A Blue Box for substrates

June 02, 2010
Written by Cam Buchan
Every year, the North American greenhouse industry uses more than 250,000 cubic metres of growing substrates. But finding a sustainable answer for used substrate is a growing concern for the industry. Grodan has an answer.

H&A Mastronardi Farms general manager Albert Mastronardi.

Albert Mastronardi looks over the 24 acres of greenhouse vegetables, including cluster and beef tomatoes and mini-cucumbers, in Kingsville, Ontario. He sees a lot of opportunity that, in the past, has simply gone to waste.

Each year, his operation goes through approximately 100,000 slabs of Grodan substrate, and the general manager of H&A Mastronardi Farms knows there’s increasing pressure to recycle this material.

It’s a challenge for the entire industry.

Processed rockwool after it has been separated from the plastic
Every year, the North American greenhouse industry uses and discards enough growing substrate to fill over 4,500 household swimming pools. Much of that used substrate is disposed of in non-sustainable ways – it ends up in landfills or in applications where it ultimately ends up in the ground.

Grodan is changing all that with a true recycling program. In partnership with Brampton Brick, used Grodan substrate will be incorporated as a raw material in the brick manufacturer’s building products. This symbiotic relationship will allow the Ontario company to offset other raw materials normally used in its bricks that are extracted from limited quarry resources.

“Given these green days, it’s very important to recycle as much as we can,” says Mastronardi. “And this is a major step in the recycling and reuse of the growing material that we use.”

“Think of Grodan’s recycling strategy as a Blue Box program for used substrate,” says Chris Marshall, Grodan’s North American business manager. The program looks like this:
  • At the end of the growing cycle, greenhouse operations deposit the material into Grodan-supplied bins and it is removed for processing.
  • Once collected, the product is processed to separate the rockwool media from the plastic wrapping, which is recycled using traditional methods.
  • The rockwool component is ground up and transported to Brampton Brick, where it is incorporated into the brick manufacturing process as a raw material to offset a portion of sedimentary shale rock that is typically required for production.
While still in its infancy, sustainability is gaining traction throughout the distribution chain, from consumers  to retailers and growers.

“We see this trend developing from our customers’ perspective,” says Marshall. “When you look at their current marketing direction, our customers are very much focusing on sustainability as well. So they’re looking at reductions in their overall environmental and carbon footprint. We also see demand for reducing the environmental impact coming from retailers all the way back to consumers.”

The collected Grodan substrate is used to manufacture bricks that are specified for Leadership in Energy and Environmental Design (LEED) certified building projects, according to Brampton Brick representative Brad Cobbledick.

“What it does for us is displace 20 per cent (by volume) of the shale that we have to mine in a nearby quarry and transport,” says Cobbledick. “So it extends the life of our quarry – which is a non-renewable resource – and allows us to have a certain amount of recycled product in our brick.”

The inclusion of used Grodan substrate has no effect on the colour, texture or physical properties of the brick – a positive attribute that means the bricks can be specified with no compromise in quality.

It’s a long-term relationship that’s paying dividends for all parties, and making the greenhouse industry even greener. ■

Cam Buchan is a freelance writer in Ontario.

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