Perspectives for utilization of green liquor dregs: Considerations for future studies

The utilization of industrial residues is a growing area of global research interest, as environmental concerns, such as overconsumption of natural resources, have increased, and the adoption of circular economy models is becoming more popular. At least partly due to these developments, many different types of industrial waste have been successfully converted into resources, although vast amounts of waste still end up in landfills. This Timely Advances perspective article focuses on green liquor dregs (GLD), a residue from pulp mills, which has a low degree of utilization. GLD originates from the chemical recovery cycle of a kraft pulp mill and is mainly landfilled as waste. Its chemical and physical properties vary significantly, making it a difficult material for utilization. The key factors affecting the composition of GLD arises from the chemical recovery cycle and especially from the separation method of the dregs from the liquid. In this perspective letter, explanation of the formation and processing routes of GLD and their impacts on the properties of GLD will be given. Since these processes, including the separation method, have a clear impact on the composition, they also influence the utilization possibilities. This letter provides a focused summary of utilization considerations and suggestions for future research directions for academia and industry.