymatic action leading to a significant change in the chemical structure of a material. (Reference: ISO 162929, section 3.3)
Compostable: said of that which is capable of undergoing biological decomposition in a compost site such that the material is not visually distinguishable and breaks down into carbon dioxide, water, inorganic compounds and biomass at a rate consistent with known compostable materials. (Reference: ASTM D 6002) .
Degradation: an irreversible process leading to a significant change in the structure of a material, typically characterized by a loss of properties (eg. integrity, molecular mass or structure, mechanical strength) and/or by fragmentation. Note: degradation is affected by environmental conditions and proceeds over a period of time comprising one or more steps. (Reference: ISO 16929, section 3.2)
Compost: solid mature product resulting from composting (Reference: CAN/BNQ 0413-200)
Composting: managed process of bio-oxidation of a solid heterogeneous organic substrate including a thermophilic phase. (Reference: CAN/BNQ 0413-200)
Compostable plastic bags and compostable products must be compatible with the dynamics involved in the composting process and not detract from the physical and chemical quality of the end product, compost.
In Canada, for a plastic bag or other product to claim compostable, it must:
★disintegrate by at least 90% within 84 days of the composting process
★biodegrade by at least 90% within 180 days of the composting process
★have no ecotoxicological effect greater than 10% on the germination rate
of seeds and
★vegetation biomass rate
The process to establish the Canadian criteria for the evaluation of claims for compostable plastic bags originated because of plastic bags being introduced into the Canadian marketplace using compostable claims that were not valid (ie. they were not compostable).
Originally initiated for Québec purposes by Recyc-Québec and the City of Montréal, the development of the Canadian Certification Program for compostable plastic bags was expanded nationally by The Composting Council of Canada with support from the provincial ministries of environment of New Brunswick, Prince Edward Island, Nova Scotia, Manitoba and Alberta.
The Bureau de normalisation du Québec (BNQ), having had past experience in standard-setting for the composting industry, was commissioned to coordinate the review process.
Rather than re-inventing the wheel, the review process involved the examination of existing international standards for compostable plastic bags and evaluating their appropriateness for Canadian conditions as well as composting facility operational and product marketing requirements.
A 15-person review panel was selected involving representatives from municipalities, composting facilities, product suppliers and users as well as consumer groups. Following extensive discussion as well as public consultation, the Canadian Certification Program became official in September 2007.
In 2010 the certification program was expanded to include compostable products of all types, following the adoption of the standard CAN/BNQ 0017-988. This serves to adopt the standard ISO 17088 as the national standard for Canada. It is important to note that the original program for the certification of compostable plastic bags (BNQ 9011-911/2007) will soon be cancelled to be replaced entirely by the certification program for compostable products (CAN/BNQ 0017-988).
Time and rate of degradation and disintegration were amongst the criteria established. Requirements for the bags' impact on the finished compost from the perspective of visual quality as well as trace element content and plant exotoxicity have also been established. The final set of criteria selected reflects the operational and regulatory realities which composting facilities must adhere to in Canada for both organic residuals processing and finished compost product sale.
Those manufacturers/product representatives wishing to adhere to the Canadian Certification Program and use the compostable mark of conformity on their compostable plastic bags must submit an application to the BNQ for review and meet the requirements of the program.
Two review options are available:
Submit existing compostability test results from internationally-
recognized laboratory organizations. These will be reviewed by the BNQ to confirm adherence to the Canadian Certification Program.
request the BNQ to conduct the testing in internationally-recognized laboratory organizations of the selected product according to the criteria set out in the Canadian Certification Program.
Both options have costs associated with them. The manufacturer/product representative should contact the BNQ directly for further details.
Copies of the certification program documents for compostable plastic bags BNQ 9011-911/2007 and for compostable products CAN/BNQ 0017-088 and the certification protocol BNQ 0017-988 associated with these programs can be ordered directly on the BNQ website.
What is Composting?
Composting is a natural process whereby micro-organisms transform organic waste materials into a soil- like product called humus (pronounced "hue-mous"). Kitchen scraps, leaves and yard waste, paper, wood, food-processing wastes, as well as agricultural crop wastes and animal manures, are excellent organic waste materials that can be composted.
Composting has a wide range of benefits: it helps to reduce the amount of waste going to landfills and produces a valuable product, compost, of benefit to soil health & vitality in addition to many other attributes such as water and soil conservation. It is estimated that about 40 to 60 percent of the total waste stream could be composted!
For the composting process to work best, it is important that the micro-organisms have a continuous supply of food (i.e., organic wastes), water and oxygen. As well, managing the temperature of the composting material is important to make the process work.
Although most organic wastes supply all of the nutrients necessary for the micro-organisms to grow, they grow best with certain levels of carbon (C) and nitrogen (N). Paper, leaves and wood are high in carbon, while grass clippings and vegetable trimmings are high in nitrogen. The materials in the composting "recipe" need to be mixed in the correct combination to create the right C:N ratio.
Types of Composting
Composting can be done in many different ways. Types of composting range from residential or backyard composting to mid-scale and central municipal or industrial composting systems. Selecting the most suitable method depends on the amount and type of organic materials to be composted.
Residential or backyard composting means that an individual household composts most of its food and yard waste in a container located outside the home. Worm composting is a viable option to compost kitchen waste indoors. Composting at home is the simplest and most cost-effective method because collection, transportation and costs are avoided. People benefit directly from their own efforts by producing a valuable additive for their own garden soil.
However, not all food and yard waste can be managed so simply. Organic material from commercial sources, such as restaurants, supermarkets, apartment buildings and food manufacturers, needs to be managed differently. This is where mid-scale and centralized composting fits in.
Both mid-scale and centralized composting involves significantly larger quantities and a larger variety of organic wastes.
Mid-scale composting is the on-site management of organic waste generated by a group of people, such as in an apartment complex, office building or hospital. This avoids the transportation of organic waste. Centralized composting involves the collection and transportation of organic materials to a special facility where it will be prepared and processed into compost.
Centralized Composting Facilities
The design and set-up of a centralized composting site must take into account such factors as the type and volume of organic waste, waste collection methods, sorting, storage factors and the end use for the finished compost. Quality organic waste and good operating procedures ensure the production of high-quality compost.
Among the most common centralized composting process technologies, in order of increased technology, are:
Organic materials are placed in long triangular rows called windrows. Windrows are turned and watered occasionally to ensure that the micro-organisms get an adequate supply of oxygen and that any clumps of organic material are broken up.
This method is commonly used for composting leaf and yard waste, commercial food wastes, or such "specialty items" as shredded Christmas trees.
Static Aerated Pile
Organic waste materials are formed into windrows over perforated pipes. Rather than the windrows being turned, air is supplied to the micro-organisms through the pipes.
Almost all municipalities own the necessary equipment required for centralized composting operations using windrows or static aerated piles. This means that the capital costs are relatively low.
In-vessel systems are either fully or partially enclosed, and can handle more material in a smaller space than windrows or static aerated piles. However, they tend to be more costly. These systems provide better control of aeration, temperature and the moisture in the organic materials being composted, all of which result in faster decomposition.
If necessary, water can be added to maintain the correct moisture level, and air can be pumped in to provide oxygen and to control the temperature.
Although different in-vessel systems are available, they are generally of three basic types: channels or troughs, containers and rotating drums (sometimes called tube digesters).
Channels (or Troughs)
The composting process takes place in long rectangular troughs or channels. The organic waste materials are mixed so that the clumps are broken up and the material is aerated.
Composting takes place in closed containers that are supplied with air. Excess moisture and exhaust air are removed from the containers to maintain ideal conditions for the micro-organisms throughout the process.
Rotating Drums (Tube Digesters)
Organic waste materials are added to a drum which is continuously rotating. The rotation ensures that the micro-organisms are constantly supplied with the oxygen they need and that all of the organic waste materials are exposed to them. The material remains in the drum for three to five days and is then transferred to windrows for final curing.
Organic waste materials can also be digested in an oxygen-free, or anaerobic, environment by micro-organisms that do not need oxygen. The length of time required to digest the organic waste material varies according to the individual technology usually between two and twenty days. The process produces humus, methane and carbon dioxide. The methane is captured and converted into energy. Following digestion, the humus can be transferred to windrows or another method for final composting.
Excerpts from Centralized Composting Helping To Complete The Carbon Cycle, written by Susan Antler of The Composting Council of Canada on behalf of Environment Canada.