The City of Toronto announced its recommended method for disinfecting wastewater at the Ashbridges Bay Treatment Plant (ABTP).
Instead of using bulk compressed chlorine gas delivered to the plant in a rail car, the ABTP will use liquid chlorine accompanied by a de-chlorination process required under new federal regulations to treat future effluent - the final stage of wastewater treatment - from the central and eastern parts of the city.In technical terms, the city wants to use chlorination with sodium hypochlorite and dechlorination with sodium bisulphate for all effluent.While both methods are cost efficient and effective in treating effluent, Frank Quarisa, the city's director of wastewater, said the new recommended method is more socially responsible as liquid chlorine can be easily brought onto the site. The reasons behind the choice is because it provides the most effective disinfection, has the lowest greenhouse gas emissions and energy use, and costs the least.The city made its decision by keeping in mind the importance of minimizing the recommended method's economic, social and environmental impacts. Some of the main goals of the decision-making process were to protect water quality, minimize greenhouse gas generation, protect public health, protect the health of staff members at the ABTP, and minimize cost.Quarisa said the process, part of a larger citywide environmental assessment (EA) of Toronto's water treatment facilities, has been underway for about a year now.The study, carried out following the requirements to Schedule 'B' projects under the Municipal Class EA, is a subcomponent of an overall plan to improve water quality, support a healthy aquatic environment for fish and wildlife, and maintain and improve the Blue Flag status of Toronto beaches.A comprehensive project file has now been filed with the province's Ministry of the Environment.Members of the public have until March 26 to review and comment on the study, which is available at the Urban Affairs Library, Metro Hall, 55 John St. and at the Beaches Library, 2161 Queen St. E. Visit toronto.ca/ashbridges_bay to view the project file online or for more information.Anyone with outstanding issues pertaining to the recommended method can contact Mike Logan of the City's Public Consultation Unit at mlogan@toronto.ca or 416-338-2400.People are also welcome to send in a written request to Ontario's Ministry of the Environment to elevate the project status to an Individual Environmental Assessment. A copy of the request must also be sent to the City of Toronto before March 26.