Is composting organic waste spreading?

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Amanda Elliott

When asked what they do for the environment, many people say they recycle, reducing the amount of garbage they put in the trash. Composting organic wastes is another way of reducing the amount of waste being sent to landfill.

Traditionally, households composted in the backyard, but the use of municipal compost collection systems is growing. In the last few years a number of programs for curbside collection of food wastes have been initiated in large cities such as Edmonton, Toronto, Hamilton and Ottawa.

The diversion of organic waste has become a growing trend. From 2000 to 2004, the amount of organic waste composted by the waste management industry increased by 70% to 1.7 million tonnes. Close to two thirds of these organic wastes were generated by the residential sector.¹

Although the majority of households that compost do so in their backyard, access to curbside collection of organic wastes plays an important role in people's participation in composting.

How much is composted?
Composting by households
Is composting environmentally friendly?
Conclusion

How much is composted?

While diversion of all materials is on the rise, the Canadian compost pile is getting larger. According to the Waste Management Industry Survey, diversion of organic materials increased 70% in four years, from 980 thousand tonnes in 2000 to 1.7 million tonnes in 2004 (Table 1). These materials are composted at centralized facilities by the waste management industry.²

The average Canadian sent 51 kilograms of organic waste for composting in 2004, compared to 32 kilograms in 2000.

Organics also make up an increasing share of total materials diverted. In 2000, organics made up 16% of all materials diverted from disposal. By 2004, approximately 21% of these materials were composted.

The gain in organics diversion across Canada is attributable to the introduction of new composting programs and the expansion of existing organics collection (leaf and yard waste) programs to accept food wastes.

On a regional basis, the Maritime Provinces did the best at diverting organics (Table 2). Prince Edward Island, New Brunswick and Nova Scotia topped the list with the highest per capita diversion of organic materials (Chart 1). Regulations and well-established composting programs in Prince Edward Island and Nova Scotia may help to explain the popularity of composting in the east.^3,4

Over 1.1 million tonnes (65%) of organic waste composted by the waste management industry comes from Canadian households. The remainder comes from non-residential sources.⁵

Composting by households

Composting is slowly becoming a more popular activity for Canadian households. According to the Households and the Environment Survey, 27% of Canadian households composted in 2006, compared to 23% in 1994.⁶

The large majority of these households were backyard composters who used a compost bin or pile or who dug organic wastes down into their garden (Table 3).

Only 30% of households composting kitchen waste and 38% of households composting yard waste used a curbside collection system.

Prince Edward Island, which has a mandatory province-wide source-separated waste program and Nova Scotia which has a provincial landfill ban on organic waste, had the highest proportion of households that reported having either kitchen and/or yard waste picked up at the curb.  

Curbside collection means more composting

Where households have the option of getting their kitchen and yard waste hauled away at the curb, a higher percentage compost.

Prince Edward Island, Nova Scotia, Ontario and New Brunswick (Table 3) have the highest participation rates in composting and they also have the highest percentages of households that have both yard and kitchen waste collected at the curb.

More than 4 out of 5 households that compost kitchen waste do so for more than six months of the year (Table 4).

Access to curbside collection for organic materials may also influence whether a household composts for part of the year or year-round. Participation in year-round composting tends to be higher in provinces that have greater access to curbside collection.

Households in Alberta, Saskatchewan, Manitoba, Quebec and Newfoundland and Labrador, which are more likely to use a compost bin or pile, compost less year-round than the Canadian average. This likely reflects the lack of compost collection programs.

Although backyard composting can be done year-round, the process slows in cold weather. This, coupled with the walk to the backyard bin, may deter winter composting.

Households in British Columbia are the exception to the rule. Households in this province have less access to curbside organics collection programs, but more than three quarters of households that compost do so year round. The moderate climate in coastal areas of the province is a likely explanation.

Is composting environmentally friendly?

Municipal waste collection was established in the early 1900's to manage waste which was considered a public health nuisance. Rotting garbage creates odours and attracts insects and other pests that can spread disease. In Canada, burying garbage in landfills has been the primary way of dealing with this problem.

However, landfilling organic materials produces leachate and methane, both of which have impacts on the environment.

When organics are exposed to water in landfills, the liquid trickles down through the pile, picking up contaminants along the way. Groundwater contamination by leachate can be a problem with landfills that do not have a sufficient clay layer or an engineered liner.⁷ Burying organics in landfills also creates an environment where they decay without oxygen, thereby producing methane, a greenhouse gas.

Methane and leachate production can also occur at composting facilities unless compost piles are properly managed. The right combination of organics (paper, food wastes and leaf and yard wastes) and frequent turning and aeration of the piles ensures that problems are minimized or avoided. According to the waste management branch in the City of Edmonton, the only by-products of their compost piles are carbon dioxide and water vapour.⁸

Conclusion

In some areas of Canada, diminishing landfill capacity is an issue. At the same time more and more garbage is produced each year. Some of the landfill capacity issues have been addressed by shipping waste to other regions of the country and to the United States; however, waste exports to the U.S. are not a long-term solution.⁹ One way of reducing the amount of waste going to landfill is to compost organic wastes.

Some estimates show that up to half of the residential waste stream contains organic material.¹⁰ In 2004, 1.1 million tonnes of residential organic waste was composted by the waste management industry, accounting for 8% of total residential waste. Reducing the amount of organics disposed in landfills not only minimizes the associated environmental impacts, but producing compost literally adds something to the environment. As alternatives to disposal in landfills become central to waste management, organics diversion, or composting, will become a growing part of the waste management equation.

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Footnotes

1. Households are diverting even more of their organic wastes to backyard composters; however, there are no estimates available for the quantity of this material.
2. Does not include materials composted on-site by the waste generator (for example, backyard composting).
3. Island Waste Management Corporation, 2008, Island Waste Management Corporation, (accessed January 10, 2008).
4. Nova Scotia Environment and Labour, 1996, Regulations Respecting Solid Waste-Resource Management, (accessed January 2, 2008).
5. Statistics Canada, 2007, Waste Management Industry Survey: Business and Government Sectors 2004, Catalogue no. 16F0023X, Ottawa.
6. Statistics Canada, 2007, Households and the Environment, 2006, Catalogue no. 11-526-X, Ottawa.
7. Laflèche waste disposal facility Environmental Assessment application, (accessed January 2, 2008).
8. City of Edmonton, Waste Management Branch, 2003, Wastefacts: Edmonton Composting Facility, (accessed January 8, 2008).
9. City of Toronto, Solid Waste Management, 2007, Facts about Toronto's trash, (accessed November 13, 2007).
10. P. van der Werf and M. Cant, 2006, "The State of Composting Across Canada – Part 1," Solid Waste & Recycling Magazine, October/November 2006.