Background

The forest–based industry is a significant industrial sector in Europe converting wood to pulp, paper, cardboard, energy, and other wood derived products. To retain and increase its competitiveness in the increasing global competition, the pulp and paper industry needs to maximize the value addition of raw materials in its fibre refining processes and to find new and profitable businesses alongside the traditional product lines.

Today, only part of the valuable wood biomass ends up in high-value applications (paper and cardboard), whilst a significant part is channelled into different “side-streams”, such as logging residues, debarking residues and pulping liquors. Bark and pulping liquor organic materials are currently incinerated and thereby converted into heat and electricity. Some side-streams are even used as land construction material. Logging residues in the form of foliage and roots are typically left in the forest partially to provide nutrients, prevent soil erosion and regulate the ecosystem. All of these side-streams contain, however, chemically appealing and reactive constituents (cellulose, hemicellulose, lignin, extractives, chemicals converted thereof in processing) that could be further refined to value-added chemicals, polymers, materials, and fuels alongside with the sustainable forestry and paper fibre production.

The utilization of the wood refining side-streams has been widely studied during the past century. The more extensive exploitation of the wood-based components has, however, not been achieved partly because of lack of efficient separation and upgrading methods and, partly because of the uncertain business potential of components and relatively low cost of comparable oil-based products. Now, along with the market challenges in the pulp and paper industry and rising oil prices, the interest towards production of chemicals, polymers, materials, and fuels from all process side-streams is raising again. The current interest towards side-stream exploitation is also supported by recent developments in tailored and efficient biomass pre-treatment and fractionation technologies, such as steam explosion, ionic liquids, and various extraction, filtration and purification methods.

Estimated amounts of the formed and exploited products (pulp and pulping liquor components) from European kraft pulping process and their current and potential applications as such and after upgrading (excluding energy)