August 24, 2007

Innovation

Canadian Biosolids Partnership seeks end solutions

End products need better result than disposal facilities

PETER KENTER

correspondent

OTTAWA

Mention biosolids filtered from wastewater in any social situation and you’re likely to be greeted with silence. Who wants to talk about—you know what?

Duncan Ellison, executive director of the Canadian Water and Wastewater Association (CWWA), says biosolids have an undeservedly bad reputation.

“Biosolids is the term we use for processed sewage sludge,” says Ellison. “But the largest component of biosolids is not human waste—it’s the cellulose fibres from toilet paper that don’t decompose. What do you do with this stuff?

“The 49 Canadian municipalities surveyed in 2001 continue to generate more than 550,000 tonnes of biosolids annually. You can’t discharge it into a lake or river. Traditionally, this sludge is considered something you pay to get rid of in landfill.”

The CWWA is one of the proponents of the establishment of the Canadian Biosolids Partnership (CBP), a consortium of federal, provincial and municipal governments, researchers and associations working together to help improve the image of biosolids, often mischaracterized as malodorous and laden with pathogens.

“In the treatment process, the material is de-watered and lime is added to generate heat within the biosolids, which kills the pathogens,” says Ellison. “Currently, pathogen-free biosolids can be used for any application including fertilizer for food crops.”

While biosolids make excellent fertilizer, Ellison believes they can be used to greater economic advantage.

MALMBERG PHOTO

Above, a Swedish bus fueled in part by gas derived from wastewater biosolids.

Below, the Henriksdal Wastewater Treatment Plant refines gas from biosolids to help fuel public transit vehicles in Stockholm.

“On one hand, the regulators are asking for improved technologies to produce cleaner wastewater effluents and biosolids,” says Ellison.

“But on the other hand, the final product continues to be treated as something to be disposed of at a cost to the municipality.”

The Partnership isn’t advocating a particular strategy, but wants to open a dialogue to create scientifically defensible, and economically viable uses for biosolids.

Currently, a patchwork of regulations prevents biosolids from being used to their best advantage across jurisdictions.

The CBP wants to work with regulators to provide a level playing field for economic development at a national level.

“Some Canadian cities are already de-watering the sludge and incinerating biosolids to capture the energy in the cellulose, which generates steam used in the wastewater treatment plant itself, or is converted to electrical energy for pumps and lighting systems” says Ellison.

“In some countries, biosolids are processed to generate methane gas used as a source of heat or lighting in remote villages.”

Some European countries are also using biosolids to produce ethanol used as fuel by public transit system buses.

In new developments, such as Sweden’s Hammersby Sjostad—a Stockholm brownfield development, the wastewater system is designed to collect biosolids to produce gas for home heating.

Currently, the Partnership is working to create a database and reference library of legislation, guidelines and best practices regarding the use of biosolids and to establish a research fund.

Ellison says the CBP would like to see a number of pilot projects initiated to test various options for biosolids use in Canada, including the construction of an ethanol plant at an existing wastewater treatment facility.

“You have to look at an area that produces enough biosolids to make the production of ethanol economically feasible—perhaps a city the size of London, or the Region of Waterloo,” he says.

“Why tell farmers to grow corn to produce ethanol when we already have a ready source?”

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