UWO researchers magnetize algae to optimize growth, lipid yield
While scientists all over the world are hard at work employing different methods to efficiently increase growth rates and higher lipid yields in microalgae for the biofuel and pharmaceutical markets, Wankei Wan, a professor of biochemical engineering at the University of Western Ontario in London, Ontario, discovered that exposing microalgae to static magnetic fields could be another viable route for optimizing growth rate and lipid production in microalgae.
According to Wan, his research team designed and built a lab-scale raceway pond featuring a paddle wheel that gently agitated the fluid and they began growing a common species of single-celled algae called Chlorella kessleri. They then took a small side stream off the main reactor and passed it through a static magnetic field all the while measuring the growth rate and oil production of the algae. What Wan observed, which will soon be published in a forthcoming paper to be submitted in the journal Bioelectromagnetics, wasn’t short of being “an interesting phenomenon”, he said.
By exposing algae to magnetic fields, Wan and his team were able to double the growth rate and double the lipid oil production, essentially economizing the overall process by four-fold. “It’s quite a significant improvement,” Wan said.
“What’s interesting,” Wan explained, “is that the algae appear to have a memory to the magnetic exposure. The increase in growth rate actually lasted for a much longer time than the proliferation time of the algae after exposure to the magnetic field. In other words, it carried its memory for a number of generations.”
Wan added that the algae behaved differently depending on the intensity of the magnetic fields and length of exposure to them. He noticed that growth would increase steadily as field strength grew. Then, once peak growth was reached, there would be a steep decline.
“If you put too high of magnetic field intensity to the algae it actually inhibits growth,” Wan said, adding that the maximum growth rate of the algae corresponded to a magnetic field strength of 10 militeslas, which is about 1,000-fold larger than that of the Earth’s magnetic field. “There’s a certain magnetic field intensity that would enhance the biomass yield.”
In addition to increased growth rate and lipid oil quantities for biofuels production, Wan said he noticed that the magnetically charged algae also produce high quantities of antioxidants, such as Astaxanthin, which is used as a food supplement.
“If you combine the two sides, we’re not only looking at the possibility of improving the economics of biofuels production from microalgae, but we’re also producing some very important natural antioxidants that have proven health benefits,” Wan said.
Not only did Wan’s team conduct the magnetic study in an open pond configuration, but he and his team also carried out similar studies in a thin-channeled photobioreactor designed in-house, which “works just as well, if not better, as the open pond design,” he said. Results and findings from the PBR route are being written up now in a paper for the PBR design because of the use of a different species of algae called, Haematococcus, according to Wan.
While Wan's research in the are of magnetobiologics isn’t new, he admits there is literature in the scientific community that has been published in the past few years demonstrating that magnetic and electric fields can stimulate algae and cyanobacteria, such as for seed germination. “But, nobody has gone through the detail of the study in a systematic way like we have before”, he said.
As for building on the positive results carried out by the open-pond design, Wan said he’s filed a provisional patent on the novel approach to the U.S. Patent Office and is open to partnerships and funding opportunities to transition his novel approach out of the lab and prove it on a demonstration-scale—potentially a raceway pond that’s a quarter of an acre, he said.
“Right now, we’re observing an interesting phenomenon,” Wan said, “but we really don’t know the limit of this particular treatment or what the true potential is. There’s some exciting follow-up work that we have to do, not only on the engineering and technology development side, but also the scientific investigation side as well.”