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Water Today Title June 29, 2022

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Advisory of the Day



This story is brought to you in part by Organic Teas Canada

This week we covered a lot of ground, but this is the icing on the cake. Today, we look at tap water production, waste water treatment facility and the balls dropped on the way at the environment's expense.

The water Montrealer's have access to and consume everyday comes from the St-Lawrence river and is treated in seven steps before distribution:
  • Step 1 : Sieving raw water at the source to remove particles like sand, rocks and other items that could damage machinery and pumping systems.
  • Step 2 : Water pumping to first purification stage
  • Step 3 : Ozone treatment to disinfect water from most microbial and bacterial contamination
  • Step 4 : Water then goes thru a series of 96 different filters to remove sediments up to cellular level bacteria and pollutants residues
  • Step 5 : UV Ray disinfection treatment that kills any remaining organic contaminants
  • Step 6 : Chlorine treatment as preventive measure
  • Step 7 : Pumping to the city's distribution system

    As we can see it is pretty intensive and most contamination afterwards is from obsolete lead and brass piping present in the oldest parts of the city (which will all be replaced by 2026...) and in old buildings under owners responsibility

    Montreal has the third biggest waste water treatment plant in the world in the Rivière-Des-Prairies / Pointe-Aux-Trembles district located east of the island, the Jean-R. Marcotte plant. It treats all of Montreal's waste water. As of now, the purification process is both physical and chemical, but mainly dependant on a 1980's technology. First step is to remove all solids by sieving the water, compress and dry out on average 750 tons every year to be incinerated, ashes to be tested and disposed of in a landfill. Second step is removing all the sand and rocks residues in 14 giant de-sanding devices. Third step, chemicals are added to create a chemical reaction that will transform particles such as phosphate into flakes that deposit at the bottom and then are extracted, dried and incinerated, tested and sent to the landfill. The remaining water goes back to step 1 along with some new waste water. Nothing in this process removes, chemical contaminants from industrial wastes and pharmaceutical bi-products, which as of today still are rejected into the Rivière-Des-Prairie's natural waterflow

    In March 2015, Mayor Denis Coderre announced a 100 million dollars investment to upgrade the facility with an Ozone treatment system to be operational in the course of 2018. We spoke with Mr. Richard Ethier, Chief project manager of this operation. We asked Mr Ethier about the impact this new addition will make on the pharmaceutical bi-products when it becomes operational. "This ozone process will work on 3 fronts, bacterial, microbial and metabolites derived from pharmaceutical products." When asked in which proportions Mr. Ethier continued: "In terms of bacterial contaminants we're talking 99 to 99.9% will be destroyed, viral contaminants around 99%. As of emergent contaminants like anti-depressant residues and the likes on average more than 75%, hormonal bi-products (from contraceptive pills mainly) around 85% and most anti-biotics around 90%." This is a very big step up for the environment, plagued in recent yearswith wildlife disturbances at the genetic and reproductive level.

    One last very important detail remains; on the way to the plant, waste water goes thru a system designed more than 100 years ago, that was until 1980 going to collectors which threw waste water straight to the island's surrounding water flows. Since 1980, the collectors have been fitted with interceptors equipped with overflow systems. In dry times, everything is fine and dandy. The problems arise when rain and spring snow melting activates the overflows... In an October 10th interview broadcasted live on CBC's RDI news network, Mr Raymond Desjardins Engineer and Professor of Civil Engineering at Ecole Polytechnique de Montreal explained that when the overflow systems were activated "The interceptors are very big, between 4 to 5 meters in diameter, so when the overflow is activated and goes straight to waterflow there is a very big volume involved."

    Let's hope the 2018 upgrade will pay off on the environment level, but the overflow systems of more than 160 points on the island are the weakest link that would need improvement along with stricter municipal laws concerning industrial waste water obligations.

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