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By Niecole Killawee

Hugh MacIntyre was having a friendly conversation with a local distiller in Nova Scotia when a lightbulb went off: what if the wastewater leftover from distilling alcohol could be diverted from waste disposal and instead be used to help grow hearty, nutritional phytoplankton?

That might not be where most people's thinking takes them after enjoying an adult beverage, but for MacIntyre — a biological oceanographer — it was an idea worth exploring.

The by-product of distillation is called distillery tails. Tails make up less than 1 per cent of all the sewage in Canada so the environmental impact of their remediation is on the lower side. Even still, there are always benefits to recycling.

Image Credit: Rory Macklin

Given how and why they're created in the first place, the tails are considered food-grade waste. That makes them the subject of great interest to MacIntyre's team. These nutrient-heavy liquids full of dissolved organic materials could be diverted from industrial waste streams and instead be used to feed and fertilize phytoplankton. Then, in theory, the microalgae could be harvested for use in products that are safe for human consumption.

"We're testing the use of food-grade waste streams and trying to scavenge useful nutrients out of them," says MacIntyre, a researcher and professor at Dalhousie University. "That would remediate them. Basically, it would clean the nutrients up out of them, so they have less of an environmental impact when they're discharged."

Phytoplankton are an incredibly high source of in-demand molecules for nutritional supplement and pharmaceutical industries: proteins, omega-3 fatty acids, and carotenoids. Extracting these from microalgae could reduce the demand for and overfishing of oily fish that contain the same high-value molecules. The problem is, cultivating the conditions for optimal phytoplankton growth in a facility isn't very economical at the moment.

With the help of a grant from the OFI seed fund, MacIntyre set out to change that with a proof-of-concept project. Now his team is in the process of publishing their papers, planning follow-up studies, and has partnered with industry and government researchers to pursue next steps.

"I don't know of any comparable levels of funding here in Canada that are as open to low-cost high-risk proposals," says MacIntyre, a professor and researcher at Dalhousie University. "These grants are extremely tolerant of blue-sky thinking."

The phytoplankton species used in MacIntyre's project are mixotrophic, meaning they acquire energy through sunlight, like all other plants, but they can also consume organic material for energy.

"The interesting thing about food waste is that it contains a lot of dissolved organic carbon," explains Macintyre. "Sugars, ketones, fatty acids, amino acids — there's all sorts of nutritious stuff in there, and many phytoplankton can grow on it."

Since the phytoplankton get their energy from these compounds, producers can actually save on the operational cost of growing in a facility because less artificial light is required. The distillate includes some of mother nature's best fertilizers too, and when those are added to the growth medium, producers can save even more while increasing their overall return-on-investment.

"It's an exercise of recycling, and the recycling subsidizes the cost of growing the phytoplankton — the energetic costs and also the cost of purchasing nitrogen and phosphorous," says Macintyre.

OFI's $13,000 grant packed a big punch. Macintyre's team now has proof-of-concept and they've been able to expand into more projects that move his original idea closer and closer to market.

"We've identified at least one organism whose growth rate we can double by adding a low percentage of distillate to the growth medium," he says. "When you're talking about an exponential [growth] process, when you double that exponent, you have an enormous change in productivity. I think the early signs are very promising."

At a commercial scale MacIntyre would target the dairy industry for this innovative remediation technique too. The process of cheesemaking produces similar by-products that require costly and highly regulated disposal.

Next steps include partnering with the National Research Council (NRC) and industrial partner Nature's Way to look specifically at food quality. Together, they'll collaborate to explore whether or not the resulting biomass of this innovative remediation technique remains a good food source filled with nutrients.

MacIntyre's undergraduate honours student Mab Speelman is also contributing to next steps. With the help of her own grant from the OFI seed fund, she plans to study the effectiveness of using UV radiation techniques to reduce bacterial contamination in the phytoplankton cultures.

"Another thing I really like about the seed fund is that it's very supportive of students. Two in my lab have been able to fund their own research. It's an opportunity to learn how it's done, from getting an idea to finding the funding for testing it. The seed grants are at an ideal scale for that and are great CV builders," says MacIntyre. "[The fund] is really high-value for my own research and for starting their careers."