Sewage sludge is a problem we all need to think about
March 2, 2012 by Ellen Moorhouse
SPECIAL TO THE STAR
Trash Talk delves into some nasty stuff occasionally, but Toronto resident Maureen Reilly has been doing just that almost daily for 15 years. Her subject: sewage and sewage sludge.
We spoke to her over a year ago and thought it timely to check back to find out what’s happening with the waste we all help generate. Indeed, just 120 kilometres northwest of Toronto, Dundalk residents are challenging plans to build a facility that will take sludge, some from Toronto, mix it with septage and industrial waste, turn it into a liquidy fertilizer product for spreading on farmers’ land.
Reilly has immersed herself in disposal issues ever since she fought (successfully) to keep industrial paper sludge off pasture surrounding her country house near Cannington. Her experience with regulatory authorities, politicians and waste haulers changed her life.
Reilly has made it her mission to cull the media for information about sewage treatment technologies, sludge controversies, industry misbehaviour and failures, scientific studies, environmental contaminants, hygiene and health issues. She sends these reports, with critical commentary, to subscribers of her Sludge Watch-l email service in a dozen countries.
She and many others believe spreading urban sewage sludge on agricultural land is a grave mistake given the contaminants and pathogens that end up in sewers because of our chemicalized and medicated lifestyles and effluents from hospitals and industry. The impacts of these substances on soils, health and ecosystems are not understood, and as Reilly says, “Of the 10 of thousands of toxic compounds that could be in sewage, the sludge is tested for less than 12.”
On the other side of the fence are other environmentalists who believe nutrients in sewage should be restored to the land. Embracing that view is a posse of companies, scientists, consultants and haulers in the waste water industry, municipalities with sludge on their hands, and some farmers, who are usually paid to take the stuff and have benefited.
So what trends are of particular concern for Reilly as we flush or pull the plug?
• Antibiotic resistance: This is a growing worry in hospitals but consider this: sewage plants, which collect both pathogens and pharmaceuticals from hospitals and homes, are a breeding ground for multi-resistant superbugs, studies have shown. Despite treatment, the bacteria can survive in sludges. “Putting sewer wastes on farms is not consistent with clean, safe food,” is Reilly’s view.
• A question of prions: Scientists are starting to explore a possible connection to Alzheimer’s disease of these misfolded proteins, already linked to mad cow disease and Creutzfeldt-Jakob in humans. Even more alarming, a recent study in mice suggests, is that Alzheimer’s could be infectious. Prions have been shown to survive in sludges after conventional sewage treatment. “We have more and more exotic diseases that would call for greater sanitation of our sewage waste,” Reilly says.
• Canada-wide policy? The Canadian Council of Ministers of the Environment, which addresses environmental issues of national scope, has produced a draft policy suggesting all sewage sludge be identified euphemistically as “biosolids” and be directed for use in agriculture or as fuel without defining any quality standards. Reilly says the document, to be completed this year, was circulated to an undisclosed list of individuals and organizations and not released for public review.
• Mining the public purse: How do you make stinky sludges acceptable? More processing — pelletizing, composting or converting to fertilizer using often troublesome technology — as well as trucking it further afield. “There’s more and more treatment required, which runs into $100 to $200 a tonne,” she says. “What we’re seeing is a stubborn persistence of the land application agenda at enormous public cost and without any public debate.”
• Deregulating sludge? As with so many other issues in Canada, federal and provincial jurisdictions overlap. “My concern in Canada is they’re moving materials into the less and less regulated area,” Reilly says. For example, if sludge is designated a fertilizer (as in the Dundalk proposal), then it comes under federal law, Reilly says, and the feds are mainly concerned with accurate nutrient designation and do not regulate land application.
So what’s Reilly’s solution? Tap sewage for energy. Europe does it. Munich is a prime example with a two-step process of methane production followed by combustion in what’s called a fluidized bed incinerator. Half the plant’s cost goes into the stack and its emission control system, Reilly says, and energy is captured for district heating.
Ironically, Peel Region operates the largest example of a fluidized bed incinerator in the world at its Lakeview Waste Water Treatment Plant. According to a 2008 report in Canadian Consulting Engineer: “After considering 11 alternative approaches to biosolids management, it was found that incineration is the most environmentally friendly and cost-effective solution, and it produces the least odours.”
Reilly would agree.