A golden garbage opportunity

Methane Digester

We’re on the cusp of a revolution in waste disposal. If what I’ve heard in the past few days turns out to be true, we won’t need trains hauling garbage to old mine shafts in Kirkland Lake. We won’t need incinerators. And we’ll send a lot less to landfill sites.

We would be able to let nature handle all of Toronto’s organic garbage — in other words, kitchen and greengrocer wastes, yard wastes, everything that can rot. Together, it accounts for half of everything that Toronto sends to landfills.

And, to put the icing on the cake, we would end up with fuel to generate electricity, and provide heating and cooling to buildings.

All this could be done by relying on the smallest cellular organisms in the world: bacteria, specifically, methanogens that live only where there’s no oxygen, as in landfills. In a process called anaerobic digestion, they convert garbage into methane, water, and soil. They’re so small that a single gram of decaying matter can contain as many as 2.5 billion of them.

The benefits of anaerobic digestion have long been recognized. For years we’ve been tapping and using the methane seeping from landfills for fuel.

What methanogens do in landfills, they can also do in methane digesters — large vats in which the decomposition of garbage is accelerated. The technology has existed for generations. The problem has been that people have looked elsewhere for ways to get rid of garbage. And with digesters, there was the difficulty of keeping contaminants out of the process. Contaminants ruin the soil produced by digesters. Why build a digester if you end up with a lot of soil you can’t sell?

A tiny lithium battery from a hearing aid or a camera, for instance, can contaminate a tonne of soil. Broken glass is notoriously difficult to screen out.

Now, however, Paul Blanchard, executive vice president of Canada Composting Inc.,  is proclaiming the dawn of a new era.

Canada Composting, which is based in Newmarket, has acquired North American rights to methane digester technology being used in eight German cities. Blanchard says the garbage-to-methane process can be completed in the astonishingly short period of slightly less than three days.

The key is something called a hydropulper that removes contaminants. It’s a vat filled with water that is swirled round and round at high speed.

Swirling water creates friction that forces things apart, such as the layers in a juice box — the box board container, the tinfoil lining, the inside plastic coating, and the polywrap that seals everything.

The friction also turns the box board into pulp — along with newspapers, cardboard, hedge trimmings, and other organic material– and mixes it with food scraps. The resulting slurry is piped to the methane digesters. What’s left behind are the contaminants, some of which can be recovered for recycling.

We’ll soon learn if the technology lives up to its billing. Canada Composting is building a $26-million plant in Newmarket to process 180,000 tonnes of garbage a year collected from commercial buildings. The plant will open in February and, from the methane produced, it will generate 5.5 megawatts of electricity, of which 3.5 megawatts will be available for sale. That’s enough electricity to power 7,000 average homes.

Meanwhile, Canada Composting is building a $9.4-million demonstration plant at the city’s Dufferin waste transfer station, near Dufferin St. and  Sheppard Ave.  It will come into operation next summer, and the city will test its abilities for a year.

In all of this, there’s a golden opportunity. If the test satisfies city officials, they could integrate methane digesting with the operations of the Toronto District Heating Corp., and use the methane as fuel to provide electricity, heating, and cooling for the downtown office buildings TDHC serves. Such integration would be a model environmental approach.

But time is short. Closing of the city’s Keele Valley dump is imminent, and officials are working on a plan for handling the city’s garbage beyond 2002. An integrated approach now would be far better than a patchwork adaption later.

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