Identifying Applications of Wood Ash by Matching Its Characteristics with End-User Quality Requirements: A Case Study

Despite being a bio-based material, wood ash generated by pulp and paper mills is mainly landfilled in Canada. This is because it is perceived as waste material and the certification requirements and regulations controlling its use are complex. To promote wood ash utilization, ash samples from mills in British Columbia (BC), Canada were characterized, and the properties were compared to quality specifications for potential applications. Three types of ash samples were collected: bottom ash, multi-clone (MC) ash, and electrostatic precipitator (ESP) ash. The characteristics of each type of ash were analyzed, and their suitability for various applications was determined. The study found that ESP ash had a higher calcium carbonate equivalent (CCE) value than MC ash, making it more useful as a liming material in agricultural land. The study identified quality criteria for industries where wood ash can be used, such as construction, agriculture, composting, stabilization/solidification, liming, mining, and fire-retardant. Each type of ash was evaluated for its use in these industries, and the environmental regulations for each application were considered. It was observed that the quality criteria for one application could differ dramatically from those for another. Intuitively, an ash producer would cross-check the characteristics of their ash types against the quality requirements for potential uses near the ash source because different applications have different quality requirements This article is believed to help identify promising applications of ash thereby removing ash from landfilling and promoting the circular economy.