It is called “human manure”, “brown gold” or “biosolid”. Municipal sewage sludge is sometimes used as fertilizer on farmland. Quebec now wants to impose a threshold to limit concentrations of some pollutants found there.
In the crosshairs of the Ministry of the Environment: perfluorinated substances, often described as “forever pollutants” or known by the English acronym PFAS. This large family of thousands of chemical compounds is ubiquitous in everyday objects such as non-stick pans, waterproof clothing, food packaging, or stain-resistant fabrics. They are distinguished by their harmful effects on health.
The Minister of the Environment, Climate Change Control, Wildlife and Parks, Benoit Charette, announced on Friday that he will launch an expert consultation to impose a “preventive threshold” to reduce the risks associated with the presence of these “emerging ‘interest’ pollutants” in sludge.
He said in a press statement: “The proposal that we present to specialists for consultation is one of the most ambitious proposals in the world.”
This threshold will determine the maximum allowable concentration of 10 per- and polyfluoroalkyl substances (PFAS) added together. This will be the first of its kind in North America.
Quebec will also measure two of the most studied compounds on the planet, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS).
Endowment
When municipal wastewater is treated in a factory, a solid substance called “sewage sludge” appears. It consists largely of organic matter that can be recycled as fertilizer in fields where plants intended for animal feed grow. Sludge can also be buried or incinerated.
Last March, the Quebec government imposed a temporary moratorium on the agricultural spread of biosolids imported from the United States. This decision was made following a report by Radio-Canada which revealed that imported sludge presented a concerning concentration of PFAS.
The moratorium does not include sludge generated by municipal water purification plants in Quebec.
“There’s a different industrial historical reality in the United States than in Canada. The United States is a PFAS-producing country, so it’s still causing some really direct industrial pollution in some states, as is known,” explained agronomist Agatha Viale, advisor to the deputy directorate in This matter, in an interview. Environment and Climate Change Combat (MELCCFP).
“Since there is no way to control whether these biosolids are contaminated in one way or another in a direct industrial way, we have suspended the use of these materials in an agricultural setting, and therefore preventively, until we can implement the necessary tools to reassure ourselves. […] We have not imposed a ban on Quebec because that date does not exist here. »
However, in Quebec, PFAS can also be detected in municipal sludge. How do they find each other there?
“We have products [où les PFAS] It is found in higher concentrations as some fire foams. So when we put out a fire, the rainwater will then end up in our sewers,” explains M.I Viale.
Another example ? Water resulting from washing clothes made from materials that contain it. “It ends up in the sewer. “When we wash our hands, there is some in the hygiene products,” she confirms. “It’s really our daily lives that we put back into the municipal sewer. »
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