Recovery of pulp waste strengthens paper products

Heather Trajano and Rodger Beatson

Heather Trajano and Rodger Beatson

In August 2012 Assistant Professor Heather Trajano joined UBC’s Department of Chemical and Biological Engineering and joins the Pulp and Paper Centre (PPC) as a faculty associate. Her research focuses on finding ways to enable chemical and fuel production from biomass in order to meet the growing demand for energy, reduce greenhouse gas emissions, and add value to products from British Columbia’s forest industry.

“Biomass, such as forestry and agricultural residues, contain a wealth of building blocks for the production of renewable fuels and chemicals but recovering these building blocks is challenging,” says Trajano. “It is critical to find ways to integrate these new bio-refining technologies with established pulping processes.”

It was only natural for Trajano to team up with PPC Faculty Associate Rodger Beatson, PhD, a pulp expert from the British Columbia Institute of Technology (BCIT) who has extensive expertise with pulp modification and fibre properties.

“In 2011, the Canfor Pulp University Grants Program was announced. This unique investment was conceived as an opportunity to encourage the wealth of academic talent to develop innovative manufacturing and products from our forest resource,” said Brett Robinson, President of Canfor Pulp Products Inc. at the August 28th award ceremony held at the PPC. Thanks to a grant of $75K over three years from the Program, Beatson and Trajano will examine the recovery of hemicellulose monomers and oligomers from pulp mill waste streams for use as strength additives for pulp. If successful, this will be a low cost, sustainable way of enhancing the strength and adding value to Canfor’s pulps. This market pulp is sold around the world to strengthen paper products, mainly printing and hygiene grades.

Much of the world-wide bio-refining work to date has heavily focused on hardwoods due to their advantages in terms of growth and plantation style. Trajano and Beatson’s unique focus will be on extraction of hemicellulose from softwoods, which have distinct lignin structure and a distinct hemicellulose structure relative to hardwoods. Almost all of British Columbia’s forest is softwood and is much more relevant to companies here.

Data shows that the addition of hemicellulose sugars back into the pulp improves the tensile strength of the pulp and also helps to reduce and limit the extent of hornification. As a result, more strength can be regained when pulp is rehydrated from the dry state in which it is sold. There are already multiple sources of “waste” solid materials readily available at pulp mills, including for example the bark and the trimmings, and both contain hemicellulose. “Typically they are used as a burner fuel, but there is a possibility that we can derive additional value by doing an extraction first to recover some of the hemicellulose monomers and oligomers from these solid residues” says Trajano. This ensures that more value is derived from waste and forest resources.

The team will examine the amount of hemicellulose monomers and oligomers needed to improve pulp properties, and how to best recover the hemicellulose monomers and oligomers from residues without compromising the heating value of the solid residues.

“Depending on the method of hemicellulose extraction, a wide range of hemicellulose polymers may be obtained, giving ample opportunity to discover those that demonstrate the desired properties,” says Beatson. The initial groundwork will be conducted on site at BCIT’s pulping and papermaking facilities and will give BCIT students studying for their diplomas in chemical process technologies a chance to work on the innovative project. The solid residue extraction portion of the research will be conducted in Trajano’s lab at the PPC.

The research will “assist Canfor in deriving value from waste streams in its three pulp mills in Prince George” says Mr. Robinson. The stretch goal of the project is optimizing pulp performance by fine-tuning the process of how hemicellulose monomers and oligomers are absorbed and how they improve pulp properties. If the research team can increase the quality and strength of B.C.’s pulp, it can ultimately lead to more jobs at mills throughout the province, and strengthen the competitive position of Canfor in the world market pulp business.

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