Water filtration leftovers to be recycled

Metro Vancouver has found a way to recycle material left behind when drinking water is treated at the region’s largest filtration plant.

Last year, Metro Vancouver and Lafarge conducted a trial of using drinking water treatment residuals — a wet, clay-like material left over after water is filtered — from the Seymour-Capilano Filtration Plant in the production of cement at Lafarge’s plant in Richmond.

The trial was successful and Lafarge solved operational problems presented by using the treatment residuals. Stack tests conducted while residuals were being used showed that emissions levels remained within Lafarge’s air quality permit.

On Friday, Metro Vancouver’s board authorized a three-year contract with Lafarge.

“There’s not a lot of places that actually do recycle their water treatment residuals. From my experience, most of them go to landfills,” said Laurie Ford, Metro’s utility residuals program manager. “That’s really the mandate of my group, to find beneficial uses for these materials.”

The filtration plant produces about 9,000 tonnes of residuals a year, which Lafarge plans to use to replace 21,000 tonnes of rock quarried from Sumas Mountain in Abbotsford. This means no residuals will end up in landfills and Lafarge will be able to reduce the emissions produced by quarrying and trucking the shale.

Metro will pay Lafarge about $435,000 a year, which covers capital expenditures, such as additional storage facilities, and the additional mixing that Lafarge needs to do in order to use the material.

But the deal will eliminate landfill fees for the residuals, saving Metro about $1.3 million a year. “I think it benefits both parties, and helps us all meet our targeted sustainability goals,” said Ford.

There’s not a lot of places that actually do recycle their water treatment residuals.