Montreal’ to build World's largest ozonation waste water treatment centre When completed, the ozonation centre located at the J.R.-Marcotte water and sewage treatment plant in Pointe-aux-Trembles at the eastern edge of the island will have an estimated cost of $285 million and be able to purify 2.6 million cubic litres of water daily, the equivalent of two Olympic Stadiums full flushed into the St. Lawrence every 24 hours. Contrary to the current filtration technology, the ozonation system is expected to eliminate 95 per cent of bacteria, in particular E. coli bacteria produced from fecal coliform. It will also eliminate most viruses, as well as pharmacological drugs and cosmetics that have proliferated in the last 30 years, in part because Montreal is a leader in those industries. The J.R.-Marcotte plant is one of the largest in the world, treating 75 per cent of Montreal’s residential and industrial waste water and 50 per cent of Quebec’s total. The decision to use an ozonation system came in 2008 under the administration of mayor Gérald Tremblay, in collaboration with Quebec’s environmental and agricultural ministries. City officials and some environmental groups recommended the plan at the time, saying using ozone gas, a powerful cleaner, disinfectant and bleaching agent, is the most effective system to treat the city’s industry-heavy effluent, and the least disruptive ecologically. But McGill professor Ronald Gehr, speaking as a private citizen with 20 years’ experience in waste-water treatment, said ultraviolet technology is more widely used, and could prove considerably cheaper than ozonation, which has never been used on the scale proposed in Montreal. Up to 85 per cent of the costs of the plant are to be covered under grants provided by the federal and provincial governments as part of their infrastructure programs. Monday’s announcement pertained to the $99-million contract awarded to French firm Degrémont Ltée, which was the only bid deemed suitable out of two submitted after a tendering process that took four years. Degrémont’s bid was also 40 per cent higher than the city’s initial estimates, a variation the city put down to the fact it had no other projects of a similar scale to use as a benchmark when it created its cost estimates. Degrémont is responsible for building the ozonation plant that will develop the ozone gas. City officials said the risk of a hazardous leak of ozone gas was minimal because Montreal’s plant will only produce as much as is needed on a daily basis and can cut production immediately if necessary. Opposition party Projet Montréal applauded the environmental benefits, but said the fact it would only be running from May to October suggested the city and province were favouring recreational users of the St. Lawrence over the environment. City officials said they were using the shorter schedule to start while the system was tested, but intended to extend it to year-round soon after 2018.