Whoever said money is like manure because it does a lot of good if you spread it around might have had a future in sewage treatment.
More solid waste from the Ashbridges Bay Treatment Plant is being directed away from landfills than ever before, largely because it is going to a wider range of users.
About 85 per cent of the solid waste collected at Ashbridges Bay got used in 2012, mostly by farmers who applied it to their southwest Ontario fields as biosolids ‘cake’ or fertilizer pellets.
That means the Ashbridges Bay plant is now putting as much biosolid material to beneficial uses as it once hauled to landfills, said Frank Quarisa, director of wastewater treatment.
“We’re now at the point where the program is well diversified and seems to be self-sustaining,” Quarisa said. “And it’s no longer the significant headache it was for us to manage in 2006.”
It was in 2006 when a Michigan company that had been landfilling 13 to 15 trucks a day of Toronto’s treated sewage decided to quit its contract because nearby residents were complaining about the smell.
That left the City of Toronto scrambling to find new outlets for the stuff which is produced every day of the year, and which totalled some 140,000 wet tonnes in 2012.
Quarisa says a lot of the plant’s current success is thanks to the diversity of its six contractors.
Last year, nearly 40 per cent of the plant’s solid waste was applied directly to farmland as biosolids cake – the most conventional use. But a slightly higher amount went out as fertilizer pellets.
Unlike the cake, which farmers can only apply in early spring and fall when their fields are empty, and which has to follow stricter handling and application rules, the dry pellets can be stored and used year-round.
“It’s a juggling act,” Quarisa said, noting that relying on the conventional cake application alone would mean periods with larger build-ups of material than the plant can store.
Along with the pellet program, which was delayed until 2008 because of a fire during the pelletizer’s construction, Ashbridges Bay has added new contractors, including companies that mix the plant’s biosolids with compost and waste from pulp and paper operations to replace topsoil at mine sites and timber plots.
Quarisa said that by adding new contractors, especially those running the pelletizer operation, the whole biosolids program at Ashbridges Bay is costing the city about $5 million less each year, even as it redirects more waste away from landfills.
In 2009, city councillors set a target to find beneficial uses for 100 per cent of the solid waste at Ashbridges.
Quarisa said that goal remains, though a recent year-long request for new biosolids users only yielded one new company. That company will take a relatively small amount in 2013, about 10,000 tonnes, but hopes to take more next year.
Ashbridges Bay is the largest wastewater treatment plant of its kind in Canada, serving about 1.5 million people.