Plan to improve phosphorus removal unveiled

The Regions of York and Durham have released a study that offer ways to further improve phosphorus removal during wastewater treatment at the Duffin Creek water pollution control plant.

Phosphorus is a nutrient found in every living organism and makes up one per cent of the human body. Phosphorus, in wastewater, comes from humans, food waste, fertilizer, dishwashing and laundry detergents, household cleaners and numerous commercial and industrial products released into the sewer system. It’s also found in soils and sediments, plants and animals.

Ministry of the Environment and Climate Change officials requested the study as part of an environmental assessment to address future capacity limitations of the existing plant outfall (where a sewer or drain empties into a water body). The plant is part of the York Durham sewage system and treats wastewater from 80 per cent of the residents and businesses in York Region and all of the residents and businesses in the Town of Ajax and City of Pickering in Durham Region.

The 18-month study included a peer review by an independent expert in phosphorus removal strategies. The proposed strategy to optimize the existing secondary treatment process at the plant, to achieve lower annual or seasonal-average phosphorus concentrations, promises to maintain the plant as an environmental leader. According to a press release issued by York Region, the system reports having the lowest phosphorus discharge limits of any plant discharging to the open waters of Lake Ontario, lower than those recommended in the Canada – U.S. Great Lakes Water Quality Agreement.

Over the past 10 years, York and Durham Regions, together with the provincial and federal governments, have invested more than $850 million in new technologies, equipment, training and best practices to ensure the Duffin Creek plant continues to protect near shore water and local environment.

The Duffin Creek Plant removes, on average, up to 94 per cent of phosphorus from wastewater arriving at the plant and disinfects it before releasing clear, treated, water into the open waters of Lake Ontario. In the Great Lakes, phosphorus is a nutrient that has a great influence on the health of lake ecosystems. Invasive mussels, temperature, light sources and high phosphorus levels are just some of the factors leading to algae growth and affecting the balance of the ecosystem of the Great Lakes.

Visit for more information. The public is invited to provide comments on recommendations included in the Phosphorus Reduction Action Plan. Comments must be received by Feb. 23 and can be submitted, via email, to Kathleen O’Neill, Environmental Assessment and Permissions Branch director at [email protected]

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