Quality Standard Stamp

Compost Quality Standards

Canadian Council of Ministers of Environment (CCME) Quality standards for Selling and Distributing Compost in Canada

Composting is a natural process; however, it was not until the 1990s that medium to large-scale composting technologies became a public interest (Golueke and Diaz, 1996; Zheng et al., 2020). During the nineties, the public became more concerned and aware about ecology, resource conservation, and environmental quality (Golueke and Diaz, 1996). During this time, composting at the industrial and municipality level emerged in Canada to redirect organic waste from landfills and restore carbon back into the soil (Golueke and Diaz, 1996; CCME, 2005). More people became interested in buying and applying compost for home gardening and landscaping.  To ensure compost that was distributed to the public was safe, the Canadian Council of Ministries of the Environment (CCME) created a report titled Guidelines for Compost Quality published in 1996 and then updated in 2005. This article briefly summarizes compost quality factors discussed in the CCME 2005 Guidelines of Compost Quality. The CCME guidelines are directed towards those who generate compost to be sold or distributed. Those who generate compost and apply it to their personal property are not required to meet the CCME guidelines, but these guidelines are worth reviewing for any type of compost operation.

The CCME 2005 quality guidelines include two categories of compost. Category A compost is unrestricted and can be used for any application, including gardening, agriculture, horticulture, and landscaping. In contrast, Category B is for restricted use. For this article, the focus is only on the Category A guidelines.

1. Foreign Matter: It is common for compost to have foreign matter. Foreign matter includes any material over 2 mm in dimensions, such as metal, glass, plastic, or rubber. Compost that contains sharp foreign matter is a concern. Materials such as nails, broken glass, electrical wires, needles, staples, bottle caps can cause injuries to humans and animals.  According to the CCME guidelines for Category A, a compost should “have no more than one (1) piece of foreign matter greater than 25 mm in any dimension per 500 ml”, AND have zero (0) pieces of “sharp matter of dimensions greater than 3 mm per 500 ml”.

From our experience having a community composter, stickers and rubber bands have been found in the compost. To avoid these foreign materials in the compost, we inspect the fruit and vegetable waste we received from the grocery store; then removed all stickers, rubber bands or other synthetic polymers before adding the organic waste to the Actium batch composter

2. Trace Elements: The CCME 2005 includes the maximum concentration limits for the presence of eleven trace elements in a compost product. Some elements such as cadmium and lead can cause toxicity to humans, plants, and animals when they are present in excess within a compost or soil. Other trace elements in compost are beneficial to plants, animals, and/or humans as micronutrients.  Nevertheless, as the classic toxicology principle states, the dose makes the poison. All elements can be toxic if too much is consumed or absorbed. The toxic limit for each element is different.  For instance, the CCME limit for zinc concentrations for a Category A compost is 700 mg per 1 kg of soil (700 ppm). In comparison, the limits for selenium concentrations in a Category A compost is 2 mg per 1 kg of soil (2 ppm). 

3. Pathogens:  Pathogenic organisms (including some fungi, bacteria, viruses, and parasites) can cause diseases and health risks to humans, animals, or plants. The CCME 2005 guidelines for pathogens have different criteria depending on the type of organics added to the compost and the approaches used to compost (e.g., in-vessel, windrow composting, and aerated static pile). The Actium composters use an in-vessel approach.

When an in-vessel compost contains only yard waste, the compost temperature needs to be 55°C ( 131 °F) or warmer for a minimum of three days. OR have a fecal coliform test that resulted in less than 1000 most probable number (MPN) per grams of total solids calculated on a dry basis, AND be tested for Salmonella sp. with results that have a detection level under 3 MPV per 4 grams of total solids calculated in a dry weight basis. 

When an in-vessel compost contains other feedstocks (e.g., pet waste, manure, a variety of food waste, etc.), the temperature needs to be greater than 55°C for a minimum of three days AND be tested for fecal coliforms and Salmonella sp. Keep in mind that the criteria for preventing pathogens in compost can also include processes recommended at the provincial and territory level. 

4. Organic Contaminants: These contaminants include dioxins, herbicides, pesticides, polychlorinated biphenyls (PCB), or polycyclic aromatic hydrocarbons (PAH). These chemicals can be present in compost, though most likely in trace to low amounts. The CCME does not have a routine analysis guideline recommendation for organic contaminants. Instead, the CCME recommends being mindful of what items are being composted and avoiding products that have the potential to contain high concentrations of organic contaminants.  

5. Maturity and Stability: Immature compost can negatively affect plants, cause unpleasant odours, and attract pests. To ensure compost is mature and stable before being distributed or sold, the CCME 2005 directs that compost be cured for a minimum of 21 days AND meet one of the three requirements. The first two requirements involve measuring compost respiration rates or carbon dioxide evolution rates and meeting CCME criteria. The third requirement is based on temperature (the easiest of the three options to measure). For this requirement, the compost must have a temperature of 8°C (46.4°F) or less relative to the ambient temperature to be considered mature or stable. 

Compost quality guidelines by the CCME ensure consistent standards nationwide, protecting both the public and the environment. It is highly recommended for those who have composting operations in Canada to read the full CCME 2005 Guidelines for Compost Quality Report. The compost industry has expanded over the years, and the practice of composting has become a routine practice for many households (i.e., participating in a green bin program). The compost industry is a crucial component to waste management and is expected to advance as more everyday products and packaging are developed to be compostable. 

References:

Canadian Council of Ministers of the Environment (CCME). (2005). Guidelines for Compost Quality (PN 1340). CCME, Canada. https://ccme.ca/en/res/compostgdlns_1340_e.pdf

Golueke, C. G., & Diaz, L. F. (1996). Historical Review of Composting and its Role in Municipal Waste Management. The Science of Composting, 3–14. https://doi.org/10.1007/978-94-009-1569-5_1

Zheng, X., Aborisade, M. A., Liu, S., Lu, S., Oba, B. T., Xu, X., Cheng, X., He, M., Song, Y., & Ding, H. (2020). The history and prediction of composting technology: A patent mining. Journal of Cleaner Production, 276, 124232. https://doi.org/10.1016/j.jclepro.2020.124232