It is possible for a new tree to be grown in the area where a mature tree has been harvested, making wood an ideal natural resource for biomaterials.

Woodfibre company Sappi, is looking into ways to use the sugars (as well as lignin and organic acids) extracted from the wood during the pulping process. This includes entering into partnerships to modify extracts into higher value products for use in a wide variety of applications.

The biorefinery process for second generation hemicellulose sugars at Sappi involves recovering them from prehydrolysis liquor and separating them from the associated lignin and organic acids. There are various levels of processing and purification depending on end uses. The products Sappi is targeting include sugar alcohols such as xylitol (a low energy sugar substitute), lactic acid (used in the production of polylactic acid (PLA), a renewable plastic), glycols (the main applications are to produce PET for plastic bottles and unsaturated polyester resins and other products).

Second generation sugars are attractive because they do not compete with first generation sugars which are sourced from agricultural crops. This is extremely important because of a rapidly growing global population and worldwide pressure on agricultural resources. There is a strong, growing market demand for renewable biochemicals from non-food sources as companies intensify their search for ‘green’ products that offer enhanced sustainability and offer product value chains with a lower carbon footprint – all of which are aimed at a better quality of life for all.

In terms of sustainability, Sappi’s pulp mills have an advantage because the sugars are a co-product from an existing process and removing lignin and sugars can offer benefits in terms of pulp production efficiencies.

Sappi has commissioned the construction of a second-generation sugar extraction demonstration plant at Ngodwana Mill in Mpumalanga Province, South Africa. The demonstration plant will extract hemicellulose sugars and lignin from Sappi’s existing dissolving pulp line. The sugar platform will include beneficiation to higher value organic acids, glycols and sugar alcohols, which are used in many everyday products.