Cast-off cedar logs used for more than just heating at UBC

July 26, 2016

On her regular runs through Pacific Spirit Regional Park, Dr. Heather Trajano doesn’t just see the trees: she sees a wealth of compounds contained in every branch. One tree in particular has caught her eye lately. It’s western red cedar, a tree that’s emblematic of British Columbia. Used extensively by Aboriginal people for millennia, the tree is today a cornerstone of BC’s forestry industry.

In normal forestry activities, valuable tree extractives go to waste, either burned with the wood, turned to pulp, or otherwise lost. Under the Peter Wall Institute for Advanced Studies’ research mentorship program, Dr. Trajano, UBC Assistant Professor in the Department of Chemical and Biological Engineering, is working on a process to capture at least some of these chemicals along the way without disrupting the usefulness of waste wood for energy generation.

Heather Trajano, UBC Professor of Chemical and Biological Engineering, used her Peter Wall Research Mentorship award to extract valuable chemical compounds from western red cedar for a wide range of antimicrobial and anti-fungal uses.

β-thujaplicin is one such chemical. It’s what makes cedar decks naturally resistant to rot, but it has uses outside of the wood as well. Because of its antimicrobial properties the chemical can be found in food and cosmetics as a preservative, and its anti-cancer properties are being investigated as well.

“The thing that’s exciting about β-thujaplicin is the range of uses that are available. It serves as an anti-fungal aid; it serves as an antibacterial compound,” says Dr. Trajano.

Cast-off wood from western red cedar logging is already being put to good use on the UBC campus in a gasifier that produces 5 MW of electricity along with heat for campus buildings. Trajano proposes to intercept the wood before it enters the gasifier, extracting the β-thujaplicin without losing the heating value of the wood. She would do this by adding superheated water to the wood, which would dissolve the β-thujaplicin and other water-soluble extractives in a highly impure solution. Then the real work begins.

“Isolating the β-thujaplicin from the other extractives is the challenge,” says Dr. Trajano.

But she has some ideas for how to achieve that, too. Industrial chromatography, an expensive process used in pharmaceutical production that involves running the solution over a bed of particles tailored to attract only the preferred chemical, can purify the compound. She says the whole process will keep the wood intact for gasification while still extracting the chemicals, which can then be put to work in all manner of products.

β-thujaplicin isn’t the only product Dr. Trajano is looking to rescue from the woodpile. Tree sugars can be converted into fuel for transportation, but converting cellulose into fuel would impact the province’s supply of pulp.

“We produce some of the strongest pulp in the world,” she says. Another family of sugars, hemicellulose, may be able to take the place of cellulose in creating a so-called drop-in fuel or a fuel that can be used for gasoline-like functions. So the question is, according to Dr. Trajano, “How can we extract the hemicellulose without damaging the cellulose?”

The Peter Wall Institute’s funding has given Dr. Trajano a “jumping-off point” to pursue her studies and she has leveraged this to raise additional funds for her research. Her work has taken her all around the province, visiting mills and forestry sites to understand the industry.

“Given that western red cedar is an endemic species to BC, it was a nice fit to be able to make that my first tree to work on in BC,” says Trajano. “I’m at UBC, and I’m working on something for BC.”