Biosolids Beneficial Use Options for the Edmonton Region, Alberta

The biosolids in the Edmonton Region are produced from the City of Edmonton’s Gold Bar Wastewater Treatment Plant and the Alberta Capital Region Wastewater Treatment Plant. The population serviced by both wastewater treatment plants was estimated 1,150,000 people. The biosolids are managed in the City’s Clover Bar Lagoons. Currently, these two wastewater treatment plants generate a combined 25,000 dry tonnes (DT) of biosolids. This annual generation is expected to grow to 40,000 DT per year by 2042.Historically, the generated biosolids in the Edmonton Region are managed beneficially through the agricultural land application program, known as NutriGold, and as feedstock in composting.The City of Edmonton’s NutriGold agricultural application program was established in 1978. Biosolids from the storage lagoons at the Clover Bar Lagoons are applied to selected agricultural land operations within the Edmonton area to improve soil fertility and physical properties. The NutriGold program is expected to manage 8,000 dry DT of biosolids annually. Wet weather and wet soil conditions are big challenges for NutriGold program and can shut down the program sometimes for long periods. In addition, hauling routes and distances to application fields are also factors that influence the amount of utilized biosolids every year.Composting is an integral part of the City’s current biosolids program. The processing capacity of the current composting system is currently limited to 15,000 DT/year. The reliable market uptake for biosolids compost in the Edmonton area is 12,000-15,000 DT/year. It is estimated that the existing Clover Bar dewatering facility has an operating capacity of about 26,000 DT/year.Despite the relative success of these two biosolids management options, the City of Edmonton started investigating new options such as beneficial use of biosolids in non-agricultural lands. The City of Edmonton looked at sustainable alternative land applications (non-agricultural lands) for the biosolids. The major factors prompting the need for this assessment included:1. Uncertainty in the long-term sustainability of the NutriGold agricultural application program due to seasonal challenges.2. Concerns regarding the social and environmental impact of the existing storage lagoons as they reach to their ultimate capacity.A phased approach has been taken for the non-agricultural land applications. In Phase 1 the project land application options were evaluated to augment the current Edmonton Region Biosolids Management Program.Phase 2 involved the securing of land application projects to demonstrate the prioritized land application options which included mine reclamation, biomass production and marginal land improvement.The third phase of the project involved the implementation and evaluation of the projects.The projects have demonstrated that biosolids management using these options is environmentally protective and beneficial to the receiving soils and crops/vegetation. Research findings and data obtained from the demonstrations were provided to Alberta Environment and Sustainable Resource Development (ESRD) to support guideline updates that will facilitate enabling policies to expand biosolids management options in Alberta. Based on the success of these demonstration projects, beneficial use at non-agricultural land applications was also recommended as a primary option in the City of Edmonton’s Biosolids Long Term Strategy that was developed in 2012.Currently, the provincial regulatory biosolids guidelines are limited to biosolids applications to productive agricultural lands. All other uses require additional authorization.The City of Edmonton’s successful demonstration program has advanced Alberta’s knowledge of beneficial use opportunities for biosolids and provides compelling case studies for biosolids generators who are considering program diversification.