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2001 Wastewater — Co-winner 2

City of Windsor, Ontario

Turning biosolids into a marketable fertilizer

Population: 200,000

The City of Windsor has resolved serious environmental problems and improved quality of life in its community by opting out of traditional solid waste disposal methods and adopting a pioneering biosolids disposal process. In a public-private partnership, the city has contracted American Water Works Company, Inc. to take biosolids (sewage sludge) from Windsor's two sewage treatment plants and convert the material into marketable fertilizer pellets. The process allows for the beneficial reuse of biosolids, reduces odours and cuts down on the city's handling of these materials. The build, own, operate, transfer (BOOT) partnership stipulates that ownership of American Water Works' processing plant will transfer to Windsor after 20 years.


From mid-1980 to June 1999, Windsor disposed of its biosolids by stabilizing the substance with lime — a process that kills bacteria — and then applying it to area farms as a soil enhancer. Although the practice worked, it was problematic: contracts for land application were short term with fluctuating costs, odour problems plagued the open-air lime stabilization process and residents objected to the release of lime dust and ammonia. (Both can be extreme irritants to the eyes.)

City staff recognized the need to find a solution that would provide an effective biosolids treatment system and allow the city to be a good neighbour. Furthermore, the land being used for lime stabilization had been slated for future expansion of Windsor's water reclamation plant. The city wanted a biosolids treatment solution that would use less space.


Windsor's partnership with American Water Works has led to:

  • a substantial reduction in odours that, under the old treatment system, had plagued the lime stabilization process;
  • the elimination of stockpiles of material at the city's treatment plant, which frees up land for the future expansion of the water reclamation plant;
  • a 20-year contract with secure rates, which has shielded Windsor from the fluctuation in pricing structures inherent in the old system;
  • the production of a more marketable product. The lime stabilization process destroyed much of the nitrogen content of the city's biosolids. Nitrogen content, which is a key component of organic fertilizers, is protected under the new process;
  • a substantial reduction in materials handling. It is less cumbersome to transport dried pellets to area farms than it is to transport lime-stabilized biosolids. This will lead to a decrease in greenhouse gas emissions; and the creation of 12 maintenance jobs in Windsor. American Water Works hired unemployed or underemployed people.

Lessons Learned

  • Interdepartmental co-operation and collaboration were essential to the success of such a large project; it was critical to draw on expertise from various city departments.
  • The city's decision to include the community living close to the project site in all stages of planning was invaluable to the credibility of the process. Local environmental groups and other respected citizen representatives were involved in the entire process. They visited sites where applicants had facilities and were instrumental in analysing the proposals the city received. Local residents trusted the process in large part because Windsor involved the community.
  • This project marked the first time that this leading edge biosolids processing system was used on biosolids from two treatment plants simultaneously. The two plants used different processes and, therefore, different chemicals, which led to serious problems. The chemical mix resulted in a fire at the facility during the commissioning phase. The problem was resolved when the partners made changes to their respective processes.
Page Updated: 21/12/2015