Reclaiming Mined Land, Utilizing Biosolids Waste, and Producing Biomass Feedstock
Approved for funding through ERA’s Partnership Intake Program in 2019, Sylvis demonstrated their approach to improving soil and reclaiming old coal mines, while also producing biomass for feedstock. By completion in 2023, the project demonstrated proof-of-concept of the BIOSALIX mine reclamation system by utilizing municipal biosolids and growing short-rotation coppice willows, which act as a carbon sink and source of renewable fuel – but faced challenges in demonstrating the approach at full commercial scale.
The BIOSALIX program was a mine reclamation and wood biomass production process undertaken at Westmoreland Coal Company’s Paintearth Mine and took place near Forestburg, Alberta. The program utilized municipal biosolids and other organic residuals to add to the existing topsoil at the mine, improving soil tilth, meaning the soil’s suitability for growing crops. This soil amendment enhances reclamation and leads to more productive soil, which was then used to plant short-rotation coppice (SRC) willow trees as a sustainable biomass crop to be continually harvested on the reclaimed mine land. The willow trees provide a carbon sink and produce a woody biomass that can then be used as a feedstock in clean energy, reclamation, or bioproduct development. Project partners included EPCOR Water Services Inc., Westmoreland Coal Company, Alberta Innovates, Bionera Resources, and Natural Resources Canada-Canadian Forest Service.
BIOSALIX system demonstrates feasibility, but faces environmental challenges
The project found that biosolids amendments can support positive reclamation outcomes and that TRL advancement of the BIOSALIX system is possible, but requires greater success of biosolids management and willow establishment in a mine reclamation setting at an operational scale. That was not possible with this project. The project was unable to demonstrate long-term survival of the willow plantations due to specific circumstances such as high temperatures, drier soil conditions, and insufficient resources for planting and weed management. Therefore, full-scale operational implementation of the system could not be achieved. The challenges of the establishment and survival of the SRC willows and results may or may not reflect future sites or applications of the concept – this has to be further assessed to demonstrate the technology’s commercialization potential.
Due to challenges in sustaining willow growth, meaningful greenhouse gas reductions were not achieved. However, the system proved it was possible to sequester 540 tCO2e/hectare, and the project exceeded waste utilization targets of 6,000 dry tonnes (dt) of biosolids per year. This demonstrates the potential of the system as a cost-effective and environmentally safe method for beneficial use of biosolids. The project found blending subsoil with biosolids and woodchips can reduce reclamation soil volume requirements by 29 per cent.
Sylvis’ final outcomes report contains detailed account of the lessons learned, in both SRC willow establishment and the use of biosolids in mine reclamation, and extensive project results and data, including stockpile monitoring study among others. These results provide information for successful implementation of future projects on mine sites and a regulatory pathway for similar projects.
What’s next?
Unfortunately, due to unanticipated poor willow plantation results, Sylvis must forgo the planned project operational season and will be turning over all BIOSALIX project areas to Westmoreland in 2024. As the mining company, Westmoreland is focused on broad reclamation, and it is unclear they will continue the BIOSALIX program efforts on their own. Follow-up reclamation projects at other mine sites, utilizing biosolids and organic residuals, are being developed based on the outcomes of the biosolids demonstration projects at Paintearth Mine. Planning and regulatory authorization at two mines sites in Alberta has been completed, with operational work anticipated in 2024.