The official website of the City of London300 Dufferin Avenue519-661-CITY (2489)
November 2012 aerial photo of the Greenway Wastewater Treatment Centre

City Wastewater Treatment

The City of London operates six wastewater treatment plants and 36 pumping stations.  The wastewater treatment plants are located along the Thames River.

The Wastewater Treatment Plants use:

  • Screens and settling tanks to remove solids;
  • Bacteria to consume organic material and convert ammonia to nitrates;
  • Chemicals to remove phosphorous; and,
  • Ultra-violet light to disinfect.

Material that does not pass through screens is removed and hauled to the landfill.  Suspended solids are removed in large settling tanks (primary treatment).  In secondary treatment, bacteria are grown to break down organic material in the aeration section.  To enable the bacteria to consume organic material, the aeration section provides oxygen, mixing and time .  After the aeration section, the bacteria settle to the bottom of the final clarifiers and the treated water goes to the disinfection unit. The bacteria are recycled to the aeration section to consume more organic material .  The population of bacteria in the aeration section is controlled to ensure bacteria do not die off due to lack of food.  The waste solids, bacteria and primary section settled suspended solids, are dewatered and incinerated.  The treated wastewater is disinfected using ultra-violet light (during the disinfection period) and released to the Thames River.

Interested in a tour of a Wastewater Treatment Plant for groups?

There are some restrictions for tours such as minimum age, number in a group, date and time of tours, etc.  Please contact  the wastewater treatment plant Supervisor to arrange a tour.  Phone number and e-mail are listed in the Contact US side menu on this page.

Annual Wastewater Treatment Plant Reports for 2017



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