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Composting and Candy Making: Facts and Fairy Tales

The Selkirk College School of Environment and Geomatics IEPT program has a new course which examines sustainability. The course was designed for 4th semester students who are completing applied studies in environmental land use planning, geographic information systems, environmental chemistry and hydrology.

The objective of studying sustainability is to examine the relationship between humankind and the environment, a relationship famously described as meeting the needs of the present generation without compromising the ability of future generations to meet their own needs.

The Integrated Environmental Planning Technology program is an applied technology program, so an underlying theme of the Sustainability course is to go beyond theory and explore real world applications of sustainability. To that end, topics such as waste management, cradle to cradle manufacturing and renewable energy are addressed.

Canadians generate 380 kg of solid waste per person per year which creates a small mountain of garbage annually when multiplied by over thirty-four million Canadians. Understanding the composition of solid waste opens doors to its sustainable management.

Remarkably, paper products represent one third of Canadian solid waste – which isn’t truly waste but a valuable resource when properly recovered and recycled. Recycling paper products reduces the need for logging and permits the manufacture of new paper products at a lower cost than if they were manufactured from wood.

Yard and kitchen waste account for the next two largest fractions, totaling 25% of solid waste. If glass, metal, wood and plastic is included, three quarters of household solid waste can be profitable if diverted from landfills.

IEPT students study solid waste management, waste diversion programs and public policy strategies to shift toward a zero waste paradigm. They tour a landfill, recycling facilities and they experiment with composting.

From a chemistry perspective, composting is surprisingly similar to candy making. In both cases, organic matter is partially decomposed by heating such that raw materials are converted into a more stable end product. For candy making, the raw material is sugar. It’s carefully heated over a stove so as not to burn. At critical temperatures, sugar changes. First it passes through a soft candy stage, called caramelization that converts white sugar into darkened toffee. With additional heat, it becomes hard candy.

In a parallel process, yard and kitchen raw material waste is compacted into a composting bin. The naturally occurring micro-organisms generate heat, which favours the growth of heat-loving bacteria. The heat-loving bacteria generate even more heat. As the compost exceeds 50°C, spontaneous chemical reactions cause the compost to change, to darken and caramelize into apeat-like substance. Any pathogenic bacteria are destroyed by high temperatures. What was once waste, is transformed into a valuable soil supplement that may be sold at garden centres.

IEPT students experimented with two composting processes. They filled two bins with chipped brush and straw. Into one bin crushed limestone, sugar beet pulp and alfalfa pellets were added while the other received no supplements. The supplements improved the environment for composting and provided nutrients for the micro-organisms. The results were remarkable.

In the supplemented bin, the compost temperature rapidly rose to over 50°C while outside temperature hovered around freezing. The composter was steaming as it caramelized chipped brush into peat, transforming waste and demonstrating that landfill is an option of last resort for managing the majority of our residential solid waste.While a fairy tale ending might be to compare composting to a beautiful princess kissing an ugly toad to reveal a handsome prince, composting parallels candy making in a process that spins straw into gold.

For more information on the Integrated Environmental Planning Technology program, please contact Selkirk College School of Environment and Geomatics Chair, Brendan Wilson, bwilson@selkirk.ca.

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